HOW THE DUAL PORT INDUCTION SYSTEM WORKS
The Dual-Port 360 can best be described by saying it’s actually two separate manifolds in one. The entire manifold 1s divided from the base of the carburetor to the head flange. The percentage of separation is, of course, a closely guarded secret on this now-patented design and 1t varies from engine 10 engine. PRIMARY WATER In operation, the primary mixture is fed into·the bottom runners and the engine operates on this smaller port until the driver or engine demand cuts in the secondaries – the top port. Many good things happen with this induct, on the system. In the Dual Port, the primary system further restricts the air flow after passing the carburetor and increases it to the “speed of sound.” This means that even at low engine rpm (see dyno charts) we’re getting near perfect aerodynamic efficiency, or translated – more HORSEPOWER! This extra horsepower on the primaries comes from a more perfect mixture moving at near sonic speeds, a larger volume passing 1he Intake valve and greater turbulence in the combustion chamber for a highly efficient use of fuel. The primary system being on the bottom uniquely provides 1wo layers of manifold casting and a high-speed mixture flow which acts as a perfect insulator for 1he secondary runners. And since the secondaries are insulated from engine heat, this means that when cut in the secondary mixture will be “cold” and “dense” – afurther increase in performance. Then, when the secondary mixture gets to the end of the runner it is picked up and “rammed” into the combustion chamber by the sonic velocity of rhe primary port. Again, an aid in passing a greater, colder and more dense air/fuel mixture past the intake va lve and se1ting up an ideal combustion chamber condition to increase horsepower output. All the dyno tests so far – using a great variety of engines, have shown substantial horsepower increases over their entire rpm range. By measuring the “brake specific” which is the amount of fuel consumed per horsepower, per hour, further proves the va lue of the highly efficient Dual Port system as less fuel was used 10 gain more horsepower.
Due to the high efficiency of the Ottenhauser Dual Port Induction System, it has also proven itself capable of greatly reducing exhaust emissions in tes1s at an elaborate facility in the mid-west. This makes Offenhauser the F IRST speed equipment manufacturer 10 produce a product that reduces exhaust emissions yet increases horsepower! Bv taking an active inerest in air pollution problems, Offenhauser engineers are. attempung to help the automobile industrv as a whole and to spotlight the high performance facet with their achievements
Offenhauser Dual Port intake manifolds
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