We lost a very expensive engine a while back while out at the local strip (thank gawd for warranties). Long story short, the number one piston (custom forged pieces) collapsed it's ring land and actually was missing a little material. The engine builder claims that the fuel pump that we used was too small and leaned out our upper end (7000rpm!). I always thought that if you leaned out to the point of damage, that it was caused by detonation. We didn't hear any detonation when the engine died, but the engine builder claims that a localized hot spot caused the damage and not detonation.

So, just for my own personal reference, if you lean out an engine to the point of internal damage, is detonation going to be the cause of that damage???

Or in other words, could a knock sensor and esc have saved this engine???

 

Lean tends to run hotter, hotter tends to lead to detonation.

Destroying ring lands is common in power added engines that have been run lean.

 

Not all detonation is audible to the human ear. The knock sensor retards timing long before it can be heard. So just because you didnt hear it doesnt mean it wasnt there. Knock sensors can only due so much. If base timing is too far advanced or the mixture is way lean it will do little to protect your engine. In your case i dont think a knock sensor would have done much good because with an extreamly lean condtion the comustion temps would still be very high.

 

So you can still critically damage an engine by running it too lean even if detonation (audible or inaudible) doesn't occur? And this damage is soley due to combustion temps being higher than ideal??

I'm talking NA here if it makes any difference.

 

Yes, definately. You might be OK at 6K rpm, but go way lean at 7.5K because of fuel delivery problems, as stated. If this is the case, your heat would build so quickly and detonation be so bad that there is no way a knock sensor would be able to retard enough to keep it from doing damage.

If your fuel delivery at high end is seriously inadequate, the onset of detonation would be so fast that the first you "hear" of it is too late. That is why you ALWAYS work from rich to lean when doing jetting, never lean to rich. Power adders and high RPMs make the damage so instant that you never have a chance to shut it down before it does it itself (boom)

Sorry about the mess...

Troy
So Cal

 

Test your fuel pump for volume flow, then you'll have some ground to stand on.

 

If theres no detonation you wont be doing any damage to your engine. All engines nowadays run very lean with very high temps. The key is to not go to lean. The leaner an engine gets the hotter the combustion temps get. The hot combustion temps are what causes the detonation. When an engine leans out the combustion temps increase dramatically and the detonation that occurs happens very quickly. Thats why i dont think a knock sensor could have helped you much in this case. Even thou the timing being retarded would bring down engine temps some i dont thing it would have been enuf to save the engine.

 

Did that piston sorta look like this