Kevin Johnson

"Ghoti" also borrowed. He was one of the people I studied in linguistics.

No. It took a long time to truly believe in myself and the first time involved esoteric areas of logic, mathematics and philosophy. The most difficult part of that was finally deciding to stop struggling, striving and arguing because the applications that would make people believe, in my lifetime, would be weapons.

I let my mind have free reign in engines because it is an acceptable means of expression. It quickly solved a fundamental problem for this group and the problem is I stayed too long. I can only vicariously enjoy the applications but I think that is enough. It needs to be.

I understand what you mean and I hated it when I experienced it while younger. It is tragic that one often embodies that which he despised most but at least to recognize this and try not to poison young minds is something. That is why I do not teach.

A lot of people are waiting for their parts and I need to get that work done.

ptuomov

Looking at the photo at:
https://rennlist.com/forums/attachme...od-journal.jpg

In my opinion, there's a lot of misinformation about this out there. I don't know what's right, but I know that contradictory explanations can't all be right! ;-)

As far as I know, fluid dynamics theories predict that in the above oiling setting with a constant-diameter distributing channel, the oil pressure is highest in the main bearing furthest from the source and lowest in the main bearing closest to the source. This is because the static pressure has to be the lowest at the first/nearest main bearing channel mouth where the flow velocity and therefore kinetic pressure is the highest.

A possible solution to this would be to increase the diameter of the distributing channel slightly past the first main bearing entry one the oil path. This would lower the oil velocity and thereby increase the pressure and oil flow into the first main bearing entry. Consequently, the 2/6 rod bearing would be oiled better as well.

Perhaps this is the super-secret German oil passage modification solution to the 2/6 rod bearing failure. Who knows.

As always, any corrections to the above (mis)information would be very much appreciated!

ptuomov

Kevin Johnson

Porsche did do as you suggest -- it is just not clearly visible in the referenced photo. Sterling had a picture of his bedplate with RTV on it that showed the changing depths and diameters of the cast passages. There is no doubt that the Porsche engineers understood that theory and it is one of the many reasons the engine was quite advanced for its time.

ptuomov

Since you've thought about the oiling issue a lot, let me ask you a question. Have you tried the following experiment:

Mock install the block with the crank but without the conrods. Pump oil thru the passage. Crank the engine and measure the oil flow from each rod journal. Is the flow equal?

I also have a question about your oil control system. (You are the J of I-J, right?) Does it play well together with an oil pan spacer? Will an oil pan spacer help if one has your oil control system installed? Do you make oil pan spacers?

ptuomov

GregBBRD and others--

Help a novice understand something here. I am not pretending to understand the issues, just asking some potentially stupid questions.

The main bearing oil inlet is always closer to the axis of the crank than the rod bearing oil outlet. This is the case no matter how the crank is drilled. Correct?

If this is the case, I am going to make a bold (and thus possibly untrue) claim. Higher rpm will always increase the oil pressure at the rod bearing. It doesn't matter whether the oil passage first goes to further away from the axis and then comes back inwards, the effect of rotating accelerations on the oil pressure is determined by the net distance differential between the outlet and inlet. This irrespective of whether the path is straight or first goes out further and returns back inwards.

The way I am thinking about this is like a watertower. As long as watertower is higher than say a three level apartment building, the water will flow out just fine on the top floor. The pressure is determined by the net height difference, regardless of whether the water pipe goes underground somewhere in between.

Perhaps this is wrong, someone please educate me if it is. Perhaps what I am writing is true, but the issue is only about semantics.

Now, this does not mean that drilling the crank to have the oil outlet on the outer orbit is not beneficial. It probably is, and I don't understand the issues well enough to comment on the overall benefit. It seems that further out in the orbit the outlet is, higher the oil pressure, which is obviously good.

Here's another question. If we put the oil outlet on the outermost point of the rod journal, does the oil have to fight itself back to the inner orbit on the other side of the journal inside the bearing? Or does the rod bearing rotating back and forth around the journal take care of it?

ptuomov,
in search of an education.

hacker-pschorr

Yes - in 944 land:

https://rennlist.com/forums/4772367-post4.html

ptuomov

Boy, would this be worth it in our world as well!

