BC

Well, the chevy metal has had 30 more years to figure out how to get oil to the bearings properly. Not that they always do properly either.

The_Remora

I like the dry-sump system that belgiumbarry just got for his race car (last post of his 'hi from belgium' thread), looks real nice for the price , i'd be real temped to cut right to the chase and get that if i were building a track car.

heinrich

I'm willingto accept that (not sure it is correct) for now ... so, in that case, what do Chevy do differently, that we don't? And, can we do that "magical thing"?

rockcrete

Chevy has a rear sump, stock oil pump is lower volume and the revs are typically lower.........

High revs, high volume pump and front sumps all combine to create issues.........

I wouldn't call the Chevy oiling system superior though.........

heinrich

I was watching Top Gear and he was raving that the Z06 was revving to 8k ... no?

heinrich

Why would a high throughput oil pump cause issues?

hacker-pschorr

Just tossing this out there....

It has been proven over and over 2 & 6 are the most prone to detonation. When you detonate a cylinder, you are causing massive blow by and stress on the rod bearings. These cars knock straight from the factory - just imagine what your race engine is doing. Relying on the knock sensors to protect against this is wishfull thinking.

As the coolant / oil heat up, so do the heads. A hot cylinder head increases the chance of detonation.

I'm not trying to say detonation is the only factor in a bearing failure, IMO it is the most over looked. Before the shark tuner there wasn't much we could do about it. Now at least we can try to tune away from it.

The current ZO6 is a dry sump, a better comparison is the C5 ZO6. They are a wet sump and spun past 6,000rpm. Common stroker packages on those engines reach 500+rwhp.

Even the vintage carbed enignes are spun up to (if not past) 6,000 rpm. The guys who spend real money show up with a 400+ small block, pushrod, carbs, mechanical fuel pump spinning up to 8,000rpm (I'm not talking NASCAR). Running lap times faster than any 928, except Anderson and Fan, at Road America.

heinrich

Hacker, good point about the det .... Agreed on the revs.

IcemanG17

I remember reading somewhere that when piston temps get above 500 or 600F detonation is pretty much a given.....

Another reason to remove the factory oil cooler....928 radiators have a hard enough time keeping up with just water....then asking them to deal with 250+F oil just make things worse......

heinrich

Well ... theoretically don't have to remove the rad cooler, just add more externally.

justaguy

I have experienced noisy or colapsed lifters on a couple of ocasions at the track never really thought too much of it but having read this thread i am worried about my 2/6 rod bearings. I have been wanting to do my motor mounts so now might be a good time time to do the mounts drop the pan and inspect the rod bearings. Anyone have any idea how long that should take?(with the car on a lift)

I bought a windage tray and crank scraper from Carl I'll install that and a pan spacer and pick up extension while I'm at it. I would appreciate advise on what else to look for while I am at it. Car is an 87 S4 5 spd daily driver used for about 10 track days a year

rockcrete

More likely to drain the sump.

I just googled "LS6 spun bearing" and got more than a couple of results.......

My experience is with GT-R's which are well known for oiling problems as well - I would say the 928's seem relatively minor compared to them.

There are a number of fixes that are commonly employed on GT-R's

1) Increased sump capacity - preferably by adding side extensions and not by increasing depth.
2) Oil restrictor to head - they pump too much oil into the valvetrain.
3) External oil return line from rear of cylinder head directly back to oil pan.
4) Installation of trap door system around sump (isolates some oil and keeps right around oil pickup during hard cornering / acceleration/de acceleration.
5) Aftermarket oil pump - stock is failure prone - drive requires upgrading on early motors as well.
6) Aftermarket windage tray - stock is quite good actually, but better is available.
7) Proper oil cooler (not an ebay special).
8) Accusump - not really needed if the above things are done, but a worthwhile insurance policy.

There are some other things that can be done, but those are the common ones - a stock oiling system is virtually guaranteed to fail on a GT-R on the track.

To identify the cause of your spun bearing, look at the cylinder it happened on.

With the 928 if it is on 2 and or 6 (judging by the previous post), I would presume detonation to be the likely culprit.

Lizard928

Getting the oil out of the radiator is a very good step to take.

I actually just pulled the pan on my 81 (86 engine) to begin to prep for the drysump and to install the scraper assembly and inspect the rod bearings (I have new ones here).

A friend came over and I had him start by draining the oil. He took out the drainplug and there was the usual stuff on it, except for one thing. There was a screw.
It appears to be a tensioner pad screw! So I will be fully removing them and inspecting them. DOH.

However checking the rod bearings is easy and I would recommend it STRONGLY. I opened my filter and there was no metal particles or shiny bits on it which I had been alittle worried about.

And again I recommend drysump!

Cheburator

My GT was experiencing the same problems at the Nurburgring on street tyres as the Black Widow. Installed a dry sump system and hey presto - no more oil consumption and no more oil pressure fluctuation. The 2/6 was not too bad considering the fluctuations in pressure that I saw in track.

Send me a pm if you are interested...

123quattro

The pump puts too much oil in the heads, which then drains back over the crank. Semi-common problem on OHC engines.