TheWhopper

Is there anyone out there with JDM ITR pistons (p73-00) 81.25mm - all other internals stock - running a JRSC on a GSR?

Had my head rebuilt so I'm in a process of getting my block rebuilt.

My GSR is a daily driver so I'm not going to go crazy on it. I'm only using OEM parts for the rebuild. The only thing I'm modifying are the pistons. Sort of leaning towards the JDM ITR pistons (81.25mm).

I figure I'd go with the slight overbore (+.25mm) to make sure the cylinder walls aren't tapered or out of round..and to get a little more "umph" in the motor.

Is the increase in compression and slight increase in displacement counter productive when adding a JRSC?

Someone suggested it would be better running a lower boost on your JRSC while slightly increasing the compression.....but.....you would have a smaller room for error when getting the car tuned.

Thanks for any input.

integrawow

I'm also curious about this seeing how a roots charger always seemed to be better suited for lower compression. However, I do happen to see that B16's are running them, and they have approximately 10.4 to 1. Then it goes back to the camshafts such that if you bump up the compression ratio, then you could use a set of larger cam profiles to reduce the dynamic compression ratio that was increased by putting in a higher compression set of pistons. In the end, the larger cams should improve power, and the roots charger will like it more.

To be honest with you, I wouldn't even bother with the ITR pistons with a roots charger. You can safely run more boost with a lower compression setup. The thing to remember is that you're going to make more horsepower per pound of boost than you would make per point of compression. That's just me though.

By the way, I was wanting to put a Jackson setup on my GSR for the first time in its life. How has it worked out for you? How much boost are you running with it now? Any problems?