So I知 new to the LS stuff but I知 starting my 370 build and having trouble figuring the pistons to run with the 317 heads. What is a decent compression ratio to run on 93 octane fuel?

 

 

Why not run a smaller chamber head or have those milled?

 

im at 12.3:1 on 93. and mt tunet had Zero issues making it work. Just low timing. The setup was specd for e85.
If I were to build it again for 93 oct I would shoot for around 11.5:1 . so I could keep the timing in the upper 20's

-Mavn

 

These might help bump the compression up if using the 317 heads, valve reliefs, though a little heavier. I believe the product number has changed to PTS523A3.
https://ls1tech.com/forums/generatio...u-pistons.html

 

 

I was considering the domed Wiseco ones but opted out because of my smaller chamber. Also took advantage of the SRP's that were 30% off yesterday.

 

The PTS523A3 series are a slight departure from the old Pro Tru PT124 pistons. With a 71cc chamber and net .045 piston to head clearance, they pump 10.9:1...still a little on the low side. Milling the heads .020 would net you about 11.25:1 which allows for full timing with an average street cam. Also, the pistons are 4032...so not quite as strong as a full blown Wiseco, but still good. As forged valve reliefs so you can run them with about any cam. They also have a .945 pin for the press fit Gen. 3 rods and you would leave the clips out if running press fit. If you are running a Gen. 4 rods, have the small ends honed to fit and you would use the clips they come with. This is a fairly inexpensive operation at your machine shop and while they are balancing your assembly. We have them in our warehouses for immediate delivery.

 

 

 

That would put you about 11.7:1 and you could mill it down just a bit to hit your target. 2.76g/cc.