My 88 has 225, I think the 91 has 240, the only difference to me seems to be the dual cats. The cam in my 88 350 tpi is alittle better than a 91 350 tpi. are the cats the only difference or is there somehing else to make up the extra 15 hp. maybe more fuel pressure. Anyone

 

I believe dual cats are worth a good 10hp, while speed density may be worth the extra 5.

 

Well 10hp came from the dual cats and 5 came from the lighter weight pistons that they started using.

Kat

 

I know they went to a better cam.

 

The 91' 350TPI in the Camaro was rated at 245hp. That is 20hp better than the 88' which was rated at 225hp.

Here is the breakdown:
10hp Dual cats
5hp Speed Density fuel injection system
5hp different cam(Lower lift and shorter duration, but tighter LSA for better top end)

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89 Transam GTA, 350TPI, auto, 3.27 rear, dual cats, gray.
Magnaflow cat-back,
K&N open element,
Best E.T. 14.63@95mph

 

My numbers were wrong. The 88' 350TPI was 230hp. 10hp came from the dual cats, and 5hp from the SD fuel injection and and cam together for a total of 245hp in 91'. You didn't specify whether you had a camaro of firebird. These numbers are for the camaro. Subtract 5hp for the firebird.

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89 Transam GTA, 350TPI, auto, 3.27 rear, dual cats, gray.
Magnaflow cat-back,
K&N open element,
Best E.T. 14.63@95mph

 

The 5 HP from 89 to 90 wasnt the speed density system itself, as the 305 5-speeds are both rated at 230 HP. Its the higher compression from different pistons on the 350's that makes up the difference.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
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