That looks like detonation damage to me , the bearings are very soft & thus susceptable , before you decide to reuse the crank get it crack tested , detonation will crack the hardening , if the crank is ok , you can go to oversize bearings ,oh by the way been there done that .

 

Check EVERYTHING!!! My last 944 Turbo was Nikasilled when rebuilt by previous owner. Also had cross drilled knife edged crank and raceware fasteners. At about 20K miles it started some rod knock and I tore it down. This is what was found.

Previous owner had used wrong ring material for Nikasil. The Nikasil was starting to chunk off the tops of the cylinders.

#4 and rear main bearings were just barely down to brass. Caught it before major bearing failure.

Major pre-detonation issues...

Wrist pins were bent.

Crank gridle was stretched.

So if you got her tore down, check EVERYTHING!!!

 

Hi,

I'm not sure I understand all you are talking about. But I would like to fix one time for eternity () that rod bearings issues in most 928 tracks cars (except the fully oiling amzoil car of Mark K !) as i am in the process of making my own 928 track car.
So first, It seems that oiling of the #2 and #6 rod bearing are not correctly lubricate because of the design of the rod bearing as well as the circulation of oil in the crank shaft.
Second, the fact is, in extensive use, there is a sort of scarvation of the oil because of the design of the oil pan wich is too close to the crank shaft. And then oil pomp receives not only oil but a mixture of air and oil which make the pump not working properly and introduce air in the system until the oiling is not as good as it could be. In addition to first oiling issue, it sinks!
Third, in addition to #1 and #2, there is a problem of detonation in clinder #2 & #6 which makes that issue even worse!

So What to do to avoid the problem except mounting corvette LS1 engine?!! or cayenne V8 TT which as a dry sump. or simply mounted a dry sump on the V8?

Another questionning about 16V issue. Is 16 V engine concerned by that issue?

Thanks

Puyi

 

This is a recurring theme here on Rennlist and I will give my 2 cents on the subject:

1. The 928 motor was not designed by Porsche to handle track use with associated high RPMs.

2. Most 928 motors will have 2/6 rod bearing failure and other issues when used for track duties unless they are purpose built for the track.

3. Unless you have years of knowledge on building Porsche 928 race motors, most will not succeed in doing it the first few times until lessons on what to do and what not to do are learned the hard way.

4. The only person that I know of that has the most success in building such 928 motors is Greg Brown, who has built up motors for Mark Anderson whose last 928 race engine lasted an astounding 5 race seasons (IIRC) with Mark A. winning races along the way in highly competitive California POC events.

5. If you want to race 928s, I would seriously consider having Greg Brown build up your engine or at least the bottom end to give yourself every advantage against catastrophic engine failures.

6. After the engine is placed into the 928 it must be tuned correctly to ensure proper running in the conditions it will be exposed to on track. The Shark Tuner developed by John Speake allows you to tune the 928 motor to a high level and should be used to tune the 928 motor using the stock computers. If the owner is using a stand alone engine management system from another manufacturer it is imperative to have someone knowledgeable with this specific system to tune the car.

I do not have any vested interest in Greg Brown's shop or John Speake. The only vested interest I have is to have more 928s on the track and kick *** at their local tracks!

Dear Mark Kibort, I know you will read this and go on about you not having any problems with your past track motors using Amsoil and there is too much being made about this 2/6 rod bearing failure. It is my opinion this will give false hope for those who want to believe your statements. Unfortunately the odds are not in their favor. No disrespect is meant to you by the way or your excellent achievements.

Cheers,
Constantine
P.S. Tracking a 928 is not cheap. Some people see the initial cost of buying a 928 and believe it will be cheap to track. This is not so and to do this correctly will cost you a lot more money than you initially think. Trust me....

 

Brian: If things don't go well when telling mama the good news just remember that we have a new flatscreen TV in the 4th bedroom down the hall if you need a place to stay for a little while.

Gerry

 

Sorry to hear this...but you're lucky!

That crank is toast. Don't fix it, get a different one. That'll be cheaper than grindng it and getting the oversized bearings.

