On the Formula 1 tech lists I have seen remarks from designers that 8% can be regained but that involves a lot of money. Also straight percentages can be misleading but that is why I try to stick with dyno info from NA engines. That is just the way the data comes out.
Church's dyno in LA did testing for a Honda team on the D16 patterns and saw 3% gains and that is interesting considering the massive girdle structure in that engine. The Honda B-series engines with full windage trays showed 2.5% increases after a scraper was added. The reason is that a windage tray serves a different basic technical function: it is a shield for sloshing or splashing sump oil. Numerous OEM and aftermarket windage trays do have scraper louvers built in -- the iterative extension of that idea is the diamond stripper expanded metal screening sold by many suppliers. However, the trays present in the Suzuki G engines (that I have seen) do not fill a dual purpose.
For a very long time (post WWII designs) positive lubrication automobile engines have had rotating assemblies that spin well clear of the sump fill line in a static engine. Windage losses occur nonetheless because they are fed by large amounts of oil ejected from the rods, mains, oil relief valves and draining oil from the head. Good places to look at the design consequences are the late model BMW engines. They have dedicated passageways that isolate draining oil from the head that flows into the sump. This is a sea change from earlier designs. [The same design evolution can be seen going from the Toyota M series straight sixes to the JZ straight sixes.]
Here is a pic of a windage tray from a BMW m52tu that virtually seals off the sump: if you look at the bottom edge there is a series of large oil drain holes that link to tubes running to the head. Also note that the tray itself has many internal facing louvers -- those are actually another form of crank scraper.
You might not have seen those percentages on the SBC because the skirts on the block are already very tightly confined around the rotating assembly (at the pan rail) and the scrapers for those engines tend to be quite narrow. Nevertheless, crank scrapers (versus windage trays) are considered to be such an unfair advantage at many circle tracks that they are banned (and often windage trays are allowed). Interesting, no?
Kind regards,
Kevin
Thats alot from straight windage control....
I say that because we never saw that kind of percentage on the Chevy Sprint Car (355cid) engines when we dyno'd them.
I still think the Suzuki has got pretty darn good oil control, but if you are getting that kind of percentage on the dyno I'll have to re investigate on the next build.
Zag
