Vanagon EuroVan
Previous messageNext messagePrevious in topicNext in topicPrevious by same authorNext by same authorPrevious page (March 2002, week 4)Back to main VANAGON pageJoin or leave VANAGON (or change settings)ReplyPost a new messageSearchProportional fontNon-proportional font
Date:         Wed, 27 Mar 2002 13:29:02 -0600
Reply-To:     Chris Mills <scmills@TNTECH.EDU>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Chris Mills <scmills@TNTECH.EDU>
Subject:      Re: Windage Trays and Lubrication Issues (Air and Water Cooled)
Comments: To: FrankGRUN@AOL.COM
In-Reply-To:  <5b.253a57c5.29d2d1f7@aol.com>
Content-type: text/plain; format=flowed; charset=us-ascii

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


Back to: Top of message | Previous page | Main VANAGON page

Please note - During the past 17 years of operation, several gigabytes of Vanagon mail messages have been archived. Searching the entire collection will take up to five minutes to complete. Please be patient!


Return to the archives @ gerry.vanagon.com


The vanagon mailing list archives are copyright (c) 1994-2011, and may not be reproduced without the express written permission of the list administrators. Posting messages to this mailing list grants a license to the mailing list administrators to reproduce the message in a compilation, either printed or electronic. All compilations will be not-for-profit, with any excess proceeds going to the Vanagon mailing list.

Any profits from list compilations go exclusively towards the management and operation of the Vanagon mailing list and vanagon mailing list web site.