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Author Topic: Whats the latest radiatior technology?  (Read 4324 times)
ChuckMC8
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« on: July 22, 2006, 04:13:14 AM »

Good Morning all-
   I'm getting ready to start pulling wrenches on my changeover from 8V71N to 8V71TA........Whenever I start a big project like this, I try to consider all the options available in the project. (So does everyone else,that's why bus nuts are (or become) insominacs.)
    I'm checking on the cooling system options. The internet is a great resource for information (remember the stoneage when we went to the library for info?)
   It would seem that the new technology aluminum radiators are the most efficent has weight 1/2 of what the traditional radiator.
It also would seem that the newer coolants have merits as well (but a gallon of the red stuff for my Lexus was $22 at the Toyota dealer, and it has Toyota on the jug, not Lexus)
  From what I read, there are more maintenance issues with the red/ earth friendly coolants....but we bus guys are used to that...

    On the chat room last night (more like a quilting bee! 8 or 10 folks at once-What fun!) There was a breif discussion on cooling systems,and someone had said that two of the major variables are proper system design and keeping the coolant from becoming aerated.
  I'd like to correspond with someone who is up to date on the latest cooling info. I'm not interested in 1977 technology....I want to talk about what is best right now. What was best now may still be the best, but I wanna know......
  A couple more items that I want to check on is adding and air to oil cooler for the engine  and one for the trans as well.
How many BTU's does the tranny add to the mix? The oil cooler? the Aftercooler off the turbo?
What would also help would be a chart of some kind that list the BTU output of the 8V71N and the 8V71TA, as well as BTU ratings of modern 4 stroke powerplants such as the Cummins, Cat etc. Anyone know where to find that info?
How about info on adding an air cooled intercooler to my engine?

  I know the drill about the 102 Radiators and larger fans and smaller pulley and that route.........Looking for more options-
It certainly doesnt mean that I wont go the 102 set up route.....I just want to know what else will work. And if there is something that will work better. If so, nows the time! I dont want to have to rely on misters (or misses either) to help cool.....
Bob Sheaves was mentioned in the chat room as knowledgeable on cooling.....how can I find him? Don Fairchild?

When my wife drives the bus, I want to sleep and not lie and wonder about the temp of the engine......

Thanks for all the help guys-
   
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DrivingMissLazy
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« Reply #1 on: July 22, 2006, 04:38:06 AM »

Marc Bourget has contact information on Bob Sheaves. He no longer posts on any board as far as I know.
Richard
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Dallas
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« Reply #2 on: July 22, 2006, 04:47:10 AM »

Chuck,

That was Marc Bourget ( Sorry if I misspelled your name Marc) and myself talking last night. Hoping that others would chime in.

Marc goes by Burgermeister on this board and you can contact him by serching in the "Members Profiles" section and clicking on "Send a personal message".

Anytime we are in the Chat Room, the floor is open to anyone asking questions at anytime! Feel free to join in anytime!

I hope this helps,

Dallas
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Burgermeister
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« Reply #3 on: July 22, 2006, 06:23:04 AM »



There's no sudden new changes or discoveries in Cooling technology.  The market driven need for lower hood profiles requires smaller (cross section) radiators (but not less cooling capacity) The statutory CAFE requirements support less weight, therefore the switch to aluminum (a compromise) These needs simply generated the decision to manufacture radiators in a manner too expensive for previous times and climes.

Bob explained to me that MCI never met DD's base criteria respecting cooling system capacity.  They chose to go a lesser (expense)  route.  shifting the  Increased cooling system maintenance was the result.   Bob doesn't participate on the BB's anymore because too many refuse to really READ what he posts, and challenge his posts out of stupidity (note I said out of stupidity, not stupid)  when other, more knowledgeable types pay him huge money for his knowledge and experience.   He was more than happy to share his time, for free, with Jim Shepherd at Busn'USA and at "my" (really his) seminar.  But that's a one-on-one situation and he can respond appropriately to certain personalities IYKWIM

So, if you were upgrading a MCI to a hotrodded 8V92 on propane you might be forced to go that route because the confines of a MCI cooling section limits the cross-sectional area of the radiator. 

Otherwise you have the luxury of excess capacity IF  the tighter fin pattern doesn't drop the pressure across the air portion of the core to the point it causes problems with the fan.

