adding a charge-air cooler

[luvrbus]

Yep Ralph you can dress these old girls or guys about anyway you choose too they are not the best looking at the party but will stay till the party is over with a little TLC  

good luck

[JohnEd]

        Clifford, yes they had that type turbo aftercooler,forgot about it.   
        The engine must have the correct water ports, N and T engines do not normally have them.
         8-71T engines highest safest, HP 350.-- 8-71TA --- 400 HP ------- Mine about 375 HP and with good radiators gets HOT on I-81 hills,,,, and I have not learned to slow down and down shift soon enough, it is a 740 auto with air only oil cooler.
         Clifford, the person here has an Eagle that they took a 8-71T military, had water ports so they added the aftercooler, moved the side turbo. He had a bad radiator so replaced it at the same time with a new radiator. The Eagle has a standard trans.  On the first tirp 

Ralph,


Thanks for that info.  Three versioins of the 8V71 block...as I understand you.

Set at 375 HP what are you getting for MPG?


Thanks,



John

[bevans6]

What a good thread, I am glad I asked the original question, whatever that was.

My new engine has the aftercooler port hole in the block but it has a pre-heater in it, kind of a diesel blow torch to warm up the air inside the engine so it will start in those cold cold winters...  so I could add an aftercooler, but I won't.  I have no intention of taking off that blower until needs force me to...

So I looked in my book.  In the 1980 V71 manual there were 8V71N's, 8V71E's, 8V71T's 8V71TA's. 8V71TTA's, 8V71TTE's, and a sub-class with a C suffix for California...  There were 8V71N blocks with no after cooler port, and blocks with that port machined in (it's on the flat block surface kind of between the fuel pump and the governor, space for a hose fitting to the cooling system).  There are at least 5 different turbo's.  This leads to many many different combinations.

Brian

[Ralph7]

         I get 5.5--7.2mpg.,the old engine had 70 injectors and was tired, it is a 8-71N and sits in my shed.  My driving is 55-60, but drifts to 65. Full speed on level 71, all according to GPS, speedo not good.
        I replaced the 4 worn throtle ball joints and now have about 1 1/4 in. peddle to full throttle.
        Also I have 1 ea 12V. 50A alt., and 1ea 24V. 50A alt.  .... My soon replace the 12V-50A with a  12V 160A alt.
        My latest addition 4 ea 210 watt solar panels, on roof, so how will this affect??
          I am glad you did also     ?E   ----TT are 2 turbos.

[rv_safetyman]

I thought I would bring this to the top again, as my mind can't grasp not having some kind of air cooling system when a turbo is involved.

Clifford, I want to make sure that you are saying that both the GM you are working on and Don's engines do not have any mechanism/system to cool the incoming air.

If that is the case, then the air entering the engine is well above 250 degrees and probably often above 300 degrees.  I arrive at those numbers through my experience.  My intake manifold air temperature will easily get to 200 degrees - after my charge air cooler.  Admittedly my charge air cooler is not as efficient as some, but I have seen 240 degrees on my first Series 60 engine.

If the air entering the blower is hot, then it will get a bit hotter going through the blower (even with the bypass). 

If the air temperature is over 300 degrees on a long hill (I think that might be low with no means of cooling the air), that is huge when you consider that temperature occurs before the combustion process.

As I say, my mind can't grasp that those temperatures will not do some long term damage to an engine.  On the other hand, there appears to be evidence that the engine can and does do OK

So, is the ability to deal with the high intake temperatures unique to the two stroke?

Anyone got a technical explanation why the engines live under these conditions.

Obviously I am asking because I have become anal about keeping my intake air temperature below 160 degrees in my Series 60.

Jim

[luvrbus]

Jim, DD had the 8v71T no type cooler what so ever DD could get outside the box with their coolers like ALCC shown in the photos,but all engine manufactures CAT,Cummins,DD whoever had engines with just turbos no air cooling that came later with the aftercooled and they all used that also.
Just to be clear I prefer a cooler of some type after or inter I think air to air is the best they need some type cooler JMO,the little aftercooler the  DD uses does help with dropping the temps

good luck

[rv_safetyman]

Clifford, thanks.  Now that you mention it, I have been to a couple of AHTS shows and see old engines with turbos and no air to air.

Now the question becomes, what is acceptable intake temperature for more modern 4-stroke engines (some of the older 4-stoke engines did not use air to air per the above).  I did a ton of looking a couple of years ago and could not find much.  I did find that the charge air coolers are designed for the 50* over ambient, but even the references I found were vague. 

The SilverLeaf VMSpc air inlet temperature gauge has an optional bar graph that shows the red area at about 140-150 degrees as I recall.  I asked Martin where he came up with that value and he said that he was guessing 

In lieu of better data, I guess I will stay with the 160* and hit the misters to keep it at that max value.

