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The KrankVent was originally invented to eliminate the problem of blown gaskets on the ET drag bikes by replacing engine crank case pressure with a vacuum. The increase in throttle responses, usable horsepower, fuel economy, and engine life were added bonuses that were obtained only when the one-way valve was finally perfected.

The unique "One-Way Flow-Controlled Valve" was awarded a U.S. Patent for a "PCV Valve" that actually produces a negative crank case pressure or vacuum! Sort of like getting a patent on the paper clip as there are so many variations in existence. The super sensitive KrankVent valve uses no springs, flapper, reed, umbrella, ball check, or diaphragms that fatigue & fail.

The velocity of the aerosol over the two surfaces of the valve material, move the valve in & out of position! Simple as that but then the 'elegant' solution is always very simple, but difficult to obtain. The array of existing valves, including the knock offs, reveal that it is easy to design a complicated, albeit less effective, one-way valve! Individual results may vary.


(For American & Metric Cycle Engines)

(Autos donít have these problems but contact ET if you have questions)


Q1. There are now several "KrankVent" type valves on the market. How is the ET KrankVent different?

A1. You know when something works when everyone wants to copy it. Well, in this case there is a difference. It took ET-Performance over four years to come up with a better mousetrap (valve) after trying everything under the sun. The other valves all use umbrella valves or a valve that is constrained in some manner. Now these valves have to operate in tough conditions of high heat, oil, water, acids, and respond to pressure differentials that occur over 50 times a second at 3000 RPM. No other valve can stand this constant torture. Below are shown the valves from a couple of these crank case valves:

Note that the three on the left are identical in appearance. Some manufacturers use better materials for the umbrella valves, but they will eventually fail and die. Besides, head breathers already have two umbrella valves that don't work ... why add a third? The KrankVent valve material is the same material used in the diaphragms of pressure regulators used to control the flow of coolant in nuclear reactors! In other words, it cannot fail or there will be a meltdown. In years of operation in race conditions, we have not observed any sign of wear. Gasoline, oil, alcohol, solvents, etc., will not harm the valve material. The KrankVent will work totally submerged in liquid, in any orientation, and is self cleaning. Finally, the KrankVent is guaranteed forever to the original owner. Now that is quite a difference!


Q2. Isn't the KrankVent just an expensive PCV valve?

A2. There is a difference. The KrankVent has been granted a Patent for a PCV valve for any internal combustion engine, but the similarity ends there. The KrankVent claims include the unique property of releasing crank case pressure and producing, and maintaining, a vacuum in the crank case. This is done with a unique Flow Controlled One-Way Valve that uses aerodynamic principles to move the valve in and out of position. Conventional PCV valves use reed, flapper, umbrella, ball-check, springs, etc., to close and restrain the valve. These valves soon fatigue and fail as they get cycled 50 to 100 times a second at 3000 RPM plus. Go to any auto store and try conventional PCV valves for yourself. If the valves do work in the beginning, they soon fail. This is true for the umbrella valves in the heads of Harley Davidsonísģ as well as other imitation "KrankVents". 

Q3. I put a KrankVent on and oil still blows from the engine! What's wrong?

A3. If you have a crank case timed breather (Bottom Breather), there are several things that need to be checked as noted in the instructions. First, the engine must be airtight in order to maintain the vacuum. Loose oil tank caps and fat pushrods rubbing the pushrod tubes with a high lift cam are often overlooked. A Kinked hose between the engine and KrankVent, or using too soft a hose that collapses under a vacuum is another area to check. Some installers have connected the KV to the oil tank breather line or even the transmission breather -- these won't work! "Head Breathers" can check the above plus have additional problems. The umbrella valves in the heads, if they work in the beginning, usually fail quickly. The new KrankVent Kits for different applications have special KrankVents and instructions for each application, and will solve the 99% of the problems -- follow the instructions. For the remaining 1% remove the umbrella valves so they do not interfere with the KrankVent operation.


Q4. Do I need a filter on the end of the KrankVent?

A4. No, not if properly installed. Remember, crank case pressure goes out but not back in, as it does with just a hose on the breather. The exception would be if riding in dusty conditions. The filter will keep stuff out of the KrankVent.


Q5. Sometimes the engine dumps oil after sitting for a few days or more. Why?

A5. The oil pump check valve that keeps oil in the tank from draining into the engine when not running is leaking. Replace or fix it or put a can under it when starting for the first time after sitting.


Q6. After a hard, high-speed ride I notice there is a mist around the exit of the KrankVent. What's going on?

A6. This is tougher to answer, but here is what I believe is happening. First, the engine must exit a small amount of air/oil while running to compensate for engine blowby, air leaks, etc., depending on how tight the engine is. However, while riding hard or on a dyno pull, often the throttle is shut off quickly, manifold and combustion chamber vacuum goes way up, and piston rings can "break seal" and start to flutter momentarily. When this happens, combustion pressures get past the rings, into the crank case, and momentarily blow out the breather. However, the KrankVent greatly reduces this effect by quickly restoring the vacuum and ring seal. If you don't believe this, take the KrankVent off and do a hard dyno pull!


Q7. I am running over 100 cubic inches. Should I install two KrankVents, one at the head breather ports and one at the crank case breather?

A7. No, connecting KrankVents to the crank case AND head breather ports is NEVER required. The reason is that once the pistons move down and expel the crank case air, the KrankVent valve closes as soon as the pistons start upward. From that point on, only high pressure crank case pulses escapes through the KrankVent, so it does not have to have a large volume capacity. This assumes that you have a real "tight" engine that does not let air in, right? If you can, hook up a vacuum pump to the timing inspection hole and, with the engine off, listen for vacuum leaks. You might be surprised! If you have both breather options available, block off the head breather ports and only use the crank case breather! After all, thatís where the pressure is generated!

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