Hey guys...

On my 88 GTA w/350 TPI, the top end is just pathetic. The low end is crazy-power, but as soon as the car hits 4400-4600, its like it drops to 25 hp. The decrease is EXTREMELY noticable. It is a completely stock 350... right down to the air filter. It has a 3" exhaust system with no cat. Would it help if I put in a K&N? Is it like... choking for air possibly? What else could I do that is cheap/easy that would help out my top end? Keep in mind that I dont want to lose an oz. of low end. K&N or no K&N?

My buddies 305 TPI car revs and has power beyond mine... he has decent power through about 5500 or so, and the motor is stock! He said that he put in a K&N, but he 'jokes' about a lot of things like that.

Thanks a lot guys!

ZachS

 

Zach,

It's all about air flow - and the fuel to go with it. If you have an adequate exhaust, the intake may be worth looking into. A knitted air filter certainly can't hurt, but on your larger engine the restriction is most likely at the front end of the intake plenum and significant mismatch at the runner tubes.

Since your engine is relatively stock, there is probably the typical amount of extra metal at the throttle body end of the intake plenum and aroung the runner tubes and intake base. Your 350 should have a much better cam than a 305 automatic, and should have less trouble breathing at higher RPMs. For almost no money ($30.00 for a gasket set) and some time you can eliminate the flow restrictions in the plenum and intake system. If you want to see a little more detail, check this file:

Plenum Porting.pdf. You'll need to have Adobe Acrobat Reader to view or print the file (see link below).

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Later,
Vader
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"No matter how hard you try you can't stop us now"
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