Piston Damage

[Superman]

Tonight got around to packing bits and bobs up from my engine and thought id take a closer look at piston number3 to see what had caused the loss of compression.

Well...

If you look closely...




Oh ****! theres a chunk missing lol








The rings seem fine though


Was also surprised at how light the piston weighed without the guide pin in, about same as a pot noodle before water!

[the mk1 kid]

Nasty!

I randomly took a piston out of a spare engine this evening.

I was surprised how strong the rods looked!

I think the 1.3 rods are forged though.. i should get a pic up tomorrow..

Tom

[JonnyGT]

hell fire that a quite alot of piston missing

[Debo]

Stock rods are cast.. just FYI. They are quite strong stubby little f**kers though

Superdan, on the txt you sent me last night, it looked like it had shown signs of severe overheating.. but having seen the pics on a full sized screen, I haven't got a clue what could've caused that to happen!

[Superman]

Yeah, well that missfire definatly did it in. This is what happened to Pauls before he rebuilt it then broke it up.

ALso i think Tom means the UnoT mk1 rods. The rods are bloody heavy ill admit.

[Goldie Punto]

This has happened to a few of us on here, when i killed mine at least 2 of the pistons looked like that.

[H8T WP]

just super glue it back together man it will be fine

[Mawbster]

here is your cause danny boy i reckon

Effects of Detonation
Other than running an engine without oil, there is probably nothing that you can do that is more detrimental to an engine than detonating it. In an ideal combustion cycle there is a controlled burning of the compressed fuel and air, but during detonation there is an exploding of the mixture with a instantaneous release of all its energy, regardless of where the piston is in its stroke. The timing of the auto-ignition will have a direct effect on where the damage takes place.
Detonation very early in the compression stroke is usually the silent killer that goes unheard by the driver. This form of combustion usually results in rotating assembly failure by attacking the connecting rods and bearings. Detonation that comes nearer to TDC or slightly after is usually heard as pinging and will likely result in the burning of the piston or the lifting of the ring land from the piston. The force from the colliding of the multiple flame fronts can be likened to the wake of two boats travelling in opposite directions on a lake. When the two wakes meet, they usually peak and absorb the energy of each other. The more dominant wake will still have some leftover energy and will proceed weakly in its original direction. The same holds true for colliding flame fronts in a cylinder. If you have one flame initiated at the spark plug and another started independently of the plug, usually the spark-initiated front is the dominant one. As the two flame fronts collide, the pressure in the cylinder rises from the compacting of the molecules. Historically, the normal flame front has enough energy to run over the abnormal one but uses a lot of its energy to do this. Add to this that the abnormal combustion has consumed a portion of the combustible mixture that filled the cylinder, and the least result is a loss of power, if not a damaged engine.

[Mawbster]

would have your block checked to see if there is any extra wear in that section of the bore like. that looks like it could have done some heavy damage. i also wouldnt bother using those rings again in my opinion.

[Superman]

what would cause Det then Dan?