Date: Wed, 27 Mar 2002 14:05:36 -0600
Reply-To: Stan Wilder <wilden1@JUNO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stan Wilder <wilden1@JUNO.COM>
Subject: Re: Windage Trays and Lubrication Issues (Air and Water Cooled)
Content-Type: text/plain; charset=us-ascii
I'd think that without the scrapers this lubrication level would remain
the same.
The tray would be stopping a continuation of pickup of oil by the oil
fans from the surface of your oil pan reservoir.
However by doing so it keeps more oil in your pan, keeps aeration or
foaming down and if I understand the scenario properly, lets your engine
run cooler. IE puts the oil back where it belongs.
Stan Wilder
On Wed, 27 Mar 2002 13:29:02 -0600 Chris Mills <scmills@TNTECH.EDU>
writes:
> Frank, what about the splash lube of the cylinder walls?
>
> Wouldn't the windage tray reduce the lube of items like this?
>
> Learning lots. Good day.
>
> At 02:42 AM 3/27/02 -0500, you wrote:
> >Stan and Matthew,
> >
> >It is really quite frustrating that modifications such as K&N air
> cleaner
> >substitutions are pitched to the masses and quick and cheap power
> increases
> >(actual power increase is around 0.05 to 0.12% in an otherwise
> unmodified car
> >- difficult to measure!) while addition of a windage tray can
> return 5 to 10
> >"free" hp. I say free because no aspect of the engine combustion
> dynamics or
> >output stresses are increased. In fact internal stresses are
> actually
> >decreased. Your comments (quoted below) are essentially correct,
> but there is
> >even more to the story.
> >
> >The oil in the sump and where it goes are critical issues for power
> output,
> >fuel economy and engine longevity. As Matthew points out, the
> crankshaft acts
> >as a gigantic egg beater. At very low rpm, the crankshaft is just
> agitating
> >the oil as it throws it around. But as early as 1500 rpm (depends
> on the
> >viscosity and film shear strength - which are in turn functions of
> >temperature and parent oil stocks) the oil wraps around the
> crankshaft much
> >like cotton candy on a spool. The crank can become a liquid
> encapsulated
> >object with slots cut out for the connecting rods and the main
> journal webs.
> >With higher rpm the oil is so strongly aerated that it becomes a
> milky foam.
> >This oil foam now becomes hard to pump with the typical gear pump,
> oil
> >pressure drops and crankcase pressure soars. Oil is thrashing on
> the cylinder
> >barrels, undersides of pistons - you name it .... and the reserve
> level
> >accessible to your oil pump pickup falls. Add moderate braking or
> 0.5G turns
> >and there is no oil under the pickup. Prescription for disaster or
> at least
> >short lifetime between bearing replacements.
> >
> >There are several solutions (all mostly developed in racing, since
> these
> >effects get worse with higher rpm and temperature).
> >
> >1. The best solution is a dry sump oil system. Here an external
> pump with
> >high capacity (actually organized into several pumping stages and
> externally
> >driven) is used to evacuate all the oil from the oil pan as it
> falls down
> >from feeding the galley, pistons and mains. The oil is removed from
> several
> >areas in a very small volume pan and pumped into a holding
> reservoir. The oil
> >is then degassed and pumped back into the engine. Dry sump engines
> also run a
> >higher quantity of oil (often 10 quarts or more). Solution good
> but
> >expensive. A Dry sump system for the VW I4 engines runs about
> $1400, and
> >costs about 10 hp (because of the work required to drive the
> multiple high
> >capacity pumps).
> >
> >2. Carefully adjust the oil level. Cheap, can work, could be
> dangerous. If
> >you keep the mean oil level below the crankshaft arc, and above the
> oil
> >pickup tube inlet, and refrain from adventure, you can minimize the
> whipping
> >whirlpool. It will still be there, but less oil will be captured.
> Careful
> >measurement of oil temperature as a function of the static oil
> dipstick level
> >will show the onset of this problem. Unfortunately, that onset is
> far below
> >the factory recommended level (often 1 to 1.5 quarts below). The
> corollary
> >here is that if you overfill (by as little as 0.5 quarts), you can
> seriously
> >drop oil pressure, increase oil temperature (the aerated oil acts
> as a
> >thermal insulator and minimizes the thermal exchange in the oil
> cooler) and
> >blow out the crankcase seal with excess pressure.
> >
> >3. Add a windage tray. A good windage tray provides a barrier
> between the oil
> >in the sump and the crankshaft lobes minimizing the amount of oil
> that can be
> >whipped up by that flying crank. This eliminates the work done by
> the engine
> >in overcoming the frictional mass and drag represented by the
> sheeting oil
> >(worth about 5 hp in the VW crankcase. In addition, oil pressure
> will be
> >higher, temperature lower and lubricity higher because of the lower
> level of
> >dissolved gas. However, there are still sheets of oil clinging to
> the crank.
> >In a good windage tray, like the VW one for the water-cooled inline
> 4
> >cylinder engines, a set of cutters (or scrapers) are formed into
> the tray and
> >run at a gap of about 1 mm from the crank lobes. The opening of
> these
> >scrapers is oriented so crank rotation is towards the scraper
> mouth. These
> >scrapers literally scrape the excess oil sheets from the crank
> lobes just
> >like a clay potter shapes his work on the rotating table.
