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Expert
 
Location: Cottage Grove, OR | The following is part of a post I made in another thread, but I would like to have a discussion about the concept of moving the radiator up to and under the front so I have started another thread. I won't be doing this for some time so we have lots of time to talk about it. "My other "someday" change that I want to do is eliminate the rear radiator. When I converted to the Allison 545, it shifted the engine rearwards about 2 inches. I noticed a slight increase in rear end wiggle. By eliminating the rear radiator, some weight would shift forward and the engine area would be much more accessable. The cooling would be done by one or two smaller horizontal flow radiators laid down at about a 15 degree angle under the front (no exterior changes). They would get clean ram air when traveling and would have electric fans to suppliment at slow speeds or under severe conditions such as climbing a grade. My auto AC condensers are there now. It could become a stacked system as is used on most vehicles. It could use dual staged fans like my Subaru Brat uses.
"That is the system that was used in the Vixen21 SE that I had for a couple of years. It runs a Buick Century transverse V6 engine and transaxel in the rear and the radiator is under the front as I described. It uses an electric water pump to ensure adequate coolant flow at all engine speeds. The system worked quite well, but the coach at 21 feet was too small for me. Think 75% of FMC length, width and height and you would about have it. Same basic floor plan. My primary reasons for wanting to move the radiator are: 1. Open up access to the engine compartment. 2. Reduce fan size and/or blade numbers to reduce sound level and belt load. I would retain a fan (mechanical or electrical) for engine compartment ventilation and heat removal. 3. Increase cooling system efficency. 4. Transfer a little weight forward to allow for other things/additions (a real toolbox, air tank, etc.) in the engine compartment and still retain coach balance. Note that my primary reasons are number one and number two. The others are supplimental reasons. The interesting thing is that the option exists for retaining the current water pump (with supplimental electric pump boost to the front) with a reduced fan capacity with it's belts or to completely replace the mechanical pump with an electric one. This would open up the possibility of eliminating that pair of belts completely along with the idler/tensioner (see the other thread to see what Barney has done). If an air dam (I have thoughts about this as well) is added under the middle of the coach, air can be directed/channelled up to the top of the engine compartment for good air exchange while driving. I currently have crossflow fans for when stopped. Being an economist rather than an engineer, my challenge is to figure out the correct sizing of the required front radiator or I could just do a "as big a one as will fit" installation. It could be possible to do a temporary installation (leaving the existing radiator in place) to test the theory and then if all goes well do a proper permanent installation. I welcome everyone's comments both pro and con. I have been told I am crazy before! Perhaps we will come up with a very well designed plan so that I will no longer be able to procrastinate. If you have an FMC, be sure to register on this site so that you too can comment. Thank you for your input, | |
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Contributor
Location: Webster, Wisconsin | Stephen,
Interesting idea. While I haven't got #426 on the road - still going through systems as time & $ allow, I've fooled around in the engine compartment enough to see how hot it get back there. Front radiators would make sense. Next time I work on the old gal I'm going to start looking at this possibility.
Can you provide the link to the "other" thread so I can read about Barney? Thanks. | |
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Veteran
Location: Illinois |
The principal reason, I would not move the radiator to the front is the 30 foot of supply and 30 foot of return piping which would give the opportunities for distress at some point in the future.
The removal of the radiator would be good for service BUT THAT BONUS would be MORE than offset by the increase potential for physical calamity.
There is no need for increased cooling if the FMC engine is setup correctly as the original 4 tube radiator will cool even the HOTTEST ENGINE on the HOTTEST DAY.
Witness when I had the 375 HP I440 with Allison Transmission in my coach, I was in the SOUTHWEST on several occasions where the ambient temperature was 110 to 135 degrees Farenheit. AT highway speed the max. temperature I saw in the coolant was 210 to 215 DEGREES FARENHEIT.
THE REAR RADIATOR WHEN SETUP PROPERLY EXHAUSTS WELL INTO THE VOID AT THE REAR OF THE COACH.
HAPPY TRAILS - Leslie Hoagland
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Veteran
Location: Kingsley Michigan | Yes, I of course do have some thoughts, alot of which are good and some you could probably do without--
The front end radiator is a good idea for a lot of reasons as you have pointed out.The biggest ones being removing the weight from the rear of the coach and putting it upfront! We did this with the spare tire which hung on a very heavy swing bracket off of the rear bumper. Now, the heavy bracket and tire are off of the donkey and just the tire is in the area where the old auto air condensers were under the front behind the front bumper. This moved an exponentially overhung load off of the rear and added some weight to the front with the handling improving greatly- less donkey wiggle with less nose bounce/wave. All of this dribble says yes to releaving rear end weight and adding more to the front. After talking to Les about this modification---he stated that an extra 900 pounds was really needed to "balance" the coach. If this is anywhere near true---any and all weight reduction to the rear and upper part of the coach with adding any of the "excess" to the lower front, can only lead to a more sportscar type handling of the road.
There is another great benefit with removing the fan from the water pump. All that heavy weight and torque working on the bearings of the hard to get and expensive water pump makes little sense in todays world of electric fans.
As far as the alternator is concerned--I would rather see you put an Idler on the auto airconditioning as that is not crucial to the operation of the machine and if the idler wanted to and is likly to do --fail--you could keep on going by removing the belts--This is in sharp contrast to the alternator/water pump relationship to you survivng the road! Once the alternator has been lowered and brought forward to match up with the pump and crankshaft, it acts like an idler/tensioner with hopefully a more reliable future.
If you would like--I will send you my old tensioner pulley and arm for your project or spare.
As always--stay healthy and keep in touch; Barney | |
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Contributor
| The weight issue would be the only reason to move the rad to the front. I have been operating mine in the Phoenix area and it doesn't matter how high the temp gets it does not over heat. Of course it would let the engine comartment run a lot cooler. It all comes down to I think it is cost prohibative for the bennies recived. If you want to spend a lot of money then insall a diesel, it would increase the fuel econ and they like to run hot.
Steve, #622 Phoenix | |
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Expert
Location: Cottage Grove, OR | AAAAKKKKK! I did this long, thoughtful response and then I hit the wrong button and it all disappeared! I'll try again tomorrow as it is late. | |
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Veteran
Location: Illinois | AGAIN, the ultimate solution for fore/aft weight discrepancy is to properly install and setup MCR's CUSTOM Hollow Rubber Spring and brackets to the REAR SUSPENSION.
This allows the FRONT and REAR SUSPENSIONS to work together for a BETTER RIDE and DRIVE and the weight discrepancy disappears.
The package for the parts is $271.36 .
HAPPY TRAILS - Leslie Hoagland | |
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Expert
Location: Cottage Grove, OR | Ok, I will attempt to respond to some of the comments and let's see where it goes.
Edited by BigRabbitMan 2006-12-03 11:47 PM
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Expert
Location: Cottage Grove, OR | Ok, I will attempt to respond to some of the comments and let's see where it goes.
"The removal of the radiator would be good for service BUT THAT BONUS would be MORE than offset by the increase potential for physical calamity."
This is a valid concern, but my feelings are that the degree of increased risk can be very low provided that the installation is well designed and properly installed. The long runs for the coolant would have to consider the exposure issue, but with proper design and instalation it could be handled. Expansion and contraction of the line would have to be allowed for in the design. Long runs for electricity are also more subject to failure and damage than short runs, but proper design and installation makes it reliable.
"There is no need for increased cooling if the FMC engine is setup correctly as the original 4 tube radiator will cool even the HOTTEST ENGINE on the HOTTEST DAY."
