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[dvst8r]

I found this in one of the dirt bike forums I am on, and thought it might be useful to some people here.

[Joseph Davis]

Not wholly correct, or complete.

The tip/entirety of the ceramic often takes time to turn brown. 50-200 miles, varies.

The base of the ceramic - or the fuel ring - only gets specks under hard detonation.  The first place they show up is on the piston crown/carbon coat as the engine runs out of octane, or if the engine is permitted to operate in the region where timing requirement starts to drop off abruptly (because you are running out of octane).

Concerning speckles.  Black specks on the tip of the plug, with most EFI vehicles that do not wash the cylinders down when engine is shut off due to injector leakdown (Ford Motorsports 42# injectors, puke), is often indicative of large injector poor atomization and NOT detonation.  Also, I rarely see silver speckles on plugs (I read the chamber) but very rarely I DO see stripes of actual molten aluminum on the ceramic - just go ahead and tear the motor down before it consumes itself and you have to replace a lot more than one piston, because when it siezes in the bore shit likes to break from sleeves to parting oil film-->rod bearing welded to crank or rod folding.

[dvst8r]

Thanks for the extra info JD.

As I stated above it was pulled off of a 2 stroke dirt bike forum, with your additional information it is probably useful to EFI car people.

[92CXyD]

I found this in one of the dirt bike forums I am on, and thought it might be useful to some people here.

So Jd can you do a diagram similar to this that would be beneficial to EFI owners. So I could have a good quick reference to use. ;D

Right now I have to look at 10 to 30 pictures (depending on what website(s) I use) to figure out what is going on in my engine.

[caged]

  Also, I rarely see silver speckles on plugs (I read the chamber) but very rarely I DO see stripes of actual molten aluminum on the ceramic - just go ahead and tear the motor down before it consumes itself and you have to replace a lot more than one piston, because when it siezes in the bore shit likes to break from sleeves to parting oil film-->rod bearing welded to crank or rod folding.

Iv noticed small silver alloy spots on the top of the ceramic's before on several cars. I always thought it was from det, i was using an otoscope. This is on wrx's which I know for a fact see there fair share of det. Is it alloy or am i trippin?

[Joseph Davis]

Detonation happends when combustion rxn reaches a temp where oxygen and hydrogen can not join together to form water, so they seek out aluminum and to a lesser extent steel.