Mike Cordero

iTrader: (122)

I have a 6.0L engine (LQ4) and was thinking to increase the compression so got a set of LQ9 pistons but I was thinking to use LS3 type heads so I'm planning to use the LY6 pistons which have the valve notches already. With those stock pistons and the LS3 heads, how higher I can go with an up graded cam (how much lift)?

Jimbo1367

Requardless what piston you get, you will need to maintain the proper piston to wall clearance. If you are going to a standard overbore size, Just get a aftermarket piston with the valve reliefs all ready in them. If this is a BUDGET build, get the LQ9/LS2 pistons and have them knotted at a machine shop OR flycut them yourself.

Jimbo1367

BTW…………… wrong forum

SNLPerformance

iTrader: (15)

Peak lift of a cam doesn't determine piston to valve clearance issues, hope that helps.

Exidous

iTrader: (11)

^ Duration and centerline are WAY more important than lift.

Prorac1

iTrader: (4)

If your intake centerline gets much below 110 degrees, you will start to run into intake valve to piston issues. IVO and Intake centerline play the largest role. Eric L

SNLPerformance

iTrader: (15)

Exactly, your IVO along with the ramp rate of the lobe is ultimately what determines PTV clearance and it's always best to check it when in doubt.