The Carpenter Racing Triumph
Rocket III “Silverback” has lived up to its billing, breaking the eight-second barrier in the quarter mile – the first ever for a normally-aspirated street cruiser. Rider Marcelo "Alex" Galligani rode the bike to an 8.993 second elapsed time Atco Raceway in New Jersey.
“Mission Accomplished,” stated Bob Carpenter. “Job 1 has been completed.”
Project Silverback takes a stock Rocket III and applies Carpenter’s world-renowned cylinder head porting, mated with custom cams, high-compression pistons and a “megaphone” exhaust system to double the horsepower of the muscle cruiser.
From the very beginning Carpenter knew the bike would have 8-second potential and he saw a path to get there. His goal was to have a comfortable, everyday cruiser that would turn into a rocket ship with a full twist of the throttle.
Keeping the bike as stock as possible was paramount. The Silverback has stock tires, stock wheelbase and stock gear ratio. Other than the highly-modified internals, the only outward sign that the bike is really a sleeping monster is the exhaust, Carpenter’s ram-air scoop, carbon-fiber front fender and new rear shocks.
The bike first hit the track in 2011. This year Galligani recorded a 9.03 elapsed time at Atco Raceway during the summer in the Jersey heat. Once the cool air of fall set in, the team went back to the track to take another shot at the 8-second barrier.
After a few laps where Galligani stood the bike up, he finessed the clutch lever and hit a 9.00 elapsed time before setting the mark with the 8.993 pass. The speed on the barrier-breaking run was 154.17 mph. The fastest speed of the day was 155.47 mph.
“Getting an everyday rider – especially one this heavy – in the 8-second zone is prenominal,” said Carpenter. “This bike is like a flying couch. A lot of guys say they have 8-second street bikes but they are rarely true streetbikes.”
Carpenter noted that the Silverback was running lean during the barrier-breaking session. “We tune the bike on the dyno and with our ram-air scoop we got more air than we were expecting and the EFI could not adjust for it,” he said. “Once we richen the mixture we will see even more performance out of the bike.”
Carpenter plans on continually moving the project forward. “We are going to work on making it sportier,” he said. “We are going to put it on a diet and get the weight down. Right now I think we are a threat to the sportbike world. We want to be a threat to anything on the highway!”