Stan.Shaw@Excell.Net

Hi Jim,

Sorry, I think you are are still missing the point.

I started the this topic and the frame of reference was a failed crank in a 928 that is track/race only. Some of the issues you raise simply don't apply to a race car and that is MY concern and may be to others reading these posts.

Kevin's approach, in my opinion, is that the scraper is THE final solution, or at least if you read some of his posts as I have, that is an impression. His scraper simply hasn't been proven long enough for him to make such a statement, again just my opinion.

I am glad to hear you are building a motor relying on the scraper system, and I look forward to reports whether good or bad about how it works out for you. I certainly want it to be THE solution so there will be more 928s out on the track

GlenL

"Proven" is a strong word. I recall that Mark A's first dry sumped engine blew up. Stan's bad drilled crank leads this thread. Maybe it's "proven" if the dry sump works right, the crank is drilled right and the rod bearings are changed every 40 hours of track time.

Everyone is making their own dry sump and there are around three running. There's risk in not getting it right but doing it right _should_ be a solution. And that's a $4000 solution that can't be done on a street car as there's no place to mount a big enough tank.

That's "exploded." Got the mark on the engine crossmember to prove it.

And now I'll quote myself and expand on it.

So ya see, I had an early experimental version with no windage screens or plates at all. I had to talk Carl, who was selling them, into providing it. The car was sick, needed help and I'd already tracked it hard in that condition. In hindsight I should have tested the oil, swapped the bearings or just parked it but it was A Project. No regrets!

And one more time...

Everyone who has the full set is very happy with the results and impressed by the quality of the product. "Proof" will take time, but I'm on to worrying about other things.

Stan.Shaw@Excell.Net

Is Carl running a 4.7 or 4.5 short block? They are rumored to have less failures, although I know of at least one. In my case I raced my Euro S 4.7L stock motor for two years after it already had 90k+ miles on it and when it was disassembled the rod bearings were still in very good shape (I did run an accusump but the crank was stock).

FlyingDog

I didn't say that his product caused your engine the break, but your engine was one of the first with his product to break. As Stan has been trying to explain, time will tell. I hope the product does everything Kevin claims.

BTW, I'm the one that recommended Kevin contact Mark to get the original engine for prototyping. I support his project, but it's too early to claim is as a/the solution.

GregBBRD

I hope the problems with the 928 oiling system and design issues can be solved with just a great windage tray and scraper set-up....and I still think that Kevin's set-up looks very thoughtful. The dry sumped engines have a tough time keeping the bearings in them for long periods of time, but this is not always due to the oiling system. Mark Anderson's dry sumped race engine was watched very closely for signs of bearing issues and was promptly looked at whenever bearing material showed up in the oil.

Mark's original crankshaft that was used for years and years was sized for 928 rod bearings. 928 rod bearings are very soft....they were designed for years and years of street service. #6 cylinder is always the first cylinder to detonate in the 928 engine. Even when this is very, very slight....the bearings get pounded and loose their crush. This is not an oiling issue....but it still can result in the same type of failure and can be very difficult to distinguish from an oiling problem. Detonation can be seen first on the head gasket.

The newer stroker crankshafts we have built are sized for Chevy rod bearings, which allows one to select different types of bearings for different applications. We do not use the same bearings for a track engine that we use for a street engine....this would be very foolish.

I have not seen a bearing failure in a 928 engine when equipped with a dry sumped system.....except when the dry sumped pan and scraper system was not up to the task. Mark once stuck a different oil pan and scraper set-up on his engine, which would suck the oil tank dry!

A good dry sump system supports Kevin's thoughts that a supply of bubble free clean oil will go a long way towards making one of these engines live. This, to me, also makes the entire discussion of the oil passages in the block somewhat of a waste of time. Clearly, these passages will correctly deliver oil when there is no interruption of the supply. When the supply is interrupted, it is obvious that #2 and #6 bearings suffer first.

Regarding crank drilling. We have discussed the problem of oil getting to the center of the crankshaft, which Kevin thinks is not an issue....with good logic. One of the things that has not been discussed here is that usually when a crankshaft is drilled, and always when a custom crankshaft is used, #3 main journal is drilled so it can supply oil to both the forward set of rods and the next set back. This allows oil to flow to all rod journals from two separate main bearings. Does this change things? Certainly. Perhaps this extra oil helps when the oil supply is interrupted.

