When things go wrong at 9000rpm

[BlackDC2]

Guy, if you are not already aware, I blew my engine last Sunday at Oran Park.

i was going down the main straight, as i backed off to brake, a rod went through the block.

Today I pulled the engine out and tore it down. It appears to have been a rod bolt failure.

1st pic - engine out of the car
2nd pic - intake side of the block, the main cap which was in pretty good condition considering is wedged in the hole
3rd pic - Things I found in the sump
4th pic - OUCH, the crank doesn’t look too healthy
5th pic - Beaten up block with a few holes in it. You can see the base of the Toda piston with the ripped out gungen pin and half the rod sitting in it.

[freakygeek]

Ouch....

Poor Jase....

[tinkerbell]

man, it is pretty bad mate... what about the head?

[BlackDC2]

so so lucky, the head only has a couple of slightly bent valves

[tinkerbell]

full on?

that is SOOO lucky!

[JCE]

so so lucky, the head only has a couple of slightly bent valves

Bad luck mate, so no plans for a three cylinder after all ?

[TeMp]

Bl mate.

Just wanted to ask a noob question for my own education.

I know your rod bolt failed, but what caused the rod bolt to fail? What could of been done to prevent this?

[e240]

Duct tape should fix the hole in the block ... Easy

[tinkerbell]

Bl mate.

Just wanted to ask a noob question for my own education.

I know your rod bolt failed, but what caused the rod bolt to fail? What could of been done to prevent this?

at 180+ at the end of the main straight in 4th and at 9000rpm, jase snapped the throttle shut to prepare for braking for turn 1, which caused the combustion chamber to be pressure locked.

at this point, the crank tried to pull the piston downwards (i.e. continue spinning),

due to the vacuum in the combustion chamber being locked, the piston resisted moving downwards whilst the crank was trying as hard as it could to move downwards.

the rod and rod bolts would have undergone significant stretching forces at such high RPM (piston speed over 2500ft/second) that it caused a missalignment in the relevent parts to the point where they could not realign before being forced into a direction that it could not continue to spin in...


that is what happened in my opinion.

[00dc2]

so the lesson is to come off the throttle slowly when your at REALLY HIGH rpm?

[BlackDC2]

also to note, eagle change their rods bolts from a 1/4'' bolt to a 5/16'' bolt after i purchased my rods.

dave, your pretty much on the ball i recon, FTIW, the engine let go at 8860rpm, but i though 9000rpm sounded better hehe

[totti]

terrible news, sorry to hear jason

how many km's and track days has this engine seen since being rebuilt?

[BlackDC2]

the engine saw 50,000kms. about 20 track days or more, drag racing...

and after all that, no oil usage.

it would have seen many more if it wernt for a couple of under spec'd rod bolts.

[kavehman]

This is the 3rd motor i have heard of in the last two months that has let go because of incorrectly stretched rod bolts.

Makes me think how important specs are on Honda engines

[tinkerbell]

This is the 3rd motor i have heard of in the last two months that has let go because of incorrectly stretched rod bolts.

you mean excessively don't you?