Well at this time even if you have some bearing damage, the crank should be fine. I wouldn't track a 4v car without some serious oiling modifications.

 

Once the oil filter is cut open it will be very telling.......

Hopefully its not much if any...that is my ideal scenario....if its really bad....then its time for some serious $$$$ decisions.... Hopefully I'm one of the lucky ones like MK and Scott.....since I do have Amsoil!!!

 

Ive raced with, or been responsible for 4 motors with no oil cooler and no accusump totaling over 200 race days! 5 bar all the time, except for turn 2, during very hot days, where it will dip around 4.5 bar, but never any lower. NEVER!

are you using the 15-50 you are using the race oil or the street oil? I think the part number is RD50. It also has less detergents now and more zinc!

you do have the higher rpm gear box for those turns in question and that could be part of it, but not all. Could there be a problem with the oil pressure control springs? If it all hasnt been disassembled, it probably isnt an issue.

Im trying to make the next NCRA event, as they are looking for more instructors. Ill try and make it so we can take some rides together!

mk

 

MK
You only drop to 4.5bar in turn 2.....damm your lucky.....I saw a tick over 2 bar ONCE...but typically 3 bar once things get warm at the end of 2.......

I'm using the 15-50 "dominator" race oil....since they don't sell the 20-50 anymore......it is the RD50

 

Another issue with this engine is air entrainment. the pump is getting a frothy mix of oil and air. That leads to lower oil pressure under duress. I think(but with no hard evidence) that this is what killed my rod bearing. I was watching the oil pressure on the track and it stayed above 3 bar all the time and mostly above 4 bar except for some slow twisty parts. Mine siezed at the end of a long high speed straight which would indicate to me that there was air entrainment and the shells just didn't have enough lube on them to keep the heat off. too much air let in. Again, I have no evidence of it, but there' a lot of windage in that big pan.

 

something is up. Oil is the same is mine. question now is oil level and the oil pressure control. might be worth a check to see if those springs are correct.

Like I said, ive never seen that kind of oil pressure drop, unless i was running the old Mobil 1 like we did in scots . with amzoil, that problem went away.

bearings? what is the history with that motor, anyone know?

mk

 

That lifter noise is not from heat...that's from the oil pick-up sucking air and sending air/oil to the lifters.
In addition to the things that were suggested, I'd remove the oil pan and check the rod bearings, before running the engine again.

Cornering loads are what determine oil sloshing problems. Different drivers can create higher cornering loads, even while turning the exact same lap times...all has to do with how the car is driven through the corners. A good way to compare cornering forces that are generated by different drivers is to compare tire wear. So people can make a set of tires last all year..others grind them off after a few sessions.

 

Speaking from experiance Greg

 

Oil level will do you in - a common trick for a stock GT-R (car I have experience with) is to put an extra litre of oil in it before tracking it.

Might not be a good idea with a 928 as I'm not familiar with the engines yet.

Going out on the track half a litre low also not a good idea......

 

Rockrete this isn't a good option for a V8. Too much oil will cause immediate aeration, and also ingestion. It's a pretty complicated equation to solve. I recommend you always run an accusump in more than road conditions. Brian, sorry to hear this, but hey I have a spare S4 motor here if you need it
Heinrich

 

Brian did you do a drip test pull the dipstic and drip some of the oil onto a black piece of cardboard go into the sun and check the oil for small metallic particles a magnifying glass will help. If you do find anything i wouldt drive it till the pan is pulled and the rod bearings are checked

 

Iceman,

Here is my thread on my Accusump install. I ran all of last year without any problems and I believe that the Accusump saved my motor last year when I blew an oil cooler line.

https://rennlist.com/forums/showthre...ferrerid=19521

Drop me an e-mail if you have any questions.

Ken

 

Ditto !!!

What I actually do with the Accusump is to run the oil level about a quart low on the track to reduce the aeration problem. The Accusump is there with 3 quarts extra if it's needed.

Ken

 

One other thing, I do have the GT baffle in the pan.

Ken

 

This is my favorite 928 topic.

First off, I've been driving a 928 at the track when it shat a rod. Two at once, actually. I highly recommend it. It's a thrilling experience and I've got some very cool metal chunks to show people. Only cost me $4k. a 1500 mile road trip and two months of nights to fix.

To the original posted problem, I'd check to make sure your cooling system is working. I've never heard of a failed oil thermostat but someone out there has to have one. Maybe it's you.

My closely and personally held opinion is that the 928 has several design flaws that build up to the 2/6 rod failure:

1) The crank is drilled wrong.
2) The girdle passages don't feed the oil equally
3) The sump is too shallow
4) A front sump is wrong for a powerful car
5) The oil pan is too slightly angled
6) The crank is too close to the pan

Take away any two or three of these and you'll solve the problem. Hammer them all and you're gold.

The reason the bearings fail is this scenario:

You're blasting down the straight. A healthy 2-3-4 gear run. And 5 at BIR and RA. Oil rolls from the sump (#3) and up the pan (#4) and draining-back oil does not flow into the sump (#4. This builds at the back of the pan (#5) and goes right into the whirling crank and rods (#6). It creates a huge cloud of oil and hangs there (#6). Now it's time to turn. You brake and that foamy crap whooshes into the sump. You turn and the oil sloshes hard and, again, the liquid rolls out of the pan (#5). The pickup now get a huge gulp of foam and shoots it into the block. The pump doesn't work well with foam and you see low oil pressure. The first gulp of foam flies towards the 2/6 rods (#2) and fills the crank passages. You come out of the corner, and the pickup finally get good oil. That is shot into the block but doesn't displace the foam from 2/6 (#1). The foam continues to feed to 2/6 bearings and is not run out fast enough. The bearings are not lubricated enough and wear metal-to-metal.

Fixing the problem first requires feeding liquid oil to the block at all times. This is best done with a dry sump system. An Accusump will maintain pressure while the pump is compressing foam instead of pumping oil. Drilling the crank will allow lower applied pressures to better lube the bearings.

The I-J windage system will prevent oil from rolling from the sump and reduce the cloud. I've got one and it's a thing of beauty. Unfortunately this in no longer available. (Or am I wrong?) If so it's too bad some people had to be internet smart-asses and offend Kevin.

As for running the oil higher or lower, check the oil level at the end of a session. A number of owners have reported that starting a half-quart low doesn't change where the level ends up. Why? Because the extra oil just increases the amount that gets foamed and ejected with the blow-by.