One of the best parts of hot-rodding is the powerful sound of a high-performance exhaust system under full-throttle,and if you're like most hot-rodders, you thrive on that sound and lots of it. So how cool would it be to be able to uncork your exhaust with just a flick of a switch from your dashboard? You could instantly turn your exhaust from docile street to full-race sound, most likely gaining some added power; Quick Time Performance offers a cool electric butterfly system allowing you to do just that. The undercar components are manufactured from a CNC-machined aluminum body and stainless steel moving parts. A high-torque DC gear-driven motor controls the opening and closing, and weathertight connectors are used for superior sealing.
To see how well this works, we spent a day installing the system on a big-block '67 Chevelle at Granatelli Motorsports. Car owner Bobby Mahoney had previously installed a big 3-inch system with free-flowing mufflers for his 468ci Rat motor, which has 12.5:1 slugs and a Comp Cams solid-lifter cam with 252/260 degrees of duration at 0.050-inch lift.
To install the kit we surveyed the head pipes for the best place (between the collectors and the mufflers) where the cutouts could be added to improve flow. On this car, this was right at the first turn away from the collectors, and most systems should have the cutouts installed in this general area.
With the kit welded in place, we ran closed and open tests on the Granatelli chassis dyno to see how much power the Chevelle produced. With the cutouts shut, the 468 Rat pumped out 433 lb-ft of torque at 4,600 rpm and 428 hp at 5,500 rpm. With the Quick Time cutout cracked open, we achieved 447 lb-ft and 442 hp. So in addition to gaining about 14 more lb-ft and 14 more horsepower, we raised the entire power curve from 3,250 to 6,500 rpm, which is right where the engine turns through the quarter-mile traps. When we completed the dyno-testing, we simply hit the electrical switch to close the exhaust opening and drove the car off the dyno and back home in peace.
Since this system already...
Since this system already had a suitable bend in place we simply welded a 3-inch-diameter pipe to the head pipe to install the Quick Time electric cutout. Rigo from Rigo's Automotive performed all our welding.
The kit from Quick Time Performance...
The kit from Quick Time Performance (PN QTEC60CP) includes the two electric cutout valves, wiring, a switch, and cutout Y-pipes.