I've got a engine thats blown and I just pulled it apart last night. 1 apex seal was trashed and also one of the corner seals for that apex seal was split in half.



I'm not sure if the apex seal busting caused the corner seal to go or if the corner seal going caused the apex seal to go. All the other apex and side seals were good.



Any comments, or would anyone want to share possible mechanical reasons for this that I might can address while I'm building this engine. In other words could it have been something I did on the last rebuild that caused this? The engine had about 11K hard miles (18psi daily on 93 octane).



Thanks,

STEPHEN

 

Detonation will take out a corner seal...

 

So you think it was just normal detonation that killed the apex seal and corner seal together?



The wierd thing is I've been running my car EXACTLY the same, (tuning boost everything) for a year and over 11K miles.



Random detonation scares me more than anything cause I wont feel safe untill I think I've addressed the problem.....and i have no idea what the prob was.



Maybe I'll feel better if I change the plugs and fuel filter haha



STEPHEN

 

use solid corner seals

 

its possible in this case that the apex seal broke the corner seal

 

It could have been a freak accident, like a bad batch of gas possibly

 

exacly the same thing happened to me last week. 1 apex was f@#ked and corner seal broke.



Was also missing a soft seal from another corner seal, think this might have been sucked in, the apex has tried to run over it, broke the apex seal, and the corner seal.



was every thing else in place?

 

Yea, everything else was in place and looked good. Something else I failed to mention was that I dont remember seeing any "dents" in the rotor, now dont get me wrong it was trashed to hell and back from apex seals but typically under detonation there are dents and I dont remember seeing any.



STEPHEN

 

Well went my car detonated (18psi on 4x460cc injectors.. hahaha yeah i know.. wsategate line fell off..)

I didn't end up with any dents at all?? I guess its just how the detonation happens.. you win some.. you loose some..

 

Probably detonated it.



Detonation is the spontaneous ignition of the mixture at a location remote from the spark plug(s) after the planned ignition event. The mixture is lit by the spark plug(s) and the burning flame front expands from the plug(s) like wave rings in a pool when you drop in s pebble. The radiant energy is super heating the mixture ahead of the flame front. The pressure increase of the burning fuel and the radiant energy is crushing the unburned mixture into the opposite ends of the chamber.



On this occaision, the temperature becomes too high and some of the trapped mixture goes off before the flame front gets to it. But this pocket of mixture has been compressed to an abnormally high pressure, and its burn rate is ten times normal. It is s very powerful explosion. The explosion itself increases the temperature if the chamber components and assures that additional episodes of detonation follow until there is a failure, or a causitive condition is changed that lowers the mixture temperature.



The sole cause of the detonation is mixture temperature. There are a text book full of factors that lead to the temperature problem. The short list is: Inlet air temperature. Ignition timing. Mixture too lean. Octane rating too low. Too much boost. Poor combustion chamber shape. Poor mixture atomization. Insufficient squish area. Plug heat range too hot. Oil temp too high. Water temp too high. Too high a throttle opening for the RPM (lugging the engine) as in skipping a gear at high throttle opening. Injector too small for the boost level in use. Low fuel level. Fouled fuel filter. Full pump too small. And if you want to go into the weeds on the subject, another thousand pages. But it all comes back to mixture temperature.



If it were possible to predict the exact instant when detonation would start, it can be avoided by changing just one thing from the list. Unfortunatly, the only thing you can change quickly is the throttle setting, and even then you would have to be qlairvouyant to save the engine from damage. If you have a knock (detonation) sensor and your computer pulls off enough advance and richens the mixture quickly enough, then you and your engine are saved.



The corner seals and the oil pump rotor and ring are made of powdered metal. There is no way around it in mass production. (they are crap) They are easy to break.



I use only the solid corner seals and an after market external oil pump.



I towed the race car from Columbus Ohio to Pocono one weekend and ran the engine for a few minutes. Not even reved up, just warming the oil when it stopped.



A corner seal turned back into powdered metal. (powdered cast iron).



If the engine is apart, put in new solid corner seals. I have used the rubber plug style seals until I found the cracked through the thinest part. No more of that.



Lynn E. Hanover