Studytime

iTrader: (15)

Need help figuring out the dynamic compression on a modified LQ9. This is for a motor going in on '01 Firebird. The heads are off and are going to be getting decked, but I don't know how much dish a LQ9 piston has nor do I know the .005" duration for Futral's cams.

Ben T.

PREDATOR-Z

Study you need to give the basic specs out.
What is the piston deck height?
What gasket thickness (compessed)?
What are the LSA/ICL of FM11 you are using?

Studytime

iTrader: (15)

I can do the calculations myself I just don't have all the variables.

It's a 114LSA FM11 installed dot-to-dot. Compressed gasket thickness is 0.042. We'll assume the pistons are 0.007 out of the hole.

Thanks for the help Predator-Z. I'd like to have the advertised duration and the amount of dish that a LQ9 piston has so I can play around with it.

Ben T.

Studytime

iTrader: (15)

Okay, it looks like people use the rule of thumb .050" duration plus 50* equals duration at .005" degrees of lift. That makes the 228 lobe climb to 278* of advertised duration. Using those figures I'm coming up with;

A 67.x cc chamber yielding around 10.9+/1 compression and 8.4x/1 dynamic with around a .020" mill and using a .042" head gasket.

This sound good to anyone else? I'm pretty sure it'll clear, how does clearance sound to other people? .042 gasket, .020" mill and a 228 intake lobe on a 114LSA +4.

Ben T.

PREDATOR-Z

It "should" clear on a stock valved 6.0 head, but better measure. Either clay or dial it in.

formybird

Its a 112LSA if that makes a difference.

Studytime

iTrader: (15)

The tigher LSA (or more advance) would both further limit the amount of clearance, but if you're going to be running a stock head gasket and, say, a .025" mill it should still clear and yield a DCR in the 8.2ish range- which still isn't bad.
Ben T.