Hooker Exhaust Tuner
Hooker Exhaust Tuner
THE BATTLE TO SAVE OUR LAND (AND OUR EARS) IS BEING FOUGHT BY HOOKER HEADERS — WITH AN INCREASE IN HORSEPOWER THROWN IN FOR GOOD MEASURE.
HOOKER HEADERS, the world’s largest manufacturer of automotive exhaust systems, seems like an unlikely place to find two-stroke expansion chambers-cum-mufflers pouring out at the rate of 350 per day. But it is real. Under the leadership of Rick Vesco, younger brother of former motorcycle land speed record holder Don Vesco, the motorcycle division of Hooker has grown tremendously in the past 18 months.
The goal? Better power for the twocycle motorcycle, with a significant reduction in the noise level of an expansion chamber. Judging from some reports on land closure in the Southern California area, one of the main reasons for the vehement fight against the offroad motorcyclist is noise, and particularly the noise produced by an unmuffled two-cycle engine. Snowmobiles are not in as much trouble yet, but Hooker is anticipating their problems and working on them already.
The easiest, if not the least expensive, way to increase the power of a two-stroke engine is to install an expansion chamber. All that is required is the initial purchase, a few simple hand tools, bigger carburetor jets, and a few minutes of a person’s time. The result
may be increased power, but, an additional result is what might be loosely described as a sound lacking agreeable musical quality or one that is noticeably loud, harsh or discordant. And loud noise can be irritating to the wrong people, for both subjective and physical reasons.
A point taken from the science of psychoacoustics reminds us that two sounds of equal sound pressure level will have different effects on a person. A deep, mellow sound at a certain volume will be much more agreeable than another at the same volume making a sharp, piercing crack. The latter sound will have a more adverse effect than the former, and we all know what makes the latter sound !
Hooker began their exhaust tuner program with increased performance as their primary objective, and reduced sound level somewhere in the background. Now, the two objectives have equal weight.
Using the acknowledged expansion chamber theory of regulated back pressure, each Hooker design incorporates a tuned core muffler which is fitted into the stinger of the expansion chamber. This muffling core is a perforated tube surrounded by a fiberglass packing to
help deaden the sound. When the packing becomes clogged with carbon and oil, it can be replaced quickly and easily with a replacement packing from Hooker.
High quality steel sheet is hydroformed into two halves for the tuner body, and specially bent tubing is used for the header pipe and stinger sections. After welding, each chamber is aciddipped and electro-cleaned before a special heat-resistant black paint is sprayed on. An attractive sheet aluminum heat shield completes the assembly.
The Hooker Exhaust Tuner provides a sizeable increase in horsepower over the entire rev range, and most often in the middle rpm ranges. A dynamometer facility indicates that Hooker’s claims are valid. Sound reduction over a conventional expansion chamber is in the neighborhood of 10 db., a significant abatement. An added bonus is a reduction of the “rider fatigue’’ factor.
Although the first Hooker Exhaust Tuners were produced for the popular street/trail machines, units are now available for a large number of strictly competition machines such as Bultaco, CZ, Harley-Davidson, Husqvarna, Maico, Montesa, Ossa, Suzuki and Yamaha. [Ö]
