@PeaceLove&S2K
Thanks mate...

@Ks320
I agree with you. Thore retainers/springs have a tendency of ruining our engines, but I cant wait for my S to get back in action!

 

man that sucks bro.

best of luck with the rebuild

 

I'm not sure you understand what I'm saying. This looks like the result of an over rev at an earlier time (not at the time of the failure). One of the things we see with an over rev is stretched valve keepers, which don't cause a problem right away (if ever). However, once they stretch a little they are apt to fail later, spitting out the keepers and dropping a valve or valves down into the cylinder. You don't have to be driving the car hard *at the time of the failure*, and that's what it seems to have happened here.

I'm not sure at what point the stock valves start to float, but once they start to float (even just a little) the cam lobes start hammering the rest of the valve train, and that's what stretches the keepers. The failure comes when a stretched keeper spits out the retainers. Do you think the 9,200 RPM plus you've been using might have been resulting in a little valve float? If not, it sure looks like the result of an over rev at some time in the past.

Take a look at the other retainers and look at the height of the valve stem; If one or more of them are lower than normal then the keepers are probably stretched.

 

maybe its just bad timing from the engine's part... the piston punched up while the valve was still open... this would have caused the piston to break the valve... dunno tho... i might be wrong...

 

Agree with RED MX5. That's why I asked how often the 9200rpm rev-limiter was used.

 

I'm not really sure with the F20C, but normally when valves float enough to hit the pistons, all the valves (either all the intake valves, or all the exhaust valves) will get bent and the pistons will show "impact craters" from the initial impact, so I don't think that's what happened here.

Obviously, since none of us actually knows the history of the motor we're all guessing, but like I said in my earlier post, it looks to me like this is a typical case of stretched retainers.

Just for the record, according to my Modifry shift beeper (which records the highest RPM reached) I frequently shift at 9,100 RPM; I also check my retainers for stretching from time to time and have not seen any signs of problems (pushing 50,000 miles now). If you leave the stock rev limiter (or at least the stock rev limiter setting) and don't over rev due to a missed shift then stretched keepers and dropped valves are not likely to be a problem. I actually let my motor run up against the limiter sometimes when autocrossing or doing burnouts, so if the stock redline were high enough to cause a dropped valve I'd know it by now.

 

I find it hard to believe that the stock redline (on AP1s) is that close to the point at which the valves float, so I suspect that the motor was over reved more than that at some point along the way.

Do you think the valves might be floating enough at 9,200 RPM to hammer the keepers?

 

I read your previous post as well... I missed what you mentioned earlier and I agree with you. Yes, the engine before that particular night, has reached the 9200rpm rev limit occasionaly and I have come to the conclusion as well that this must have been already broken/fatigue and loose. In my opinion the bottom line is the fact that, this failure was gonna come sooner or later.

After having this engine failure I would highly recommend an upgade to the retainers/springs on the cylinder head...

@Guedo512
Thanks mate...

@shotiable
No, thats not the reason at all... There was nothing wrong with the timing.

 

o... well RED MX5 was prolly right... that was just my 5 cents in...
heheh i'm just a kid so dont take my word for it...
everyone's prolly more right than me.

 

I'm really surprised that raising the limiter to 9,200 is enough to stretch the retainers, but that does seem to be what has happened here. I totally agree that the valve springs and retainers need attention if the rev limit is going to be increased, but the stock parts are fine with the stock rev limit. I keep a careful eye on my retainers because I use the limiter sometimes and am a little paranoid about it; If anyone is going to stretch the retainers without over reving the engine I figure it will probably be me.

It's amazing to me how much damage was done by the retainers and other bits bouncing around in the top of the head. If I were you I'd clean the head up and mount it on my "wall of shame."

Some of the guys with stock motors are now worried that this kind of thing will happen to them if they run their cars hard, and I want to be sure that everyone understands that this is not something we expect to see with a stock (or even supercharged) F20C (or F22C). I visually check my retainers (and the spark plug torque) at every oil change (at least every 3,000 miles) for peace of mind, but even that is more than is really needed as long as the stock rev limiter is in place.