Kevin Johnson

That does work well too. A tuning firm in Belgium has been campaigning Porsche 944s with heavily knife-edged cranks and scrapers for two or three years now. They do make a difference with them as well. The basic issue is that a pressure differential is formed around the spinning rotating assembly. Windage is a highly complex set of phenomena in the technical sense of complex. Knife-edging helps the counterweights and throws to pass more cleanly but they do nothing to stop pumping transfer between cylinder bays which must move through the rotating assembly. On a straight six this pumping transfer is a nightmare.

Hi, I am working on designs for the RB26DETT and ran across this thread. The design we use on the L series engines is also an OEM design on the Dodge Viper third gen engine (2003-2006). The clearance on the Dodge piece is about three mm. This is about the same clearance as found with the Dodge SRT4 OEM scraper. They have large clearances to avoid time consuming fitting issues. The oem Nissan SR20 scrapers in the girdle have about 1mm clearance. The 2007 SCCA F Production National Champion car was running one of our Teflon scrapers inside the stock windage tray. The scraper is the same general design as on the L-series. That 1.6 liter engine picked up 6-7 hp over and above the stock windage tray (retained) which also has scraper openings in it. Ask Prather Racing. By the way, the basic Mazda tray design can be seen in the Studebaker Type R tray from the early-mid 1960s. The technology has been around a long time. The general scraper design is considered sound engineering and is cited by GM in a modern patent as background information. The attachment method is used as oem by both Suzuki and BMW. Nissan makes huge use of scraper technology in its modern engines. It just does not seem that way because the L-series is older. If you look at the massive re-engineering of the Toyota and BMW straight sixes of the same vintage then you will notice millions of dollars being spent to add more windage control. Well designed scrapers return about 2% to 3% of the output of the engine. In a big block Mopar hemi putting out about 900 hp that is around 30 hp. That corresponds well with the reduction in 1/4 mile ETs. Some engines have a higher return. Cosworth Engineering offers aftermarket scrapers for the Evo motors. If you look carefully at their literature, they lifted our advertising. That is quite a compliment, I think. Their basic design is in line with our L-series design. Most racers like the extra hp but are really most concerned about allowing their engines to live longer. It was interesting to me that the SCCA Formula Ford banned scrapers in the Zetec engine which is being allowed as a replacement for the Kent based engines. Scrapers have been used in FF for decades so they might know something there. Porsche Cup in the UK will not allow scrapers (same basic scraper design as the L-series) because while helping to protect the engine they give a modest power boost and everyone would be forced to get one. Nasa Porsche 944 series allows them (same basic design as the L-series) because they help stop the engines from failing. Porsche uses scrapers in the stock 924 and 944 pans, by the way. As does Mercedes in their diesel engine pans but their designs are closer to the scraper used in the floor of the Ford FE pan starting over 40 years ago. Anyways, that is my experience after making them for hundreds of different engine designs. I think your statement could be re-paraphrased to yield "they are a way to make more reliable horsepower." It would be difficult to think of a technology that has more empirical evidence backing it up. IMHO Edit: I know that I am often an egotistical jerk -- as Norm mentions in the other thread. I take what I do very seriously and often react badly -- that's my nature and a character flaw. On the FJ20 forum I got into an argument with the director of a F1 facility. Oh well.