If I change the pistons in my civic (1.6sohcvtec a/t) do I have to get the compression adjusted at a shop or does it just change by itself from the different pistons. Do I have to get my rev limiter changed too? Also, what are the best pistons to get, in terms of power gains?

 

Well, first of all what is your goal for the car? Are you trying to raise compression and go N/A, or do you plan on boosting? Which pistons you go with is heavily dependant on which route you plan to take.

Which motor is it exactly? z6, y8?

 

The compression changes with new pistons because the piston surface changes the shape ofthe combustion chamber. High compression pistons make it smaller squeezing the fuel/air tighter to make a bigger boom.

One point of compression is roughly equivalent to 1psi of boost. So, if you bump compression up to 12:1 on a z6, it would be like driving around with 3psi all the time.

 

The definition of compression ratio is the volume inside the cylinder at bottom dead center (BDC) divided by the total volume inside the cylinder at top dead center (TDC). So in an engine with a 9:1 compression ratio, the volume inside the cylinder is 9 times greater when the piston is at it's lowest point compared to when the piston is at it's greater point. Like street sniper said when you change pistons you change both of those volumes because you are changing the shape of the piston. That is why the compression of your engine changes.A shop does not change the compression of your car, it's purely a mechanical thing.

 

so just out of curiosity, just getting new pistons with a different compression ratio will give you noticable gains? I asked a similar question a while ago and all i was told was that they would give you more reliability and could handle harder use (i.e. high-psi turbo, nitrous, etc.).

 

My goal for the car is to go n/a. It's a z6. I'm looking to put it up to 200+hp, with no money limit because I'm not doing it all at once.

 

I get what you guys were saying about the 9:1 and 12:1,butwith this compression9.4:1 is the 9.4 just like a regular decimal?

 

Whew... good luck mang Hitting even 150 on the SOHC's has proven to be an expensive feat

 

Yeah, 150ish is gonna be your NA ceiling.

Yes, justpistonswill give you a noticeable gain. Each point of compression should be ~ 8-10Hp.

In the compression ratios the 9.4 is just a regular decimal.

 

thanks Sniper, i didnt know that and they'll also give you reliability like i mentioned earlier?