I agree, but I didn't say that I was looking for increased cooling. I am looking for ease of engine access, reduced sound level and increased cooling efficiency (not capacity) in that order. Additional cooling capacity would be nice, but is not the object of the suggested change.
"THE REAR RADIATOR WHEN SETUP PROPERLY EXHAUSTS WELL INTO THE VOID AT THE REAR OF THE COACH."
True, but it uses a large fan that generates a significant amount of sound and uses a significant amount of power. How much I don't know, but I wouldn't be suprised if it wasn't on the order of 15 hp. Sound level was my second priority and efficiency my third.
"We did this with the spare tire which hung on a very heavy swing bracket off of the rear bumper. Now, the heavy bracket and tire are off of the donkey and just the tire is in the area where the old auto air condensers were under the front behind the front bumper."
Interesting! Last spring I was working around the swing out spare and asked myself why? I have Coach Net roadside assistance service so I took the spare off and put it in the garage. I will put it back for Alaska or for Mexico, but in the USA I will use the cell phone. I keep good tires on the coach and may have to buy a tire at a high price, but the odds are against it.
"There is another great benefit with removing the fan from the water pump. All that heavy weight and torque working on the bearings of the hard to get and expensive water pump makes little sense in todays world of electric fans."
It's starting to make more sense all the time. The fan belt has to be quite tight to ensure it doesn't slip. Why? I think it is for basically two reasons: the first is that it is turning a large fan so it has to transfer significant horse power and the second is that the belt arrangement is such that the belts only are in the pulley groove for one fourth of the pulley. Compare that to the alternator where the belts are in the groove for a much larger portion of the pulley's circle. Take away the high power requirement and the belts won't need to be so tight and this will reduce the load on the bearings and the belts.
"As far as the alternator is concerned--I would rather see you put an Idler on the auto airconditioning as that is not crucial to the operation of the machine and if the idler wanted to and is likly to do --fail--you could keep on going by removing the belts--This is in sharp contrast to the alternator/water pump relationship to you survivng the road! Once the alternator has been lowered and brought forward to match up with the pump and crankshaft, it acts like an idler/tensioner with hopefully a more reliable future."
Bringing the alternator down in the suggested manner is a very intriguing suggestion. It would allow me to install the 160 amp truck alternator that I have setting on a shelf in the garage. It won't fit in the normal alternator position. Being only dependent on one set of belts instead of two is also very attractive. Barney has done this conversion to his own coach so we know it works. Lowering the alternator also would improve access to the top of the engine which is one of the prime goals.
"The weight issue would be the only reason to move the rad to the front."
It was my fourth reason and not sufficient by itself to justify making the change. Taking the spare off was cheap and probably has as much effect on weight distribution. In fact, I would probably replace part or all of the transferred weight with other things e.g. convienient tool storage, a compressed air tank, etc., etc..
"It all comes down to I think it is cost prohibative for the bennies received. If you want to spend a lot of money then install a diesel, it would increase the fuel econ and they like to run hot."
Cost benefit analysis is always very difficult when evaluating subjective benefits. Some people feel a paint job is worth the money while others would just polish and touch up as needed. The engine access, reduced sound and increased cooling efficiency are important to me and I don't think it would cost that much. It would be much, much, much less costly than a diesel conversion and my concerns would all still be there. Possibly to a greater degree.
"AGAIN, the ultimate solution for fore/aft weight discrepancy is to properly install and setup MCR's CUSTOM Hollow Rubber Spring and brackets to the REAR SUSPENSION."
Again, fore/aft weight distribution is NOT the reason for this possible modificaion. It would be an "also ran" as a benefit and might be counteracted by putting other useful things in the engine compartment.
Ok, now are you ready for an ALTERNATE PLAN?
As I have typed this, I have thought of a modified plan. Just move the majority (70-80) of the cooling capacity to the front keeping a small, low crossflow radiator in the rear. It would sit low and be 18-20 inches high and a little wider than the existing radiator. There would still be a rear radiator, but engine access would also be good. Especially if the alternator is lowered and shifted as described above. The small radiator would use electric fans for air flow only when needed. This change would reduce the size of the front radiator as it would only have to handle normal cooling needs primarily using ram air, but not all of the high demand cooling needs. Under normal operation the front radiator would provide all the cooling necessary. The electric fans on the rear radiator would only come on if high (200-210+ temps were experienced. It would also provide a safety net radiator in the event a problem did develop with the prime system in the front. A cross over and shut off valves would allow the front system to be isolated and only the rear one would be used in an emergency. Believe me, it doesn't take much cooling capacity to be able to get to civilization at 25-30 mph. I just did it a few weeks ago when the impeller on my water pump came loose on the shaft and became effectively inoperable.
Any additional thoughts? | |
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Veteran
Location: Illinois |
The move of the RADIATOR to the front allows you the considerable opportunity to loss an ENGINE.
My POINT on the Radiator move is that if the FMC is setup properly one does not
need to change the radiator. WITNESS my FMC Coach went 250,000 miles with the gas engine and once setup properly had no heating, engine belt, or idler issues.
By claycoring the bedroom and engine compartment interior, you do not hear the fan. In fact my diesel installation with a larger fan - I hear neither the engine, driveline, or fan.
Again, I would not think of using ELECTRIC FANS since they can fail mechanically or electrically. AT road speed, one has 90 seconds to identify the problem and shut down the engine; otherwise, you have lost the engine.I changed my water pump at 150,000 miles just because of the time factor. I could detect no slop in the bearings BUT My FMC had engine service at 60 day intervals.
Bringing the ALTERNATOR down and acting as the adjustment for the WATER PUMP should result in low mileage replacement of the ALTERNATOR which is considerably more expensive than the water pump. The bearings of the alternator, I believe, would not stand the added strain of driving the WATER PUMP and FAN.
The ultimate choice is to make the cost of maintance a minimum - BUT ONE must do the maintenance on a proper time/mileage base so that your HOLIDAY is not RUINED.
ALSO, keep in mind my suggestions are based on THIRTY YEARS EXPERIENCE with the FMC COACH with some 900,000 miles of operation. We have seen many changes to the coach with a majority an outright conceptual failure.
MERRY CHRSTMAS - Leslie Hoagland | |
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Veteran
Location: Kingsley Michigan | You might find this odd that I have some to add to this whole mess-----First, the alternator bearings are made for high speed and load that they require to create the output of amperage. Second, the direction of rotation of the motor dictates that the water pump and fan are the first in line to use the power off of the belts and then comes the alternator, which results in no added "strain" on the alternator. Third, this is a 2 belt setup which, in the power transmission world, means that each belt is only supporting half of the load--i.e.--if you had a 82 amp alternator running on one belt (which was common in the old V belt days), then you could support a 164 amp with 2 belts. In other words--there is little need for high tensions and worries surrounding the bearings of the alternator using only a 130 amp one. Fourth, electric fans are just as reliable as if not more so than the water pump design as exhibited by their everyday use in millions of cars and trucks today. Fifth, there are added benefits to using the electric fans. You would use multiples of them and stage their "on" cycles as needed This would increase controlabilty, reliability and even acceptability of a partial failure while reducing the constant load like the water pump design and the sigularity of it. Sixth, placment of multiple electrics dictate behind the radiator pulling the air thru the radiator (outside of the engine compartment) like on our cars. This lends to less trapped noise and need for the big shroud inside of the engine compartment giving one great amounts of room- say an extra 8 inches or better running from the top to bottom. Seventh, with the simple addition of an "work override" switch, one could do work in the hot engine compartment--leaving some or all of the fans on , pulling heat out the back and drawing in cool air where you would have to work. Eighth, all of this would lead to greater reliability, reduced weight and need for service in a very cramped and hard to access area--a constant gripe of service people about design engineers---that they never had to work on one----
This might be the total answer for not needing the extra radiator in the front! Just to help your thinking in this area, at least one of our members who installed a diesel in their coach ran out of engine room so they mounted their radiator sideways--where our engine room side intakes are and used electrics to pull the air thru it. Wayne Jacoby even went as far as to hinge the right rear radiator panel to make it more accessable and easier to clean. That being where the fans would be--service and cleaning, if they needed it, would be a snap. By the way--some of the fans are 2 speed adding greater latitude to temperature control. I did some checking on Ebay and found brand new Procomp 14" electric fans for $20 each with a rated 2000 CFM @10amps. If you were really worried---and silly--4 of these would fit the rear area of the radiator but small children or for that matter ---anyone--couldn't or shouldn't stand behind the coach. Mass transit busses all use this setup for the very reason of speed and ease of accessability to the motor.
