2G Pistons?

[DSM93]

Can some one please tell me when did the compression ratio go up to 8.5:1 on a 4G63T that had the same O.D as a 93 GSX.
this is my understanding 91 used a 3.3465 93-95 used 3.35 and 99 used 3.3482. and what are the physical differences that one can see when compering a 1G 7.8:1 to a 2G 8.5:1 with the O.D 3.35.

 

[allwheelTSI]

they switched to the 8.5:1's in 95,i'm pretty sure the bore is the same.

 

[GRNDSM]

>Can some one please tell me when did the compression ratio go up to 8.5:1
>on a 4G63T that had the same O.D as a 93 GSX.

CR went up to 8.5 in ’95. Bore never changed.

>and what are the physical differences that one can see when compering a
>1G 7.8:1 to a 2G 8.5:1 with the O.D 3.35.

The difference is in the rods/pins. Small rods are narrower so pistions have less of a “slot” for the rod and wrist pins are larger in diameter. People who use 2G pistons in 6 bolt 1G’s must have their rods machined to fit the pistons. However, 7 bolt 1G’s rods are the same as 2G rods so you can install 2G pistons with-out any machining. The problems is that you will still have weaker, small rods.

Also, this is not "Extreme Tuner", thread moved.

Leon
RR