Boost in compression... HP gains?

[sparq]

When boosting compression on a lower compression motor ~ what kind of gains can be expected? Like I know with the H22a, if you go from 10.6:1 like the 92-95 motor, versus the 11.0:1 of the OBD2 you go from 200hp ~ to 220hp... ever .4 increase = 10% ? Is there some kind of rule of thumb or ????

Just as an example, say I want to take a 9.6:1 motor upto 12.5:1 to go all motor... what type of gain do you think I would be looking at?

[texan]

The H22 doesn't gain 17hp (the 220 figure of the Type S motor output is in Ps, which converts to 217hp) from compression alone, the Type S motor has a laundry list of small changes in parts and tune to provide that extra bit of power.

There is no hard and fast rule to how much a point in compression will give you in terms of power, since it depends heavily on the engine's state of tune at both compression ratios and what fuel is being used. Generally though, you can rely on the fact that 1 point in compression should be worth around 4% more power, with much of that coming at the lower PRM range of the scale. Higher compression pistons really boost idle and low RPM engine vacuum, which also allows you to run bigger cams for magnified high RPM power gains.

If you were to bump compression on any motor running pump gas to 12.5:1, it's my opinion that you'd run into a lot of tuning problems. You just won't see signficant or even reliable power gains and engine running with c/r's over 11.5:1 on pump gas, the tuning required to get an engine to run at those kinds of ratios is not something you can set and forget. And of course you'd also need to do more than just bump compression to optimize the setup, static compression ratio is just one of the many things required for high output NA motors.

[CiVTEC]

Put a 16:1 compression ratio and you'd be running diesel fuel!

Does anyone know the compression ratio of a Civic EX 99?

Can I just install thinner gaskets and obtain a higher compression ratio?

[F20C]

head gasket give you such small c/r boost.

[F20C]

Anyways listen to Texan he is always right.

[eightysix]

Texan is a GENIUS

[cnycivic]

9.6:1

[sparq]

Originally posted by cnycivic
9.6:1

WTF are you talking about?

n/m I see now... dont mind me, blonde moment!