pinging or detonation??

[dimps8]

I've been doing some research on pinging and detonation and i think i've been a little confused over the years on what it actually is. I purchased some country fuel while i was on holidays last week and the engine started pinging.

I'm led to believe that pinging which is short for pre ignition, occurs when the engine is so hot, a part of it will glow red and ignite the fuel mix before the spark reaches. Detonation on the other hand occurs in a high compression engine when a lower octane fuel is used and is compressed by the engine and explodes before the spark can reach not unlike a diesel engine. As well if ignition timing isn't advanced enough before tdc which allows the detonation.

Does this sound right? Maybe we say pinging because of the sound detonation makes? Anyone else confused?

[914Ghost]

I think you're close, I read a tech article on that subject once, and there is a diference between the two, but I think for regular everyday purposes for normal people they're both killers.
Especially for smaller air cooled engines on hot days.
The detail I remember most about the subject was that "audible pinging" is a last step- if you can actually hear the noise then you've got trouble.
I guess it occurs at levels we never hear- and is just as destructive.
I think Gene Berg may have written about it and said it's like "Hitting the top of the piston with a hammer" just before it reaches TDC.
Imagine the damage and power loss! I've heard it in some of the engines I've built and it scare's me.

Bob O