05 0360

Also known as Ram Tube, Bellmouth, Air Horn or Velocity Stack. This 20mm clamp-on velocity stack fits Dellorto PHF & PHBE Carburettors and other carbs with 48mm O.D. intake spigots.

• Maximum radius of the bell is 78mm
• Maximum length including net is 32mm

Velocity stacks improve the air flow into the carburetors to increase induction efficiency and increase horsepower on racing engines where air filters are not required. Fits all Mikuni RS Series Carburettors and other carburetors with 55mm O.D. intake bells. Choose length depending on chassis clearance and desired tuning characteristics.

HOW IT WORKS:

It is commonly mistaken that "stand off" (air–fuel mixture that gets pushed back out of the port, usually when using full throttle at low rpm) is somehow captured by installing a longer intake pipe, but it is actually that the intake valve is closing too late and the combustion chamber is simply overfilling and blowing back out the intake port before the intake valve closes. Installing Velocity Stacks creates a later intake pressure wave that helps keep the air in the chamber until the intake valve closes by functioning as a resonating pipe which adjusts the frequency of pressure pulses based on its length within the tract.

Power gains in the order of 2% to 4% can be obtained when inlet radii and stack lengths are optimized for the  engine. It is sometimes possible to use an additional foam type filter to protect your engine.