Same thing can happen through the water portion of the core.  Either way it diminishes the cooling system performance delivering less cooling than is actually obtainable, all other things being equal.

Restriction in the liquid portion of the system is what leads to aeration.  Proper cooling system maintenance and, on occasion, other steps to de-aerate the coolant, may be required.

The latter comment is simple in theory but complex and technical in practice, so I'll leave it at this point.  Anybody wishing to find out the absolutely best way will have to wait as I go through my installation
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Burgermeister
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« Reply #4 on: July 22, 2006, 08:05:13 AM »

Just a blurb on Bob Sheaves.  32+ years as an automotive engineer.  On the original DD Series 60 engineering design team.  Did cooling system design for GM Military Vehicle Operations, including the L-10, M-11, RTS re-engine projects and various military trucks and an Israeli tank powered by a 4 turbo 12V149 engine.  The ambient temp was 145* max,  the test included 45* slope at 7.5 MPH for a very heavy tank.  Not much ram air,there!

No, they never seriously considered misters!   Misters can have a purpose and benefit, but in the overall scheme of things, if you really know what the problems are,  there's much better ways to solve the problem.   

As I understand Bob's point of view, the need for misters arises when the aeration problem gets significant.  Aerated coolant may see a substantial drop in temperature after being passed through a radiator core. (Illustrative example follows - example only, not experimental data) but, and that's a "BUT"

Problem is dropping the temp of the coolant 10 degrees doesn't help when the aerated coolant looses 20% heat transferance capacity.  10 degrees compared to 200 overall is 5% "gain",  the fact of aeration causes the system, overall to lose a net 15% more cooling capacity than the misters "recover".  (Again, these numbers are just for example only.  A whole spectrum can exist. The engine would have to be instrumented)

When I referenced "my installation" in the previous post, I mean my 8V92 in the MCi.  Bob assures me that we can cool the 8V92 to full DD specs.  It'll take work, some custom fabrication and new pieces,  better execution of the old pieces, but  the 8V92 in my bus won't challenge the cooling system in any conditions anticipated in CONUS.

Onward and Upward

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Bosshosssport96
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« Reply #5 on: July 22, 2006, 08:24:24 AM »

Well today is the day I get my 8V92T with jakes and the radiator to boot for $1500.00.I have a 4501 Scenicruiser with the 8V71 in it.The plan is to remove and install the 92.As we all know,with increase horsepower comes more heat.The radiator,if it will fit in the cruiser will probably take care of my heat issue.I haven't dealt with radiators on buses before,but I have delt with radiators in hot rods,V8 powered motcycles,and water cooled airplane engines.The down flow radiators are old technology,and they work pretty dawn good,a person may be able to add another row or two if you had the room for it,to get the additional cooling.Another way is to get another fan,that pulls more air thru the radiator.A cross flow radiator will give you two passes for cooling before it leavers the radiator,a whole lot better.On my last project (A corvette V8 powered small block motorcycle) it consisited of having a radiator built for her($685.00),we thought a down flow radiator would be suffiencent,it wasn't,the temps were between 225 and 235 degrees,we then had a crossflow radiator built(another $685.00),same dimensions,it dropped the temps to below 200 degrees,it worked,and is stiil working today.This is one option you may want to consider.Their is another radiator out there that most people don't know about,its octagon in shape,and will cool 387% ,thats right,I said 387% more than a standard radiator,its called a Heat Sponge,and its made in Los Angelos Calif.These hand biuilt radiators consist of flared stainless steel tubes stacked upon each another,and believe it or not,this radiator is old technology,that was put on the back shelf  many many years ago .A 17" Heat Sponge Radiator( 3'' thick) will cool a Big Block chevy motor,my 502 big block chevy cross flow aluminun  radiator is 32" wide to give you an example,and this is on my other motorcycle,this is another option .A lot of times,you only need additional cooling when climbing grades,two ways to accomplish this,one is with a misting system,and the other is with propane injection,propane is cold when it enters the combustion chambers,the exhaust temps actually drop when switching it on ,and with it comes an increase in power amongest other things.I don't want to really get into propane injection with anybody,I use it,and it works (I reside next to a 17 mile 6% grade)I will probably put Propane injection on this bus as well.Anyway this is my take on Radiators,good luck on your cooling adventure.......Frank....4501
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TomC
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« Reply #6 on: July 22, 2006, 08:59:04 AM »

