: Detonation and Pre-ignition

07-18-06, 12:23 PM
I just came across this interesting article written by GM engineer Allen Cline. It's quite technical, but explains the difference between detonation and pre-ignition as well as relates octaine to the problems associated with both. The NorthStar is mentioned as it relates to the decision in 2000 to lower the compression ratio to allow use of a lower octaine fuel.

A can of worms that's food for thought: http://contactmagazine.com/Issue54/EngineBasics.html

K:getaway: C

07-18-06, 02:28 PM
That was an interesting article. It also explains why I can lean out the engine in an airplane and not have it blow up.

07-18-06, 03:20 PM
It's a good article that needs to be stickied.

07-18-06, 11:19 PM
really dogged on the HEMI, kinda how I felt, it was a good engine for the time but now the modern versions are differant and not 100% hemi.

Also lets us know that they did more than just lower the compression ratio on the Northstar, they were ahead of the curve and redesigned it for regular use as if knowing that the fuel was going to go up up up. (in 2000 this $3+ thing wasn't even imagined but who knows)