adding CAC to existing dt466 motor

[hemivolvo]

hello im a 40 year gas mechanic and now own a motor home with a 1979 international dt466, have been driving this thing for 4 yrs everything is fine just want a little hill climbing power when towing my boat.
i came across a charge air cooler [brand new] for a good price and from what i have read thought this could be a good idea, i fabricated different inlet and outlet tubes as well as hot and cold pipes, install went pretty well, it sits in front of my radiator and links up with about 2 1/2 foot tubes, i removed the stock cross over tube from the turbo to the intake manafold. before installing i had 15lbs of boost max now i have 10lbs, before you jump to an awnser i have checked for leaks i got ahold of a test kit and tested the thing installed with the hot and cold tubes installed i plugged both tubes and put 10lbs of air in sealled it and lost 1 lb of pressure in 15 miniuts way better than industry standards for leakdown. does this make senceto anybody any help is greatly appreciated

[griffy71]

Just a swag....

As far as 10 lsb versus 15 lbs. If the system was originally designed to work without a cooler, then the cooler may be doing its job. In doing that though, air contracts as it cools, expands when it heats, etc. Kinda far fetched but not outof the realm of possiblity.

The other possibility is excess pressure drop trying to shove all that air hrough the cooler. Friction loss could possibly be playing a factor. Try to find some performance specs on the CAC.

[hemivolvo]

thanks for the reply from what ive learned today the charge air cooler is if any thing too big, cooling too much. I believe your on track the turbo puts out a certain volume of air when hot,that specific volume is X number of cubic feet when cooled that volume is smaller thus the boost is less. the turbo on this truck is rather small by modern cac standards, im in process of locating a later model bigger turbo for the newer 466, should put me back up to 15lbs or maybe a little higher. now im not sure if i would have to change injector size a little bigger to compensate for the larger air volume. am i on the right track?
thanks for yor time

[griffy71]

While I am not a DT466 Expert, bigger turbo will likely want more fuel. A chip might do, or you can go to bigger injectors, depending how much turbo you put in. Unfortunately you open Pandora's box here because more pressure, air and fuel is going to stress thee head studs, then you replace those. After that, well actually way before that, you oughta spring for gauges. If you do get new injectors, and if you have a HPOP, depending how big you go it may need upgraded. Don't be fooled by the black smoke crowd. Black smoke is unburnt fuel. SEnd me the specs on your CAC and your engine. Do you know what turbo yourr currently running?

[hemivolvo]

Originally Posted by griffy71

While I am not a DT466 Expert, bigger turbo will likely want more fuel. A chip might do, or you can go to bigger injectors, depending how much turbo you put in. Unfortunately you open Pandora's box here because more pressure, air and fuel is going to stress thee head studs, then you replace those. After that, well actually way before that, you oughta spring for gauges. If you do get new injectors, and if you have a HPOP, depending how big you go it may need upgraded. Don't be fooled by the black smoke crowd. Black smoke is unburnt fuel. SEnd me the specs on your CAC and your engine. Do you know what turbo yourr currently running?

thanks for reply first this is a 79 210hp dt466 with mechanical inj pump of the early round design so there is no CHIP as there is no electronics
what do you mean gauges i have a boost gauge and have ordered a EGT hope to get it on next week, i think its the most important
dont know what a HPOP is
i dont want to over do this so i dont think head studs will be an issue i just want to get back to 15lbs boost with cold air
the engine is 210hp dt466
fuel rate@adv bhp is 99.9@210
inj timing is 17deg btdc
turbo is model to4b-25 #684 698 c91 a/r 1.32
im thinking the newer to4e17 turbo and if needed one jump up in injectors i hope the injectors are not needed
as always thanks for your time

[drcampbell]

Originally Posted by griffy71

... As far as 10 [lb/sq.in] versus 15 [lb/sq.in]: If the system was originally designed to work without a cooler, then the cooler may be doing its job. In doing that though, air contracts as it cools, expands when it heats, etc. Kinda far fetched but not out of the realm of possibility.

The other possibility is excess pressure drop trying to shove all that air through the cooler. Friction loss could possibly be playing a factor. Try to find some performance specs on the CAC.

Well said. For confirmation, check the pressure at both the inlet and outlet of the CAC. That'll tell you the pressure drop directly. Chances are, you have increased the airflow into the engine - get out your high school physics book, look up the Ideal Gas Law (pv=nrt) and calculate the before & after mass flowrates.

Originally Posted by hemivolvo

... i dont want to over do this so i dont think head studs will be an issue i just want to get back to 15lbs boost with cold air ...

If you want to climb hills at a higher speed with a load, you need more power, period.

To get more power, you need more torque, more rpm, or both. I assume you're already running up to redline before shifting, so that leaves more torque.

More torque means beefing up the drivetrain. More torque also means more cylinder pressure, which means beefing up the engine. To achieve more cylinder pressure, you need higher cylinder temperatures, which means more fuel. Once the injector pump is injecting at its maximum rate, the maximum power is achieved with just enough air to completely combust all the fuel. (stoichiometric air:fuel ratio) After that point, pumping in more air without more fuel will just quench and cool the air-fuel mixture, resulting in a loss of torque/power.

