Engine/Transmission (1998.5 - 2002) Effect of "non-use" of intercooler when dyno testing

[jlccc]

Do very many dyno facilities have a big fan to simulate a 50mph+ "breeze" when testing? Charge air cooling is very important on our trucks and I wonder how much of a hp penalty is incurred on the dyno when there is no forced air through the intercooler. Anyone have some direct experience here? Curious minds want to know.

 

[DieselB59]

I wouldn't do that. I've documented that my turbo compressed air coming into the intercooler is about 300-400 degrees, whereas exiting the intercooler, it's between 100 and 150 degrees. Taking away the intercooler will make a loss of power, as colder air is more dense, as well as making massively high egts. The intercooler is there to make more power safely.

 

[RobbyRam]

I've had my truck dynoed twice and both times the operator had a fan blowing into my radiator.

Bob

 

[jlccc]

Originally posted by DieselB59

I wouldn't do that... Taking away the intercooler will make a loss of power, as colder air is more dense, as well as making massively high egts. The intercooler is there to make more power safely.

That's exactly my point. But the one time I dyno'd my truck, I don't believe there was a fan feeding air through the intercooler. I was curious as to the hp penalty that likely resulted.

 

[Jim Fulmer]

What Chris Timochko is talking about makes sence to me, Aircraft like what I fly on (707) don't use refrigerant to cool the air you breath, what they do is compress the air with a turbo (called an air cycle machine on the acft) then when it's released after being compressed it super cools the air cause it's going from a compressed state to an released state so quick. I would think the intercooler would do this to an extent requardless if there was any air being pushed across the cooler... ... ... What is your thoughts.



Jim

 

[Steve Campbell]

I think John is ....

talking about leaving the "charge air cooler" in place, just wondering what the difference in HP output is with the truck standing still vs simulating a 50 MPH headwind. Maybe I am wrong, but I read Chris's post as if he thought John was removing the "charge air cooler" (intercooler) from the system. Maybe I misread what they were both saying and apologize if that is the case. Not trying to start a war here!!!

 

[MikeR]

I see the confusion too.



jlccc is not asking about removing his intercooler, he is asking if there is a hp loss by not putting a big fan in front of your truck to simulate air flowing through the intercooler/radiator while the truck is running on the dyno.



To answer his question with my experience... . I have done it both ways and I haven't seen a difference at 450-ish hp.



-Mike

 

[jlccc]

Originally posted by MikeR

jlccc is not asking about removing his intercooler, he is asking if there is a hp loss by not putting a big fan in front of your truck to simulate air flowing through the intercooler/radiator while the truck is running on the dyno.



To answer his question with my experience... . I have done it both ways and I haven't seen a difference at 450-ish hp.



-Mike

Bingo, we have a winner. Thanks Mike. (Although I don't understand why the intercooler didn't increase the hp, even if only by 10hp or so).

 

[NVR FNSH]

Originally posted by Jim Fulmer

What Chris Timochko is talking about makes sence to me, Aircraft like what I fly on (707) don't use refrigerant to cool the air you breath, what they do is compress the air with a turbo (called an air cycle machine on the acft) then when it's released after being compressed it super cools the air cause it's going from a compressed state to an released state so quick. I would think the intercooler would do this to an extent requardless if there was any air being pushed across the cooler... ... ... What is your thoughts.



Jim

Jim, You sure the air is being compressed by the air cycle machine? My bet is that the 707 system pulls bleed air off a medium pressure stage of the compressor and expands it thru a turbine to cool it. Later model systems do use a compressor and a turbine but the power to compress the air has to come from somewhere. Either the engine or the ACM turbine.



Brian

 

[WestTN]

non-use

You have a fan on the engine that has a thermally sensitve hub. When things heat up the fan kicks in.

My $. 02

 

[Jim Fulmer]

NVR FNSH It's from 5th or 9th stage air depending on the demand, at 20 PSI 9th stage comes in play and 5th is regulated to 58 PSI, both are cooled by the fan air control valve to 360-420 degrees F then is plumbed to the ACM were it goes through one side of the heat exchanger then through the ACM back to the other side of the heat exchanger then is either compressed further or by-passes the other side of the ACM depending on the temp requested by the user via pack temp control, low temp is 40 F. The 707's (Navy) are 88' and 89' models, last ones off the Assembly line and are a 320 airframe.



Jim

 

[DieselB59]

Oops, having a bit of a senior moment there. I did read it totally wrong. Way totally wrong, but either way, just pushing the hot air across the tubes of the cooler does help even when standing still. You probably will get better results if air was blowing onto the cooler besides the draw of the fan.

 

[NVR FNSH]

Jim,

If I remember correctly that system is referred to as a boot strap system. The pressurized air going to the cabin is from the outlet of the turbine side of the ACM. The turbine extracts work and as a result pressure & temperature are reduced. I worked for AlliedSignal on the heat exchangers in the ECS - aka A/C for airplanes.



Are you at Tinker?



Brian