As compared to the relatively simple conversion on a 4501 that uses a conventional type of radiator, the MC8 with its twin radiators and squirrel cage blowers are more of a challenge.  Quite simply, MCI had as an option the 8V-92TA at 400hp.  When you get the 8V-71TA all set up, it too should be putting out 400hp with 1,200lb/ft of torque.  So the heat rejection should be so close as to be considered the same (both engines would run 80 injectors).  When going to the TA block, one important item is to make sure you have 50-60psi of oil pressure when hot (my 8V-71N has 25-35) to both be able to supply the turbo and to increase the oil circulation.  As to the engine oil cooler-it works well-never have heard of anyone having an oil temp problem (I had 100 injectors in my 8V-92TA for awhile and didn't have any problems).
As to intercoolers for intake air-if you're going to use the TA block, you'll have the radiator powered aftercooler that is in the V of the block below the blower.  The one advantage to this setup is that not only will it cool the air in summer, it will also warm the air in winter.  But if you're not going to do any below 40 degree driving, then this would not be an issue.  The disadvantage of the TA is that it is cooled by the main radiator, so it puts more stress on it.  Also the TA aftercooler will not obtain as cool as an intake temp as air to air intercooling.  Personally-instead of going with the TA block, I would build up your exsisting block to turbo specs, add the intercooler to the right side where the A/C used to be, and power that fan with the old A/C drive.  Then it'll take the strain off the radiator, but would still change the radiators out to the 102 8V-92TA radiators for maximum cooling.
As to transmission heat, at torque converter stall, you can see upwards to 25,000btu's per minute (not hour).  Running after the converter locks up, the rejection is around 3-4,000btus per minute.  If you want to supplement the transmission oil to water cooler that is already there, I would suggest adding a Hayden type with large enough tubes to facilitate the flow (just size identically to the outlet inside demension).  The most effective would be to install the Hayden coming off the hot side of the trans. Then after the air to oil cooler the oil would flow to the now in place oil to water cooler then back to the transmission.  This has the advantage of taking the strain off the engine radiators but still being in place to warm up the transmission and keep it running at about the same temp as the engine coolant.  It can be as bad to run to cool as running to hot.
Ultimately what would be the coolest running would be- change the radiators to 102 8V-92TA radiators; use the regular 8V-71N block built up to turbo specs with the bypass blower; add an air to air intercooler (I used Sierra Technologies out of Tulsa Ok to make my custom intercooler-very nice job) with the air to oil transmission intercooler next to it with both built on a common frame running through the same fan that is in a fan shroud.  You could even use electric fans for this application too since the heat rejection is not going to be anywhere near what the engine radiators have to produce.  Also, even though it might be tempting, I would keep with no larger than 80 injectors.  You'll have a good runner with good engine life.  Good Luck, TomC
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Burgermeister
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« Reply #7 on: July 22, 2006, 09:41:29 AM »

Boss,

What's the difference, besides direction of flow, between the downflow radiators and the crossflow radiators?   The laws of thermodynamics haven't really changed.  What's the reason for the improvement you witnessed over the downflow radiators?   

If you had a choice, which way would you flow water through an engine, block to heads or vice versa? Std is block to heads. 

Tom,  Jim Shepherd attempted to cool his Charge Air Cooler  CAC with electric fans.   He couldn't get it to work sufficient to get the inlet temp to the required temp.  It may be that the fans could not overcome the pressure differential.  In any case,  Jim had other issues besides, so my comment is anecdotal.   DD S-60 specs require a max inlet temp, otherwise you start burning valves.
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ChuckMC8
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« Reply #8 on: July 22, 2006, 09:57:41 AM »

FWIW,What I will be installing (and needing to cool) is an 8V71TA with 7C75 injectors, build tag says 370 hp @ 2100 rpm It has a HT740D mated to it that I will install as a package (my bus has a HT740D installed from the factory) but I will use the trans thats already with the TA engine.
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« Reply #9 on: July 22, 2006, 10:02:21 AM »

Hey Marc,

Now you want me to believe that misters are not standard equipment on military equipment. LOL.  Roll Eyes
You will take all the fun out of combat if you never have to get out of your tank and refill the mister water tank. LOL.  Grin

Dale
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DrivingMissLazy
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« Reply #10 on: July 22, 2006, 10:50:24 AM »

Hey Marc, how does the coolant get aerated? I thought it was a pressurized system? And if it somehow gets aerated that would be internal, wouldn't it, not external where the misters are? Are you implying that the external misters create more internal aeration of the coolant which increases the coolant temperature? Would this not show up on a coolant termperature guage?