The upshot: Without more fuel, the CAC is irrelevant and might as well come out. With more fuel, it becomes a fairly complex re-engineering problem with the potential of harming the engine.

[Evel486]

The pyro (EGT) gauge is a good idea. Then turn up the fuel on your injector pump to get your boost but watch your egt gauge. The DT466 is a much stronger built engine than just about any automotive diesel out there so you shouldn't have to worry about head studs etc. Probably no need to go to bigger injectors yet either.

[hemivolvo]

Originally Posted by Evel486

The pyro (EGT) gauge is a good idea. Then turn up the fuel on your injector pump to get your boost but watch your egt gauge. The DT466 is a much stronger built engine than just about any automotive diesel out there so you shouldn't have to worry about head studs etc. Probably no need to go to bigger injectors yet either.

boy i love information, as first stated im a gas mechanic, this is my first deisel, i didnt know the inj pump is adj, i have a factory manual for the 466 and it does not go into tunning, ill do some research on the inj pump. thank s for advice ill get my egt hooked up and do some testing with the CAC and without its simple to un hook the cooler and go back stock.
it should also be simple to test for pressure drop of the cooler i dont think it is restricing my flow but ill check the cooler is 36in by 24in 2in thick with 30 or so flow tubes built by radiator specialtys in calif when i cut the tanks off for modification to fit the buss i was amazed how large the flow tubes were. i believe it was built for a big marathon provost bus as there factory is neerby and i got it from an auction handeling some of there stuff .
thank you both for the info
by the way what does HPOP stand for just curious

[RD97]

Originally Posted by hemivolvo

by the way what does HPOP stand for just curious

HPOP is the High-Pressure Oil-Pump. It's used by some engines (the 7.3L and, I believe, the DT466e) to power the hydraulic unit injectors (HEUI's). As your engine has an honest-to-goodness injector pump, you won't have an HPOP.

[hemivolvo]

well ihave done a lot of testing and reaserch
my boost pressure went down and so did my EGT
my speed on hills went up ever so slightly
to refrase i lost 5lbs boost max about 21/2lbs just medium cruise, EGT droped across the board about 100 degree from 1000 to 900 max, from 800 to 700 with 21/2 boost was able to maintain over 50 on a highway hill used to slow to 49 and down shift to third
checked ALL the posts on different forums, found much good info on adj 84- 90 inline pumps, found two reference to adj early rotary pumps that both state it can be done just didnt know how
went to oregon fuel inj today i wanted to pay them to adj pump up a notch, said they cant for safty reasons i need to remove pump and get it rebuilt,the guy was very helpful and said i could do it myself, said under the cover is a bolt with two lock nuts and to move bolt toward front to increase fuel, since i wasnt spending any money he wouldnt say how much to move bolt as in 1 turn at a time or two turs or even 1/2 turn
does any one out there know about early pre 1980 rotary pumps, and how to adj said pump?
my thery at this point is on on the right track the boost and the EGT went down so a little more fuel will bring the EGT back wich should spin the turbo back up and i get my boost back with more hill cruising speed
im not trying to get massive HP just improve on a well running bus with a little modern technology

any input is greatly apprecated thanks for your time

[CDX825]

Your on the right track. Now that your EGTs are lower you will be able to add more fuel and get more power. Just don't want to go to high as you will melt the pistons.

Where is the probe mounted for the pyrometer?

[hemivolvo]

Originally Posted by CDX825

Your on the right track. Now that your EGTs are lower you will be able to add more fuel and get more power. Just don't want to go to high as you will melt the pistons.

Where is the probe mounted for the pyrometer?

abouttwo inches after the turbo, the DT has a cast down pipe from the turbo to the exaust pipe itself, i drilled and tapped for the probe

thanks for the input still need some pump info anybodyknow these pumps?

[drcampbell]

The temperature you need to monitor for not melting your engine is the engine exhaust gas temperature, not the turbine exhaust temperature.

A turbocharger works by pulling energy out of the exhaust gas. The turbine outlet temperature will be hundreds of degrees lower than the turbine inlet (engine exhaust) gas temperature.

[LMJD]

The engine doesn't have studs, it has head bolts. Rule of thumb on bigger diesels, EGT thermocouple pre turbo versus post turbo, 300 degree difference. I'd play it safe on a DT466, put a pipe plug in the hole you drilled, re-drill pre turbo for accurate EGT reading. Plenty of room and easy to do. You probably have a Bosch injection pump if I recall correctly, the fleet of DT466s our shop maintained during that era had Bosch pumps. Stands to reason, an overly large aftercooler will drop boost a bit.

[drcampbell]

Originally Posted by LMJD

... Stands to reason, an overly large aftercooler will drop boost a bit.

Boost pressure is down, but the temperature is probably down even more and the amount of air getting into the engine is probably up. (which is why I suggested using the Ideal Gas Law)