Hey guys,

Curious about this one and would like some more input from other experienced guys.
I've been doing alot of SD tuning of late and have been logging inlet air temps over a 3rd or 4th gear WOT pull to get some data on when a turbo is starting to show the end of its efficiency zone.

Whats an acceptable limit of temp increase across a pull to maintain a nice efficient system?

Example 1:

BBKlite, ETS3.5, 30psi peak dropping to 26.5psi above 6500 (3-port)
IAT's were about ~15*C rise across the pull, above 27.5psi at 6500 though they were 30+ indicating turbo is unable to correctly support the requested boost.

Example 2:
Green HTA, chinese cooler, 33psi peak, 32psi flat (3-port)
IAT's were 28*C rising to 45*C across the pull. Unsure whether this is due to the cooler quality or not.

So yeah, what do guys look for as acceptable increases?

Cheers
Ben

 

I'm curious as well, I usually see most people trying to keep temps under 125F tops, but it's hard to use that as a rule of thumb with the variance in turbo choice and intercooler...

 

Thanks for the reply.
So the Green at 32psi was at 113*F after three pulls on the dyno with ~1min between each pull with the Chinese cooler.

 

I would think that would be pretty reasonable. I've seen upwards of 200F on a 16g at 22lbs doing back to back 3rd gear street pulls in ~75F ambient temps.

 

Holy dooley!

I haven't logged any stock turbo and cooler stuff yet, its all large turbo, uprated cooler etc. etc.

 

Yea, it starts to really pull timing at that temp. Makes for pretty pathetic airflow

 

this a much more complex question than you think. the quality of fuel used is a very important part of the equation. and so is the ending temperature, turbo, boost, engine compression, backpressure, etc. that determines how hot the air can be before detonation occurs. I could right 2000 word essay on this. but my one finger typing skills aint gonna cut it.

 

A 3rd gear pull on the street usually causes about a 10 deg F temp rise with my current setup. "acceptable" is a somewhat relative question.

 

94, you've been around the block a few times.

E70, 9.0:1 built 2L, FP Green, 33psi peak, holding 32psi flat.
No backpressure reading.

Just wondering where some of the more experienced guys stop at.

JB?

 

very few people collect this type of data. on pump gas how well your I/C works is very important. Buschur racing posted quite a bit of this data a few years back. he tested most all the intercoolers on the market. he found nothing really compares to the cooling ability of the garrett high density cores. he was reporting cars going to the 1/4 mile and seeing less than 10 degrees Fahrenheit temp rise. and this was ambient temps around 80f. he also quoted logs form one of his customers time attack cars and said the temp rise through four minutes of beating on the car was never more than 25. that was even on a hot 90 degree day.

using a high density core can have some adverse affects. air doesnt flow well through the fins so there is some restriction. both inside and outside of the core. boost response does suffer from the inside restriction. and radiator/a/c function suffers from the outside restrictions. this may or may not be a problem depending on your ambient temps. I have always used free flowing cores. I live in hot climate and I like my a/c to blow nice and cold. I have used alky injection in conjunction with free flowing core. the alky acts as a second cooler. fast spool is maximised through the core. the alky takes up the slack. here some data from one of my setups from 8 years ago.
2.4 liter 35r 93oct alky injection with jets at I/C outlet.
old crappy turbonetics core. very boost responsive
boost 34psi
ambient temp 90f
turbo out temp 325-250f
TB temp 95-100f steady
when alky tank went empty I would see temp shoot to 140-170 in just two gear pull.

e85 can tolerate higher intake temps. saw a post of temps from a compound turbo setup. that ran 9.7 at 140mph. start temp at line was 95f and ending temp was 170f. this was through a 4.5 inch treadstone intercooler.

 

Sweet as mate, thanks for the reply!

Yes i'm very aware of how pump gas is affected by intake temps, I have alot of data floating around on different setups and now with adding this extra element in, it gives you the complete picture just about!