I blew my engine in January, im getting a rebuild at Rotary Power right now, should be done next week. Here are some pics of the blown motor.

 

what did u do to it?

 

Not sure what you meant, what did I do to blow the engine or what did I do to my new motor. I'll answer both.

I was running stock boost on an untuned power fc, I had a downpipe, intake, and hks exhaust. Blew motor at around 4500-5000RPMs in 1st gear, not sure why it happened, boost spike maybe?

As for my new engine...
Rebuild with new rotor housings and rotors, race port, 3mm apex seals, water passage porting, new turbos, 750cc primaries, 1300cc secondaries, supra tt fuel pump, greddy 2 row fmic, efini y-pipe, fluidyne radiator, aluminum AST, ACT streetlite flywheel, and MSD 6A on leading. I might be forgetting some stuff, but thats all I can think of right now. The bill is gonna be pretty bad...

 

i take it that you broke an apex seal or two? that's an interesting looking rotor surface... can't say that i've seen anything like that before, but then, i'm still a newb and haven't really seen the results of a blown motor all that often yet.

sounds like you did a good job replacing it though... getting tuned this time aye? sure hope so good luck.

 

Damn! That's some damage. Good luck with the new project!

 

I'm almost thinking you didn't blow it from detonation but from foreign object damage. That's some SERIOUS damage to that rotor, with multiple impact points. Typically an apex seal will simply chip a small rice-sized piece off at the corner which imbeds itself in the rotor - pretty minor compared to that.

Dale

 

that's what i was thinking... but i don't have a clue what i'm talking about, so i didn't wanna say anything

 

I was running stock boost on an untuned power fc, that seems like a really strange way to blow a motor. I'm gonna side with dale.

 

yeah, I thought it was kinda weird at stock boost, Jeff at Rotary Power says it takes a lot of boost to do that kinda damage. I think some of the dents might be cuz the engine ran for a few seconds after it blew.

 

I would think an untuned pfc would be on the rich side and wouldn't cause you to damage anything especially at 10 psi. Did you have a boost gauge installed, and fuel meter. How long had you been running with an untuned pfc.

 

That's pretty normal damage from apex seals blowing. IT depends on how much of the seal actually made its way out of the slot, and why it broke. Usually a worn out, old seal that breaks from just wear does damage like that...since the whole thing is worn, most of it comes out of the groove and hits stuff behind it, thus there's damage on the entire width. IF it's a medium detonation break, the seal will break off a little chip at it's weakest point, the top corner of the long piece where it meets the short piece, which is the weakest point of any apex seal. That little chip will then float around and do some minor to moderate scarring which is usually repairable by filing or milling to 3mm on the rotor, though the housing is still likely trash. Then, I've seen the severe, prolonged detonation breaks too...dents the whole face of the rotor in (see my anti-det device thread) due to the force, and pushes large chunks of the seal out of the groove to do major damage.

The fact that the engine is running when a seal breaks (obviously) means that it only takes 1/20 of a second to wipe out all 3 seals and all 3 faces of the rotor if the engine blows at a moderate 4krpm. IN most cases, it doesnt matter if you continue to drive it, the damage was already done...the seals are already either locked in place due to damage, or they've exited the engine...in either case, there's not any more damage going to occur. ON *very* rare instances you can chip a small piece of seal yet it doesnt come out of the slot, just stays put and rides that way. IN these cases you lose a bit of compression but the engine still runs okay...and in these cases it's a bad idea to keep driving it, because that chunk can come out of there anytime it wants and do some damage.

 

I do have a boost gauge and an A/F gauge. Boost was always around 10 psi, sometimes it would get to 11. A/F gauge said it was running rich all the time. I had been running the untuned PFC for about 3-4 weeks.

 

wow...that rotor is going to make a great wall clock!

 

allrotorfd,

Any damage to the turbos?

 

The turbos actually look perfect, everyone was pretty amazed when they were taken apart. No visible damage at all, I went ahead and replaced the turbos anyway though.

 

Damn... sounds familiar... mine blew when I wasn't even pushing. Just now have enough money to go find out what went wrong... finally! Depending on what all went wrong, and what kind of condition the motor is in, I'm gonna do a complete overhaul below the hood.

Check it out if any of you are interested:

www.rx7club.com/showthread.php?t=411899

 

Haha, my car is at Rotary Power too. I just took it there on Thursday, April 21. Good luck with your new engine.

 

Wow, sounds like you have a nice car there, good luck, let me know how it turns out.

 

I was at Rotary Power on thursday, would your car happen to be the black one parked out front with the 99 spec front and rear? If it is, damn, you have a nice FD. I was drooling, haha. My engine is the one they were working on inside that day, my car is the black one that was parked out in the back. Rotary Power does good work. What are you getting done to your car?