Porsche-O-Phile

Ahh, sorry missed that. Just read it quickly and saw "2.8L" and assumed it was a stroker. Guess not.

Hmmm. . . Terrible news in any case! Hope you are able to find yourself a new engine in short order!

EdC

Didn't you run at very high boost levels last summer or fall?

rage2

Yea, that was like 28psi on high octane fuel. That was about 3 or 4 years ago on the same rods. I've been running about 16psi in the summer, and somewhere between 10-12psi during winter on pump gas. I haven't run high octane fuels in the 2.8L motor yet. Was going to do that this summer.

DDP

How many miles are on the rods?

DFASTEST951

Oh no! Sorry Rage. Been there done that. Damn number 4 piston. Good thing you do the work yourself. It cost me $30,000, and then I blew it up at about 6,000 miles. Had to save a year and a half for another at almost $40,000. You know, now that I think about it, call Powerhaus. David may have a block there for sale. Just a thought. Good luck.

rage2

Too much that it's embarassing. I dunno what I was thinking when I decided NOT to change them.

OK OK, it's about 220,000 miles.

And no, I don't do my own work either hehe.

ilikemy944

Sheer curiosity - what kind of sleeves?

Chris White

That does suck, not a normal rod failure (usually under load). The most common rod failure is due to the bearing letting go and welding the rod to the crank. That is followed by nut/bolt failure. I would bet on either one of those before a rod failing.
If the block is not too beat up you can weld up the hole…that’s a nice thing about aluminum/alusil.

Chris White

David Floyd

Sure hate to hear that Rage, let me know what you find on the teardown.

SoloRacer

That really sucks Rage. These cars sometimes can sure beat a guy up can't they? I still have the original block from my car and was considering building it up to 2.8 or 3.0 specs with sleeves. If it wasn't so close to summer I would be tempted to offer to sell you the 2.5 in my car and then get my old block rebuilt. Something about having the original number block in the car that appeals to me - even if the displacement isn't stock. One thing is for certain now though, if I rebuild my old block I'll be using new rods.

And guys, don't feel too bad for him - he still gets to pimp around town in his AMG SLK .

P.S. ZERO10 if you ever feel like running with a mildly modified 951 give me a shout.

inactiveuser92616

as you mentioned, you should look very seriously at the vibration issue from the balance shafts. Harmonic frequencies are no joke; the accelerations just build on each other. With the larger bore, you probably have even more unbalanced reciprocating mass, exacerbating the problem. This will wear out every moving part and their bearings much quicker.

One of my professors told us that once at GM, they had a truck/SUV on the full body suspension dyno. One of the engineers happened to program it where it spent a good amount of time at the suspension's resonant frequency. They came back to the vehicle lying on the floor on its side.

TonyG

RPM's are what causes most rods to fail, assuming you didn't spin a rod bearing, not boost, and not the HP you were making, and not the sleeves, and not the lack of balance shafts.

While when it (the rod/rod bolt) failed you might not have been at a high rpm, the previous fun at over 6000 rpms takes its toll on the rods and more specifically the rod bolts. Were you using stock rod bolts? Were they new?

The rod and even more so, the rod bolts, are by far the most stessed part of the engine.

Get a set of Carillo rods. You'll never have this happen again.

And just because the pistons are larger, doesn't mean they weigh more than their stock counterparts. Thus the assumption that the larger bore was contributory to the rod failure is without merit without knowing what those comparative weights were (are).

The elimination of the balance shafts is done by all of the big name 951 engine builders. I've done it for years, as well as many people here. While this can and does cause some problems, the problems that result are very consistant on the 951, which include broken powersteering turn buckles, alternator turn buckles, vibrating lose bolts/breaking off bolt bosses from the block on bolts that have come lose, that either don't have red locktight, aircraft lock nuts, or some sort of lock washer in place. If everything is tight and locked down, the problems are fairly trivial.

Anyway, with respect to your problem:
The block has a very good chance of being toast. Hopfully the pistons, the valves, and the cylinder head are not. The crank is probably got chunks out of it and is probably toast as well. You'll know soon enough.

Sorry... It sucks I know.

TonyG

ibkevin

Bad, bad engine!! Damn that $uck$ a$$ Providing the crank is toast, wouldn't rehabing a 3L be only slightly less expensive than a new sleeve job?

Rich Sandor

here's a vote for a 3L turbo.

If I could combine the low end of my 968 with the boost of my 951.. It would be a near-supercar...

DDP

If you need a crank, Rage, let me know. I've got a good 2.5 turbo crank.