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Author Topic: Tips for making the engine run cooler  (Read 1103 times)
ChuckMC8
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1977 MC8 and 1993 102C3 Temple Ga #322 F&AM




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« on: August 08, 2006, 05:56:36 AM »

I knew that topic would be of interest to nearly everyone!

 Well, I don't have time to work on my bus. I'm trying to get through college algebra (at age 47) and its consumed what limited brain power and resources I have.
  However, this summer I've posted a couple questions about cooling system engineering and such, and I wanted to compile what I have gathered into some sort of conclusion-
I dont know a lot of tricky terms and long winded formulas, So here goes-

1.Find out how many BTU's output your engine delivers.
2.Find other heat sources that are loading the cooling system (auto trans)
3. Total these up-
4. Figure out the capacity of your cooling system
5  Do the math.....need more cooling?

Ways to increase efficency of what you now have and some relatively inexpensive modifications-
1. Make sure that the cooling is functioning at the level it was designed to accomplish.
2. Make sure the coolant mix is proper ratio (no more than 50% a/f, it dosen't transfer heat as well as water)
3. Consider an  air-to-oil transmission cooler, Jack Conrad has details about this-
4. Check out Brian Diehls page on the manual torque converter lock up system..
5. Fred Hobe has smaller pulleys available for MCI's that increase the blower speed.
6. Have an engine with an aftercooler? That baby's dumping lotsa heat in the engine, consider an air-to- air intercooler,   
   blow that heat outside-
7. Louvers in the back door to let engine heat out.
8. Duct the factory bus heater core outside and turn on the elect fans when temp rises.
9. Put a skirt just behind the rearmost axle(but ahead of the eng/trans) to create a low pressure area under the engine
   that draws heat out while underway.
10. Scoops on the radiator grilles on MCI pull in more air thru the radiators.

Everyone knows the swapping out for larger radiators, but I wanted conclusions that weren't major $$$$$

 I tried to list things that I beleive are factual, not opinion. I dont want to pass information that would cause anyone to waste $$ or time. (We don't need help with that!)

HTH someone-


« Last Edit: August 08, 2006, 05:58:49 AM by ChuckMC8 » Logged

Far better is it to dare mighty things,to win glorious triumphs,even though they may be checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much,because they live in the gray twilight that knows neither victory nor defeat.  Theodore Roosevelt (1858-1919)
FloridaCliff
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"The Mighty GMC"




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« Reply #1 on: August 08, 2006, 12:09:31 PM »

Chuck,

Great Tips!

I see your also a fellow member of the "47" club.

Salute Tongue

Cliff
« Last Edit: August 08, 2006, 12:12:38 PM by FloridaCracker » Logged

1975 GMC  P8M4905A-1160    North Central Florida

"There are basically two types of people. People who accomplish things, and people who claim to have accomplished things. The first group is less crowded."
Mark Twain
Buffalo SpaceShip
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« Reply #2 on: August 08, 2006, 01:30:16 PM »

Great tips, Chuck!

Is "avoid driving in hot weather" just a little too obvious?  Grin

Does being a member of The 37 Club make me sound a bit too wet-behind-the-ears to hang with you guys?

Brian
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Brian Brown
4108-216 w/ V730
Longmont, CO
FloridaCliff
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« Reply #3 on: August 08, 2006, 01:43:57 PM »

Brian wrote:Does being a member of The 37 Club make me sound a bit too wet-behind-the-ears to hang with you guys?

Not at all, Just means you should have longer to fix up your Bus Grin

And besides, you have already passed me, I am still on Bus #1 Wink

 
Cliff
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1975 GMC  P8M4905A-1160    North Central Florida

"There are basically two types of people. People who accomplish things, and people who claim to have accomplished things. The first group is less crowded."
Mark Twain
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« Reply #4 on: August 08, 2006, 07:43:07 PM »

Chuck, I just ran some numbers to see how they turned out.

If you have an 8V71 with C60 injectors, 16 gallons per hour is about the most fuel that can be put through the engine. That's about 2.25 million BTU in fuel. Roughly 1/3 of that turns into exhaust heat, another 1/3 turns into heat in the coolant and the remaining third into horsepower to run the bus. That's if the engine is in good shape.

Figuring that the maximum amount of heat that has to leave by way of the coolant amounts to 3/4 million BTU, it's possible to size a radiator and cooling system to handle that.

Three things that could throw the numbers are a worn engine, an automatic transmission and a charge air cooler.

I have seen a worn Detroit that was working right alongside of another rig doing the same work that used just twice as much fuel getting the job done, so I know that these engines are a lot different than four strokes when they are worn.

In the vee drive automatics, it's been reported that they get around 20 or 25 % less fuel mileage that the standard shift transmissions. At least a part of that is horsepower that is turning into heat in the transmission; the balance is going out the radiator and the exhaust due to higher RPM. If 15 % of the horsepower is turning into heat, that's another 112,500 BTU that could be winding up going into the radiator.

The biggest surprise that I've gotten in trying to get a handle on heat rejection was the amount of heat that is removed by the charge air cooler. In one Series 60 setup that i was looking at, the charge air heat rejection was 50 % of the amount that the block put into the coolant. Geting rid of this heat actually increases the efficiency of the whole setup.

All this led me to the conclusion that getting good fuel mileage was a lot more important than just the cost at the fuel pump; anything you can do to increase your mileage is likely to reduce heating problems.

At least, that's the way that I see it.

Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska
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Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska
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