Just Dyno'd my 98 2.5 986 with supercharger

[Gary Gaukler]

I find it hard to believe that your car makes 270 hp at the wheels at 7.5psi. 7.5psi is a 51% increase in pressure over atmospheric; 270hp is approx. a 50% increase in rwhp (180 vs. 270). Hence either your supercharger is 100% efficient (which is impossible), or there are some huge gains in volumetric efficiency (which is unlikely). Maybe it's 270 at the flywheel? Even that would seem high...

Apart from this, I echo the comments made by others that unless internal changes have been made to the engine, it is likely to blow up soon at 7.5psi. Adding an exhaust or an intake is not really going to change that.

Best of luck (and I don't mean this in a facetious way)!

Gary

[Aus986]

yea
the kit runs an extra injector.

have pulled the boost to gimme around 240

apparently the suggestions are get it breathing and try to keep it at 240hp at the rears ans it swhould be fairly safe

Aus986

[Gary in BR]

That sounds tlike the TPC kit, they ran an extra injector.

My iA kit should be between 210 and 230 at the wheels so 240 will be safer than 270.

How did you change the boost?

Did you change the pully?


Gary

[Aus986]

not that mechanically minded.

I take it to my mechanic tell him it is running too much boost he returns it.
I am kinda figuring go down to 215 220hp now and with breathing aparatis it will hit a safe 240-250

you can feel the car struggling for Oxygen it is wierd

[MNBoxster]

Originally Posted by Aus986

not that mechanically minded.

I take it to my mechanic tell him it is running too much boost he returns it.
I am kinda figuring go down to 215 220hp now and with breathing aparatis it will hit a safe 240-250

you can feel the car struggling for Oxygen it is wierd

Hi,

It may not be struggling for O² at all, what you feel could be detonation...

Happy Motoring!... Jim'99

[Gary in BR]

I hear of detonation alot but what is it exactly??


Thanks
Gary

[insite]

Originally Posted by Gary in BR

I hear of detonation alot but what is it exactly??

cars are designed to combust fuel. this means that a controlled burn of the air / fuel mixture occurs. the expansion of this reaction pushes the pistons down. this all occurs in a controlled fashion at controlled timing.

detonation occurs if the fuel ignites too early in the cycle. in some cases, pressure and heat ignite the air / fuel mixture before the spark plug fires. if the piston is far enough before top dead center, there is not enough pressure to control the burn and an explosion (detonation) occurs. this can also occur because the spark plug ignites too early due to poor tuning. this detonation is NOT controlled; it is violent, uneven and rapid. it can destroy a valvetrain or break pistons.

higher octane fuel helps to prevent this because it is less volitile and not as likely to prematurely ignite (higher flash point).

[Gary Gaukler]

http://en.wikipedia.org/wiki/Detonation_internal_combustion_engine

Note the difference between detonation and pre-ignition.