Here's what I think from all of this discussion:

Kevin's windage tray and scraper system clearly is very good and works. The testimony from the team in the UK means nothing to me....I have no idea how hard this car is driven and what loads it is supjected to. However, the testimony that the Accusump temperature was "cool" at Road American speaks volumes to me. This means that the Accusump is not very active....a very good sign! This is hard to ignore....pay attention guys! I will buy one of his systems and try it.

I will continue to lower the oil pan to get the oil further away from the crankshaft. This almost becomes mandatory when using a stroker crank and a windage tray. There isn't enough room for both, from what I've measured.

I will continue to have my custom cranks built with Chevy style oil passages. Why not?

I will continue to have crankshafts drilled in other engines....with oil holes from #3 main journal that allow oil to flow from 2 main bearings toward each rod bearing. I think the only way this can be done is by drilling holes that feed from the surface of the #3 main bearing (I don't think it is possible to "center drill" this journal.) While they are drilling, why not have a couple more holes drilled so that the other main bearings feed from the edge and not the center?It is only 2 more holes. (Go back to the beginning of this thread....Stan's crank was NOT drilled to the #3 main journal.)

I believe that main bearing and rod bearing oil clearance is very, very important. I doubt that the Holbert engine has anything wierd and trick in it....but I'm willing to bet that the instructions for this engine, when it was assembled, were to use "red" main bearings and "red" rod bearings. These were easily obtainable from the 944 GTR and would have resulted in higher bearing clearances. Certainly, lessons had been learned from the 944 GTR by the time this engine was assembled. And, don't forget who was the man who was almost solely responsible for the 944 GTR....Holbert!

The Glyco replacement bearings are very tight. I think that they do this on purpose. I think that they are allowing for "some" wear on crankshafts, which most crankshaft do. However, the 928 cranks do not seem to have this "typical", slight amount of wear. This results in very tight bearing clearances. There have been threads before that have stories about someone replacing their rod bearings and then having a rod bearing failure. Use Porsche bearings. Buy several sets. Pick out the ones with the highest clearances and use them.

Different oils perform differently. Joseph Fan uses a very specific oil that he feels doesn't foam as much as other oils. Mark Anderson uses a different oil than Joseph...even though they are very, very good friends and are generally at the track together. Someone....I can't recall who....thinks Amsoil floats on water! Kevin has also indicated that different oils have a different capacity to have bubbles trapped.

There's always someone out there that is smarter and knows more about a certain subject than you do.

I don't think this thread has been very nasty or ego centered. I think good things are being discussed here. I think it is OK to disagree and put forth different theories. However, sometimes it is smarter to listen.

Cheburator

Tim Bryant in the UK runs a 5.4 GTS engine in his race car in the Porsche Open. The engine has been dynoed at 390RWHP and has run with a dry sump for the last two seasons with a limiter at 7500rpm. No problems and no bearing wear... I have made/purchased the same set up for my car - unfortunately I cannot show the inside of the pan as it is a commercial product. I will be spinning my GT to 7250 once the system is installed in the next 2 months. Will come back and report on the findings.

P.S. I was looking at the crank in my S54B32 engine (BMW Z4M Coupe) which spins to 9000rpm on a daily basis. It is not drilled like a Chevy either. Are we not loosing focus here?

John Veninger

Seems like those 7K+ rpm Porsche engines also need some help.
From the race list about early 911 motors:

----- Original Message -----
From: "James Bricken" <j911brick@comcast.net>
To: "Racing" <racing@rennlist.org>
Subject: [racing] Re: Premature main bearing failure?

> #2 rod bearing failures are common on early motors.

Subject: Re: Premature main bearing failure?
From: "Walt Fricke" <frickew@msn.com>
Date: Mon, 8 Oct 2007 17:26:17 -0600
X-Message-Number: 3

Right. #2 and #5 are farthest from where oil enters the crank.

The SC pump ought to be big enough (but you can fit a 930 or 964 or GT3 pump
in there with some modification of the case and the factory shorter IS
connecting splined tube). But you might consider having the crank
crossdrilled at the middle main bearing, and a main bearing grooved to
supply oil into the crank (and hence to the rods) from the middle as well as
the ends (where Porsche supplies it).

