Celica Forums General Discussion Exterior Can someone explain P.S.I's?

i would like to know what is PSI...and if you turbo a car what is the safest PSI to run on with out changing the internals? And how many horses per PSI...someone told me it was 10 horses for every pould of pressure, or sumin like that...is that true?

PSI is a unit of pressure (pounds per square inch) and I believe refers to the amount of pressure that the forced induction method of your choice puts on your intake.

as for the safest pressure you can put on an unmodified engine, it totally depends on the engine and how much you want to risk. Any form of forced induction is going to put your engine at risk, and the higher the pressure the higher the risk.

A modest boost of 4-6 PSI is usually ok, especially on a GT, but even 6 on a GTS can be risky due to the GTS's higher compression ratio.

However, a friend of mine had a modified supra engine that he ran at ~28 PSI successfully (which he soon thereafter destroyed)

As for the gains, it again depends on the system and the mods already on the car... if you are using a stock exhaust then there is a limit to the amount of air that the engine can put through the system regardless of pressure.

as a point of refrence... the west corvina toyota site claims that their turbo kit will put out ~230 hp on a '00 celica GT w/ 6 PSI (from ~140)

hope that helped

PS- anyone feel free to correct anything they think is wrong... i'm not exectly an expert by any means

Thanx for breakin it down...i have a greddy evo exhast will i beable to put 6-8psi...and what will i have to modify?

changing your exhaust has very little if not NO significance in how much boost your engine can handle. it's all all about compression!!! internal eng mods. lower compression pistons are great for more boost. the lower the compression, the better for turbos or s/c's. that's why the gts is having problems with forced induction. we have some God awful high comp pistons!!! 6 psi is probs the highest it can handle stock...this sux...

Honestly i love turbo's like the next guy nothing scares anyone more then a swooooooosh when you hit the next gear but if you truely wanna be fast go all motor tune that B*tch to run 240 all motor horses on a gts and i promise a 240hp all motor car will get you moving and more respect then a 4psi turbo just my 2 cents

Check out these two sites, they have some good info for you

http://www.superchargersonline.com/techarticles_detail.asp?RecordID=13

http://www.superchargersonline.com/hp_calculator.asp