Something that keeps coming up is detonation damage. Something to remember is that 2/6 fail on all versions of 928 engines from Old buggahs with CIS through GTSes. These are very different fuel systems and intakes. On S4 engines it is 2/6 that knock. On CIS engines (and L-jet?) it's 4 and 8 that knock. It's clear, at least to me, that the detonation issue is a red herring. It's an oiling problem.

 

Here is the filter from the Holbert stroker after 6 race weekends

notice if you hack saw off the end, the filter doesnt get any debris. I suppose the oil comes in from the outside and goes down the center after being filtered.

Looks like nothing in the filter, even with a magnifying glass

mk

 

It could be, but what do we know! Greg Brown talks about the one bearing being in a position to get even less oil than the other. BUT, i would think that if you had detonation, that could damage the bearing and it could have happened before Brian bought and ran the car! the other thing, Brian doesnt have a RRFR, and i noticed some pretty lean conditions with the S4 without one. with it, you get the fuel in the right ratio areas. Didnt brian talk about the mixture having issues in the beginning?

mk

 

ask me how many vets and their engines had to go home at the race track with a metal flake fest going on in their oil pans!!

Nothing's safe!

mk

 

come over to the dark side...

 

No disprespect taken. I know this is an archiles heel, no question. But, Anderson had 5 race seasons and a heck of a lot more power than I did (and do now) However, with 7 racing seasons and no hint of any issues on 5 engines racing, has got to make someone curious as to why the success.
warm up?
oil?
track conditions?
style?
tollerances?

you would think I would have even a slight hint after all these years of a problem! Personally , I think (and this is my opinon) that the engines are very sensitive and you need good oil, good warm up, care in driving at the track, and proper tuning. Remember brians problem with turns and sputtering?? at the track, under high temps that could have been some major detonation going on there. It did it ALOT and it was a fuel starvation. all you need is a few moments at 14.7:1 mixture and you have a problem!

The fact that Brian only really spun one bearing is a clue that something up might be the problem. you need 5 bar oil pressure, all the time at the track, (maybe 4.5bar on the very worst turns in racing) any less and something is up.

Oil starvation due to high g loading or high rpm is a common problem with street cars. many suffer spun bearings at the track. I think with care, you can stack the odds in your favor. Again, why 5 928 engines at the track, beat to heck and no issues???? I have the 70mph, 5krpm, left hand, 1.4g carocel to deal with at Sears point, 5 races a year!!!

mk


[QUOTE=Constantine;6466321]This is a recurring theme here on Rennlist and I will give my 2 cents on the subject: <SNIP>

4. The only person that I know of that has the most success in building such 928 motors is Greg Brown who has built up motors for Mark Anderson whose last 928 race engine lasted an astounding 5 race seasons (IIRC) with Mark A. winning races along the way in highly competitive California POC events.

Dear Mark Kibort, I know you will read this and go on about you not having any problems with your past track motors using Amsoil and there is too much being made about this 2/6 rod bearing failure. It is my opinion this will give false hope for those who want to believe your statements. Unfortunately the odds are not in their favor. No disrespect is meant to you by the way or your excellent achievements.

Cheers,
Constantine

 

Ok so oiling problem.

What are the more simple solution to preserve engine from damage.

I noticed different things :

1/ tune the "mise à l'air" (sorry! ) of the crankcase
2/ drill cranshaft
3/ Accusump to avoid teh effects of starvation

Is that solution is worthwhile and can provide the same raliability than tuned the engine to a dry sump engine...at a realistic cost?

Puyi

 

A rising rate fuel pressure regulator is a band-aid for a poorly tuned fuel injected car.

 

Brian I will give you a crank and a clutch disc for free, but I do recomend you get the crank drilled and if you stay with the single disc clutch have the pressure plate modified for more pressure. I have plenty of good used stock ones here and I can send it out to be done for you.
I'm sorry this happened but like you say the bright side is you caught it in time.

 

Brian, my 100,000 mile clutch looks BETTER than your 10k one