adding a charge-air cooler

[luvrbus]

JC, you cannot take a standard turbo on a DD and make it work on a air to air changes need to be made like a different turbo with different A/R or you will have low boost

good luck

[lostagain]

I remember getting the turbo that is specified for the stock 4-71T. (I don't remember the numbers for it). I just built a basic engine, and am happy with a great increase in power and it runs well.

The 6V92 in my 5C could use some tweeking as well, such as different injectors, different turbo, etc, but it runs well as is, so I will leave it alone for now, at least until I have a really slow winter, 

The moral of the story is that there are many factors involved in building an engine to achieve a desired result, such as port hole size, injector size, std versus advanced timing, size of turbo, etc, etc. As well as tuning like injector height, valve clearances, etc, etc.

The DIY care and maintenance of the bus is what makes this hobby so much fun for me.

JC

[luvrbus]

Yep and if you start with the wrong blower drive ratio and blower you are screwed to start with lol 

good luck

[TomC]

On the subject of turbochargers, on my setup, Don Fairchild used a turbo from a 12.7 Series 60 that has a waste gate to keep the boost below 15psi since I still have the high compression pistons.  It works well with virtually no smoke on a pull.  The only draw back is the long exhaust run where Don had to mount the turbo (above the engine and behind the top valve cover on a V drive).  It takes a couple of minutes to warm up with a bit of smoke-once warm-no smoke.  If you open the engine compartment, you can really feel the difference between the hot side and cool side of the intercooler.  Good Luck, TomC

[rv_safetyman]

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

JC, something is not right here.  You should not have lost half of your boost through the air to air if everything was sealing properly and the air to air was properly sized.  There will be flow loses, but that could not begin to account for your huge pressure loss.  All modern trucks use air to air and the boost is not drastically reduced by the cooler circuit.

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)  

JohnEd, it sounds like you are citing Boyle's Law (http://en.wikipedia.org/wiki/Boyle%27s_law ) but that is for a closed system.  This system is definitely not a closed system.   There is just no way that a properly designed and installed air to air cooler will drop the boost by half.

Jim

[TomC]

Jim is correct.  Considering the new trucks have boost pressures up towards 50psi.  And that's after the air to air.  My guess is that the plumbing was either leaking or wasn't big enough to flow the air properly.  I use 4" hoses for my air to air and 5" exhaust for the 8V-71.  Good Luck, TomC

[luvrbus]

 A older DD turbo will not supply enough volume with a air to air to make much boost DD is very specific on what turbo and blower to use for air to air on a 92 series don't think you will find any info for air to air on a 4-71 engine lol you guys are leaving the blower out of the loop for some reason that thing sucks a lot of air away from a turbo that is why DD mounted those on top of the blower or as close as they could get it for the after cooled engines  

good luck  

[JohnEd]

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

JC, something is not right here.  You should not have lost half of your boost through the air to air if everything was sealing properly and the air to air was properly sized.  There will be flow loses, but that could not begin to account for your huge pressure loss.  All modern trucks use air to air and the boost is not drastically reduced by the cooler circuit.

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)  

JohnEd, it sounds like you are citing Boyle's Law (http://en.wikipedia.org/wiki/Boyle%27s_law ) but that is for a closed system.  This system is definitely not a closed system.   There is just no way that a properly designed and installed air to air cooler will drop the boost by half.

Jim

Jim,

That was my point.  His system was NOT properly sized.  He took a design that did not include a intercooler and added one.  The pressure MUST go down if the turbo is NOT waste-gated due to his cooling the charge air..  Now "how much" it should have gone down is the sticky wicket.  I sure dunno.  But, at least part of what JC experienced should have been anticipated.  Maybe not by him, and for sure not by me, but in retrospect and having the question it clears up.  I asked if JC still had that IC for two reasons:  One is that it is a valuable item and secondly he might pressure test it for additional info.

Jim,

Boyle's law?  Naw, way to brainiac for this kid.  I took High School Physics and have found it to be the most useful course of my entire life....bar none, and I have 4 degrees and a MBA.  I am pretty sure the teacher mentioned "Boyle's Law", or should have, but you can't prove it by me.  I just know that if you heat air it expands and if you chill it it contracts.  Actually Boyle's Law does not apply because in that Law the temp is held constant.  That is exactly not what I was saying.  It is Charle's Law (AKA Chuck) that draws the relationship of volume and pressure being affected by temperature and how. The "hole" thing gets tied together by the "Combined Law", appropriately monicker, that does what you might expect.  Now don't get me wrong....I am not pulling rank on you, Jim.  I never heard of those laws till I read your Wikipedia reference that you kindly included in your reply.  Great info and thanks.   

John the enlightened