Hope all of this is of some use---Merry Christmas to one and all--!!!!!!!! Barney
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Veteran
Location: Illinois |
The use of electric fans is viable, no doubt, BUT - again - should one risk a many thousand dollar engine installation to electric fans that would be operating in a HIGH LOAD operation.
The added load on the alternator bearings would only be negligible if one would be went to the extreme and eliminated the fan.
The noise of the fan and engine is truly negated by the claycoring of the bedroom/engine compartment as previously described.
In fact, we at MCR give the Diesel Conversion owners the option of NO MUFFLER.
I have ran my coach for 11 years and 160,000 miles with NO MUFFLER and we do not hear extraneous noises while driving down the road at 60 to 80 MPH.
In fact, KAREN said to me back then that this installation is quieter than the gas engine. BUT she did not know about the CLAYCORE until then.
An electric fan w/ 2800 CFM works well to minimize the ambiant temperature of the engine compartment. On many of the engine compartment fan installations that we have done at MCR - we have included both manual overide and a thermostat circuit. This thermostat circuit allows the fan to continue on after coach is stopped.
I started with fans in the engine compartment over 30 years ago to remove the heat soak which would penetrate the bedroom area of the coach.
But in the FINAL ANALYSIS, if said improvement functions well and lasts over many years and miles - then ONE can CONCLUDE the PROJECT was WORTHWHILE.
MERRY CHRISTMAS to ALL - Leslie Hoagland | |
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Expert
Location: Cottage Grove, OR | In a private email I was asked to comment on using electric fans with the existing radiator. My response covers some of the same points covered by Barney above, but I have reproduced my response below. Hopefully it helps with the thought processes!
"I earlier thought about replacing the belt driven fan with an electric fan without changing other aspects such as radiator size and location. Under this scenario the belt driven fan would be removed and 1-4 electric fans would be installed. The following are various things to consider in such a conversion in addition to or as described by Barney Martin in the thread at www.FMCOwners.com .
Fan type: push fan or pull fan?
While I can not document it, it is my understanding that generally pull type fans are more efficient in moving air than push type fans. This would be a reason to switch to an electric fan on the outside of the radiator.
Power used: belt vs electric.
It is more efficient to use the mechanical fan IF ALL OTHER THINGS ARE EQUAL as the only power loss is the friction within the belt and pulley whereas with electric the mechanical power is converted to electricity and then the electricity is converted back to mechanical power with the attendant conversion losses. The challenge becomes determining what “other things” are NOT equal and how they balance out when they are all considered in their various combinations and permutations.
Things that are NOT EQUAL:
Pulling air is more efficient and uses less power to move the same amount of air.
By having multiple (2-4) electric fans the system can be temperature staged to only move the amount of air needed to cool the engine rather than being configured to move the maximum amount of air needed all of the time. This would reduce the power needed for cooling until approaching maximum cooling needs when the actual power used (due to conversion losses) would exceed the current system UNLESS the greater efficiency of the pulling fans actually reduced total power needed (the increased efficiency of the pulling fans exceeded the conversion losses).
With the current fan shroud removed (replaced by individual shrouds for each of the exterior fans) air would be pulled from the entire height of the engine compartment and not just the bottom 2/3.
The stock alternator may or may not be adequate. If a large capacity alternator is felt to be needed, then I would NOT rewind the present alternator as more heat will be generated with the same alternator cooling capacity. Mine is a rewound original and had to be replaced 5 times. Others have also had problems with the rewound units, but some others have not had any problems. I would either stay with the stock alternator or replace it with a unit that has a larger original design capacity. This does present some bracket and pulley complications if changing basic alternator.
Not all fans have the same efficiency as to the amount of power (amps) used to move the same amount of air. Generally larger fans tend to be more efficient. The efficiency gain from using a single large fan would probably be offset by using three or four smaller fans staged by temperature so that only the needed amount of air is being moved. Nowhere have I been able to determine the cubic feet of air moved by the present mechanical arrangement at a given speed such as 3200 rpm. Fan efficiency also generally diminishes with higher revolutions as a given fan pitch works best at a given blade speed. This allows electric fans to work at the most efficient blade speed for their pitch.
If the amount of air moved with the stock fan at cruising rpm (3200) was known, then the needed cubic feet of fan capacity could be targeted in the fan selection process.
Wear and tear on the water pump bearing and belts would be reduced.
If I were putting an electric fan system on my coach using the existing radiator arrangement, I would probably use a four fan arrangement. The first fan would be on all of the time while the engine is running to provide engine compartment airflow. It would be the top, left fan. Slightly lowered and to the right would be the second fan and it would come on at about 185 degrees. During cooler times of the year or day at normal cruising speeds, I would anticipate that those two fans would be all that would be needed. Lower down and to the left would be the third fan and it would come on at 190 degrees and I would anticipate it coming on at cruising speed during hotter times of the year or pulling a grade during the cool times. The fourth fan lower yet and to the right would be set at 200 degrees and it would only come on pulling a grade during hot weather or some other high load situation as more air would be moved by these four fans than the existing mechanical pusher fan provides. Actually, I think the first three would equal the maximum air flow of the existing mechanical pusher fan. Would the fans be all the same size? Possibly, but possibly not. One thought would be to have the first fan a smaller unit and then numbers two and three larger and then number four back to being smaller again. Draw a rectangle in the proportions of the radiator and play with different sized circles and their arrangements and you can see the possibilities! The individual shrouds would be either squares or rectangles so the entire radiator would have air drawn through it if all fans were operating.
Hopefully this has given you some good food for thought.
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Expert
Location: Cottage Grove, OR | Further thoughts:
The big unknown relative to the above is: What is the rated capacity of the stock FMC fan? There is a standard procedure for rating the cfm of a fan. The result would be a certain cfm @ xxxx rpm. The easiest method of obtaining the information if the original manufacturers data can't be located would be to take a fan to a facility that has the epuipment and have the fan tested at 2500, 3000 and 3500 rpm. An engineering student at some college may take it on as a project that could be used for class credit.
Who could take/ship their fan to a college or other facility and have the fan tested? Who has a child in college that has friends in the engineering dept?
Leslie, would you loan the fan if a facility can be located? | |
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Veteran
Location: Illinois |
Stephen -
Yes, we would have the original fan that could be returned after the test.
I would assume from theoretical calculation that we would see 5,000 or more CFM thru the clean rad.