Jim

[luvrbus]

Jim, I just got off the phone with Cole he said 165 max for the non EGR series 60, 172 for the EGR 12.7 or 14 L he going to send me the chart on flows and temps then I'll forward it to you he told me your DD dealer should have the chart.
Fwiw he said the flow is the most important part of the system they spent tons of money for research on the flow and temp he got too technical for me on the rest lol your type guy


good luck

[bevans6]

I have a feeling, unsubstantiated by anything in particular, that one reason 2 strokes might get away with a higher intake charge temperature is that the 2 stroke engine is so inefficient, relative to a 4 stroke.  Given that we have twice as many combustion events per rotation compared to a 4 stroke, we don't get even half as much power per combustion event.  That means that we don't generate as much heat and our exhaust gas temps are a lot lower.  Maybe a little extra heat helps a bit, who knows?  I have heard that the blower alone heats the intake air charge to over 200 degrees.

Brian

[Don Fairchild]

Brian a turbo charged 2-stroke engine is twice as efficient as a 4-stroke. You can get more power per cu in to weight ratio then with a 4-stroke. you have half the parasite loss of a 4-stroke.

Don

[HB of CJ]

Have you considered going to a DEDICATED SEPARATE RADIATOR just for the intercooler WATER going thru the air to water DD intercooler under the blower?  Also a dedicated SEPARATE air to air intercooler radiator location that keeps the extra heat from the water engine radiator?

Also consider a much bigger, lower resistance intake air filture?  Finally, have you considered going to 5" intake turbo plumbing with gentle SWEEPS instead of the abrupt tight bend 3" to 4" typical on most installations?  Finally finally, a low resistance LOUD exhaust system that sounds bitchin'?

Like already said, the whole shebang must be designed to come apart into separate pieces soss it can be installed and removed while your mighty Detroit is installed in your Bus Conversion.  Sounds like a whole bunch of fun and games figuring out all of this.  Lower temps, more boost, lesser increased fuel= high power, lower EGT, no smoke, long life.  HB of CJ (old coot)

[bevans6]

Don, I was thinking purely on a per combustion event basis, disregarding the other inefficiencies, in order to translate combustion efficiency into exhaust temperatures.  I was thinking that the intake/exhaust events could be more optimized in a 4 stroke, hence more efficient.  Also the intake porting could be better than dumping air into the air box then through the intake slots in the cylinder.  On the other hand, getting twice as many events/rotation is a handy advantage.  I recall the two stroke motorcycle engines of my youth, expansion chambers on a buddies RD350, and my own Kawasaki 500cc triple that would wheelie at 60 mph in third gear if you weren't careful...  Mind you, it got 25 mpg, had a three gallon tank, and got around 500 miles per spark plug.  It came stock with a set of three spare spark plugs...Ah youth - that seemed so logical at the time!

What is your thought on the charge air cooler debate?  I would love to know what your research has shown!

Brian

[TomC]

Difference between an air to air intercooled 8V-71 turbo and just a straight 8V-71 turbo-with the same 75 injectors, the turbocharged 8V-71 will put out 350hp and 1,035lb/ft torque.  With my setup of the 9G75's and a custom made air to air intercooler with 4" hoses to properly flow, my engine on the dyno put out 375hp and 1125lb/ft torque.  This is why virtually all pickup and big rig trucks have air to air intercooling-makes for the densest air possible coming into the engine.  And as you can see, there is a difference in power with the same injectors.  Good Luck, TomC

[lostagain]

I turboed the 4-71 in my Courier 96 a couple years ago. I built a air to air intercooler for it. I was only getting 8 to 10 lbs of boost with it. I quit fooling around with it and removed it after I noticed the pictures of the 4-71T engines in my DD manual without air coolers. The turbo is plumbed straight into the blower. So that is what I did. I now get 15 lbs of boost and it still works very well after 20 000 miles. I don't have overheating issues.

JC

[JohnEd]

JC,

That seems to make sense to me.  You compressed the air and heated it up.  Then when you cooled that air and it shrank and that registered as a drop in pressure.  The air also became more dense and oxygen rich by weight/mass. By removing the intercooler you increased the pressure but you also increased the temp of the charge air.  The temp bump cost you power and efficiency and the pressure you picked up is only "hot air"....no pun intended nor sarcasm.  I think the solution you might have been looking for would have been a turbo that was sized for your system design considering that you would cool the air.  The "stock" system assumes that you will be dumping that hot air into the blower. I think cool air at 15 psi would net you better all around performance than the hot air design you have arrived at.

Can't argue with success, however.....if you have the power you want then you have arrived.  Did you keep your Inter-Cooler?  That you have no heating problems follows as you now seem to have a "stock" DD designed system.  If you cooled the charge air on you current system you would get a cooler exhaust and I guess cooler is better. (Fonze quote) 

Thanks,



John