The Halls Of Destruction

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kdeal · #261 Post by **kdeal** » Tue Oct 14, 2008 1:39 am

Those last pics are detonation city! Looks like a few Banshee pistons I have seen.

wistech · #262 Post by **wistech** » Tue Oct 14, 2008 1:50 am

Pretty cool eh? The piston looks much worse because it has been sitting for a very long time and also has corrision on it. I like how it turned to paste and oozed down the cyllinder.

cannondale27 · #263 Post by **cannondale27** » Tue Oct 14, 2008 11:45 am

QUOTE (Wistech @ Oct 13 2008, 07:46 PM) <{POST_SNAPBACK}>

Here is a lesson learned the hard way. We were desperate and installed the big bore duals on the 480 engine last winter with no time to get back to the dyno. Only ran a couple laps before melting the piston down. Should have settled for the 54 hp with the fmf pipe. Ill bet it was getting close to 60 for those last few minutes. A chunk fell down into the one way gear and locked up the engine. Hard to believe it had enough speed out on the straights to spin the engine long enough to do that much melting. Looks like the crank survived and the head. Just amazing. That poor cp .
On the bright side the big bore duals obviously like the bigger engines and show that they need much more fuel. This will also be the next project for the fall engine building class.

Holy Cow! I have never seen one that bad in a 4stroke.

jinx44 · #264 Post by **jinx44** » Tue Oct 14, 2008 2:48 pm

QUOTE (cannondale27 @ Oct 14 2008, 11:45 AM) <{POST_SNAPBACK}>

Holy Cow! I have never seen one that bad in a 4stroke.

No kidding.

A friends blown/sprayed cobra melted one down badly, but it just melted through the ringland, not the entire piston.

wistech · #265 Post by **wistech** » Tue Oct 14, 2008 7:16 pm

It smacked the exhaust valves pretty hard but they must have been super hot because they seats seem to be ok . I leak tested the head and its good. Ive never had valves folded up so bad and not had major seat damage. LOL It might have been because of the valve mods that the valves were able to easily bend up and cram into the seat pocket . Less metal to resist the forces.

cdale55 · #266 Post by **cdale55** » Thu Oct 16, 2008 1:10 am

Man !! Who could have built a motor that did that !! LOL

cdale55 · #267 Post by **cdale55** » Thu Oct 16, 2008 1:12 am

LOL The bad part about this is I was in first when it happened !!

cannondale27 · #268 Post by **cannondale27** » Thu Oct 16, 2008 11:45 am

Did it happen that fast? Would think if it was a lean condition it would have been running terrible. Maybe it is just massive detonation. Like someone put some Trinium in your gas tank! Wow!

2000ex · #269 Post by **2000ex** » Mon May 04, 2009 7:45 pm

Here are some good ones. Lucky my head was salvageable. Piston was at the bottom of the stroke when it happened. It was still sitting in the bore and what was left of the rod managed to put a massive dent in the bottom of the cradle when it carved through the bottom of the case. Definitely a good one.

From my eye it looks like maybe the clip popped out causing the wristpin to walk out make contact with the side of the sleeve HARD causing the wristpin to sheer off and snapped the rod at the same time. Crank kept spinning and smashed through the bottom of the case and the cradle. Anyone else is more than welcome to come up with a theory.

Sad thing is the piston was still in great shape after 2+ years of racing abuse. I am going to change out the circlips and wristpin every season after this issue just for piece of mind

[attachment=8400:Destruction_002.jpg][attachment=8401:Destruction_003.jpg]
[attachment=8402:Destruction_004.jpg]
[attachment=8403:Destruction_005.jpg][attachment=8404:Destruction_007.jpg]

cannondale27 · #270 Post by **cannondale27** » Mon May 04, 2009 10:51 pm

Wow! Was the rodend still in piston like you show? If so I kinda think the rod broke first and then came up alongside and sheared the wristpin off. If wristpin broke first I would think piston would have cracked.

Here is my latest. Like a moron I forgot to tighten exhaust cam caps after doing cam timing. Got maybe 15 min off this motor. Oops! [attachment=8405:Cam_Cap_Loose.jpg]