Which begs the question should it be tested with rad and shroud or go with approximate reduction in clear flow.
All the Best for the Joyous CHRISTMAS Season - Leslie Hoagland | |
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Expert
Location: Cottage Grove, OR | For comparative purposes, any fans would have to be measured in some standard arrangement. This would not measure the actual air flow thru the radiator. Below is the airflow description as used by a fan manufacturer. Obviously, the actual airflow through something would be less. The greater the restriction, the greater the reduction. This is also affected by the puller/pusher issue and the amount of air flow reduction for different blade designs with the introduction of a fixed resistance e.g., the radiator. A starting point would be to measure the unrestricted air flow from the stock fan. Lets say that at normal operating speed it generates 8,000 cu ft per min. That would mean that any electric fan arrangement would have to be capable of that same amount or more to be able to replace the stock fan. That would then lead you to the amperage requirement under maximum load. Right now we don't know if that base air flow is 4,000 or 8,000 cu ft or some other number.
Airflow-Cu. Ft./Min. at 0º Static Pressure
Food for thought is the following data for three fans all manufactured by the same company:
1. 15" 8 blade/26 degree, 2800 cu ft, 13.9 amps = 201.4 cu ft per amp
2. 15" 8 blade/16 degree, 1950 cu ft, 9.8 amps = 198.9 cu ft per amp
3. 12" 10 blade/30 degree, 1050 cu ft, 9.0 amps = 116.6 cu ft per amp
Notice the difference in cu ft per amp. That means that any fan selection would have to be done very carfully! Look at the difference in blade degree between the first two fans and the difference in cu ft of air, but the very close cu ft per amp end result. In this application the cu ft per amp is very important as there is a limited amount of amps available.
The next question is which of the two fans would best maintain its air flow with resistance (a radiator) introduced to the air flow? Would the fan with the lower degree of blade angle maintain it's air flow with better than the one with the higher angle of attack?
Yep, lots of questions with out any firm answers. There is at least one FMC that uses an electric fan with a side mounted radiator. How was that one engineered? Probably by guess and by golly, but if the engine is cooled adequately that is all that counts.
At this point, I don't know what to assume except that any assumption would be very shakey at best.
Still looking for the person that can do the test work so that we can borrow Leslie's fan! | |
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Veteran
Location: Kingsley Michigan | Yes Steve, you make some very valid points and some of which, I can help with. Our groups new up and coming, international VP, Frank Borman, who hails from Canada, is a very capable and experienced person that others use for help. A conversation with him might be in your best interest.
I have just recently pulled the motor out of the coach and can now report that mathematically figuring the area of the present mechanical radiator fan in feet multiplied by the pitch of the blades multiplied by the number of blades equals .55 cubic feet per revolution. Multiply this by whatever RPM you need--say 3200 and you get the total CFM at that speed being 1760 cfm. This also means 2750 cfm at 5000 Rpm-the max of this motors range. All of this is subject to whether or not the blade and radiator are clean, belt slippage, etc. and the fact that this rate (Speed) is then channeled out over a larger area--namely--the radiator. These factors cause a slow down of the air--being spread out over a 28 by 30 inch area or 5.8 cubic feet. You see, all of the cfm in the world will not be effective if you don't give it time or the area to transfere the heat.
Of course, one of the great advantages to electrics is that while that power neccessary to run them will eventually be needed to be replaced, the battery does the initial buffer job and then, later on, the alternator plays catchup. With the mechanical one, as you are trying to pull out in traffic or such, robs you all the way of the punch that you need now!
Let me know what your final design will be and if I finish first--I will report to all the findings; Barney | |
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Expert
Location: Cottage Grove, OR | Status report: The radiator/cooling project is still on the list, but other things have surfaced and are higher on that list. Due to the overheated and lost engine caused by water pump impeller failure discussed in another thread, engine rebuilding came first so that we are at least operational. That has been done. Converting/installing a captain's chair for my co-pilot has now been inserted as the next major project after converting the auto AC to a Sanden compressor as discussed in another thread.
I have definately decided to install front cross flow radiators where the AC condensers are on late model coaches (a fresh water tank on early coaches). The AC condensers will most likely be moved to the engine compartment where the existing radiator is located with an electric fan rather than stacked with the radiators in front. There will be three short, wide radiators placed one behind the other about a foot apart and plumbed in parallel. Six temperature staged fans will ensure air flow under severe conditions (up steep hill in the summer). The front two radiators will be placed in such a position (height and angle) to allow air to be scooped into them at speed. The third one will only provide significant cooling when it's fans turn on. The radiators will be mounted into a framework and then lifted up and secured to the coach. Each radiator will be a three row with about 300 sq. inches of cooling area for a total available area of 900 sq. inches.
Cruising on flat land will allow ram air to handle the cooling. As the gradiant gets steeper, one fan on each of the front radiators will engage. That will be followed by the second fan on the front two radiators and then, last, the two fans on the third radiator. The third radiator will be flow restricted so that most of the coolant flow will pass through the first two radiators. One option would be to use a thermostat to only open flow to this one above a certain tempurature.
Exact routing if the coolant lines is to be determined. Copper will be the main line with hoses at each end. I am leaning towards the addition of an electric booster pump (readily available) to allow for smaller diameter lines and greater flexibility in locating those lines. I anticipate this project being started in the spring of 2009.
As always, comments are welcome. | |
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Veteran
Location: Oslo Norway | Hello Stephen
I am sure you have this project worked out well, your research is always good.
This might be me getting the wrong picture because of difference in language again, but do not understand " plumbing in paralell". Are you not going to pump the coolant thru all the radiators (or two if third is actuatet by valve) one after the other? Like one would call a series coupling if talking about electrics.
Have you taken into consideration that the radiators (and fans) are designed for flow with the air hitting straight on when designing your system. Do you need some ducth design to lead the air to the radiators? Air intakes in the fiberglass front would be optimal?
An electric water pump is an good idea I think. If you do not find any automotive pump you can trust I guess there are industrial 12V pumps capable of doing the job very well. With an adjustable waterflow (variable pump) you might have full control of your cooling capasity without controling the fans or shutting down the third radiator. If you build a simple control board for your pump you can have a system with a programable (preset) engine temp. All this of course assuming the radiators have enough capasity.
I think you should go with the largest pipe dimensions possible to add more margin to the design. Smaller pipes equals more resitanse, and higher system pressure.
Keep pushing
Kjetil
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Veteran
Location: Illinois | Stephen, etal -
After 425,000 miles on my personal FMC Motor Coach with rear radiator - properly setup - I have experienced no abnormal heating with original 4 tube radiator and 7 psi radiator cap.
Therefore, I would never consider for my personal use or recommend for customer to use front radiator or electric radiator fans.
