Vilhuer

AFAIK 8bar relief pressure and 5bar max gage value were constant through entire production run. Parts related to these are mainly same if improvements done because of other reasons are not counted. So there were no lets have 8bar first and no lets make it 5bar later changes done if thats what you are saying Kevin.

Mike Simard

I know you think highly of the poster and I'm sorry to upset you but I feel that we're not being treated respectfully with the salesmanship.

I also think there are indeed others more qualified to discuss windage trays, selling them no, there's no dispute about who's most qualified to do that.

Anyway, I hope you don't resent me because of this, I just feel that Rennlist deserves better than sales seminars among it's threads and I'm sure Kevin will do just fine as king of scrapers.

SwayBar

No chance of that as you're one of my favorite posters, as well as Greg, Erkka, Jim, Bill, Louie, and Kevin. I like all for different reasons, but the common thread is that each delivers no-BS technical accuracy which I really appreciate.


Going back to my earlier statement though, who would that be? Does that person post here, and has that person taken the time to develop an oil-control system for the 928, let alone one that has been proven to work on the track?

I consulted 'The Google', a quickie I admit, but I did not find another solution for our car.

Knowing now that Greg has a wet-sump oil-control system, would I buy it from him? No, because that's Kevin's specialty. If I needed someone to build me an engine, would I have Kevin do it for me? No, that's Greg's specialty. Evidently Greg can put together an oil-control system, and Kevin can probably build an engine, but I'm willing to bet neither can come even remotely close to matching the expertise of the other in their respective field due to all their hard-fought, and hard-won minute details that hardly anyone else will ever see.

I do not understand where this animosity is coming from. If someone were building a wet-sump 928 track engine and needed an oil-scraper NOW, like I did last winter, where would they go for a proven solution?

GlenL

Unbelievable. This guy obviously knows his stuff. If you disagree with his conclusions at least appreciate the discussion.

As for pimping products, this list is out-of-control with the pushing products and shilling for them by "loyal" listers. "Hey! Here's a great deal and/or product from my sponsor and/or buddy!" "Wow! That is a great deal and/or product!"

"Solving" the oiling problem in a cost-effective way is a real challenge. A good windage system is a good step. For myself, a dry sump and drilled crank is not cost effective. $500 is.

Someone mentioned that 2/6 gets the oil last. Actually it gets the oil first. The inlet to the bearing feed is just outside the outlet from the filter. Check the passages in the ladder.

Bill Ball

I don't get why this has to deteriorate into a "you-don't-know-what-you're-talking about" thread. Can that line of thought and just get back to sharing ideas. It's fine if you disagree and say why, but the BS beyond that just ruins the exchange.

Stan.Shaw@Excell.Net

Sorry, I almost missed this

A) The Devek drilled crank failure was at Sebring in February. Greg's point about the use of rod bearings is of note, as they were aftermarket and the motor was assembled too quickly, so perhaps clearance was an issue as well. This was nearly two years ago and I do try and forget it at times.....

B) Easier question. Amsoil Synthetic racing oil 20-50W

Mike Simard

Ok, this will be my lasting posting on this thread. Sorry I've upset everyone but I do stand by the reason I was on the soapbox in the first place, it's not animosity, I just feel that we've been treated dishonestly in the interest of selling a product by someone who is not a typical Rennlister but only shows up the promote the product. Kevin, I wish you the best even though I feel the way I do.

Abby Normal

Insert Train Wreck Photo...

Vilhuer

I suspect its more likely evidence that there is really large variation with different individual parts that have exact same part number. According to his tests one mm difference in washer thickness made huge difference in actual relief pressure. He tried several different thicknessees before he found setup he liked and differences between trials were minuscule. So spring was right on the edge of maintaining too little or too much pressure.

I'm not saying this simple adjustment will solve all oil problems we are seeing. Just that having wrong adjustment spring can not help the cause. Thats why I'm doing both your scraper and this spring adjustment in stroker build. Since its easy to check the pressure while doing cambelt change I would also add this to long list of to do tasks while belt is off.

I have Spare Parts Catalogue dated February '77. It lists different spring part number than all later PET versions etc I have. Difference is only last digit which change from 0 to 1. So there are only two different part versions according to these consecutive numbers. Both '78 and '79 MY yearly changes documentation gives pressure as 8bar and it seems '85 MY 32V documentation says 8.5bar. So there are infact two different specs but they are both high ones.

