Does anyone knows a good way to increase compression, cuz ours is very low and RSX-S, XRS are 11 or Higher (and they are fast) ours is 9.5

How can it be increased?

Anyone already done it?

 

you can shave the head or you can buy higher comp pistons....

 

Yea, that should do it.... but too expensive to do... how much would it cost to shave the head?

 

Anything less complicated?

 

nope

 

also if you plan on going turbo may want to hold off on that since good ratios for n/a and FI are different.

what kind of gains could you see from the lower comp pistons anyway? and what else would need to be tuned/changed?

 

If your refering to going turbo, I dont know much about it but since you´re already pushing a higher volume of air inside the engine, I guess that if you compress it too much the pressure inside the cylinder will be to high for the rods and pistons to handle...If anyone that knows more can clear things up, it will be very appreciated.

Anyways, as for tuning, you need to tune the AFR for the bigger amount of air pushed in, and also the timing to decrease the chance of detonation.

 

Sow how much would it cost me to shave or cut a Head?

Anyone?

 

Take the filter off your intake, drive around for a few months, and build up a bunch of carbon deposits in your combustion chambers. This effectively increases your CR. Might help if you get a piggyback and richen up your A/F to speed this up.

 

You are saying that if I drive around for two month with out air filter my compression will increase if that’s so... would it damage the engine in the long term?

 

That has to be the worst advice EVER, running your car without your filter out can and will cause irreversibly bad damage to your engine as well as only change your compression unnoticeably if at all!!

 

thanks for the advice

 

i cant belief i just read what i read.im out.

 

^^.....anyway, see if you can find a local machine shop by you. and give them a buzz, i dont know if anyone has done it on a RA so their is no set price. and a machine shop probably will give you a wide price range and wouldn't be able to give you an accurate estimate until the head is out of the car and in their hands. also PM rock at RRM about the pistons he might be able to give you some more info on it.

also yes i was reffering to going turbo. and again rock or one of the turbo guys may have a better idea about changing the compression and going turbo but i think RDC is right.

 

This sounded funny to me, so I hope I can clarify for those who don't know enough to even think it sounds funny

Changing compression has no effect on how much are goes into the cylinder, only the forces that are applied to the air are changed. Higher compression just means that the pressure in the cylinder is higher due to the smaller amount of space at the top of the piston stroke. As the piston goes up it compresses the air. If you shave the head the piston will be closer to the head at the top of it's stroke and compresses the same amount of air into the now smaller space. You will have to tune after this, but not because of more or less air.

And to the OP, those cars you mentioned also have a much shorter stroke so they can produce power up to a much higher redline. This is the main reason they create so much more horsepower, the higher compression just comes along with the shorter stroke as a package. These are high revving high horsepower examples, what do you think they sacrificed to get so high up on the tach?

TORQUE!!!!!!!!!