silver91gt

has anyone experienced a broken ring from over-revving?

about a month ago I revved it up to 6200 rpm and when I let off the gas, I heard a loud ticking noise and it sounded like something was bouncing around in the combustion chamber, and I did my head gaskets yesterday to find a big gouge taken out of cylinder #8, and the piston has a bunch of dents in the top.

is it possible to break a ring when reving high?

I cant think of anything else that could have gotten in there.

I put my heads back on, and am going to run it at the track anyways.
oh ya, I run a 100 shot of nitrous too, and I bet it doesnt help any.

silver91gt

I wasnt using the nos when it happened though.

kartracer55

Not on a stang, but It def. can Happen. Its not uncommon when people take the governer off of a briggs and stratton for a minibike or something, and its a common thing in our kart motors. Alot of the time the ring shatters instead of just breaks. I have a feeling (depending on the depth and length of that gash) you will either burn a little oil or have low(er) compression or both.

Jim

Quik

you could of floated a valve and the valve hit the piston. thatwould dent a valve. did you inspect the valves for damage? ive never seen a ring go sour but hell anything can happen in a motor

JD1969

I have broke a piston before, but never had a ring fail. I would be carefull about racing that motor, it may run fine now, but when/if it fails there is no telling what other parts of the motor it will take with it. could end up costing you alot more to fix it.

Derf00

Quik called it...you floated a valve. That's when your engine is turning so fast the valve doesn't close all the way and gets smacked by the piston head. The ticking sound you heard was probably the chip from the gouge in the piston. Did you check your valve in that cylinder to make sure it wasn't missing part of the shoulder?

That's why new cars have a free rev-limiter, keeps you from running at high RPM without a load and causing such damage. You can also spin a main or rod bearing just free reving that high.

I wouldn't run that motor until you have the head and piston(s) thouroughly checked. May lose the entire thing when you hit it with NO2

nhdungeonracer

Hope you have a tow truck handy next time you run it at the track...

silver91gt

well, I didnt float a valve because there are a bunch of dents about a 32 of an inch wide and about half inch long, some look like the letter "T" and the bottom of the cylinder head has some dents too.

anyways, I put it all back together, and it runs good, well except for the super excess pressure in the crankcase.

I took it for a rip around the block and when I came back, I took off the oil cap, and there must have been 25-30 psi of pressure under it. I blocked off the breather that goes to the intake.

my intake gaskets are already leaking oil, and a little coolant.

this makes me very depressed.
I just spent a week tearing it down and re doing all the gaskets and putting on my ported heads.


I cant think of anything that would cause excess pressure in the bottom end besides a broken ring.
oh ya my cylinders are worn out bad
there is about 1/32" of a ridge at the top of each cylinder.


and for the first little bit of me driving it I looked in the rear view mirror and it looked like my head gasket was blown. lots of white smoke, but it cleared up.

can you guys think of anything else that will cause the excess pressure?

Quik

PCV clogged up will do that

silver91gt

I thought the same thing, and I got a new one and replaced the hose for it and cleaned my upper and lower intake too. there is nothing blocking the hose or anything.
oh well, I am just going to get a rebuilt shortblock and swap everything in that.