HAPPY TRAILS - Leslie & FMC #0938 | |
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Expert
Location: Cottage Grove, OR | Duramaxer - 2008-02-24 5:17 PM Hello Stephen I am sure you have this project worked out well, your research is always good. This might be me getting the wrong picture because of difference in language again, but do not understand " plumbing in paralell". Are you not going to pump the coolant thru all the radiators (or two if third is actuatet by valve) one after the other? Like one would call a series coupling if talking about electrics. Kjetil
Kjetil, your language skills are better than you think. You have correctly interpreted my description in that they will indeed be in parallel and not in series. The coolant will not flow from the first one into the second one, but the flow will be divided with half going into one radiator and the other half going into the second radiator (or thirds if three radiators). Why? The reason is that to place a radiator where I propose doing it, the radiator core has to be approximately 10 inches by 30 inches with the tubes running the long, horizontal dimension. In my estimation, too few tubes would be available in a 10 inch, three row setup to allow free flow of the coolant at reasonable flow rates. By spliting the flow through two radiators, they would function like one 20 inch by 30 inch radiator. The flow rate and resistance through the cores would be half that which a series arrangement would create with two cores. The maximum flow rate would be on a similar order as that of the stock radiator (28" x 30" ) with the three cores in parallel. To get good ram air flow through the radiators it will take some ducting to direct the air flow. The front radiator would have a small scoop below it to help catch the airflow and direct air up and back into the first radiator. Between the front radiator and the second radiator there would be a baffle that goes from the bottom rear of the front radiator to the front top of the second radiator. This directs the hot air from the front radiator up and over the top of the second radiator so that the second radiator's air scoop (which is placed lower than the front one's so that it remains in the direct air flow) will draw fresh, cool air into the second radiator. The hot air from both the front and second radiators is then allowed to exit down and out with some going through the third radiator and then down and out. A negative air dam can be placed angling down and back from the rear edge of the third radiator to help create a low pressure area behind that radiator and assist air flow. The first two radiators will be tipped forward at approximately 45 degrees to put their face into the rising airflow and, for the second one, to also allow space above it for the air flow from the front unit to exit unimpeded. I don't plan on creating any openings in the fiberglass as that area is behind the bumper and so I don't think it would add much airflow. One of my goals is to make this as unobtrusive as posible. To those people that doubt that a rear engine/front radiator can be done, they need to realize that this is not my original idea. It is just a modification of the factory arrangement for a Vixen21 which had a Buick V-6 mounted to a transaxel in the rear and the radiator in the right front. The radiator leaned forward and the air came from under the front of the vehicle. It worked very well for the two years I had the coach. | |
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Expert
Location: Cottage Grove, OR | MCR - 2008-02-24 9:15 PM Stephen, etal - After 425,000 miles on my personal FMC Motor Coach with rear radiator - properly setup - I have experienced no abnormal heating with original 4 tube radiator and 7 psi radiator cap. Therefore, I would never consider for my personal use or recommend for customer to use front radiator or electric radiator fans. HAPPY TRAILS - Leslie & FMC #0938
Leslie, I am glad that you havn't had any "abnormal heating" with the original radiator. But that is not relevant to why I am going to change my radiator arrangement. My reasons are stated in my original post and none of them relate to curing any heating issues. It is all for other reasons. As to electric radiator fans: They are more reliable in normal service than fan belts as proven by the millions of vehicles worldwide that use them. My 1983 Postal Jeep uses a belt. My Subaru, Chevrolet, Honda and Cadillac all use electric fans so as a customer I already use a lot of them. I also expect that virtually ALL of your customers also use electric radiator fans on the vast majority of their other vehicles so I doubt that the proper use of electric radiator fans would be of concern to them. | |
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Veteran
Location: Illinois | Stephen -
After reviewing your original post(11-26-96), I am reminded of your original concern about fore/aft weight transfer.
When we at MCR install Diesel conversions in the FMC Coaches, we add as much as 1000 pounds to the rear of the coach - but add no adverse effect to the Steering/Suspension Modification by simply adding a stronger Hollow Rubber Spring Stabilizer to the rear suspension and modify the alignment specs accordingly.
My concern with the electric cooling fan setup is actually due to the corrosion caused by the rear dual spray and the resulting corrosion that I have watched over these last 30 plus years and high mileage on my personal coach. Now if one were to install a front radiator, I would assume that one's attention should shift to the plumbing pipe size to maintain proper coolant flow.
And when I speak of my FMC Coach, I have seen the same results on customers coaches resulting in electrical corrosion, lack of engine overheat, proper braking, and on and on...
My point is always that if the FMC Coach is setup properly in whatever concern we are addressing - then all of the unwanted abnormalties are eliminated or minimized.
Engine belt reliability is properly maintained by changing belts annually if one has made certain that engine pulley shives are in the same plane for each of the belts. This Preventative Maintenance is good for all engines but particularly for the higher torque engines.
HAPPY TRAILS - Leslie & FMC #0938 | |
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Veteran
Location: Kingsley Michigan | Steve and everyone else---
I had great success with the radiator after throwing the old brass dinasoar away. I was able to purchase a 2000 Ford F-250 diesel radiator with 200 miles on it from Ebay for $60 plus shipping----It was about the same size as the original except it is only 1.500" thick and weighs 12 lbs thanks to being made out of aluminum and plastic. It uses a single core and consumes about 2 gallons of antifreeze with the overflow tank (which I was stupid not to have gotten with the radiator but for $20 more plus shipping---). The earlier models of this radiator and tank used a half turn cap---just like on the old FMC radiator. The newer overflows use a screw stlye cap which I was unable to locate a 7 lb. cap for so they won't work as the rest of our system is not set up for higher pressures (15 lbs.).
I hinged the rear ladder and used clips at the base to make it possible to flip the ladder up out of the way. I also removed the rear alluminum panel on the radiator side and put pins on the bottom of it and destaco clamps on the top side so with the rear generator side door open---you can flip the clamps and remove the passenger panel for easy access and cleaning.
Originally---I had the stock fan in backwards---and the motor never thought of overheating--left the spacers out too! Now--the fan is in like it should be but further changes are coming with electric fans which would eliminate the shroud and give an extra 8 inches back there.
You have to understand that the stock fan weighs a ton and is hard on the water pump bearings. I changed the old alternator out for a 130 amp delco and made a bracket to remounted it rearward and lower--eliminating the idler pulley----another possible trip stopping feature. Now. the lower engine pulley, alternator and water pump share the same belts. This also makes it easier to see and work on the distributor. You would be surprised at all or the room I have gained and the weight ole 801 has lost. | |
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Veteran
Location: Oslo Norway | Stephen
You are absolutely right, one can have the radiator where ever one wants to. I have seen some designs in busses and armoured personel carriers that one would not belive to be functional. And after all up front is normal ;-) :-)
I did not think of the double resistanse in a series arrangement, good point.
Just in case....I noticed today at the workshop there is a (available) 9 cm gap between the front frame cross member and the coach flooring. The top og the frame cross member and the top of the bumper is aprox level so this gap could be used for a cold air intake if needed. The usable area of this gap is 20 square inches if my conversion is right. This ram air could be lead into a duct witch also takes air from under the bumper.
When I think about it, I have never seen the Duramax in my GMC showing any signs of getting "hot" even when towing and running a total of 6+ tons. We do have some hills and mountain passes over here you know ;-) I have been thinking about the exhaust temperature some times and wished I had a gauge to monitor it.
Stay cool
Kjetil | |
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Veteran
Location: Oslo Norway | Duramaxer - 2008-02-26 3:34 PM
The usable area of this gap is 20 square inches if my conversion is right.
