intercooler piping question

[slimtastic]

im trying to conserve the interior volume of my intercooler piping cause im gona be getting a front mount . but the question i have is if the compressor outlet of my turbo is a little less than 2.5 and the intercooler inlets and outlets are 3.00. would it hurt performance any if i kept the piping from the turbo to the intercooler at 2.5" inches and had the piping from the intercooler to the throttlebody at 3.00 inches(70mm tb also). my thought was that the outlet of the turbo is smaller but the velocity is still the same as it left the turbo and went into the same diameter pipe, than extra restriction would be present and spool up would be a tad quicker. what are ya'lls thoughts.

 

[ijames]

The air will be much cooler and at a little lower pressure between intercooler and throttle body, so if anything you need a smaller pipe there than between the turbo and intercooler. Tony DeQuick said several years ago on the gnttype list that 2.5" pipes were fine down to mid 11's, and that's what he supplied standard on his V2 front mount. PTE and Cotton have always used 3" pipes, and Tony offered them as an option. Bigger won't hurt here so if you have the option you might as well build 3" pipes. Don't worry about pipe volume since the spoolup difference will be unnoticeable (I started with a big neck stock intercooler, then went to the V2 wtih 2.5" pipes and couldn't tell any difference in lag, then to 3" pipes and again, couldn't see a difference). Tony just felt that the bends were sharper in 3" pipe and that made them as restrictive as 2.5" pipe with gentler bends.

 

[bruce]

Originally posted by slimtastic
im trying to conserve the interior volume of my intercooler piping cause im gona be getting a front mount . but the question i have is if the compressor outlet of my turbo is a little less than 2.5 and the intercooler inlets and outlets are 3.00. would it hurt performance any if i kept the piping from the turbo to the intercooler at 2.5" inches and had the piping from the intercooler to the throttlebody at 3.00 inches(70mm tb also). my thought was that the outlet of the turbo is smaller but the velocity is still the same as it left the turbo and went into the same diameter pipe, than extra restriction would be present and spool up would be a tad quicker. what are ya'lls thoughts.

In my I/C delete experiments, I tried 2.25, 2.5 and 3" piping. The 2.25 cost alot of power. The 2.5 wasn't near as bad, and there was not much difference in going to 3".

All I found with a 75mm TB, was the need for alot more Accleration Enrichment, and that the throttle was *Full Open* at like 3/4 of the foot travel, so I had to really lift to get the car out of wheel spin. Thou I'm no where near 10s in the street tune that I run.

If you're marginal on injector, or not able to really dial the Accleration Enrichment, one or the other might see better.

If you look at Lingenfelter's Cavalier, you'll see that he was using the entire intake tract as plenum volume, and I believe the more plenum, the better, thou others will argue.

 

[slimtastic]

so basicly if im gonna do a custom intercooler....i might as well go 3.00". gotcha. my idea was 2.5 for the hot side of the intercooler and 3.00 for the cold side to the tb, in an effort to up efficiancy on the hot side and keep the pressureized air as calm as possible for air dist. past the tb. thanks guys.