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excellent thread! any engine info? particularly controllling oil movement...

Above: Key to oil control is the windage tray. It helps suppress slosh out of the sump and into the heads.

BOLT-ON OIL CONTROL IN RACING (without dry sumps!)

The big problem with racing boxer-design engines is because the cylinders are sideways, oil can rush out to the heads and pool in the valve covers, and leave the oil pickup sucking foam for a few seconds. At high RPM, that can mean the rod bearings will starve and wear. Oil is expected to drain back to the sump via the pushrod tubes.



Above: Boxer design invites oil transfer to heads and valve covers.



Above: the red line represents the windage tray. More on the deep sump to follow.

From the beginning, the VW engine had a small oil capacity, just 2.5 qts. to fill. Oil slosh control was thought to be sufficient by the internal shape of the engine sump, which put the oil level just below the lifters, forming a sort of natural windage tray.

That worked until Porsche 356's and then VW's begin to pull high cornering G's, and the oil was forced to slosh sideways.

The very rotation of the crankshaft in the VW/Porsche design blows oil ("wind" as in windage) toward the 3/4 cylinder side, and tends to fill the valve cover on that side completely full of oil at 5000 RPM and more, with no windage tray in place.



An early Porsche racing trick was to fabricate about a one-inch pushrod extension into the case (we give thanks to Richard Luke for this simple but effective mod) that helped prevent oil from flooding out of the case via the pushrod tubes into the heads in a long, sweeping turn. So effective was this mod that Porsche copied it and the 912 engine came standard with "windage" pushrod tubes.

http://www2.cip1.com/ProductDetails.asp ... 2D335%2DWG

Windage tubes are available from most parts houses, and no racing engine should be without them.

Special Tip. Get rid of your oil strainer. The fine filter mesh acts to restrict flow.
(This tip applies only to racing engines that have good full-flow filter systems. Do not remove the oil strainer on street engines! The screen acts to block big pieces of metal that can damage your oil pump)

The windage tray itself, at first a hand-fabricated piece for racing Porsche 356's, is also a highly effective item of competition equipment. And cheap, too. California Import Parts lists theirs at $9.95

Together, the windage tray and pushrods tubes are excellent insurance against oil sloshing. Our 1965 Pan Americana Ghia raced 2000+ miles straight with little more than these two innovations.

Porsche solved their racing oil starvation problems with the dry sump, beginning with the four-cam Carrera engine, and being carried on in every dedicated Porsche racing engine. The tradition extended even to the street 911's, but the Boxsters are a different story as we'll explain below.

You can get most of the benefits of a dry sump with an extra wet "deep" sump. As the windage tray illustration shows above, the deep sump provides for the oil pickup to be immersed in its own well of oil, and is a virtual guarantee of oil delivery under high cornering forces.

Even Porsche blurs the distinction now between the dry sump and deep sump on the Boxster engines. They use an integrally-cast wet sump, but describe it like this (clip from Boxster ad):

"Porsche has long featured race-proven “dry sump” oil systems. In past engines, Porsche used a separate, remote oil tank. The Boxster engine features an integrated dry-sump system – the sump sits inside the block, next to the crankshaft."

To help justify the "integrated dry-sump" twist, Porsche uses pump suction in each cylinder head to scavenge oil and return it to the sump.

VW racers have plumbed extra oil return lines from the heads to the case, to help gravity return the trapped oil more quickly. But this post is about oil control without drilling any holes.

VW drag racers have a special oil control problem, which is in the first few seconds of high RPM full throttle, the big-gear (32mm) oil pumps commonly used can pump enough oil out of the sump that in the course of a drag race run, the oil does not time to fully return to the sump!

It either tries to blow into the dump can or pools in the heads and valve covers. Drag cars can blow a quart of oil or more into the 3-4 cylinder side valve cover and dump can in one run.

The answer is to run the smallest pump you can (which helps power, by the way) and the thinnest oil you can. It flows faster.



Above: Oil Suction Pickup http://WWW.CIP1.COM C26-115-205 - OIL PICKUP & SUCTION KIT

Another bolt-on oil control device that works is the oil pickup suction kit. This was another part of our Carrera Panamericana engines, and helped keep it alive. The pickup adapter (anodized red) is pressed onto the engine pickup tube (with a nice 0-ring fit) and faces flat to the special oil plate, and has slots on both sides to draw in oil. This little kit works very well.

The pickup also has a wire screen to block bits of metal from being ingested. This is a reasonably wider weave than the stock strainer mesh, and offers no restriction to flow.

These simple bolt-on parts, the windage tray, the windage push rod tube, deep sump, and suction oil pickup will give you racing oil control almost on par with a dry sump system.

