john gill

Mmmm

THants great , interesting your projects, had a look here and of course only being a quarry , there are no local suppliers for these shells , so I would have to order from the states to do some testing .

JG

GregBBRD

I tried to order that rod bearing shell, today. They tell me that part number is no longer being made. The "HX" designation is a standard reference for Clevite. The "H" means that the bearing is high performance. The "X" means that the bearing is .001 oversize. They do still have the bearing in just the "H" designation. I ordered one of those to see how it "measures up."

I'll let you know what I find out.

gb

john gill

I checked the clearance on the stock conrod bearings today whilst connected to the crank .
I find the bearings sides that are on the offset side (outside) do not span the conrod bearing face, there is a small clearnce to the crank , the same thing occurs on the inside face although it is tighter .
I guesss logically this makes sense as they are softer , they are as a compressive area for the combustion process . The friction areas I would guess taken care by the rod and bearing cap and adequate oiling .
So based on this the other bearings should be fine , now only to find a supplier .

JG

Strosek Ultra

The following rod bearings, not high performance though, will fit. The first one do have the same width as the stock Glyco bearing. Most of the bearings (material TM-1) will probably outperform the Glyco bearing. The TM-77 material is used for high performance applications.
CB-981P
CB-1173AL
CB-1280P
CB-1628P
Cb-1437P
CB-1457P
Cb-1639P
CB-1657AL
Expect to machine new notches in the con rods for a proper fit.

Ake

Strosek Ultra

The following rod bearings, not high performance though, will fit. The first one do have the same width as the stock Glyco bearing. Most of the bearings (material TM-1) will probably outperform the Glyco bearing. The TM-77 material is used for high performance applications.
CB-981P
CB-1173AL
CB-1280P
CB-1628P
Cb-1437P
CB-1457P
Cb-1639P
CB-1657AL
Expect to machine new notches in the con rods for a proper fit.

Ake

john gill

Hello Ake

ALl the bearings you have listed have you measured tham against the stock units ?

I for one am now desperate for a solution , as I have just spun another bearing in the GT engine last club outing ion the weekend .

Oh and this angine has the I and J windage system fitted to it .
Most dis heartening as it did the same thing just over year ago and certainly do not to pulling the engine every year .

SO knowing what the differences are other then haveing to machine a new locating tag would be a distinct advantage.

ptuomov

Greg / Rob --

This thread caught my attention.

A very clever setup. Kudos.

I have some questions, as always.

Any reason not to use an electric pumps / pumps to scavenge the heads? Some are designed for hot air/oil mixture, I think. Turbo guys use those to scavenge the turbos. The air pump would not need to be removed in **** California.

The "secret sauce" must be inside the valve covers. I have many questions about that, but I'm not going there! ;-)

Best, Tuomo

(P.S. Too bad the thread went pear shaped, disappointing but not terribly surprising.)

(P.S. Long time since last had time to read RL. Day job has been all-consuming having to be up both the US and European hours.)

Rob Edwards

Tuomo!

Good to see you on the board again- must be a heck of a day job...

Dunno about electric pumps, but aren't the scavenge pumps on the E39 and E60 M5 motors electric? I seem to recall those motors having multiple scavenge pumps, not sure how you'd mechanically drive multiple pumps. My pump is a 4-stage Dailey SP-series pump- no idea what sort of max volume output it generates at 6000 crank rpm, but I'd guess it's a lot more than the little M5 motors.

RE: the sub-valve cover special sauce, I'll let Greg address that- He's moved on from this setup for street cars, but it is still a very effective (if silly overkill) system on mine- the post-Provent return lines and intake are all bone dry. I'm sketching out the next project engine, I may swap this setup over to it.

ptuomov

I already have one electric scavenge pump in my 928, for turbos, so I figured why not use an electric pump to scavenge the heads as well? It shouldn't take that much power to move oil two feet down, even if it's against a little bit of crankcase pressure that's not fully equalized thru the head oil drain holes.

I'd be interested in seeing what's inside the heads, if the design has been deprecated.

I would be really tempted to use one of the existing breather holes to vent out the oil.

What's the new system for street cars?

Rob Edwards

It's not so much scavenging as an improved crankcase ventilation setup:

https://rennlist.com/forums/928-foru...ation-kit.html

blazing928

enjoying the read , though most of it is beyond my understanding, thanks for researching these issues and finding fixes.

My car a 87 S4 did indeed break the l/h chain about 5 years ago. Fortunately no valve or head damage.

UKKid35

Rob - is there any chance you could repair the broken photo links?

This is definitely of interest to a lot of people.

Many thanks

Rob Edwards

All my pictures (5005 as of today) are stored on a local server here. For some reason the webserver here takes a coffee break from 6 AM to 7AM Pacific time every day, which sometimes blocks my pics in all my threads. If you still have a problem outside those hours, point out a post # where pics are not loading and I'll have a look.

Thom

Apologies for bringing this thread back to top, but since it started 8 years ago it would be perhaps interesting to get some long term report from owners who have installed this system and used their car hard, say for prolonged 6000+ rpm runs, and the results they got.

Has this system been tested together with any crank scraper or other device proven to reduce oil foaming at high rpm in a wet sump engine?

Kevin Johnson

This thread just popped up again. Sorry about the greatly delayed response John as I have not followed the Rennlist for many years now. If you are/were consistently losing bearings that simply means you should move to a well designed dry sump system. The 928 is very sensitive to driving technique; the surface of the oil forms a catenoid with a forward to rearward bias depending on attitude/yaw.

Tuomo and Herr Kuhn have come up with many improvements for the platform recently.