Can your pistons do this!

[JR @ CFS]

Hope you enjoy this!






Here are some pictures of our broken engine. The engine is a 2004 Fazer with a compression ratio of 12.2 and 600cc. We are using an Autorotor supercharger and the highest boost we were using was 0.45 bar. The fuel we were using was E85 but during winter there is only around 70% Ethanol in it. So the knock resistance is lower than the orignial one. We couldn't notice knock tendences at all.

We saw that something was wrong when the engine started to blow white smoke out of the crank case ventilation. The engine could still run so we started the engine several times but as soon as we put load on it it started to blow smoke. After removing the sparkplugs we saw that one was melted and one cylinder was wet. We looked into the cylinder and then we could see that the cylinderwall was damaged. Then we removed the cylinderhead and you can see the result on the pictures.

So, anyone out there in FSAE land have any ideas on the issue? What we found strange was it only happened to one cylinder! Why does it happen only to one cylinder and all the other cylinders were still good? Maybe the compression ratio is too high and it looks like the temperatures are very high in the combustion chamber.

We have received a few opinions from different people and are wondering if anyone else has had the same problems in testing?

[JR @ CFS]

Hope you enjoy this!






Here are some pictures of our broken engine. The engine is a 2004 Fazer with a compression ratio of 12.2 and 600cc. We are using an Autorotor supercharger and the highest boost we were using was 0.45 bar. The fuel we were using was E85 but during winter there is only around 70% Ethanol in it. So the knock resistance is lower than the orignial one. We couldn't notice knock tendences at all.

We saw that something was wrong when the engine started to blow white smoke out of the crank case ventilation. The engine could still run so we started the engine several times but as soon as we put load on it it started to blow smoke. After removing the sparkplugs we saw that one was melted and one cylinder was wet. We looked into the cylinder and then we could see that the cylinderwall was damaged. Then we removed the cylinderhead and you can see the result on the pictures.

So, anyone out there in FSAE land have any ideas on the issue? What we found strange was it only happened to one cylinder! Why does it happen only to one cylinder and all the other cylinders were still good? Maybe the compression ratio is too high and it looks like the temperatures are very high in the combustion chamber.

We have received a few opinions from different people and are wondering if anyone else has had the same problems in testing?

[Dr Claw]

are the red X's a metaphore for the current state of your engine/pistons? In that case, im sure our pistons do that at some point durring the year

[Jonathan S]

Melted spark plug = pre-ignition from sustained REEEAALY high temps, detonation. Bad stuff...

Maybe check your fuel injectors to make sure they are all flowing evenly. Are you logging O2? Were you logging water temp - was your engine running hotter than normal?

Sounds to me like you may want to spend a little time on a dyno.

[JR @ CFS]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">

Sounds to me like you may want to spend a little time on a dyno. </div></BLOCKQUOTE>

This did happen on the dyno :S

[Wesley]

Probably detonation - but the way that broke makes me think the bore was a bit on the tight side and the ring ends butted from thermal expansion, breaking off the ring land.

The detonation didn't do the destroying, just allowed the piston to get hot enough to get rid of your ring gap and they butted, which caused the galling of the cylinder and the missing ring land. Then you had a piston bit flapping around that messed up your spark plug.

That's my theory.

(And excellent title, BTW )

[Marshall Grice]

yeah we've done that on our gixxer motors on the dyno before. We were running it hot (water temp, not on purpose) and hit a lean spot on the map. that spot on our motors seemed to just be the hottest spot and was the first to melt. Melted piston scores the cyl. wall.

[Nima]

See this:
Queens FSAE: Everything Breaks
It may help you.

[Dallas Blake]

I dont think what happened here is the same thing that happened to me, mine was simply a broken plug that was ejected from the cylinder, no damage resulted and I actually put another 50 hours on that engine and it still runs strong.

This situation looks like a lean burn with detonation. As for why it only happened to one it could be any number of reasons, different charge distribution, different combustion temperature caused by variations in the exhaust from cylinder to cylinder, seized thermostat, air pocket in the cooling system with the engine continued to run for an extended period of time.

Were you logging AFR or EGT at the time? were either of them abnormally high? What about water temp or intake air temp?

[Grant Mahler]

Do you have an inline fuel filter?

Might I suggest you see what it has in it, as well as flowbenching your injectors to determine if one is clogged...It would be unfortunate if you blamed this on the fuel maps and then blew up another motor due to a clogged injector.