(727) 808-8602

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?

·       Less rotating mass for the engine to accelerate because of the removed oil

·       Less loss of power because of excessive drag caused by the windage cloud

·       Helps reduce engine damaging oil-foaming

·       Helps avoid oil starvation by keeping the oil in the pan during hard braking and  turning as well as during off-road driving

·       Helps to cool critical engine parts by quickly returning heated oil to the sump

·       Helps to prevent the cylinder walls from being overloaded with oil

·       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...

	Left: Here is a picture of a Dodge 3.5 windage tray with scraper louvers -- the louvers even have cutouts for the rod bolts.
Right: Joe Donnelley sent us this picture of a scraper in the 1966 Oldsmobile Toronado oil pan.   Thomas R. Leonard holds patent 3,354,988, which was assigned to General Motors.
Right: Mercedes diesel with multiple scrapers.
Left: Gen III Dodge Viper V10.
Right: Ford 390 pan, crank scraper on the floor
	Left: Porsche 968 pan, multiple crank scrapers on floor
Right: Nissan VG30DETT; numerous scraper devices; patent 4986235.

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 Teflon® 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?

Windage:
During normal engine operation a significant amount of oil adheres to or becomes entrained in a cloud surrounding the spinning bottom end. The oil droplets are drawn into this cloud by the phenomenon known as the Tea Leaf Paradox, first described by Albert Einstein in 1926. This oil eats up horsepower your engine is making by increasing the rotating mass and also creating parasitic drag. Windage is actually a highly complex set of phenomena. Windage effects increase with: vehicle movement; rpm; stroke; blow-by (atmospheric pressure); bearing clearance; component surface characteristics, oil squirters (there are many types); draining oil from the head, cams, balance shafts and other internal components as well as oil returns from turbos, air-oil separators and catch can drains. Closely related topics are those of pumping losses, crank case ventilation, NVH (noise, vibration, harshness), oil aeration and the cooling function that is required of oil in addition to its lubrication tasks.

There are a number of different types and degrees of oil aeration starting from the baseline solubility of air in a given oil formulation at a given pressure and temperature (about 9% in a paraffinic base at saturation at one bar and 100 degrees C) and progressing through to actual foaming of the oil into a shaving cream like mix. Oil aeration can cause innumerable problems but some common ones are bearing failure, lifter collapse, oil pump failure and over heating and subsequent destruction of oils (and engines).

Baffles, windage trays and scrapers:
An oil baffle is a physical barrier to oil movement that is generally all or partially submerged in the wet sump oil reservoir. Sometimes small fins in other areas of the pan floor or engine can be seen that guide draining oil back to the main sump reservoir and these can be considered oil baffles as well. Typically these are seen in OEM cast aluminum sumps. Here is a picture of a Mercedes diesel engine sump with many baffles that are also crank scrapers.  The idea is to keep the end of the pump pickup tube constantly submerged in oil so that it does not suck in air. Some baffles include trap doors that swing and close to enhance this function. So, baffles are ultimately intended to guide fluid consolidated oil to, and keep it around, the oil pump pickup.

A windage tray should prevent fluid reservoir oil that is sloshing from coming into direct physical contact with the rotating bottom end. Windage trays are also meant to shield the reservoir oil from the aerodynamic forces of the rotating assembly. These two basic functions often are in direct conflict with one-another with respect to decreasing the total effects of windage.

A crank scraper (sometimes known as an oil wiper, etc.) is a broad term for technology that actively strips away oil entrained in the air around, as well as oil physically adhering to, the rotating bottom end. Crank scrapers also serve to disrupt the pressure differential that forms in and around the rotating assembly.

Baffles, windage trays and crank scrapers all serve related functions and all can be of mixed design, i.e. dual or even triple purpose. Remember that different OEMs and cultures often use ideosyncratic terms for these various devices so this is only a general guide.

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:                                            

Contact Information

Telephone

727 808 8602

Postal address

P.O. Box 2168, Land O' Lakes, FL 34639-2168 USA

Electronic mail

Customer Support: sales@crank-scrapers.com           

Copyright 2002-2012 All rights are reserved on our product designs -- a great deal of hard work goes into each one.

Teflon® is a registered trade mark of E.I. du Pont de Nemours and Company. Only DuPont makes Teflon® resin sourced by Ishihara-Johnson Crank Scrapers from authorized DuPont licensees.

We Ship World Wide!

Jean-Claude 1919-2003

A good friend.