Ishihara-Johnson crank scrapers and other windage control products are a very simple but effective way to improve the performance of your engine!
What are some of the benefits?
ˇ Less rotating mass for the engine to accelerate because of the removed oil
ˇ Less loss of power because of excessive drag caused by the windage cloud
ˇ Helps reduce engine damaging oil-foaming
ˇ Helps avoid oil starvation by keeping the oil in the pan during hard braking and turning as well as during off-road driving
ˇ Helps to cool critical engine parts by quickly returning heated oil to the sump
ˇ Helps to prevent the cylinder walls from being overloaded with oil
ˇ Can help with fuel efficiency
During normal engine operation a significant amount of oil adheres to or becomes entrained in a cloud surrounding the spinning bottom end. It must be remembered that the particular characteristics of oil adhesion and/or oil-in-air entrainment vary depending on engine rpm and what the vehicle is doing at the time. The oil droplets are drawn into a tornadic cloud by the phenomenon known as the Tea Leaf Paradox, first described by Albert Einstein in 1926. It is counterintuitive that oil droplets would be drawn into rather than completely expelled out of the windage cloud. An equilibrium of entrained oil is reached for the particular operating conditions. There are many alternate terms used for crank scrapers including oil wipers, oil skimmers, and baffles.
This oil eats up horsepower your engine is making by increasing the rotating mass and also creating parasitic drag. At low rpms and in extreme conditions where the rotating assembly is flooded by sump oil, the crank scraper mechanically strips off excess oil by coming close to, but not touching*, the moving crankshaft and rods. At high rpms it interferes with the pressure differential that draws oil into the windage cloud.
Our crank scrapers are constructed from steel unless noted and include installation instructions. The scrapers are installed in a variety of positions but generally between the oil pan and engine block or along the main bearing caps. Some fitting to your individual engine may be required and the procedure for carefully checking this is explained in the installation instructions.
Do they really work?
Yes! The drysumped Merlin V12 aircraft engine from WWII had a rudimentary scraper directing oil to the scavenge pump. Crank scrapers in various forms have been in use in stock passenger car engines for about 90 years!* More importantly, they are currently in use in a variety of OEM engines of both large and small displacement -- from relatively low RPM V8 engines to high RPM straight fours. Most auto enthusiasts are surprised to learn just how common they really are. In short, it is an extremely well-proven technology that is often simply not recognized. The modern trend is to have many more oil control devices in engines. Crank scraper technology is OEM equipment on various modern engines from Nissan, BMW, Chrysler, Ford, Mazda, Honda, Toyota, VW, Porsche, GM, Pontiac, Chevrolet, Mitsubishi, Mercedes and many other manufacturers.
[* In 1923, Clair Smith applied for a patent for a device used in splash lubricated engines to reduce an overabundance of lubrication in some areas and redirect it to other areas receiving less lubrication. This design was a forerunner of the scrapers subsequently used in positive crankcase lubrication engines; patent 1,569,404.]
For example, here are a couple quotations from a recent patent held by General Motors; click here for more information about Mr. Tom Bishop:
Some pictures of OEM crank scraper technology in passenger car engines...
Is a windage tray the same as a crank scraper?
No, a windage tray serves a different but related basic function. It is present to act as a physical barrier between the rotating assembly and the sump reservoir. A crank scraper actively removes excess oil and returns it to the sump. Some windage trays do have scraper technology built into them but even then a dedicated scraper will approach the moving parts much more closely.
There are all sorts of industry terms for parts that function as a windage tray (often in addition to other functions) such as baffle, deflector and so on. Many times multiple levels of windage trays are used. This is because the design requirements for windage trays in an engine under acceleration are often diametrically opposed. Care must be taken that a windage tray does not become a de facto second sump by sealing the actual sump well area off too effectively.
Above: Honda B-series engine showing an installed TeflonŽ scraper on the left and the factory windage tray covering the entire assembly on the right. The windage tray shields the rotating assembly from splashing sump oil while the scraper actively removes excess oil. Before 6000 RPM the standard steel version of this scraper returned a 1.5 % to 2 % hp gain and from 6000-8900 RPM the hp gains averaged 2.5 %. Remember that this was on a statically mounted engine already having a full windage tray as with the Suzuki G10 mentioned below.
A windage cloud will still form on a statically mounted engine with a full windage tray. For example, roller dyno testing of a scraper in the Suzuki 993 cc three-cylinder G10 engine with a full windage tray still showed an average 3 % hp increase (over four pulls data ranged from 2.4 % to 3.5 %). Power began growing at about 2750 rpm and peaked at 5300 rpm (the maximum for that economy cam). Here are the dyno charts. In a moving car the oil would be sloshing around and making at least partial contact with the rotating assembly creating larger windage losses -- consequently the gains would be greater when using a scraper.
Will my engine still get enough internal splash lubrication?
Yes. The rod and main bearing journals are constantly spraying large amounts of oil in all directions when the engine is operating. Much of this oil lands directly on the cylinder walls and other internal components which depend on splash lubrication. The scraper removes oil directly only from portions of the surface of the crankshaft and the rod big ends, neither of which depend upon lubrication of any sort. These components, as well as the pistons, do depend upon a flow of oil to cool them. By constantly removing oil that has contacted these hot surfaces and allowing fresh oil to re-wet and cool them the thermal efficiency of the engine is enhanced. Hopefully, too, the user is reassured by over four decades of the successful and dependable use of scrapers in OEM stock engines as well as competition engines of all sorts.
Many enthusiasts remember splash lubricated engines where the big ends of the rods dipped directly into the sump reservoir for lubrication. This is essentially pre-WWII technology and does not apply to modern engines with positive pressure bearing lubrication from an oil pump.
Can the retroactive application of this technology help solve longstanding problems with certain engines?
Yes. In 2005 we designed a complex system of scrapers, windage trays and baffles that allowed the wetsumped Porsche 928 to survive a full season of high rpm racing without the well-known 2/6 rod bearing failure. This was unprecedented in the history of this engine.
General answers: What is windage and what are the differences between an oil baffle versus a windage tray versus a crank scraper?
What about dry sumps: do they eliminate windage?
There are many levels of dry sump technology as well and windage is still an important issue in their design. Dry sumps are primarily intended to deliver an uninterrupted supply of quality oil to the bearings under all reasonable types of vehicle movement (aircraft systems are more complex). Oil aeration is reduced but not eliminated. The faster the engine spins the higher the quality of the oil supply needed and so in F1, for example, many more stages and/or scavenge points could be in use along with active versus passive oil deaerators. F1 engineers have remarked that up to 8% of the output of an engine is available (and, at great expense, presumably achieved).
Here is a company that makes dedicated vacuum pumps to lower the crankcase pressure in a wet sump:
Copyright 2002-2012 All rights are reserved on our product designs -- a great deal of hard work goes into each one.
TeflonŽ is a registered trade mark of E.I. du Pont de Nemours and Company. Only DuPont makes TeflonŽ resin sourced by Ishihara-Johnson Crank Scrapers from authorized DuPont licensees.
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