It was not....it should be 200 square inches. I better stick to metric's 
Kjetil | |
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Expert
Location: Cottage Grove, OR | I will have to look into using the gap that Kjetil has identified. I never turned my head around and looked the other way! Maybe my coach will end up with a "smile" on its face! Barney, thank you for the update. I was wondering what the status was with your coach and was thinking of emailing you. As you are aware, adding thickness to a radiator doesn't porportionately add cooling capacity. As air enters a radiator the maximum difference in temperature between the air and the coolant exists. As the air passes through the radiator and gathers heat, the temperature difference diminishes along with cooling capacity so that by the time the air exits it is gathering significantly less heat from the last row of tubes than it did from the first row. A frequent cause of reduced cooling capacity of an aging radiator is not internal, but is the separation of the fins from the coolant tubes. If they are not properly bonded, the fins don't gather the heat from the coolant tubes and as a result don't transfer the proper amount of heat to the air that is passing across the fins. Based on the input of others, I am feeling better and better about making this change. To be able to open the rear aluminum panel and see the engine will be great as that is the primary reason for making this change (followed by no fan noise!) When the time comes I wil be starting a new thread about ram ventilation of the engine compartment without external scoops. This will be independent of any radiator placement.
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Expert
Location: Cottage Grove, OR | Just to ensure the fullest inculusion of thoughts, the following is a transfer of Louis Cruse's comments in the Yahoo Group site. I trust he approves. I do suggest that he contact the moderator to see about joining this site. There is an interesting discussion going on at the other FMC site.
Not being a member of that elite group, I offer some comments here.
Experienced auto mechanics know that a heating problem on the highway
is a radiator issue, and a heating problem in street trafic is a
thermostat, fan, or pump issue. Front mounted radiators rely on ram
air for cooling at highway speeds, and on the fan to move air when at
slow speed and when sitting still at a light. Except for hill or
mountain climbing the highway speed power required and the
corresponding heat rejection requirement is less than the stop and go
acceleration power and heat load in traffic.
I am not convinced that the fan in the shroud ring setup blowing air
into a larger "plenum", the rest of the shroud, blows air any place
thru the radiator except a blade tip ring about 2 or 3 inches wide.
That is where the dirt collects and I can feel on my hand that
airflow and all the rest of the "dead" area, standing behind the
radiator with the engine at high idle. Just reversing the airflow is
not the same as when the fan sucks thru the radiator, then plenum,
then the fan/shroud ring. The high mounted exhaust manifolds
certainly raise the temp of the air entering the fan. I have fiddled
with plastic sheets placed over left, right, both, of the side
grills, and there seems only a slight airflow thru them at high idle.
Guess a lot of the air comes up around the engine from the open area
under the engine and transmission. I have no idea what the airflow is
like at highway speed. A box (typical truck trailer 18 wheeler,
delivery truck, etc) does have a low pressure area at the back at
speed. That is the "draft" that the Nascar guys try to run in when
they are very close together. But I don't know what the open side
grills do to that type of airflow in our FMCs. I might try some "yarn
strings" all over the back and try different speeds with pictures
from a following car. Got a feeling the stock "shroud" might
be a poor setup.
Now, the point of this! The stop and go "hot day and hot asphalt"
driving seems to me to be the toughest design condition for the front
(actually under the front) radiator(s) set up proposed. Recirculation
sitting at a light must be minimised. Suck thru electric fan(s) with
full shrouds similar to those used on dragsters
(see http://www.rondavisradiators.com/Radiators.htm)
might be more effective than other configurations. The "ram air" duct
(s), deflector(s), scoop(s), other, will be a compromise that still
give(s)suitable cooling in stop and go traffic. Have no ideas for a
stone screen that is not restrictive to airflow. Friend of mine wrote
the US ARMY Handbook for Liquid Cooled Vehicles. He often reminded me
that any "thing" with more than 10 fins per inch is FIRST a FILTER.
Other than the leaking fluid and dirt load, the stock FMC radiator is
pretty protected from FOD and other debris or clogging. Large
diameter copper tube to and from, with hose/other at the ends, would
also act as a radiator. Remember the surface radiators on the
Schnieder Cup seaplane racers from the 30s ? Fuselage sides, wings,
and finally the sponsons were covered with surface radiators.
Press on, Lou #120. | |
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Expert
Location: Cottage Grove, OR | Quoting Leslie Hoagland: Lou -
You should sign on the FMC Owners Club site and add your thoughts.
Here at MCR, some 15 or more years ago, we added 5 inch long ribbons every 4 to
6 inches across rear grille of an FMC Coach.
In the video, it was interesting to see the ribbons hang straight down at coach
speeds of 50 to 70 mile per hour except at the radiator grille where they stuck
straight out.
The airflow across the radiator is maxed when the fan is 2/3 in the shroud and
the engine belts are tightened so that fan can not be slipped by pulling from
top thru the passenger side grille door.
Electric fans on the side doors or radiator had little discernable indication
on the heat guage during my tests with the fan shroud, fan, A/F mixture, and 8
more factors all setup properly.
Thirty years and more ago, I went thru all of the above and more to lower the
coolant temp at my favorite cruise speeds of 80 to 100 mph.
Intially, my FMC's coolant temperature would rise to 230 degrees Farenheit at
advanced speed on 85 to 110 degree Farenheit ambient temperature days.
I finally got the coolant temp down to 210 to 215 on those hot summer days at
advanced speeds. The gas engine coaches run about 185 to 195 at 60 to 70 mph
with a 180 degree thermostat.
On one occasion many years ago, we were driving in Indiana with a white
Limestone shoulder on that highway. I noticed a white 20 to 30 foot vortex
rising fron the rear bumper which explains the strong stagnation point in the
airflow across the rear of the FMC.
Once the cooling system setup is completed, all one has to do is watch the
engine belt tension and wash the radiator on a regular basis with a good
cleaner like GUNK followed by a Kerosene wash and a rinse with clear water. The
Kerosene film allows one to wash the engine and radiator with much less effort.
HAPPY TRAILS - Leslie & FMC #0938,
I basically concur with the comments and observations of both Louis and Leslie. I would like to see the string test done, not on the outside of the rear grill, but stationary on the radiator itself. It would be interesting to see the pattern. Like Louis, I have passed my hand behind the radiator and noted significant dead air area. I have not done an actual test, but that is one reason that I feel the front radiator arrangement will provide an increase in cooling efficiency - with ram air the entire core area will have a similar air flow rate. I would also anticipate either full or almost full shroud for the fans. If that is not done the fans will not create the needed air flow across the entire core under high heat generation conditions. I have thought of two possible rock guard designs: 1. 1/4 mesh hardware cloth with a few cross braces for strength (big rocks!). This would be cheap and easy to install, but ugly. 2. My next option would be a ribbed design. Imagine a number of ribs laser cut from 1/16" material that angle down in front of the radiators and curve to continue back underneath. These ribs would present their edge to the front and down. They would be spaced about 1/4 inch apart (slipped on 2-4 support bars with 1/4 spacers) to provide a good ratio of open area to solid surface and yet have significant strength. Thin material presenting its edge can be quite strong. If a large rock is encountered, it would be easy to remove the ribs, straighten or replace and reassemble. This is a modification of a very effective classification screen design used in some heavy duty agricultural equipment that I am familiar with. This would be effective and attractive, but significantly more costly. The next question that needs to be addressed is the copper tubes that pass between the front and rear. My initial thought is oval copper tubes about 2.5" high and 3.5" wide. They would be attached to the bottom of the coach near the center. Copper would allow impacts from rocks without breakage (would just dent) and some additional heat rejection. The diameter would have to be large enough to ensure unrestricted coolant flow (this could be boosted with an electric coolant pump). Your comments? | |
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Veteran
Location: Illinois | Stephen, etal -
After reading this text, I am reminded that we hang the transmission cooler and oil cooler(gasoline engines) on the radiator between the radiator and grille. The transmission is cooled only thru the external cooler in our installations.
