89IROCZZ4

For max power, I am thinking about swapping to lower compression forged pistons. Is this the best way to go? If so, what all is involved? Can we just pop off the heads and swap out the pistons, or will machine work be needed, and pulling the motor, etc?

SpitotRs305

well how new of a engine are we talking about?

the engine will have to come out of the car... if it is very new like 500-1000 miles i wouldnt do anything that wasnt messed up... maybe run a hone through it lightly...

as for actually swapping pistons that is a nother story... i dont remember what rods the ZZ4 has but i am guessing they are pressed wristpin...

i would get new rods with floating wrist pins and a set of 22cc dish pistons from speed pro about $450

i would also get a good head gasket from cometic i think they have the best copper head gaskets ...probably use studs for the heads too

but if you plan on making real power like 700+ HP i would say you should at least have the block O ringed...
and probably a bunch of other stuff i have over looked but we cant all know everything

89onlyZ51

iTrader: (3)

That's pretty much what I'm doing with a corvette L-98 (close to the ZZ4 except 2-bolt mains). With the ZZ4, you need to lower the compression to run FI. So, either the heads or the pistons need to be changed. Pistons are going to be much cheaper although involve more labor as the motor will need to come out. The ZZ4 has hypers and you want forged anyway.

You've got pretty good rods in the ZZ4 (GM powdered metal), and I would keep those unless you plan to upgrade to a bigger blower than the 600b in the future. If you want, you can get them honed and bushed to be full floating while you have them out.

The -22cc speed pros (same ones I have ready to go in mine) are a good choice and will put the CR at about 8.7 with the ZZ4 heads. Measure the bores for clearance and roundness, and you should be good to go if all checks out OK.

The speed pros supposedly come in weights within factory balancing tolerances, but I'd have the rotating assembly checked for balance for good measure (probably ahead of doing full floating rods).

89IROCZZ4

very interesting! so how much would it cost would you say for a shop to pull motor, swap pistons and install again?

89onlyZ51

iTrader: (3)

I really don't have any idea. If I had to make a guess, I'd say it's 10-12 hours of labor or so times whatever the going shop rates are in your area.