Compression Ratio limits for Big Blocks
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
any HP engine including the BB Chevys compression ratio is only limited by the fuel used....the L72 which is the basis that GM produced with a 11-1 ratio can still manage quite comfortably with 93 pump fuel....... any thing higher will place you into a danger zone by the limited availability of 100+ fuel......but in a pinch pump gas could be used for those over the L72`s ratio {11-1}....just don't hammer it as it will rattle.......
Burning Brakes
Joined: Sep 2011
Posts: 896
Likes: 7
Turbocharging, supercharging, nitrous oxide were all developed in WWII to get more performance out of fighter plane motors. They also developed methyl alcohol/water injection to cool engine parts and act as an octane booster. Meth injection is common on turbo set ups and nitrous.
Many people are using this system on NA motors as it will allow the use of lower octane fuel in a higher compression engine. I plan on installing the system on my motor when the the time comes. Most systems are $500 or less.
Meth/water injection uses uses windshield washer fluid and injects it into the cylinder. Octane is increase by 10-15, water acts as a damper on detonation and steam cleans engine components in the process.
Just thought I would throw this out there as it makes a lot of sense to me after studying all of the data. It seemed crazy when I first started reading about it, lol.
Many people are using this system on NA motors as it will allow the use of lower octane fuel in a higher compression engine. I plan on installing the system on my motor when the the time comes. Most systems are $500 or less.
Meth/water injection uses uses windshield washer fluid and injects it into the cylinder. Octane is increase by 10-15, water acts as a damper on detonation and steam cleans engine components in the process.
Just thought I would throw this out there as it makes a lot of sense to me after studying all of the data. It seemed crazy when I first started reading about it, lol.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
All depends on the cam and dynamic compression ratio
Done right you can run compression
Kemco sells some nice stuff to truly boost your octane.
Adds roughly $10 to a tank of gas give or take.
The stuff at the auto pts store that says it raises it 1-3 pts or whatever. Means it may go from 91 to 91.3 lol not 93or?
Do have aluminum heads but right now run 11.5:1 sbc on Cas crappy 91.
Playing with the advance curve helps.
