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gu 2.8 boost

Posted: Sat Apr 07, 2007 5:10 pm
by mr nismo
I have a couple of questions that some of you could probably answer.
I have a GU 2.8 which has a 2.5" mandrel exhaust, and a steinbauer chip.
I am only running standard boost, would there be any harm done turning it up a little???
Since the chip was fitted, it does blow a little more black smoke so i can only presume the fuel has been turned up, so you would think the boost would help a little to make more power. I know a guy who had a motson chip fitted and his was running 14.5psi boost and mine (according to the guage) is 11psi.

Also have a mate that says a dump pipe will produce 1 or 2 psi more boost?? Is this possible? I dont undersand how it could.

Posted: Sun Apr 08, 2007 9:06 pm
by mr nismo
Im guessing nobody knows????
How much boost are others out there running on their 2.8 GUs???
Does 14 PSI seem too much?

Posted: Sun Apr 08, 2007 9:43 pm
by PGS 4WD
Boost is a juggle, without an intercooler more boost may just mean more heat, also a small turbo turning fast to produce more boost also produces more intake air temp, this means higher combustion temps and higher exhaust temps. I suggest get a pyro and get yourself onto a dyno, I find most std turbos over 11-12 psi generate excessive air temps and there is often no increase in power above 11-12 psi.
Imagine a pressure cooker with nothing in it but sealed, put it on the stove and as it heats up the pressure gauge goes up, there has been no increase in volume, there are no more molecules of oxygen to combust, in fact the additional heat without the addition of volume will cause a drop in power. Boost isnt actually what makes the engine more powerful its the increased volume of air.
Joel

Posted: Sun Apr 08, 2007 9:57 pm
by mr nismo
OK COOL.
IT DOES HAVE AN INTERCOOLER.
WILL HAVE TO GO BACK TO WEST END AND GET THEM TO PUT IT ON THE DYNO.