ZX9RCAM

Sorry this happened, but I have to ask.....how would they know it happened
at the track......just askin.....

tkerrmd

if it happens to my new motor with a 2 year warranty, they wont!!

Wachuko

Body damages??? How??

So you decided on a new engine? No mods then? I would have thought you would go with something modified by Kevin to cope with the additional stress from tracking the car (GT3 pump, better internals, etc.)

ltc

I'm glad it wasn't worse. The engine failure could have resulted in oil being dumped, causing Tom to lose control and others behind him.
A contained internal engine failure was about as good as you could hope for.

BTW, a dealer and/or PCNA can "infer" track use by looking at the number of Type 1 and Type 2 overrevs. Multiple Type 1's "imply" abuse, a Type 2 is considered worse.

manny_g

How would they be able to tell..through the ECU? Is that information stored there?

ltc

Yes.
This has been discussed many times in the past.
It is stored in non volatile memory, along with other stuff that Porsche would rather you not know about.

tkerrmd

Thanks Lewis, when it happened the wheels locked up and skidded about twenty yards, but stayed on track and out of the way!!

ltc

Great car control

tkerrmd

rather be lucky than good any day!!

Geoffrey

Well, I guess that is what happens when you try to track what is effectively a 993 N/A bottom end. We've seen a number of 993 crankshaft/rod issues in cars that have been tracked. It appears that part of the issue is the smaller journals which do not give the rod as much support as it needs. The other looks to be the tighter rod side clearance which heats the oil.

Jean

Geoffrey

Are you talking about 993N/A engines or 993 TT engine failures, what is the magnitude (numbers) of failures that you have seen, and where those cars running with stock programming?

Also if oiling is the issue with narrower journals, wouldn't the same issue exist with Carrillo rods and same crankshaft? Are narrower journals always weaker than wider journals?

Thanks

Geoffrey

Jean,

I don't want to confuse the two issues I think exist. One is the oiling of the #2 and #5 rod journals at higher RPM, the second is the smaller bearing support on 993 rod journals. I think they are unrelated and are separate, but could found together. There may be a third issue, but I'm not sure. In the 964 engines, we have noticed that bearings from Porsche over the last three years have been subpar and the bearings have not held up in a track environment, failing prematurely. I no longer use Porsche bearings for 964 engine rebuilds, but rather a proper race bearing of the same size as the Porsche bearing. We have had much better success with them with virtually no wear between rebuilds. I don't know if the 993 bearings are affected or not and the engines I've seen fail have been mostly stock engines, factory built.

The engines I have seen primarily have been 993N/A, some with stock programming and one or two with someone's chip. I can't recal the last tt engine with a rod issue, but then I don't deal with stock type turbo engines much and would not run a 993 crankshaft in any performance engine (my opinion). Further, the fact that the 993RSR engine utilizes the wider 964/930 connecting rod bearing suggests that they too thought that in a racing environment, there was some performance or longevity reason for the change.

Depending on which Carrillo rod you order, your rod side clearance will be different but a stock dimensioned Carrillo rod is much stiffer and will not twist like a stock rod, so I think that because they are more sturdy, they may be a little easier on the rod bearing by providing constant pressure over the entire rod bearing. This may be minute, but I think there is a difference.

There are many other people with far more experience than me with these engines and these are just my opinions from my own personal experiences.

The Mahle pistons are extremely heavy for their application and this puts additional strain on the rod bearing which as you know, is exponential with RPM. The thinner rod bearings provide less oiling surface to support the forces. I don't think the 993 journal is sufficient. Further, the stock connecting rods have a .005" rod side clearance which, again, in my opinion is too small, especially with a crankshaft end play specification of .004-.008". I run wider rod side clearances in all of the racing engines I do.

The internal oiling passages of the Porsche crankshafts are likely too small for higher RPM usage which can be seen in failures of #2 and #5. I know some recommend cross drilling the center main journal, however, I have never liked that solution and have not done it on any of my engines. The GT3R crankshaft has better oiling in that the journals have 180 degree oiling which is in part why I think they can be turned so high, the other is the smaller diameter rod journal which slows things down. I am running one in my aircooled engine, but cannot comment on the longevity.

tkerrmd

So are you saying this car shouldnt be tracked???

Geoffrey

No, I would never say that, I am just not surprised. I'm saying that in my opinion, the 993/996tt bottom end is a) not as strong as the bottom end in the engines Porsche designed for racing engines of that period (993GT2 as the exception), b) I'm not surprised as I've seen a few stock internal 993 engines with rod/crank issues, and c) I run different rod clearances on the racing engines I build than Porsche does on their stock 993/996tt engines.

I have one completely stock internal 996GT2 engine where I've replaced the Motronic with MoTeC and it is in its 2nd season of racing, however, I am running the car at slightly less boost pressure than stock. I'm hoping the engine will come apart after this year for inspection because it has always made me uneasy knowing it is running on the stock bottom end which is why the power has been limited with boost pressure.

tkerrmd

Any suggestions on how to keep this thing running well at the track? I do an oil change after every event, boost is always below 1.2 and shifts are at or below redline. Car runs on pump gas.
I dont want to worry every time I take it out. Longest runs are 45-60 minutes.
thanks for any suggestions. It is an X-50 engine.