It is usually a stamped piece of sheet metal that is mounted between the crank shaft and the oil pan.
To be used with our oil pick-up (shown below). Our Windage Tray is a stud girdle/ Windage tray combo! It ties up the #2, 3, and 4 main caps (excludes #1 for oil pan clearance). A windage tray prevents oil from splashing onto the crank by channeling the oil safely away. The most effective way is a big,wide,deep pan. Short of that, most of the the windage trays don't work. On a 400 dirt engine a tray on extended studs was a 8hp loss at 7000rpm. I just don't see how the oil coming off of the crank can do anything but bounce back up into it with a solid tray there.  Windage Tray. The most inexpensive horsepower available. Specially contoured solid trays with louvers that permit oil rapid return. Proper oil control can contribute up to 20 HP on street engines and even more on race engines. Made in USA.  A wind-age tray is usually a stamped piece of sheet metal that is mounted between the crank shaft and the oil pan. On slow revving i.e. stock applications there benefit is slight. However race and high RPM applications claim that they actually free up more horsepower. A wind-age tray acts like a scraper and removes the oil from the vortex letting it drain back to the oil pan. It does not actually touch the crank shaft but it is close enough to it to skim off the oil and let it drain. Oil control is extremely important for power and durability. I use Esslingers windage tray, and am convinced that it will contribute to a significant reduction of HP loss due to oil whipping around, and trying to follow the action of the crankshaft. We are using ARP main cap studs and a windage tray. The tray came from Racer Walsh, but looks identical to the one offered by Esslinger Engineering. It is a very nice unit and comes with 4 main cap bolts with a small stud protrusion on the head. Merge this question into. Split and merge into it. Answer by David Theiler. Confidence votes 17.4K. That is a medal tray that is bolted to the main caps on the bottom of the engine that is designed to keep the engine oil from splashing up in the engine and stop the oil pump pick-up tube from sucking air instead of oil. It also stops the engine oil from foaming in the oil pan due to splashing.  SOLID, LOUVERED WINDAGE TRAYS Specially contoured solid trays with louvers that permit rapid return of oil to sump. This windage tray provides optimum protection against oil splash-back, and provides increased power. Ideal for street and strip applications. The most sophisticated windage tray available today! This exclusive Milodon design features hundreds and hundreds of small louvers that quickly scavenge oil from crankshaft rotation, but prevents reversion common to screen-type windage trays. Which leads to why a wind-age tray is such a great thing. (1) this much swirling oil acts like a small load on the engine and robs HorsePower. (2) with that much oil NOT in your oil pan at High RPM you could have a potential oil starvation or cavitation problem, KABLOOWE. A wind-age tray acts like a scraper and removes the oil from the vortex letting it drain back to the oil pan. It does not actually touch the crank shaft but it is close enough to it to skim off the oil and let it drain. A windage tray will help improve engine lubrication by controlling the interior windage at high engine speeds. By controlling the windage from splashing against the crank the factory claimed a 7 hp increase in power for a 340. A wind-age tray acts like a scraper and removes the oil from the vortex letting it drain back to the oil pan. It does not actually touch the crank shaft but it is close enough to it to skim off the oil and let it drain. Windage is a force created on an object by friction when there is relative movement between air and the object. There are two causes of windage: 1  The object is moving and being slowed by resistance from the air. 
http://www.moranav6racing.com/category.html?CategoryID=4 http://speedtalk.com/forum/viewtopic.php?t=5481 http://www.jegs.com/p/Milodon/Milodon-Windage-Trays/745645/10002/-1 http://forums.hotrod.com/mopar-muscle-magazine/70/7141434/mopar-engines/what-is-a-windage-tray/ http://www.merkurencyclopedia.com/Motor/windage_tray.html http://www.answers.com/Q/What_is_a_windage_tray http://www.milodon.com/oil-system/windage-trays-studs.asp http://forums.hotrod.com/mopar-muscle-magazine/70/7141434/mopar-engines/what-is-a-windage-tray/ http://forums.hotrod.com/mopar-muscle-magazine/70/7141434/mopar-engines/what-is-a-windage-tray/ https://en.wikipedia.org/wiki/Windage
what is a windage tray