your broad band engine

Is it Useful?
On the trail 1000cc or larger engine has big torque on the bottom end and is very responsive, no doubt. Take that same engine and lower the exhaust port 1/4-inch. In the 4000-6000 rpm range you'd have a sled that could challenge a trail groomer to a pull-off! Think how big of a helix it would pull and still backshift instantly. You better be hanging on when you come out of a corner on such a sled. A 1000cc variable exhaust engine on the trail is the ultimate.

On the track, some racers contend that variable exhaust race engines don't E.T. better than non-variable exhaust engines because there are many variables in high-compression high-horsepower race engines between manufacturers and builders. A drag race, however, is measured from the time the green light goes on to the time you cross the finish line. That's more than just E.T. Here is a fact. If you take any race engine, whether it has a long-stroke or short-stroke, 220 hp or 260 hp, and lower the exhaust port 1/4-inch it will pick up tremendous torque in the 4000-6000 rpm range but fall off soon after. If you could modify the port height once the engine is through the low end torque, you could maintain your power and accelerate through the race. That's what variable exhaust valves will do.