> >
> >3A. Many professional engine builders find that the functions of
> windage tray
> >and oil scraper should be separated and they use thick strong steel
> scrapers
> >to run with a 0.010 inch clearance to the crank. These are followed
> by a
> >windage tray with the extensive use of screen over open return
> paths. This
> >screen deaerates the oil before it drops back to the holding sump.
> >
> >But this still doesn't treat the oil sloshing caused by starts,
> stops and
> >turns. With a boxer engine, these issues can become critical as
> large amounts
> >of oil can go to the pushrod tubes and the cylinder barrels.
> >
> >4. This is handled by the use of baffles in the oil pan and, in
> some designs,
> >by trap doors which protect the area around the oil pickup tube
> entrance.
> >
> >So, the best solution for the I4 crowd (Vanagons) with the engine
> mounted at
> >the Golf angle is to buy the windage tray (I've posted part numbers
> and
> >prices in the archives - VW dealer is around $90, but internet
> prices go as
> >low as $29). It includes a reusable rubber gasket. You will need
> longer
> >bolts. 1 hour operation including cleanup. I would also add a
> baffled oil pan
> >by Shrick. Aluminum and around $250+.
> >
> >For the I4 crowd at the diesel mounting angle, buy the windage tray
> (note
> >there are benefits here for gas, diesel or turbo). Your diesel pan
> has two
> >small baffles to stop front to back or back to front oil movement.
> I find
> >this inadequate. As part of my turbo Audi 3A I am building a
> modified oil pan
> >with an internal hexagonal core. The core has 1 cm open zones and
> is 2 cm
> >thick. I am mounting it 1 cm above the pan floor with openings for
> a revised
> >oil pump pickup. On top of the hex core, I have mounted a 1 mm.
> open mesh. In
> >laboratory tests, the oil moves freely under the core to replenish
> the oil
> >pickup, but it doesn't slosh since its constrained within the hex
> cores
> >vertically. I have also prepared oil level sensors for the pan and
> will
> >calibrate the optimal oil level, probably reducing capacity in the
> pan by one
> >quart. I'm also adding the dual oil filter system with external
> >thermostatically controlled oil cooler from the Audi 5000T. Also
> keeping the
> >VW coolant to oil heat exchanger. I will make plans and drawings
> available
> >when I'm done for anyone who wants to fabricate their own.
> >
> >For the air cooled crowd, the installation of the windage tray is
> harder
> >since it involves a case split. But I would add the 914 part at the
> first
> >opportunity. But there is another nice trick. (probably wont work
> with the
> >2.0 Air Cooleds but a clever man with time (is there anything else
> on the
> >Texan landscape???) One could add a 2.5 quart sump extension from
> the type 1
> >engine placing the oil pickup down in that extended sump. This will
> do two
> >things at least. First, it will reduce the engine case clearance by
> 3 inches.
> >I think this is now the lowest engine point, but only about a 1
> inch
> >reduction in ground clearance. Second, If you keep the same amount
> of oil in
> >the crankcase, this will drastically drop the oil level (helps the
> windage
> >tray) and the small central fill will eliminate sloshing issues.
> >
> >Just one more point. You can see it all! As I reported some time
> ago, I have
> >placed a borescope in the crankcase and watched all hell break
> loose in the
> >RV engine I'm currently using. It is my intention to video tape the
> results
> >as I calibrate optimal oil levels on the Turbo 3A, and "field test"
> the
> >baffled diesel pan.
> >
> >Sorry for the length, got carried away again.
> >
> >Frank Grunthaner
> >
> >
> >On Tue, 26 Mar 2002 06:57:28 -0500 "G. Matthew Bulley"
> ><gmbulley@BULLEY-HEWLETT.COM> writes:
> > > I've wondered the same thing. Having ripped apart and re-built
> a
> > > bunch of 914/912e motor, I was a little shocked to see no
> windage tray in
> > > the vanagon.
> > > My understanding of the function of the tray though went beyond
> just
> > > oil "sloshing" around, but was more to prevent the upper surface
> of the
> > > oil from forming "fans" of oil that followed the crank throws.
> > > These fans not only slowed the crank (if ever so slightly) but
> also
> > > created tiny foam bubbles in the oil, which essentially dropped
> the
> > > oil pressure/viscosity at the bearings. Why VW would eliminate
> it, one
> > > may never know. >>
> >
> >In a message dated 3/26/02 6:35:37 AM, wilden1@JUNO.COM writes:
> >
> ><< I would go along with your "fans" theory.
> >There is a hell of a lot of things going on in the internal engine
> >chamber that we don't even conceive of and will never be privileged
> to
> >see.
> >
> >Stan Wilder
>
> Chris M. <Busbodger - "TEAM SLOWPOKE">
> Cookeville, Tennessee
>
> ICQ# 5944649
> scm9985@tntech.edu
>
> '78 VW Westfalia (67 HP -> that is...67 Hamster Power)
> '65 Beetle - Type IV powered
> '99 CR-V AWD station wagon
> '81 CB900 Custom moto-chickle
> 2.5 Corvair engines for my Trans-vair Conversion
>
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