LT4 LT4 compression and pump gas

[northcountry]

Can anyone suggest the best and easy way to lower the compression on a LT4. Thicker head gasket? Know that chevy makes one that can drop it about 1/2 point. Any other ideas that will help making my supercharged LT4 run on pump gas OR what is the best way to up the octane?

 

[MoeJr]

You MAY be able to get a thicker head gasket but that probably won't drop your Compression Ratio enuff. Dished pistons would work best or lower the boost on the S/C. No real good way to boost the octane of gas unless you use a 25% mix of Toluene which is sold by the gallon at some paint stores. Hope this helps.

 

[northcountry]

Thanks, I have been mixing 1 gallon toluene to 15 gallons, but that is a real pain. Hate to go inside the engine until I HAVE too.
Only have 8500 miles on it, but maybe that would be the best cure, pistons.
Thanks again

 

[MoeJr]

Turbo/Superchargers are great when they are done as a complete package. It is very hard to just bolt on a supercharger and get it to run just right. The stock CR on your LT4 I believe is 10.8:1 and really the max u wanna run with 8 psi boost is 9.25:1. I woulda rather seen you do other mods before the procharger. I wish you the best of luck.

 

[Vettelt193]

You don't have an intercooler? That should really make your 8psi equate to about 6psi non-intercooled, which should be just about the limit of a stock LT4...

anyway, one really easy way to get the car to run on pump gas is to kick the timing back, which can be done through the computer thanks to the opti spark

 

[No Go]

What gasket does Chevy make that will drop compression?

Stock head gasket thickness (installed) is already supposed to be .049...

Curious...