Hole In Piston

[Dragg-on]

I got a mean hole in my piston on the pto side, does this only happen from over advanced timing? or will a lean condition punch a hole too?

[bignasty1]

uhh generally from what i understand is that detonation or having ht timing advanced to far is what causes it. but a lean condition wouldnt help any either.

[die_infidel]

what octane gas you running with that advanced timing and how far are you advanced??

[MotulMonsta]

Lean condition, too far advanced timing & A spark plug that's too hot. All those will cause predetonation. Which is what cause a hole to be punched into your piston.

[banshee04le]

A lean condition could cause it and predetonation do to too much advance

or not enough octane could cause it too. But could you please explain why

a plug that is too hot would cause it? I don't believe that it would. The spark

merely initiates the combustion process. The conditions in the combustion

chamber (temperature) that would cause piston meltdown will be determined

by the fuel/air ratio, compression and fuel octane. What am I missing here?

[Dragg-on]

im running alcohol, I advanced timing from +8 to +10 and went 1 clip higher on my needles, then made like 3 passes and BOOM! piston skirt was fine, ring were crushed and a hole went through the top of the piston, just trying to find what exactly caused it.

[Nighty]

A hole in your piston is caused by:

 

To far advanced timing,

To high compression,

Or to low octane fuel to cope with the above 2.

 

a lean condition will heat up everything and thus speed up the process.

Lean jetting on itself will not punch a hole in the piston.

lean jetting will burn a spark plug or melt your piston most commenly on the exhaust side.

 

Sorry man

[Nighty]

But what i am wondering about:

 

howcome almost always theres only a hole on 1 side off the engine and not on both sides.

since compression would be the same for both jugs.

aswell as octane and same goes for timing advance.

 

if the crank would be out of phase.. that might change your timing advance for 1 jug.

 

Anybody have an explenation for this?

[boonman]

04LE, lean condition will not cause it. BUT, it may contribute, and sort of to speak, "add fuel to the fire". You had a problem with detonation. Alot of above mentioned factors can cause this. Now, on the too hot of plug thing, what happens is that when you run too hot of a plug, the plug doesn't shed the heat in time, and it remains to hot. Now, you compress the mixture, and the plug is still sitting there, hot as hell. It pre-ignites the fuel. This creates a shock wave called "spark knock". It happens because the fuel is burnt prematurely, and you hear the shock wave as a "ping". Not good. THis builds alot of pressure. he fuel explodes before TDC, and as the piston is still travelling up, the explosion is trying to push it down. That's where the hole usually comes from. Now, oln the question as to one side or the other, it just depends where the factors are present at the right time. SLightly lean jetting will contribute to failure when pre-ignition is also present. Heat and detonation are killers....

[svtkid78]

All of you guys are saying detonation which is true for the collapsing of the ring land around top of piston which is caused by a low octane fuel. But the hole in the top of the piston is caused by pre-ignition which can be caused by improper air/fuel mixture(lean) or improper ignition timing. causes too much heat which melts hole in top of piston. I would bring your needle clip down a notch and retard your timing a bit.

[boonman]

Pre-ignition contributes to detonation....