My take on this is that spring was changed at same time as 32V engine came along and oil pump was changed to have wider gear meaning '85 MY. Changed part was taken into use in all engines and only this later style part was used after that and is now available as spare. So I would say its fairly safe to say factory spec at the time was 8bar for '78-84 and 8.5bar for '85-95 and now is 8.5bar for all engines.

Some of the factory oil flow diagrams show totally different path whan what reality is in block. According to pic it would go to last main bearing first and them come forward from there making 1st main bearing and passager side head last ones to get pressurised oil. This is obviously totally wrong and 2nd main and thus 2/6 rods are actually first ones to get both oil and air depending on what oil pump is pumping.

marton

A couple of years ago a friend of mine did some experiments with a stripped block & his conclusion was that the 2/6 was the first to get whatever the oil pump distributed. He therefore concluded that if the oil was excessively aerated then the 2/6 would be the first to "benefit".

From where I sit any solution to the 2/6 problem should include some, preferably all, of the following;

minimise oil aeration
maintain suitable oil level in sump
deliver good volume and pressure to rod bearings
prevent excessive oil temperatures
maintain suitably high oil viscosity under extreme conditions; i.e. high engine revs

This implies that no single solution would be enough on its own; of course, some might have a more benificial effect than others.

Marton

Vilhuer

Scraper
Scraper
Relief valve adjustment. Mystery German mod which no one know what is done to block.
Factory cooler used in last MY's is good start.
Amzoil

90 S-4

Recap for the novice please,
Would it be safe to say there are seven areas that need attention in improving the oiling system on the 928 motor. Please add ones I’ve missed, I’m just trying to get
An official agreed on list started.

1. properly drilled crank
2. a suitable windage tray/scraper
3. an oil filtration that helps to eliminate air bubbles
4. higher oil pressure at higher rpm ( shimmed spring ) ?
5. correct bearing material & clearance
6. good crankcase ventilation
7. The right oil

There has been a lot of good info exchanged in this thread, but like most thread’s of this type when it’s reached the last post everyone leaves & goes
Their separate way leaving the novice to guess what the general consensus
Was/is . The oiling system has got to be the biggest Achilles problem area
The motor has. I think there should be an official “Rennlist Recipe” to build
A dependable high performance motor , regarding the oiling system part of
The build up that is. The other variables like blower’s & cams ect, have been
Covered already.
We should have a list of the problem areas, see( 1 thru 7 ) list ect,
Then perhaps each week we could beat to death a good fix for problem # 1
Then # 2 and so on .
Obviously each mechanic is going to have his own specialized tweek he would
Incorporate into a rebuild but the idea here is to come up with a recipe that would work for anyone attempting this type of project.

Vilhuer

Person doing these tests is first class automotive engineer with several decades worth of full time professional experience in the field and he is very highly regarded in local 928 circles. I trust his word 110% in this matter. There are other issue we have had heated debates but his testing methods and results are not questioned by anyone who knows him. For example regarding this matter he contacted Glyco bearing factory some time ago and asked information on what design parameters like oil pressure were used and to which oil pressure he should aim for without getting any real reply. This just goes to show how thorough he is in everything he does. When Glyco engineers heard him mention Porsche they went completely silent for some reason. They refuced to give out any info on what oil pressure they had kept as target when they designed bearings for 928. They could be just following orders not to give out info to outsiders but it would really be interesting to know what those numbers are.

Jim bailey - 928 International

There has been some discussion that the thermostat springs in oil chamber which directs the oil to flow into the oil cooler have needed to be replaced to function as designed perhaps the springs for the oil pressure blow off ALSO get weak with age ? 20-30 years of being compressed ?

Vilhuer

He tested Porsche spring and since it didn't meet his expectations he sourced other one which did with smaller washer setup. Porsche spring would have needed thicker washer than he was willing to use. Very simple really, Porsche part was substandard for the job and he found better.

It is possible that one single Porsche spring had some quality problem and all other 60k+ springs made will always result exact 8 or 8.5bar but somehow I doubt they will all be that accurate. Whole point of the story is that its in my opinion very good idea to check the pressure especially as its so easy to do while putting engine together or changing belt. Once few people have done this and report back in here we will have actual data to say how large tolerance those springs have. I certainly hope its not between 5.5 and 8.5 or something like that as it could then explain a lot if we are to believe how critical high pressure is above 6k rpm.