Andre Hedrick

I have a crank to get drilled ... who does the taylor work again?

Stan.Shaw@Excell.Net

You mean, you want:
Taylor Engine
8145 Byron Road "D"
Whittier, CA 90606-2690

entropy_engineering

Ok I should probably stay quiet but have to ask anyway. I've read the posts in this thread (or atleast I think, they all started blending together) and a couple other threads. The recurring question keeps popping up to me, why the 2/6 failure if the oiling path in the crank is the same on the other throws? What single element has riddled this throw but not the others? To affect this throw only you can't blame oil quality or pressure or really crank design. I'm not refuting the validity of the dry sump, windage tray, or especially a drilled crank, but they don't answer my question. The only information I have really found is the distribution network in the bedplate/block design. And if it was aeration the dry sump alone should fix it. If it was harmonic resonance the other stroke/make cranks should have other problems. Do the #2 mains show faster wear as well?
Has anyone tried tapping an external oil pressure line to feed the #2 main? or the others for that matter? It's cheaper than any other mod I've seen besides Amsoil. Makes me think of Ford trying to race the old FE big blocks. Cranking up oil pressure never helped enough, but the side oiler block with priority feeds to the mains took care of it.

BC

Sometimes problems are complex. Sometimes they are very simple. The story about NASA needing to come up with a writing instrument that works in zero-gravity, spending millions of dollars and not getting it right. The (Insert other country here - probably russians) just used a pencil.

The crank issue may be very simple. It may be very complex.

Two things have fixed it.

1) Dry sump - This branches into two underlying "solutions"
- Oil aeration in the crank area not getting enough time to DE-aerate.
- Oil pickup uncovering.
2) Drilling the crank - which is a bit more straight forward - oil was not getting to the rods *as well* at high RPMS. Over 6800 I think. Call it 7k.

Doing these TWO things can seem like a big deal. The dry sump is "expensive" but any real race car has them, so its kind of a no-brainer. The drilled crank is even more straight forward. When you rebuild a motor - any person wanting to win would - you have the crank in your hands - why not send it in to get it drilled.

The situation changes when you want to drive your car every day like me. You would need to find a very interesting place for the oil tank. Probably in the fenders in front of the doors. Thats alot of weight in a weird place, but it would be "low". Another place is in the back, but that adds weight and complexity.

slate blue

By ptuomov O.K this is not stupid at all, in fact you are right on the money in the 2003 season of F1 the cranks were redesigned by the top teams this way, the reason was to try and stop some of the parasitic losses in the oiling system, it allowed for lower oil pressure You should request membership to 928racing.com as we are discussing this issue presently, I am sure you would be welcome. BTW I just got back and will look at your email again soon.

Greg

Stan.Shaw@Excell.Net

I suspect you mean the yahoo group, not 928racing.com, as that is a domain registered to me

Kevin Johnson

This is not the issue and (the studying of) pumping neat oil through will not solve it. Oil with high amounts of dissolved and entrained air will be stratified by the passages in the crank under acceleration (a centrifuge).

If you want an example of a properly cross-drilled crank, then look at the Mazda BF/B6 and BP cranks. People seem to think I pull this out of thin air. These cranks run reliably well in excess of 8000 rpm. Mazda understands stratification. Ricardo did as well.

I have always encouraged people to use a spacer. This was Porsche's initial attempt to solve the issue by increasing the thickness from 2mm to 4mm and this mod was retained through the life of the engine -- others were not. In the 944 derivation of the 928 block the gasket was increased from 2mm to 8mm in the attempt to solve the same issue. There is simply more room available in the 944 to do this. I do not make spacers but surely others can (have) and should.

Kevin Johnson

The stratification badness is proportional to the goodness. A slug of high pressure gas won't cut it. Study the Mazda design.

I think that you are thinking of the filling soaker hose analogy (Greg?). Initial conditions in a system can be very different. During operation of the engine the passages are already full and there is an equilibrium established with the bleed rate of the bearing.