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.

Steve, I don't feel your tunning of the timing maps are OFF. I'm thinking the PFC is not correctly adjusting timing advance under boost and keeping the engine running a retard timing under boost causing Xtremely high EGT's. Next dyno session I'll be there helping Mike with his car. I'll be checking proper timing advance under boost.



The exhaust port opening is under 5mm vs the stock exhaust port opening. It opens 2mm earlier then the stock port. I have almost seen it all in the world of porting. Done just about everything. Big port's vs small ports and I've yet to see this problem Mikes car is having. I've only seen warped apex seals in 2 cases. Lean air fuel mixture or high EGT's ... The air fuel ratio mixture has been addressed in this case, but the cause of high egt's has not been checked through ignition timing under high boost.

Need a log. Got any of the old ones? Would be able to tell in the log what was happening with IGN. If a sensor went caca, that could take you down up to 6 degrees advance alone. Couple of sensors....maybe more.



I like that Mike is getting EGT bung(s) now. That is going to be nice to watch.

Couple of questions, how is your fuel rail hooked up(plumbed), and does the POwer FC fire the injectors in batch or sequential?....Maxt

One thing with Russ' engine is that he specifically requested that Pettit port the exhaust. Cam was reluctant but Russ believes he did port the exhaust as well as the intake. Russ runs a Power FC with a 550/1300 combo. He does not have an EGT guage either. The problem on his engine is being looked at by Pettit. No final conclusions yet as the engine has not been opened up. I'll have to double check, but Russ may have mentioned some Power FC issue. Too tired to remember. I'll ask or Russ, if you're reading, chime in :-)



I know of one other car that has "issues" similar to what's been described but the car has yet to even make it to the dyno. It seems to have some of the same issues under boost and the need for much fuel to run properly. Installing the same maps from my car doesn't get things working too correctly.

Does the PFC allow you to set trigger edge for the ignition, and if so is it set correctly? Just a guess.

was there ever a final conclusion about what caused Mike's seals to warp?

there were only a few things I could think of that could cause an apex seals to warp.



1.) warp rotor housing

2.) soft apex seals

3.) bad OMP

4.) too high of EGT temp

5.) not bevel on closing of exhaust port



other than that, i coulnd't think of anything else.









[quote name='alberto_mg' date='Apr 17 2005, 12:42 PM']was there ever a final conclusion about what caused Mike's seals to warp?


[/quote]

[quote name='alberto_mg' date='Apr 17 2005, 12:42 PM']was there ever a final conclusion about what caused Mike's seals to warp?


[/quote]



Hi Alberto I heard about your problem. It must have seemed eerily familiar after witnessing Mike go through the same thing on the same dyno the previous year.



We still don't know what caused Mike's problem. I purchase the car from him after he went through the last motor. The Ito motor was pulled and examined by another builder. For what it's worth, the other builder made the following observations:



1. Despite Mike being told 2 piece seals were used in his motor the builder found 3 piece seals -so I guess the new apex seals were not the problem as we previously suspected.

2. The clearance on the side seals was out of spec

3. One of the irons was severely worn.

thanks chris. i was going to reach out to you, but too busy with work, classes and the wedding.



that day was kinda like watching someone crush their balls while trying to hop over a fence. except that person was now me.



i'm keeping low key about it till I get things settled with the involved parties. hopefully it doesn't turn into an unprofessional pissing match.

Re: Losing Compression On Dyno, Any Ideas?
 

Any updates? Im having same issue.with a factory port engine. Whats ironic.is that it happened at 13-14psi.for me.as well.