FJC

FJCamper wrote: Special Tip. Get rid of your oil strainer. The fine filter mesh acts to restrict flow.



Above: Oil Suction Pickup http://WWW.CIP1.COM C26-115-205 - OIL PICKUP & SUCTION KIT

Another bolt-on oil control device that works is the oil pickup suction kit. This was another part of our Carrera Panamericana engines, and helped keep it alive. The pickup adapter (anodized red) is pressed onto the engine pickup tube (with a nice 0-ring fit) and faces flat to the special oil plate, and has slots on both sides to draw in oil. This little kit works very well.

If the small area of the screen of the oil pickup suction kit is ok, why is the much larger screen area of the stock strainer a restriction?

Hi Bruce,

You may be aware that Porsche used a much larger rectangular-shaped oil screen in the 356 engines, to compensate with area for flow restriction.

To feel the effectiveness of fine wire screening, stand inside a screened-in porch on a windy day. The screen wire itself blocks a lot of the wind's force. In fact, the wire screen sets up a boundry layer as it deflects air. In the hydraulic and fluid dynamic (read plumbing on a grand scale, nuke plants, etc.) industry, some valves have internal screens. They use no screen as fine as VW's filter mesh. One of my company's engineers is a specialist in this, and advises me on all the esoterics of fluid flow.

The smaller VW stock oil strainer (very fine filtering screen) was recognized as a flow restrictor back in the 70's, and racers (at that time mostly Formula V) would substitute a ventilated circular shield welded to the oil plate that acted as a crude baffle to help keep oil around the pickup. I think there is even a photo of one in Bill Fisher's HOW TO HOTROD VW's.

The oil suction kit's pickup adapter has a screen, but not nearly as fine as the factory filter screen. The adapter screen is just supposed to block the big pieces.

When I was building our Mexico engine, and knew I could not use a deep sump (which would have been knocked off fast somewhere), I decided to experiment with the oil suction pickup and its increased pickup area.

All I can say here is it works, and I've just incorporated it into the Mexico engine's replacement.

FJC

The genuine VW filter screen has the finest mesh. A Brazilian one is coarser. Then there are mystery brand screens with a huge mesh. If you believed the stock screen is a restriction, you could always step up in mesh size.

Regarding what happened in FVee in the 70s, I'd say so much has changed since then. For one thing, they were using 1200cc engines with a much smaller pickup tube. I just don't think it applies to a 1600 based engine with a deep sump like we use today. Were the FVees full flow filtered? Multi-vis oil?

I recommend against removing the stock screen. I've never been able to demonstrate that it restricts in any way. I use the finest mesh, genuine VW screen.

Hi Bruce,

I fully agree that a screen is good if there is no restriction with it, and if you are having no trouble, no reason to change.

My engineer here says a fine screen catches bubbles from the oil foaming, and the bubbles then stick to each other and to the mesh. They then become a boundry layer as the strainer becomes a bubble trap. The oil pickup starts sucking bubbles and oil, and of course, bubbles don't lubricate.

I would imagine better oil formulation that reduces foaming reduces this situation.

Joe Chirco was one of our PanAm sponsors. He does a lot of FV racing. I'm going to ask him what he knows.

FJC

That's a fascinating theory. I wonder how he got a camera in there to see that?

I agree with you on the oil. If you have foaming, you are using lousy oil. This is one reason I would never use any oil rated for diesel engines. A typical diesel engine doesn't rev as high as a gas engine, so the oil companies don't need to add as much anti-foaming agents.

Bruce2 wrote:That's a fascinating theory. I wonder how he got a camera in there to see that?

I agree with you on the oil. If you have foaming, you are using lousy oil. This is one reason I would never use any oil rated for diesel engines. A typical diesel engine doesn't rev as high as a gas engine, so the oil companies don't need to add as much anti-foaming agents.

Umm... A modern spec Diesel oil very likely has the best and highest percentages of antifoaming agents in it you will find..
Common rail injectors despise foamy engine oil far more than bearings do.

Modern Diesels oiling systems have tolerances easily 10X tighter than any gasoline engine.
(Mostly pertaining to the common rail "pumps")

I agree if you have foaming, you are using a lousy oil.
That's why I only run Shell Rotella T 5W-40.

Always remember-- Commercial oil certification or recertification cost $500K++ bucks, and has to be done for ANY formulation change.
"Gas engine" non commercial certifications are far less stringent and the mfrs can alter the blend at will later.

Mark Herbert ran the screen because it supports the pickup tube from breaking and coming loose from the case. That is a great reason to run it, even if you gut the assembly and just leave the support frame. The screen has saved me a few times when lash caps end up in the sump. You can blow up your engine from the tiniest little hard piece getting in the pump gears.

