SLP IROC-Z

iTrader: (14)

I don't see 20hp from 10.2:1 to 11:1. Maybe 10hp

Utinator

Oh sweet! There is some math for this. Based on that chart/formula, I would probably only get about 2% more hp with a head gasket swap only. The gasket/piston swap might give me 3% more. Right now, I'm getting 382hp to the wheels. So, increasing the compression would only give me about 390-393 Whp. I don't think the extra 8-11 hp is worth the effort right now. If I have to pull the heads for some other reason, then I'll get thinner gaskets. Until then, I'll keep what I have.

Krom

quench is easily measured with a piece of large diameter rosin core solder, and pair of calipers. roll the engine over to just before tdc compression stroke, and feed the solder through the plug hole untill it hits the cylinder wall on the opposite side of the chamber. spin the engine back and forth past tdc a couple times, pull out the solder, and measure how thick it is

ChopperDoc

Wouldn't the chamber be what you're measuring to? I might have to give this a try, just out of curiosity. It anything, you might be able to check PTV this way, kind of like the clay method. Because on a zero deck piston, the gasket is the measurement, essentially.

Bad346

Like others have said the head gasket is more for setting quench than adding compression, although in this case getting the quench right will add a little compression. I believe Tony Mamo found that ~.028" quench was the point where he ran into trouble. Also remember head gasket thickness =/= quench, you have to take into account the piston protruding .006-.009" from the bore so on a stock bottom end ls1 you wouldn't want anything less than a .040" gasket. I wouldn't waste the time pulling the heads just to change a headgasket if it didn't need doing, but if I had to have the heads off anyway I would 100% do it.

handyandy496

iTrader: (9)

Keep in mind a lot of these articles and charts are based on cast iron head and or block's. The rods will expand some but with aluminum ls blocks expanding up to .010 with them you should be able to run at the lower quench numbers. I have been running a .036 quench with good forged pistons at 11.7 on 93 pump gas without any issues in cool air, 22 deg timing.