My actual mountain driving experience indicated that the mister would drop the coolant tmemperature at least 20 degrees within five minutes.


Hey Marc,

Now you want me to believe that misters are not standard equipment on military equipment. LOL.  Roll Eyes
You will take all the fun out of combat if you never have to get out of your tank and refill the mister water tank. LOL.  Grin

Dale
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Burgermeister
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« Reply #11 on: July 22, 2006, 01:51:52 PM »

Richard,

Where are all these ideas cominng from,  I gotta go back and look at my post!  LOL !!

Due to a physical chemistry phenomenom called "partial pressure"  as the temp of the coolant rises it has a greater and greater tendancy to go into vapor.  100%  partial pressure is when the boiling point is reached.  The partial pressure is IIRC expressed as the percentage of the ambient pressure, so  50% partial pressure in a 30" Hg system would be 15" Hg.  As typical engine temps I wouldn't doubt you're above 80% PP so it doesn't take much delta P to "trick" the coolant into thinking it's time to boil (actually no trick just a plain and simple immutable law of physics)

The coolant will seriously aerate when the total resistance or restriction between the outlet from the thermostat housing as compared with the inlet to the coolant pump exceeds 10" Hg.  This can happen for all sorts of reasons, principally precipitation of silica and phosphates from the coolant additives in the radiator core.

The suction from the pump drops the internal pressure so that "tiny bubbles" form in the "wine" of the engine coolant.

Coolant passages in the block and heads typically induce aeration for other reasons.  Aeration is always present, just to what degree.

The aeration is internal for the reasons given.

No,  external misters don't create internal aeration. (RICHARD!!!!!)

Misters don't increase coolant temperature!   (RICHARD!!!!!, RICHARD!!!!!)

The bubbles in the coolant are tiny  insulators and restrict the ability for the coolant to pick up heat  - more than the drop in temperature of the mass of the (mister cooled) coolant increases the POTENTIAL for the coolant to absorb more heat  (which it would if it werent for the "tiny bubbles")

Depending on the conformation of the cooling system in its entirety,  sometimes extra steps to de-aerate the coolant must be taken.

These steps have the potential of permanently improving coolant system capacity, won't Trick the engine into damaging overtemps and are less maintence and hassle than misters.

You've got a bunch to digest, TTYL
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Happycampersrus
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« Reply #12 on: July 22, 2006, 03:40:28 PM »

Hey Richard,

I was just making a funny, I thought. Grin

My Actual Mt. driving is I don't need misters Tongue. I live on top of Fancy Gap Mt.in Va. about 4k feet, although that is not as high as the folks out on the left coast. I do believe that a cooling system can be designed, so you wouldn't need misters.

To add to the debate I think that a cross flow system is just to picky to deal with. For example the chance of a cross flow radiator to have an internal leak and cause aeriation is greater than a downflow radiator. Not to mention a cross flow is harder to burp the air from.

Dale
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DrivingMissLazy
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« Reply #13 on: July 22, 2006, 03:56:53 PM »

OK, Marc I understand somewhat now. For some reason I was getting the idea that misters caused internal aeration, and I just could not see how. I cannot and do not want to understand all of that! LOL
Thanks for the explanation
Richard
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« Reply #14 on: July 22, 2006, 06:34:51 PM »

Burgermeister....the difference is that the same amount of coolent gets cooled twice (or more),you have to understand how a cross flow radiator is built.On my particular application,inlet coolant enters the left side of my radiator gets cooled as it travels from left to right,drops down to another level and gets cooled again from right to left and then out ,or in some cases drops down a third level, and then out.Same amount of coolant getting cooled twice or more ,depending how you want them to build it.Being that it takes longer for the same amount of coolant to be cooled,the tempertures are lower. Its not from point A to Z as in a downflow design.Its from Point A to Z then back again to A.  This is more or less how it all works

In so far as which way I would like to have the water flow...block to head...I have no problem with.

Well got to go,my 8V92T just arrived with jakes, radiator and they also gave me a fan,god bless them.....*smiling*.....HTH......Frank
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