The dust pattern on these coolers indicate a strong airflow that results in a trans. temperature of 150 to 160 degrees Farenheit on my FMC at 18,000 GVW / 22,500 GCW.
This trans. temp. stays in the range even with the diesel coolant temperature varying from 180 to 210 degrees depending on the ambient temperature and the highway grade.
Stephen, what would your thoughts be on stainless tubing rather than copper to minimize effects of corrosion and impact?
HAPPY TRAILS - Leslie & FMC #0938 | |
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Expert
Location: Cottage Grove, OR | Leslie, it needs to be one or the other. I do not know the comparative metallurgical characteristics in this use enough to comment on the difference in expected performance or corrosion characteristics. I also do not know the cost differential. If cost is reasonably close, then personal preference based on strength, heat conductivity, etc. can make the determination. Either would be able to take a major beating and still not fail if of the correct wall thickness. A basic rubber lined SS pipe repair clamp or section of hose could be carried as an emergency repair kit if desired when traveling to remote areas.
I believe that in the not too distant future (month or two) I will be able to conduct a "yarn test" (if I get lucky and can locate a suitable airflow meter it would be much better as it will be objective, recordable and duplicatable) of the air outflow pattern on a new, clean, freeflowing radiator without any other coolers affecting the pattern. While the results will not affect my decision as I just want to get the radiator out of the engine compartment for other reasons, the results will still be interesting and informative and may help others. Knowing the pattern of a clean radiator will let someone know if their radiator is starting to plug as a result of being a "filter" or not or if their fan is properly adusted or not.
One thing that I haven't resolved yet is whether or not to retain the transmission cooler/heater that is in the bottom tank of the radiator. You have eliminated it, but my reason to retain it would be to provide transmission heating during startup and during cold weather. My transmission runs in the 180-200 degree range and I get good, smooth shifting at that temperature. When colder it tends to shift harder and late. We both have the Allison AT545 transmission. You are diesel and I am gas. | |
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Veteran
Location: Illinois | Stephen -
I would tend to believe that the Stainless Steel tubing would be stronger with greater resistance to corrosion while the copper would have greater heat transfer and cost less.
The cost differential should be not that great so I would tend to choose the Stainless Steel Tubing.
If you are concerned with cold weather operation, mount the remote transmission cooler behind the radiator - I have never experienced harsh shifting when cold even when operating at 10 degrees Farenheit based on 30 plus years of operation. I notice no difference with the diesel engine which takes longer to reach operating temperature.
All the Best - Leslie | |
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Expert
Location: Cottage Grove, OR | MCR - 2008-02-27 9:43 PM Stephen - I would tend to believe that the Stainless Steel tubing would be stronger .... All the Best - Leslie
Stainless steel comes in many different blends. The focus of the blends is to prevent rust, e.g. stainless! Yes, a number of them are "stronger" in that they won't bend, but that also makes a number of them brittle. In this case, brittle is not good. Copper also comes in diferent blends, but all of them are more flexible than stainless. I am tending to lean to copper for the heat transfer ability and also for the flexibility. If a rock hits it, it will dent but not break. If a metals person comes along with more information, I could be persuaded to change my mind. | |
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Contributor
Location: Webster, Wisconsin | Stephen, I worked as a stainless steel fabricator for 8 years after I got out of college. I've cut it, bent it, drilled it, and welded it. As far as strength and corrosion resistance goes, nothing beats it. I never found SS to be brittle so your concern about it breaking if hit by a rock is unfounded. If hit hard enough it will dent. A couple of years ago I made a trailer hitch for my VW Golf TDI out of stainless and have had no problems with it. I didn't paint it and it looks just like the day I bolted it on the car.
While reading the latest postings I visualized a tubing system running back to front that had fins on it like a base board heater in a house. If it could survived under the coach imagine how much heat it would dump! | |
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Veteran
Location: Oslo Norway | Stephen, just a few thoughts on the options of piping material even if I am not a metallurgic expert either.
I think I would have wanted stainless tubing. I really do not think copper tubes are more resistant to any damage from flying stones and such. A stainless hydraulic pipeline for instance has to be very resistant to pulsating pressure and therefore the qualities in use is not brittle, I would guess less brittle than most copper. Also one of the characteristics of copper is that it gets more and more brittle when exposed to stress from movement and vibrations. This is easily experienced if you bend a copper piece a few times back and forth it will be stiff and break. Also the corrosion aspect makes me think ss is far better. There is also a risk that you might have problems with electrolytic processes in such long copper lines circulating coolant, if so the corrosion could be very aggressive from inside out.
There is aluminum tubing suited for this purpose also I’m sure. Corrosion resistant aluminum is widely used on modern vehicles, but you need some good source to help work out that option I think.
Also you might want to consider running dual pipelines of smaller diameter than the 2-3” you mention since you are plumbing in parallel anyway. You will have some more resistance due to lager wall area but the same will give an upside in cooling. Smaller pipes will not be as low under your coach and the routing will be easier in both ends. Connecting hoses in each end will be easier and you have to come down to smaller dimensions for the radiators anyway. You’re the engineer so you have to do the mathematics on flow rates and pressure ;-)
K-man | |
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Expert
Location: Cottage Grove, OR | It appears that the concensus is heading towards stainless steel! Along with Greg, I have had visions of cooling fins the length of the transfer lines. I quickly put it out of my head to attempt to protect my wallet! I have also quickly considered dual lines as Kjetil has suggested. I hadn't thought of the improvement in connectivity at the front of the coach, but now that I think of it I does sound like a good idea. It would also add some of that heat shedding ability Greg thought of.
I am going to investigate the addition of some fins to the line, particularly if they end up being SS as I have a local contact that is very reasonble when it comes to strange and different welding jobs. He could probably weld/brase longitudinal copper fins to SS lines. If I have four lines with some finning added, I would eliminate the third radiator for sure and just have two. That would probably allow them to be slightly larger and with the "smile slot" added the front radiator (of the two) could be larger.
Ok, how does dual 2" SS lines each direction with some finning added sound as the final configuration? If that is it, I can start looking for a supplier. | |
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Expert
Location: Cottage Grove, OR | The following is from Jim Black of RVS: At FMC we built a modified nose cap to accept a front cross flow
radiator. We used 1 1/2"copper tubing to route coolant to the
front. Cooled poorly. We added a 12 V boost pump to secure proper
flow. Worked much better but the boost pump could be weak link. FMC
canceled the project as not cost effective,as well as, having
questionable engineering area's. FMC added perimeter aluminum
shields aft of radiator to the inside of rear grill. BIG
IMPROVEMENT!!!! Also, added aluminum shield between aft engine
cross member to bottom of radiator. This provided protection from
gravel bouncing up into the engine fan and helped air flow. ALSO
ADJUSTED RADIATOR TILT TO POSITION ENGINE FAN 2/3 OF CROSS SECTION OF
BLADES INTO SHROUD. REPLACED oem SUPPLIED 180 THERMOISTAT WITH NOW
OBSOLETE 160 CHRYSLER THRMOSTAT. ALSO CHANGED RADIATOR CAP TO 7 LB.
