I read on another thread that the JDM engines that were 10:1 also had sodium filled valves. I thought the sodium filled valves were only on the DET engines, but I am rarely correct about that stuff.

Now my question is, if it is true that the 10:1 engines have sodium filled valves, can I put 10:1 pistons in my US engine without putting in new vavles?

Yes you can it will be fine. People go up to crazy compr3ession like 11:1 or 11.4:1 and stuff on the stock valves.

Brent

Thank you coach. You are a gentleman and a scholar.

I have 10:1s in my '96 motor. I'm still using the stock valves. I only have 96 miles on the motor, so I can't tell you how the new pistons feel yet.

Most newer 10 to 1 motors have sodium filled valves. There is no problem with running a motor even at 11 to 1 with stock valves. You will be fine

now my big question here, is how much extra power would we be pushing by upping our compression to 10:1 or even 11:1?

the JDM engines are 10:1 and they pull like 10 HP on the US SR20, you should expect even if not better gains.

Brent

Originally posted by coach
the JDM engines are 10:1 and they pull like 10 HP on the US SR20, you should expect even if not better gains.

Brent

Actually, they are 150ps which is about 145-147hp. Much of that is due to the tubular exhaust manifold. A half-point of compression is only good for a couple of hp. Going to 11:1 isn't worth all that much either. It's something to do if you are building an engine - you know, while you're in there. But I wouldn't go out of my way to get 11:1 considering the expense.

Oh, I thought those HP numbers were JDM motors with US intake and exhaust manifolds. Well, now I know. I agree then, if the compression isn't giving you numbers it isn't worth it right now.

BRent

That's the only reason I am doing it. I took apart my engine just for kicks, really, and thought "Why not put in 10:1 pistons while I am in here?" Thanks all on the all good information.

Originally posted by nissan_dan
That's the only reason I am doing it. I took apart my engine just for kicks, really, and thought "Why not put in 10:1 pistons while I am in here?" Thanks all on the all good information.

You do strange things for entertainment. ;)

But, as long as you're in there, you should go with NA Z32 pistons. They are a 1mm overbore and will yield 11:1. You'll need your ECU remapped to run that much compression though.

I'd love to do the Z32 NA piston mod, but with work being as sketchy as it has been latley, I really can't afford the $500 JWT ECU Reprogram. Also I am getting married in December and want to buy a house, so the SE-R has to be a low budget project.