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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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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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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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Moving radiator to front - thoughts?
