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EMPI Windage tray as sold by CIP.



Above: Cross section of a 1950's 1300-1500cc series Porsche 356 Super engine, roller crank and all.

Oil sloshes back and forth and sideways inside an engine oil sump under racing conditions so much that sometimes the oil pickup is sucking air.

The original VW-Porsche case has a reasonably good built-in anti-slosh design, with the sump area contained as the above illustration shows. But even the normal slosh inhibitor design was overcome as braking and cornering power increased.

By the 1960's, Porsche racers had oil forced up through the pushrod tubes into the head on hard cornering, and oil starvation was killing cranks. The factory responded with "windage" pushrod tubes (now commonly sold for VW's) that helped stop unwanted oil transfer, and Porsche racers began to cut and make their own custom windage trays to keep the oil in the sump.

A windage tray is just a piece of metal fitted below the cam and above the oil sump that stops slosh. It has to have provison for enough drainage to let the oil slinging off the main and cam bearing surfaces to return to the sump.

Formula Vee racers embraced windage trays as one of the cheapest racing-reliability parts on the shelf. Windage trays came standard on VW/Porsche Type 4 engines, but never on Type 1's.

For those people building engines that cannot have deep sumps because of ground clearance, the low-tech windage tray is the way to go. We used one on our winning 1600 Carrera Panamericana Ghia and never had a problem.

Conversely, we don't use one on our 2liter+ road course engine because we have one of the 3.5 qt. shallow but wide sumps and that serves the purpose, and we can save the weight of the steel tray.

There is also a little "free power" in the use of a windage tray, as oil that would slosh and make the rods and crank fight to spin through it is reduced. Oil is a lubricant, but just like you doing a hard bellyflop into a swimming pool, you know hitting liquid at high speed is almost like hitting a brick wall.

Drysump engines typically register a HP increase due to reduced "windage friction."

FJCamper wrote: There is also a little "free power" in the use of a windage tray, as oil that would slosh and make the rods and crank fight to spin through it is reduced.

If the windage tray is fitted below the cam, how is it going to stop the crank from splashing THROUGH the cam and into the sump?

Dear Bruce,

The windage tray fits at the top of the sump, and just below the cam. In fact, some designs have cam lobe cutouts or indentations to keep the cam lobes from striking the tray.

Oil comes squirting out from the bearing journals on the crank and cam, and returns to the sump via the tray's drainholes.

But, the oil in the sump, as a single mass, cannot easily slosh sideways or forward.

Sideways slosh causes a wave of oil to run up the pushrods into the valve train area, which is oil taking a detour, and since the amount of oil available is limited, less is available for the oil pickup.

The windage tray keeps the oil (mostly) where it should be. It's simple, and it works.

Various attempts at sump baffels, usually drop-in sheet-metal fabrications or devices welded to the oil plate, have been tried, but the simple old windage tray has survived them all.

FJC

I'll side with Bruce on this one aspect of the crank and oil. The Porsche cut away you posted has some considerable detail differences in the sump area when compared to a VW 1600 case and even more if compared to an ally aftermarket case. While the plates do help control oil, I'll give you that, I feel they don't keep oil away from the crank as that isn't an issue.

I see more trouble with keeping the valve covers empty than anything else.

FJCamper wrote: Drysump engines typically register a HP increase due to reduced "windage friction."

That's the magic (I know, probably not legal in your racing class). One of the Mikes (Sheldon or Lawless) had a nice setup in a recent HVW's article. Installing large bore drain lines in the rocker boxes to get that oil back to the sump. Does little for the oil slopping on the cam and crank, but it does a lot to stem oil starvation.

And you can add vacumn pumps to that magic bag o' tricks. And both Mikes run the big drain back from a head(s).

fortyeye wrote:

FJCamper wrote: Drysump engines typically register a HP increase due to reduced "windage friction."

That's the magic (I know, probably not legal in your racing class). One of the Mikes (Sheldon or Lawless) had a nice setup in a recent HVW's article. Installing large bore drain lines in the rocker boxes to get that oil back to the sump. Does little for the oil slopping on the cam and crank, but it does a lot to stem oil starvation.

Hi-

The purpose of the windage tray isn't to keep oil away from the crank, although it does stop high slosh, but to stop the wave of oil from running up into the rocker area.

The Porsche sump area was a little deeper and held more oil. The VW, as shown above, has a slightly different wall shape, but both designs benefit from a windage tray... and the VW needs it more.

The drawing above shows the tray's location in red.

That the tray keeps some fore-aft slosh oil off the crank is just a good side effect.

FJC

FJCamper wrote: That the tray keeps some fore-aft slosh oil off the crank is just a good side effect.

The camshaft/lifters/lifter bosses do exactly that.

Hi Bruce,

Yes, the shape of the VW and Porsche sumps and the constriction of the camshaft, lifters, and lifter bosses do help supress slosh.

The point is that under racing extremes, they don't do enough. That's why the windage tray was born for the VW-Porsche.

The big slosh problem in the VW is under very hard braking, where about 2/3 of the oil swamps the cam gear, and the gear churns and sprays more oil internally than usual, making windage friction worse. Remember the old trick of grooving the cam's helical gear? That really helped free up oil drag.

Porsche addressed this problem early on with a three-piece case, totally isolating the cam gear from the case itself, and the windage effect.

FJC

Is a sump a good idea? It helps with slosh yes?

FJCamper wrote:Hi Bruce,

Yes, the shape of the VW and Porsche sumps and the constriction of the camshaft, lifters, and lifter bosses do help supress slosh.

The point is that under racing extremes, they don't do enough. That's why the windage tray was born for the VW-Porsche.

The big slosh problem in the VW is under very hard braking, where about 2/3 of the oil swamps the cam gear, and the gear churns and sprays more oil internally than usual, making windage friction worse. Remember the old trick of grooving the cam's helical gear? That really helped free up oil drag.

Porsche addressed this problem early on with a three-piece case, totally isolating the cam gear from the case itself, and the windage effect.

FJC

Did you mean under hard acceleration?

Hi 1955ccbug;

Yes, under hard accelleration when the engine is in its normal place in the rear. Don't forget you have reverse-mounts in the Spyder chassis! I should have been clear about that.

And Leatherneck, a deep sump is better than a windage tray. It contains all the oil.

Today Porsche cheats on the very definition of dry sump by allowing the oil in a Boxster to reside in an extended horizontal sump to the case rather than in a tank itself, and calls it a dry sump!

FJC

Oil control was a big problem my first year doing autocross in the Ghia. Long corners would drop my oil pressure to zero.

The windage tray I purchased did not fit well and I did not install it.

I found this fix on a German web site. Install drain lines from the valve covers to the sump.

This works,

Hi Theo,

Yes, I can see how effective that would be.

Wrap some heat tape around that J-tube, or make a heat shield for it. Rubber heat-ages fast, and splash!

I've had a commercial windage tray that failed to fit. I tried to cut and modify it, then finally just threw it away. By good luck, the next one I got was a slip-in. No problems.

Anyway, great modification.

FJC

Bringing one back from the dead here:
What brand of windage tray actually fits or what mods are needed to make the next best thing work?
Thanks
Kenric