[BRUTAL64]

Originally Posted by Vettezuki

If going to a thicker gasket to drop CR, the only way to maintain quench (assuming I even have vaguely correct quench as it is), would be to change pistons right? If not, you need to elaborate.

If you pull the heads, some chamber work---a little cutting here and a little grinding there and with a little smoothing of the cast Iron chambers ......... we could get a 1/2 point drop easy. With anything close to a 11cr--- quench is important.


Don't forget we would have the piston tops to work on also.

[enkeivette]

I'm willing to bet the original compression happy owner of this LS went with the thinnest HG he could find and you might not even have enough quench. Which could also cause pinging.

[Vettezuki]

Originally Posted by enkeivette

I'm willing to bet the original compression happy owner of this LS went with the thinnest HG he could find and you might not even have enough quench. Which could also cause pinging.

The motor was reassembled and we used stock GM MLS gaskets.

[BRUTAL64]

Originally Posted by enkeivette

I'm willing to bet the original compression happy owner of this LS went with the thinnest HG he could find and you might not even have enough quench. Which could also cause pinging.

Not ENOUGH quench would mean the piston would hit the head.

[enkeivette]

Originally Posted by BRUTAL64

Not ENOUGH quench would mean the piston would hit the head.

Could hit the head.


Bem, how far down are stock LS1 pistons?

[enkeivette]

And is your motor/ HG earlier than 2003?

[Vettezuki]

Originally Posted by enkeivette

And is your motor/ HG earlier than 2003?

Yes.

Bem, how far down are stock LS1 pistons?

Don't know. Maybe a question for LS1Tech?

[enkeivette]

With some quick research it looks like you'd have a 3.91x.051 HG. 2003 and later ran a .054 HG so I think we can all agree that .054 would be fine. Cometic makes a .054 x 4.19 HG which should drop your CR .25 points while keeping your quench the same as 03+ LS engines.

But this is just rough math without knowing a lot. You really should get all of the specs before you take anything apart. I'm assuming the pistons are flush with the deck, otherwise the quench would be more than .054 stock. Which wouldn't surprise me. I'll bet GM thinks about it less than we do.

[Damian]

Originally Posted by Vettezuki

Looks pretty good on the dyno.

I honestly think your colder plugs will help out quite a bit. Looking at the dyno sheet, I doubt quench is really a problem. You pulled out your spark plugs and they looked like crap. I wouldnt touch anything until you put the new plugs in and drive around the block.

I would even try and richen it up a bit as well.

[Vettezuki]

The plugs I got Autolite 5144 are very slightly longer than the plugs I had. The 5144 are supposed to be the colder version of the 5245, which is defined as the stock replacement for my plugs. Should I be concerned about this .01 or so extra length?