cbr600rx7

iTrader: (12)

Trying to get a rough idea of what my correct static compression is. I know what pistons are in the engine, bore, stroke, head chamber size, and head gasket height is but need a rough idea of what piston to deck height would be on a typical built LS engine. guessing .035-.025

cbr600rx7

iTrader: (12)

Any body have a rough idea of what is typical of a LS motor. I know that most LS1 are even with the deck or just above deck at .002-.008 but is that typical of all LS engines.

cbr600rx7

iTrader: (12)

basically my question is when guys build LS motors do the pistons typically come to the top of the deck or are they down in the hole a little bit. When i read about the LS1 coming .002-.008 above the deck i find that very interesting and didn't know if engine builders would drop the piston down into the block a little more when building a motor for durability or if they would do the same thing and bring the piston to the top of the deck. When i say down in the hole i am talking about .025-.040.

Sorry i know this is a very noob thing to ask but i am trying to learn so if i am way off or just talking crazy please tell me.

69LT1Bird

iTrader: (1)

Most all stock LS engines have the pistons above the deck .004-.010 from the factory.

cbr600rx7

iTrader: (12)

And do most engine builders continue to do this or do they drop the piston down a little for durability.

69LT1Bird

iTrader: (1)

Hopefully the big builders will chime in here. There is nothing wrong with leaving them as the factory had them, the key is knowing, accurately, what you have. Check all of the pistons, find the one that is out the farthest, this will drive the rest. You will want your quench at no more that .035 for a street car, if you are out .005 you could a .040 head gasket. PTV is the rest of it and that comes down to the reliefs in your pistons so your valves will clear. Some builders will zero deck the block so the pistons are flush, but for street stuff its probably not necessary.

cbr600rx7

iTrader: (12)

Thanks for the info. Thinking about going with a .040 gasket and milling .012 or going with a .051 gasket and milling .018 off. Not sure whats the best choice but it would seem like having more gasket there to absorb any differences from the head to block would be a good thing. But once again i am very much a noob still so if i am way off track feel free to beat me in the head and correct me.

95wannabe

iTrader: (20)

Why would you mill .012 w/.040 gasket, but .018 w/.051 gasket?

cbr600rx7

iTrader: (12)

Keep compression up. Going to a .051 gasket from a .040 gasket would drop compression along with the bigger chamber on the heads by about 0.6 so milling the heads would be needed to keep compression up to support the cam.

Whistler

iTrader: (46)

Moving to Internal Forum

95wannabe

iTrader: (20)

yeah, I understand the reason, just not the math....
using a .011" thicker gasket would only require .006" additional milled to keep same compression?

KCS

iTrader: (20)

That depends on the rest of the engine. A lot of places are going to keep the piston out of the hole so that the customer can use the inexpensive GM MLS gaskets and get a tight squish clearance.