Senior Tech Team
Join Date: Apr 2012
Location: Yerington, Nevada
Re: Compression, Timing and Detonation
Those compression ratios are nothing new, ZZ4 engines come with that C/r.
THE single most important part is to GET THE QUENCH RIGHT. Early Chevy engines ran a quench of between .039 and .045, they did it this way, pistons down in the bore between .020 and .025, and a .020 compressed thickness steel shim head gasket.
Along comes top tuners complaining about head gasket failures after 150K miles, and, too high a C/R, so, two things were done, both disasters.
Silv-O-Lite builks a "destroked" piston for all sorts of engines, stock piston with the piston pin moved up another .020 to lower the piston dome down into the bore, lowering the C/R, which wasn't the problem in the first place.
Gasket makers actually listen to moron engine bozos, and make thicker head gaskets, so they don't blow as easily as the steel shom stuff. Sizes, oh, heaven, compressed thickness, .040, .042, .045, .055, .060 and more.
DISASTER. Think about a deck with .025 stock, Destroked another .020 down in the bore (this gets us a strange build, the quench to be right, would need to NOT use a head gasket), and a .055 thick head gasket. On this one, quench will be a whopping disaster of .080, PING AND DETONATION CITY.
So, this is why most saavy engine people ZERO DECK blocks, and use a .040 to .045 thick pack type head gasket, the gasket creating the proper quench distance, as Chevrolet did it in the first place, only now, done differently.
And that is the evolution of worse and worse pinging "for no reason", and detonation. NOTHING ever happens "for no apparent reason", NOTHING.