No, that is a windage tray with scraper louvers added to it. The principal function of a windage tray is to prevent consolidated, often flowing, sump oil from splashing onto or being hit by the rotating assembly. It can also serve to isolate the sump oil from the pulses of air generated by the rising and falling pistons.dontbugme wrote:People are throwing around a lot of terms that are intermixed. An oil scrapper is not a windage tray. Scrapers usualy cover almost the whole sump from the crank throws, with louvers to drain the oil back, to prevent oil being slung by the throws.
No, those are baffles. A quick check to see whether say, a horizontal baffle is a windage tray or just a baffle is to fill the oil pan to its static capacity. Windage trays, generally, will just cover this amount. Some windage trays just cover the amount left in the sump well after subtracting the oil in active circulation in the engine. A good example to look at is the Toyota 4AGZE pan. The windage tray (with scraper louvers) just covers about 3.5 to 4 quarts. The lower baffle covers exactly 2quarts.dontbugme wrote:... Windage trays are in the sump and usually incorporate swing type check valves and baffles, left to right and fore and aft, that hold the oil in the vicinity of the pickup tube during hard g's.
Windage is a highly complex set of phenomena. At lower rpms scrapers do shear off adhearing oil removing rotating mass. At higher rpms they physically block the oil entrained in the windage cloud which has little to do with surface adhesion of oil and a lot to do with pressure differentials but, yes, this does reduce friction. The scraper disrupts the pressure differential and the change in system dynamics allows the entrained oil to be ejected.dontbugme wrote:... Scrappers are suposed to reduce friction from slinging oil around, windage trays prevent oil starvation under high high G's
A windage tray could help prevent oil starvation by limiting the amount of oil that is taken up in the cloud surrounding the spinning crank. The addition of scrapers or scraper louvers helps to return any oil that does become entrained back to the sump. Often rod bearing failures, for example, due to excessive oil aeration are blamed on a total lack of oil. Rod bearings can typically only tolerate about 30% entrained air.
More often it is baffling that is used to trap fluid oil and keep the pickup submerged. During sustained high g turns it is critical to have some sort of scraper array present over the area directly above the pickup. If this is not done a motor running at high rpm could easily draw out all the trapped oil in a matter of seconds. Oil entrained in a windage cloud will tend to distribute itself along the length of the crank so by having scrapers over the sump well proper a continuous renewing of the oil supply can result.
Yes, well, that was what was thought by many back in the mid to late 1960s when Chrysler introduced windage trays for the B/RB blocks to great skepticism. Surprise! About 13 hp appeared. Ed Peters (Chrysler engineer) who did joint windage studies with Mobil Oil on the the Shelby 2.2 turbo back in the mid 1980s found 7hp at 6000 rpm with dino oil using a windage tray and 9hp when using Mobil 1. Ask him -- he is very much alive and kicking.dontbugme wrote:... Windage trays don't free up any Hp ...
Well, I guess you have a simple difference of opinion with factory engineers from Porsche, BMW, Cadillac, Nissan, Honda, Mitsubishi, Dodge, DaimlerChrysler, Pontiac, GM, Toyota, Chevrolet, and VW (off the top of my head). They all use scraper technology in many oem stock engines and Nissan particularly so. I have also seen the Nismo racing wet sump oil pan for the L28 -- scrapers everywhere. With the extra oil from squirters, scrapers are called for even more. What sense does it make to try to cool pistons with a fluid that you are allowing to be subsequently churned up and further heated -- that uses/wastes energy that could otherwise be diverted to drivetrain motion.dontbugme wrote:... and scrappers would help a miniscule amount especially since some of the Nissan's have oil squirters and there's a lot of oil being sloshed around.
Just remember the vector sum of the "whatever" forces equals zero in an ideal fluid. Maybe you are hinting at the unpredictable nature of oil with entrained air in it under several bars of pressure? There is a good SAE paper on this from a couple years ago though the authors focus mostly on how this affects hydraulic lifters.dontbugme wrote:... Regarding spun bearings at high rpms, if you look at th e crank and the way the rod bearings are fed their oil through the drilled passages, you have to wonder if the crank doesn'tr act like a pump, slinging the oil out before it gets to the bearings due to centrifigal, centripital or whatever the physics geniuses are calling it nowadays. There's a lot of theoretical speculation about this - who knows?f
Just don't go around any turns too quickly, as you say. Or maybe drift sideways for a while.dontbugme wrote:... You want a couple more Hp and aren't autoxing it? Leave out a quart of oil on the next refill, probably do the same thing as that scrapper.
It is well known from drag racing (and static dyno studies) that the removal of more and more oil yields more power right up to when the engine sucks air into the pump. Scrapers might let you safely get away with running a quart low.
As for terminology or jargon in general, it varies in use from manufacturer to manufacturer as well as by country. I also have little doubt that many performance items or enhancements are referred to by blase or non-descriptive terms in order to slip their inclusion in an engine past accounting reviews. Engineers have told me that excellent windage control systems for powerplants have been nixxed because of cost.
Modified by Kevin Johnson at 3:03 AM 6/17/2006
Modified by Kevin Johnson at 3:11 AM 6/17/2006
