I have been doing enignes for over a year now and have taken apart many cores in all states of disarray and tonight I took apart one that had damage I had never seen. Background:

89 vert with jspec conversion, s5 t2 motor with stock injection, full intake, exhaust, and reprogrammed ecu, running 15psi when it blew. The owner also mentioned it had over heated before, so i didnt know what to expect. He reported to me that he thought it had 0 compression, at all, which I thought he was full of **** or just running the test poorly.

We pull it out and replace it with the one I built for him, and I took apart the core to find BOTH rotors destroyed by apex seal damage. The front one was absolutely crushed...more scars on it than flat places. The rear one had a single deep gash about1/4" wide on one side, on all 3 faces. and part of an apex seal was stuck onto the rotor housing in that spot. This engine had 0 compression.

To any of the other engine builders out there what are your theories to how this happened? I figure one of 2 things: 1) severe detonation on both rotors took each one out at the same time. Sorta unlikely. 2) the front rotor got destroyed, and pieces flew out the exhaust at high speed(we found springs and seal pieces in the turbo and manifold), hit teh spinning turbine wheel, and got thrown back into the manifold where they entered the rear housing and bounced around, jamming against that rotor and housing and killing it.

Any other ideas? This is the damndest thing Ive ever seen as far as blown engines, next to that time I took one apart with a gaping 1" round hole in the side of the iron(combustion face) thast allowed oil and coolant to leak into the chambers.

 

This is a theoritical reply, but what if at wot at 15psi this persons motor went thru sever detonation on the front rotor, blowing the seals, then with the extra stress of that and still at wot without lifting his foot and still excelerating "Running leaner" Caused the rear rotar to go. Just a thought.

-CHris

 

wow! do you have any pictures of the engine?

 

That sounds like what happened, unless something came apart before the irons or garbage was injested into both chambers.

I pulled an engine Friday that has to go back to Dave Gibson for a core. The No. 2 rotor is absolutely FUBARRED, and I'm pretty sure the housing and *maybe* the irons are too. Both Steve and Dale said it was the worst one they've seen with their own eyes.

 

Maybe something broke off in the compressor?

Though I tend to think that it was simply severe detonation. One rotor let go, he kept driving, then very shortly after the second rotor let go...

Pictures!

 

Yea, I do not think anything would be making BACK into a motor at WOT, there is just to much exhaust back pressure.

 

did he ingest some water into the engine. at high boost, and the fact that water doesn't compress.........i can only imagine the results. even a little could be bad if he was just running enough fuel.

 

That sucks. but very interesting.

 

pictures please!!!

 

my guess, one of two things:

First, Check all the bearings on the eccentric shaft. If one of them took a dump, maybe both rotors could have smashed into a housing and destroyed themselves (or one rotor hit and jerked the other rotor, causing it to hit also).

Second, possibly one rotor blew in a rather spectacular way, and as it was still spinning, a piece of rotor or seal or something somehow wedged itself between a housing/port/something, and the rotor, and it caused some high stress on the eccentric shaft, twisting the other rotor into a housing, and destroying it also.

 

REAR ROTOR FRONT ROTOR

IM sticking by my earlier theory about the piece flying back into the engine...if you look closely at the first pic of rotor 2, youll see that there is only ONE gouge, and the apex seal piece is stil lodged in the housing that made that one gouge...it came from the front, as most all the apex seals for the rear are still there, albeit cracked.

Here is few more of a SP s4 NA engine I built for a local guy, no emissions, dual RB race exhaust, painted manifolds:

 

that's a nice header! about the rotor above, OUCH! looks like someone's in need of new rotors and housings... looks like it's time for a JDM engine!

 

I love how the oil injection system always creates a high spot of carbon up by the apex seal like that

And people still ask if carbon buildup is harmful :P