What would cause the intake manifold to separate from the "block" on one side of the engine and put a hole in the other side where a spark plug is seated?

I was changing lanes in traffic, rolling along about 25mph in 3rd gear, dropped down to 2nd and stepped on it. About 6000 rpm, it sounded like something external broke. All the lights came on and smoke billowing out the back of the car.

The car seemed to be running just fine. I had just put in an Optima Redtop, 10 minutes prior to meltdown. The only other thing I noticed that was winky, was the tachometer would bounce in time with the turn signal.

 

damn! that thing blowed up real good. never seen that happen before. must have sounded like a bomb exploded. which housing is that?

 

Actually it didn't sound very loud at all. It just sounded like something broke. The rearend had been making some noise, so I thought it was that.

This is my first rotary, and I've only had it since this past Saturday. If you're standing on the driver side, looking at the engine, the piece came from the lower rear spark plug area.

The engine had been street ported about six years ago. I don't know how many miles are on the rebuild, but the car show 137K on the odometer. The guy I got it from had it for about 1 1/2 yrs, and put about 7k on it. He did admit that he drove it very conservatively, almost never taking it over 4000 rpm. I, on the other hand, had no reservations about ringing the motor out. Just to remove any carbon build-up, mind you.

 

well since i've never had this happen nor seen it happen til now, i can't even begin to guess as to what caused it. only thing i can think of is the housing was already damaged when built. i have over 60k on my build and had only one incident when i had detonation a few yrs ago, but that was only at wot. since being fixed it's seen 7-8k many times since then and have yet to blow a housing apart like that. i'm guessing u have this part of the housing after taking the engine apart, right?

 

I didn't know it until today, but I know a guy that used to be an instructor for Mazda. He seemed very confident that it was the stationary gear that failed.

 

HOLY ****!

I don't even know what to say. That is just incredible.

Seeing as you can now look directly into the engine, is the eccentric shaft broken? Catastrophic eccentric shaft failure at high RPM could be about the only thing that can cause something like this, and that is exceedingly rare.

 

huh 25mph in 3rd?

holy crap batman ... detonation ... timig was? engine temp was? was this engine boosted? NO2?

 

traffic at quitting time stinks.

I don't know about the timing; temp was good, below half; no turbo, no nitrous, it was street ported.

not positive (i was watching car in the side mirror), but I think it let go between 5k-7k.

 

very freakin interesting the way it failed like that,

oh was just teasing my SA would be b1tchin a storm that high a gear at that slow a speed

 

Holly Molly I think I might build a sploding shield on my drag bike that's gettin pretty close to the boys, I wouldn't want to blow them off i'd kinda like to keep em ..===

 

I'm getting around to fixing my 7. I took some more pictures during the engine removal.

 

never seen anything like that in 13 years of RX-7 ownership..how and why, lol?

 

Not so sure a case of detonation would cause that too happen... Almost seems like a tremendous mechanical failure from when the engine was built. Crazy man just crazy. Does it still run? (just kidding)

 

Friend of mine blew the side out of this Gen 3 motor a few years back when running in a Texas Open road race at 130 mph. It ended up being a catastrophic coolant seal failure that hydro-locked the rear housing and blew a hole the size of a tennis ball around the spark plug. He showed me pics of the spark plug wire still attached to the plug which was still screwed into the housing, but dangling next to the gaping hole. Weird!

 

Stationary gear, I'm told.

It will run as fast I can push it.

In the process of giving it a new heart.

 

Same thing here.

 

I have more recent photos, with the engine out of the car, on my profile page. https://www.rx7club.com/members/retodd1000-151738-albums-catastrophic-failure-4114/

 

damn that's incredible! Can't imagine how much force it took to do something like that to the housing wow. good luck with a new motor