Walt

marton

Posted by Abby
I was thinking about "post 140 et al" where it said that the WSM states "at least 5bar at 4K rpm". But the oil pressure relief valve is set to 8 bar (I assume higher rpm = more bar?).
I guess if one is talking to Accusump manufacturers with the aim of fixing problems at high rpm then such points need to be understood by them?

Marton

Ian928

Erkka, just a thought:

Maybe more pressure is not better, more pressure equals more flow, which again equals more oil being everywhere else than in the oilpan being deaerated.

Just maybe Porsche lowered oil pressure in an attempt to reduce foaming?

John Veninger

Then they can go racing without drilling their Porsche cranks.
Big market out there in the 911 world. Don't think they will like you calling them VW engines.

Vilhuer

Less could be good but according to PET and other factory documents Porsche didn't lower pressure they were aiming for. Infact they went 0.5bar higher in '85 MY.

How low is high enough and how high is too high? Since relief valve spring can be changed to provide practically any pressure it would be easy to adjust if some number other than 8.5bar is desirable.

Jim Morton

FWIW, I realize that Stan started this thread about the benefits of crank drilling. As is only natural, we want to tie the cause and effect of the 928 oiling issues into nice tidy solutions. No biggee...

For the two 928 engines I have in process in my "hobbiest" shop, we are working on solutions broken into three basic categories:

1.) Feed oil supply as needed to keep the oil pump / oil galley fed during all operating conditions
2.) Keeping the crankcase breathing managed such that blow by is managed at high RPM.
3.) If using a stock crank, how to improve con rod bearing oiling for the second rod bearing off the main bearing feed.

From forensics on the 928 bottom end, these issues seem to appear as issues needing addressing if high RPM's are to be sustained. Most notable, for a wet sump engine, the crankcase itself seems to lack total volume given the engine's displacement. I suspect this was a design comprimise for keeping the total engine hieght down as to fit under the hood, combined with Porsche's past experience of using mostly dry-sumped engines with the 911 series engines.

In additon to lack of total air volume, the sump of the pan is quite simple as a means to prevent oil pick up starvation during high "G" loads and the "chimney" of the block is completely open to the reciprocating components below with no sheiding / means of air / oil separation.

For the two engines in process, we have tried to isolate our use of solutions to explain and address the items listed above. Kevin's windage kit is our starting point to help with oil / air seperation and also prevent the oil draiing from the heads from reaching the reciprocating pieces. In addition, we plan to add some breather solution to the sump to assist in keeping the crank case pressure down.

For oil supply, we are planning to lower the pan and pick up as Greg has suggested. In additon, I am planning on re-working the shape of the pickup screen to lessen the likelyhood of drawing in air if present.

With regards to crank drilling. One engine is running a Taylor drilled stock crank. Our belief in using the Taylor drilled crank is that the additional oil feeds to the con rod jornals, with any given rod bearing no longer having a shared feed should obviously help. Given that the center main is now drilled and supplies the rod journals, that bearing is being grooved like the rest.

For the custom displacement motor, that crank will be drilled like a Chevy V8 crank as many other have done. This style of drilling is simple and easy to know how to feed it !

Although I cannot say that any of the work we are doing represents completely known and proven solutions, the efforts seem reasonable to offset what we see forensically. Once both these engines have several hundred hours on them with bottom end inspections, we can then attempt to say we know what solution contributed what to the observed solution.

If anyone is curious about the efforts, please feel free to PM / e-mail me as I have more pictures that could be shared. If you are local, consider yourself invited to drop by for a "looksie".

After experience with other windage products I have used for other performance engine applications (Chevy, BMW, BMC "A" series, Triumph), Kevin's kit is sure nicely thought out and executed. Simply my $0.02.

Regards

BC

A total separation of the rotating assembly from the oil pan?

http://gallery.patel360.com/v/Video/...embly.flv.html

GlenL

I'll wager a million space bucks that the separator is windage screen.

http://www.jegs.com/webapp/wcs/store...45613_-1_10459

mark kibort

amzoil
90+ race days
mk