Hi Bruce, Steve;

Screens are valuable, and the suction pickup kit uses one.

I did some researching, and find a great anti-aeration oil test from MIT, which explains how they measure and see bubbles, foam, etc. They don't actually use a camera as Bruce guessed, but do have sight glasses in some places.

http://dspace.mit.edu/bitstream/handle/ ... 145859.pdf

The MIT test is not specifically about anti-aeration screens, but my engineer here tells me in-line screens under specific pressures are used to act as bubble traps.

http://www.system1filters.com/oilpumps.htm

System 1 oil pumps mention using screens for de-aeration, so that shows some consistency.

I am thinking here that in the VW engine, with the strainer acting as bubble trap, the strainer itself is contributing a little to de-aeration, but because it is not a controlled in-line screen, not doing a good job of it.

Steve, you mentioned supporting the oil pickup. The Formula Vee guys actually fabricate pickup supports. I like your idea of removing the strainer screen but leaving the housing. It would do the same thing.

FJC

FJCamper wrote: http://dspace.mit.edu/bitstream/handle/ ... 145859.pdf

What a great link!
I found it very interesting that they concluded that the windage tray had no significant effect on aeration.

I've always been skeptical of the windage trays people install in VW engines. The VW engine already has a windage tray, it's the cam and lifters and the castings supporting them.

Bruce and I are both Engineers, as well as you FJC. Great link. Sunday fireside chat.

Hi Bruce,

Yes, the MIT report says the "open area" [drainback hole] of the windage tray has no affect on aeration, but it does say by the tray blocking the "wind" from the spinning crankshaft from contact with the oil, it does prevent some churning and foaming from aeration. And later emphasizes how vital is oil level (to keep the oil below the tray and out of the way of the crank).

Of course, in this test they were using an upright engine. We have our opposed boxer design.

For us, the windage tray is also there to help slow down slosh, keeping some oil out the heads and valve covers.

The windage tray is worth it in either engine design, but more valuable to us.

FJC

Above: Making a window in a valve cover. The old cover chosen for sacrifice was stamped aluminum, reasonably flat, and easy to work with.

The Oil Crisis (in your engine)

To continue this oil control subject with some facts, we have input from Muffler Mike, Bill Fisher (How To Hotrod VW Engines from HP Books), and Duane Spencer (Porsche 356 Performance Handbook from Motorbooks International), and yours truly, having just recreated Muffler Mike's window-in-a valve-cover experiment.



Above: Common windage tray. Oil spray from the crank drains back to the sump via the center holes.

Duane Spencer says the windage tray is essential, citing on page 29 (with two photos of a home made aluminum windage tray being fitted inside a 912 case: "This tray is absolutely essential in keeping the oil in the sump in high-g cornering unless a deep sump is fitted in its stead."

Bill Fisher says the windage tray is "a moneysaver, especially if you don't buy one," stating on page 98 that the design of the VW case, in that the camshaft, tappets, and contour of the case create a natural windage tray. (Both he and Spencer both praise the windage pushrod tube, however.) So, who is right?

Because the VW and Porsche engines rotate clockwise as they run, the actual wind, or force of air from the spinning crank, blows oil out of the sump, up the pushrod tubes, into the 3/4 cyl head and fills the valve cover.

The physical block between the wind and the oil is the windage tray. The issue is how effective is the use of a windage tray in the VW/Porsche boxer design engine in oil control.

My money is on Duane Spencer, because he built and raced Porsches, and spoke from experience. Windage trays made engines last longer. Fisher (actually a V8 guy) put together a great book but a few holes show through in his relationship with VW's, especially where he comments that "no VW teapot is going to suck air like a 300-inch V8 revolving at seven grand." He went on to own and run HP Books at one point.

Muffler mike had no windage tray when he took his photos. We have one.



Above: At a 900 RPM idle, the lens speed was fast enough to stop movement of the 1:25 rockers. The adjusting screws almost touched the Lexan window.



Above: At 2000 RPM, the rockers are a blur, and the oil level is still below the window.



Above: At 3500 RPM, oil is just beginning to show in the bottom of the window. At this point, Muffler Mike says his valve cover was halfway full of oil, and by 5000 RPM, totally full.

We did run our engine to 5000 RPM briefly, and saw a slight increase in oil level, but were worried that the Lexan windows was not going to hold, and backed off.

Higher speed photography would have helped here, but the results were with a windage tray in place, the oil transfer to the 3/4 cylinder side was reduced considerably from what Muffler Mike experienced.

FJC

I agree with Duane Spencer, that's why I don't have a windage tray in my engine.

When the oil is down in the deep sump, no amount of wind is going to pull it up and put it into the heads.