1 post tagged “piston swap”

Happy New Year!

Well, it seems as though I've finally blown a cylinder on the old 6G72 :(  I lost about 20 psi of compression (155 down from 175) on #4 (which is ~5 psi out of spec) after smashing a plug twice on that cylinder.  I've yet to tear the top-end down, but I expect that piston's ring land is chipped.

Needless to say, I'll be tearing down the top-end and bottom-end to replace the pistons.  I ordered new forged aluminum pistons from Tearstone; they are custom CP Pistons designed for the stock bore spec of the 6G72 (91.1 mm).  I need to pick up some tools such as a new torque wrench, hex/allen-drive sockets, and a cylinder hone.  Also, I need to buy a gasket set for the top-end along with a new timing belt.

Not boring the block should be okay, since I only have 60,000 miles on this engine.  I'll just give the cylinders a nice new cross-hatch and check the ring gaps with a feeler gauge.

After replacing these pistons, the block should easily hold 15+ psi, above which the intake manifold and heads start to limit the 6G72's horsepower potential.  So, my next step is to replace my supercharger pulley to bring the boost up to 12-14 psi; this will be done in tandem with the installation of a methanol/water boost cooler from Snow Performance.  I guess I'll have to get used to filling up my methanol tank every few weeks or so; good thing methanol is cheap!