Compression ratio and tuning - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Nevyn04 · 12-15-2013, 08:36 PM

I know keeping your compression low allows more boost. And the reason we prefer boost is because it can be cooled after compression whereas engine compression cannot. But, my stock turbo is only efficient up to about 15psi. So i figured a decent compression will allow me to make the most of that limited boost level. But i guess 9:1 will give a decent bump, all the better without requiring new injectors or ecu, and allow for later turbo upgrade and more boost.

Eventually I plan to run Nistune for tuning.

Reason i'm looking to rebuild the motor now is because not sure when the last time the timing chain was replaced and have valve cover gaskets leaking oil. Nothing serious. But while getting into it I figured replacing all the seals so I know when everything has been done would be a good idea, and just feel that 7.8:1 compression is way too low.

So my issue now is to find out if the NA pistons will clear my valves. Anyone have experience with this swap?

I can buy the NA pistons new aftermarket, the ones I found come with floating wrist pins. I'm not sure if my motor is "W" series or not. If it is not and it has press fit pins can I use the pistons with floating pins?

12-15-2013, 08:36 PM	#1
Nevyn04 Join Date: Aug 2013 Location: Florida Age: 37 Posts: 16 Trader Rating: (0) Feedback Score: 0 reviews	I know keeping your compression low allows more boost. And the reason we prefer boost is because it can be cooled after compression whereas engine compression cannot. But, my stock turbo is only efficient up to about 15psi. So i figured a decent compression will allow me to make the most of that limited boost level. But i guess 9:1 will give a decent bump, all the better without requiring new injectors or ecu, and allow for later turbo upgrade and more boost. Eventually I plan to run Nistune for tuning. Reason i'm looking to rebuild the motor now is because not sure when the last time the timing chain was replaced and have valve cover gaskets leaking oil. Nothing serious. But while getting into it I figured replacing all the seals so I know when everything has been done would be a good idea, and just feel that 7.8:1 compression is way too low. So my issue now is to find out if the NA pistons will clear my valves. Anyone have experience with this swap? I can buy the NA pistons new aftermarket, the ones I found come with floating wrist pins. I'm not sure if my motor is "W" series or not. If it is not and it has press fit pins can I use the pistons with floating pins?