So about a year ago in november my car ended up on the chopping block since the engine decided to die on me. After a compression check the front bounced at 95 on all three faces. The rear however was 80 0 0.

I ended up buying another engine and put that into my car. Well, i finally got some time to take it apart and found more damage than what i thought. I had thought maybe i just fractured a seal since i could see the entire apex on through the exhaust on each face.

Anyone know what might of caused something like this to happen? let me know your input.



To my surprise this is what i came across.

This is the Rear housing.




The Rear Rotor





The Apex seal that did all this damage

 

You want to know why the engine blew or why so much damage? The apex seal generally fails in that exact spot as that is where it is the most fragile/weak. The broken piece of seal did not go out the exhaust port immediately and looks like it got drug around a couple times. Damage looks pretty common for a broken apex seal.

 

those are some deep divets was it running at all like that?

 

looks like normal damage to me.

 

Yep, normal blown engine.

 

That is actually fairly minor damage, not reusable of course, but right in line with a chipped seal. When the complete set of seals goes it is absolute carnage.

 

Yeah the car was actually running on both rotors still just idled a little funny. I was more curious as to what leads to an apex seal failure, I would think something would have to cause the seal to become weak and break off?

 

Detonation

 

Would a one-piece seal possibly survived that? and not caused the engine failure?

 

Possibly, but it would still be a band aid for an inevitable failure down the road, along with dealing with all other issues that come with a one piece seal.

 

how much boost do you run and what were your afr's tuned too?

 

Detonation, pre-ignition, or in some cases extreme wear on the seals that weakens them. Likely culprits are a bad tune, poor quality gas, etc.

 

It was tuned just a week or two before. Always ran 93 or higher in it, and never got bp gas or other crappy stations. usually speedway or sunoco. I was running 14psi but for some reason it was only coming online at 12psi that day. 11.3afr

 

Strange that you just had the car tuned and then it blew. Those afrs are a bit leaner than I like, but not terrible. I would look at the map in that boost range and see if anything stands out. I blew one motor years ago after I had been running 20 psi all weekend on c16. A day later I was heading to the gym and just cruising at about 12 psi. Went to hit it and detonated bad and blew. Turns out the timing was off in that part of the map. Found some negative split. Bad gas can be as easy as the truck putting 87 octane into the 93 tank by accident.

 

Or, as often documented, on purpose, at some shady stations...

 

I've blown a motor from bad gas (exxon '93'), back in 2001......

 

Wow thats scary to look at. I always run shell v-power now because it always made my cars run better. What are you plans for the new engine?

 

11.3 AFR is perfectly safe for those boost levels even using 91 octane. It could be a variety of things but at this point your only guessing unless you know exactly what happened. Possibilities...

bad gas
a part of the tune
fault in the fuel delivery system (injectors, fuel pressure, pump, wiring resistance etc)
AFR meter not reading correctly (so you think your safer then you really are)
uneven air flow's
something electrical
carbon chunk broke off
AND I'm sure there's many more possibilities.

thewird

 

My next setup includes so far:
Xcessive LIM
Flow Balancer
Dual EGT's
Datraloggit
PFC
(Lots of other slightly unrelated bits)

Still need to get:
WideBand
AI System (Looking at Howard Coleman's info to settle on this aspect)

The stock Mazda Seals can handle 18psi, reliably, correct? with a proper tune? Sorry for the slight Hi-jack.

 

Spend the extra money on the ALS seals if you plan to run 18psi, they are worth the extra money. If you prefer using OEM seals at least go to 3mm, you will not regret the decision. I still say go with the ALS seals.

 

Here is the map from that time if anyone is interested.

 

I don't like what I'm seeing on the fuel map... It's very inconsistent. Timing is fine and everything else seems fine, its just the fuel. Might have just been some lean spots.

Also, since your going into the motor again, I recommend you install 550cc primaries again. You don't need so much fuel. Your car will idle better and tip-in better as well assuming its tuned properly of course. 550/1680cc is even enough for more most singles @ 16 PSi unless your looking for monster horsepower.



thewird

 

just wondering did you tune or have someone do it?

 

someone else

 

It looks bad, what else do you want to know >_>

thewird