Hey, whats the ideal compression for pistons?

 

it depends..for forced induction engines, it will be lower. maybe around 8.8:1 like the 4G63. For NA engines, it will probably be higher around 9.5 or 10:1. It can vary a lot tho

 

It all depends on how much performance you want from the car, fuel octane, ignition timing, induction/intake, bore and stroke, block strength, cylinder strength, rod strength, etc. etc. etc. So like Bobaab said, there's a lot of variables.

 

well say i supercharger my car and want an ideal compression that runs enuff psi to at least beat an evo, then wat compression values do you think i am looking at then?

 

Beating an Evo is a myth.

Optimum compression ratio for forced induction is 8.8:1.... that is the sweet point of torque and HP. Any lower you sacrifice TQ, too high is not boost friendly. Of course for our cars anything between 9.0 and 9.5 to 1 will work perfectly.

 

Trouble with beating an evo is if the evo gets modded your out of it's league with out forking over some serious cash... if your talking about beating a stock evo then just leave your compression the same and go forced induction. There are a couple good kits to use for this and as posted the RRM kit(Stage 2) puts out power equal to the evo and the lancer has less weight. Beating the AWD is the real trick to get around.

 

stock compression is good enough for quite a spin, beating a stock evo, yes, but if you have the cash and time to put in a full standalone ignition system, and to completely, i mean, COMPLETELY rebuild your entire motor, then you could expect beating modded evos with dropped compression

 

going lower than 8.8:1 compression doesn't sacrifice much. My SR runs 8.5:1 CR and it has plenty of torque (over 200 from the factory) and leaves headroom for some lofty boost numbers.

 

Lowering the CR . . . I can feel the difference between the 1g and 2g DSM.