This is true Ito, didn't think about it, too much retarded timing will cause really high EGT's, did no one check this?

well maybe the oil temp or something is a little high, and the timing is a little retarted, and maybe a little of something else. it might not just be 1 thing

Whoa, melted turbo?

Did I miss that somewhere?



If the turbo was melted, this really points to overly retarded timing.

I concur with Ito.





-Ted

Coolant temps should be noticable higher too with retarded timing. Although if its just under high load, then you may not notice that as much if you only make short burst.

I had to reread everything, since this intrigues me also...



Oh crap, I just reread what pluto said in the first page...





EGT doesn't lie.



I bet the coolant levels could've been a little high (good call 94touring), but the oil temps should've been down.



This all points to a timing problem or retarded timing.



This all kinda makes sense now. Fuel igniting out the exhaust is violent on the engine (and apex seals), and this explains the apex seals rocking and producing the weird wear patterns.



My money says the ignition timing is messed up or too retarded...





-Ted

I"m pretty positive that it is caused by extremely high EGT. The only thing that confuses me is the fact that it only happens when I lean out the a/f ratio closer to 10.5:1 and above. Why would running richer a/f ratio prevent it from losing compression? Since I was the one that did the tuning and I know my timing map pretty well, There wasn't a time where the leading timing gets below 10 degrees in advance. Split timing should be around 6-14 depending upon where it is in the map matrix. Retarding the timing a little helps spool up because of increase in heat to help move the exhaust velocity faster but it doesn't maintain at 10 degrees of advance through out the rpm. I have been using this timing map for over 100 cars and there were only two cars that seems to lose compression after a WOT pull. One is mike's car and the other is Russ's car.



Hey Ito, How early does the exhaust port open? The reason why I asked is because opening the exhaust port earlier serves similar purpose as allowing hotter temperature out to the manifold to help spool and maintain boost.



I wonder if the combination of my timing map and early port timing causes too high EGT?



Ihor's engine was ported down at least 5mm from factory port and I have never seen his engine loses compression. I guess mike's car is one of those ringer that doesn't want to stay running for too long... https://www.nopistons.com/forums/pub..._DIR#>/sad.png

Haltech or Power FC?

If it's Haltech, I would just double-check the ignition map.

Glitches on an upload can cause for bad data and corrupt the map and/or settings.

Sorry for stating the obvious - just trying to cover all the bases.





-Ted

It's a PFC.



Hey Steve or Mike, got the logs? Point me to them or compare recorded against actual. There are factors in the PFC that will cause the ignition to retard beyound what is intended. Thinking that could be part of it.



Tony

water pump is not working..... and housings are getting too hot

Yeah but then that would look like a overheat...temps climb until she pops. They can run the engine at lower boost and off the dyno and no over-heat.