END OF COOLING PROBLEMS UNLESS OIL LEAK PlUGGED AIR PASSAGE OR LOWER
HOSE WAS REPLACE with HOSE WITHOUT SPRING INSIDE OR MOULDED INTO HOSE
ALLOWING HOSE TO COLLAPSE. The next problem was OEM radiators
supplied approx 100 total had 90+ of the 190 total plugged with
solder. Subject problem was found and corrected. After FMC #646
Chrysler derated their engines due to Ca smog from 8.9 to l in 1973-
74 to 7.9 to l in 1976 and removed some head gasket holes to raise
cylinder head temp,.changed cam grind,changed distributor curve. All
of these modifications reduced power an caused the FMC motorhome to
enjoy elevated coolant temp. Nasa Ames asked RVS to assist with a
engine temp study by installing 9 heat sensor in the engine area
connected to a graph recorder. At 65 MPH on
i-5 w/l00 ambient temp
the engine compartment exceeded 350, above the carborator. Reduced
temp in engine area by replacing dondaldson muffler with dual exhaust
engine compartment temp down to 160 to 1780. The donaldson was a big
heater. RVS has also been usng 6-row radiator cores when replacing
bad cores with great success for many years as guided by FMC
engineering.
The correct FMC motorhome waterpump is not a shelf item (obsolete).
Factory remanufactured available. Correct impeller is 4 3/8 OD with
8 blade paddles. Also, note: Do not over lubricate water pump.
NEVER A POWER GREASE GUN, 1/2 pump mad 2 times year. Most engine
water pump failures are caused by OVER lubrication.
JIM Thanks for the additional information. | |
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Veteran
Location: Kingsley Michigan | Steve and the rest of the gang---
Boy---you sure can tell when spring fever is in the air-----I am in the process of giving the kitchen a makeover with more water capacity under the belly there---but enough of that---
This is about Radiators and Engine access, noise, power and our general happiness---so first---an overview of our changes and the outcomes of tinkering.
We had the idea of moving the rear swing spare tire off of the rear bumper to under the front where the auto air condensers were and it dramaticaly changed the weight distribution---- a big plus as the handling improved to less of the bucking bronco effect. Yes---we have the Timbren rubber bushings----which helped take some of the rock and roll out of the coach but moving weight forward with the spare tire was a more noticable change---hench--the added water tank for this years improvements.
Next, The old radiator---what a piece of junk-----Brass has no intention of giving up heat---and four cores means 4 times the weight and inefficiency x 4. Now with the single core aluminum radiator we installed---there is no weight to start with (12 lbs.) and less coolant (2.4 gallons x 7.8 lbs) involved with ultra fast heat dissipation. Side note---We tried to use 4-14" with 2500 cfm each electric fans on the old brass hunker but just couldn't get they to pull out the heat----and while they were quieter than the stock fan--- it was like standing behind a jet when you were near the rear bumper---and that is when the idea of scraping the old radiator technology hit me. I will resurrect those fans for the next go around back there and that will eliminate the 8 x 30 x 32 inch space wasting projection of the fan shroud.
Then there is that steel fan and it's idler pulley----another piece of junk that means to harm you all the time. First---there is it's weight---that works hard on your water pump bearings and belts. Then there is the horsepower required to spin it up---at a time when you need to pull the old gal out into traffic and you REALLY need the power--but don't need the increase in cooling just yet---Not Good! Newer lightweight fans---you know---on 1978 model cars and trucks---employed a clutch for that very reason. Now we have thermostatically controlled electric fans---for the very reasons of not taxing the mechanical (read "prone to fail") essentials of the internal combustion engines. Hence---the great lack of need of service of todays engines---but now I am ranting----
With the moving of the alternator forward--it becomes the idler (another loss of 10 lbs and a needless prone to fail area)---gives an open view of the distributor and the valve cover on the hard side---and also allows for a increase of amperage if desired.
Have toyed with the idea of making a spoiler---you know--mounted up on top rear like the old muscle cars---or like the 73 fmc but in the rear above the window following the slope upward--to house a set of cooling tubes and fins for that high speed ram air cooling that Steve and others have talked about. This would be beneficial in getting away from the hot pavement plus shorten up the length and an exposed location of the hoses. Yes--it would be good for higher speeds only but that is when you are developing the most heat. At lower speeds--let the uncooled coolant from above go past the rear radiator/electric fans and back to the motor. I think it might even prove to add to the looks of the coach. Just a thought!
Until then, I will go take some pictures of the new setup that includes the alternator repositioning---that was a major improvement for engine accesss on the hard side. If we used velcro (just joking) or hinges on the radiator-----it would take less than one minute to gain full access to the rear of the engine. We did spring clip the rear ladder and back grating to make the radiator easier to clean---
Your fellow thinker and tester likes to hear from you with all of your trials and tribulations: Barn
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Veteran
Location: Illinois | Barn and All -
The proper Hollow Rubber Springs preloaded a mimum of 1/2 inch will minimize the pitch, roll, and yaw of the FMC Coach. The 4 HD One way Shock Absorbers will further minimize the coach motion.
To those who may have become concerned - the idler and water pump, when properly maintained, will last the life of the engine (150,000 miles) as proven by many of our customers over the last 23 plus years. In fact, I changed my idler bearings twice and water pump once in 250,000 miles on my personal FMC Coach before going diesel. So not to worry just do the Preventative Maintenance.
Trust you all will enjoy your FMC's this year and remember for every 10,000 miles you travel you will spend $5,000 for gasoline. Now unless you sit at home - the gas for the car, food, and motel will cost you much more than motorhoming once you have the coach.
HAPPY TRAILS - Leslie & FMC #0938
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Veteran
Location: Kingsley Michigan | Hey---We just had an idea-----If anyone would like the old radiator----We will be glad to send it to them for the cost of the frieght---or we will bring it to the GLASS rally in May. If we get no responses by then, Connie is going to make yard art with her newly found welding skills. Sorry, we already gave away the idler--- as the bearings were growling and I had replaced the need for it.---
Lookin forward to finding this a new home--Connie and Barn | |
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Expert
Location: Cottage Grove, OR | For those that prefer a rear radiator and mechanical fan, take a look at this film clip of dual, mechnically driven, rear fans. http://blip.tv/file/738493 | |
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Expert
Location: Cottage Grove, OR | The following is a copy of a post on the Yahoo site that I have copied here so that the infomation is included for anyone perursing this thread.
"Heat Transfer Coefficient, usually a lower case k, in
BTU/(hr.ft.degreeF)
for certain metals:
304/318 Stainless Steel - k = 8 to 10
3003 Aluminum - k = 90
Yellow Brass Cu65,Zn35 - k = 69
Cartridge Brass Cu70,Zn30 - k = 56-60
Copper - k = 225
Someone on the "FMC Owners Site" commented that radiators are not
made of pure copper anyway. (I could not get on that site for some
reason to find who had made that correct comment). The Yellow Brass
and Cartridge Brass were listed as being used for radiators.
Additional consideration could be the surface heat transfer
coefficient between the "coolant" and the inside of the pipe, and the
outside of the pipe to the "air". There is a "coefficient" for those
two interfaces as well, but someone else can look those up.
Press on . . . Lou #120."
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Veteran
Location: Kingsley Michigan | Good morning Steve and the rest;
Hey--this thread is quite lengthy--obviously of importance to most---. On the "Heat Transfer Coeffieciency" of different metals---You are quite right that Aluminum is a far better chioce in this department--but you have to understand that this coeffiecient is for the same thickness of matterials. The newer radiators have a 30% or better reduction in tube wall compared to our old yellow brass dinosaurs. They also have tiwce as many fins attached to the core as our scrap yard wanabes. I finally got out and took some pictures of my high speed radiator cleaning set up--a process of moving the ladder via hitch pins and slide latches that takes less thatn 10 seconds to expose the back end--Will put in an album for the group---
Enjoy; Barn | |
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Moving radiator to front - thoughts?