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What is windage loss

what is windage loss

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 oil droplets in the windage cloud

· Helps reduce engine damaging oil-foaming both on the surface and bubbles deeper within the oil

· 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 the rotating assembly or becomes entrained in a "windage" cloud surrounding it. It should be remembered that the particular characteristics of oil adhesion and/or oil-in-air entrainment vary depending on the engine rpm and what the vehicle is doing at the time. How the oil droplets are kept and drawn into the tornadic windage cloud is explained by the phenomenon known as the Tea Leaf Paradox. which was first described by Albert Einstein in 1926. It is counterintuitive that oil droplets would be kept and drawn into ("entrained") rather than completely expelled out of the windage cloud due to centrifugal force.

When a portion of the total droplets are small enough in physical size the predominate influence on their behavior switches. Rather than just their momentum due to being ejected from or impacted by the rotating assembly they are guided by the air currents in the windage cloud.* This droplet behavior in a gas atmosphere, which is a type of "fluid", in the confined volume of the crankcase is what the Tea Leaf Paradox addresses. The oil droplets have a

greater density than the gas molecules.

Remember that an "equilibrium" of entrained oil is reached for the particular operating conditions. This means that not all the oil is held but rather that the amount rises until a certain point is reached and then the extra is not taken in or it swaps places with oil already in the cloud that is then released. Generally the higher the rpm, the more oil that is held because of the higher pressure differential. It is not unusual for a quart or more of oil to be suspended in the cloud at high rpms in many engines.

There are many alternate terms used for crank scrapers including -- but not limited to -- oil wipers, oil skimmers, and baffles.

* "High-speed video observation and phase Doppler anemometry measurements of oil break-up in a model engine crankcase" S. Begg, G. de Sercey, N. Michй and M. Heikal, Presented at ILASS - Europe 2010, 23rd Annual Conference on Liquid Atomization and Spray Systems, Brno, Czech Republic, September 2010. Full text available here:

This impacted and entrained 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 and allows a new lower equilibrium of entrained oil to be established.

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.

Category: Forex

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