Name That Engine Failure... Feel like I lost a child!

[DSM]

Originally Posted by onboost

Those don't look like 98mm cylinders.. they should be full fin unless the stock ones were bored and plated.

Good Info. Thanks!

[DSM]

Originally Posted by TurboKraft

+1
Those are standard 1978-89 97mm "bald" cylinders i.e. no fins across the tops of the cylinders.

We've seen them fail this same way, along the clearance groove for the head stud, the thinnest point of the cylinder.

If they've been bored and re-plated, that's not good. It's taking an already weak design and making it weaker.

Good Info. What are your thoughts on my cam timing numbers? Thanks!

[Oheggem]

Hey. Good job tearing the engine down and finding the actual fault. Now lets hope you find the cause.

Can you please send me your tune of your tec3? I want to compare a few things.

Also, i'm a bit envious when i see the rest of your garage and cars. Lovely cars all of them!

[DSM]

Originally Posted by Neil Harvey

You still have work to do to find and fix the cause.

For future reference, your very first post showing the Spark plug told you you did not melt the Piston. The Spark plug looks clean.

It also is telling you your actual "in cylinder" Ignition lead.

As stated earlier, I believe this is what caused the damage. Had forgotten that I adjusted the boost controller map so to decrease spool up time. Didn't fully test it and no failsafe in place for over boost. Think it made a bunch of boost early with advanced timing.

[DSM]

Originally Posted by Oheggem

Hey. Good job tearing the engine down and finding the actual fault. Now lets hope you find the cause.

Can you please send me your tune of your tec3? I want to compare a few things.

Also, i'm a bit envious when i see the rest of your garage and cars. Lovely cars all of them!

As stated earlier, I believe this is what caused the damage. Had forgotten that I adjusted the boost controller map so to decrease spool up time. Didn't fully test it and no failsafe in place for over boost. Think it made a bunch of boost early with advanced timing.

I'll add a link to my bin file shortly for all to access.

[DSM]

Link to Bin File for download:
https://drive.google.com/file/d/1ycrZUuZclZLnsZwCs8JTnH_c8crWGAQg/view?usp=sharing

I went to look for the bin file and decided to look over some parameters. So there is over boost safety and it was on. Boy did I have a brain fart earlier. Running 2 bar map sensor in kilopascal (kPa). I set fuel cut off at 208 kPa based on all the tables believing its actually going to cut at 108 kpa or 15.6 PSI of boost. When I get it all together I’ll test this with low values to see if it works.

Table Example:

[GJF]

I have mine tapped to the #6 cylinder head. The J&S has some sort of ties with the system used in the 944 Turbo, I can't remember the story but they have something to do with that system. It is a true standalone controller. I was introduced to their product back in the 80's from Carlos Lopez Racing. He is probably the most experienced turbo rotory engine builder in the world. (Havent spoke to him in a while but I know he's still has his shop in Homestead) The fact that the J & S was the only device that could actually detect knock in a rotary engine was it's unrivaled ability. Rotary engines when they detonate, they crack the rear plate at the oil pressure sending unit in the upper corner. that is one of it's Achilles heel. Carlos would set the timing to something like 30 degrees, and let the J&S unit control timing. It would back off timing until no more detenation on his setups. Never having a ignition related failure. At the time I had a RX-7 that was turbocharged, and for a while, I use to weld up Intake manifolds for him. So I made my own setup, but used Haltech injection and interfaced the J&S to the Haltech. And from there I simply started using J&S from that point on, because they work!

[Speedy Squirrel]

Is this 98mm cylinders on a turbo or 3.2 crankcase with steel studs by any chance?

[DSM]

Originally Posted by Speedy Squirrel

Is this 98mm cylinders on a turbo or 3.2 crankcase with steel studs by any chance?

97mm / 930/66 turbo / Head studs appear to be Canyon.

[DSM]

Need one cylinder. Its machined for Ni-Resist ring also.

[DSM]

Posting more pics for reference and because who doesn't like more pictures! Everything except cylinder appear to be good.











Cylinder is stamped height group 5. Does that line up with measurements?





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[DSM]

New cylinder machined for flame ring and installed. Cam timing setup next. New wing is done. Its like a mini 935. I like it. Replacing aero mirrors with flags. Full old school. Might look into aero base with sebring mach 1 mirrors. Those look great to.

[DSM]

Learning a lot about this engine. Went to put the intake on and said WTF? Someone goes thru all the trouble of port matching 930 heads to Carrera intake then uses stock gasket without adding extra material to head? Way to many hacks out there....

[Dmond]

I hope it's just a blown gasket or something... GL

[motorracer]

Scammer trying to get his number of post up

[DSM]

Learning a lot about this engine. Went to put the intake on and said WTF? Someone goes thru all the trouble of port matching 930 heads to Carrera intake then uses stock gasket without adding extra material to head? Way to many hacks out there....

[gorskined]

Great job on the gaskets looks professional . i need to stop by and check out the progress .. it will give me an excuse to give mine a shakedown and see if i still have the running rich issue under full boost . i took the entire top end apart made 100 percent sure i had no air leaks. if its still running in the 10s under full boost its going to stay that way.