power levels at lower compression

[12SecGSR]

Is there a set rule as to how much power you loose at lower compression? I dyno'd 258.4hp 184.6tq @ 7psi with a stock b18c, when I built my motor /w 9:1 je's I only made 259.6hp & 197.9tq @ 10 psi. The torque and hp increased substantially under the bar, but I am curios why I didn't get more top end horse power? Torque also slopes off more quickly on top... from 6k to 7.5k I loose about 25 ft lbs, before I only lost about 10 there...

[G3-TEG]

Hmm Interesting question.. I blew my B18C1 as well, and i'm biulding it up as we speak with 9:1 pistons..

Interesting to see what the results would be.. It obvious that if you lower the CR and run the same boost level, you will drop in HP and TQ... but the advantage of lowering CR is so you can run more boost safely... get your fuel management tuned up and you can hit 12+ and that will make up for the HP/TQ loss

anyone have any theories on gains/losses vs boost when you lower CR?

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-Temporarily NOT - TO4e powered

[lundgren]

time for cam gears. Different compression rates, and different crank angles.

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[cfjohnson]

Isn't 9:1 too low for boost levels lower than 12 psi or so? If you're only going to run 10 psi, why not go 9.5:1?

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93 B18C Civic Coupe
Boosted in spirit

[Lithiasis]

I agree that 9.5:1 is a good ratio to run with. Before I sold it, my JRSC at 10:1 and 8 psi had about the same hp as a 9:1 at 12 psi. At the time, I wished I had 9.5:1.

Lithiasis