Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/720681
FEATURE TRIUMPH INFOR ROCKET STREAMLINER P98 THE POWERPLANTS "W e have a MoTeC dash, and two MoTeC ECU modules, one for each engine, which were built here by MoTeC Systems East, rather than at their HQ in Australia. Bob Carpenter is our engine builder, and he's in New Jersey, so the MoTeC East office in North Carolina helped us out a lot. We use two turbocharged three-cylinder Triumph Rocket III engines, but these have been modified from standard bore and stroke. They call the Land Speed Record class Unlimited, but really it's limited to 3000cc by mutually agreed con- sensus. We considered the option to bore and stroke the stock 2300cc Triumph engine to three liters, and we knew that we wanted 1000 bhp, neither of which was an issue. But then with a single motor the transmission loads get pretty crazy, the engine breathing gets problematic, and being too light in weight is an issue, as well as length; we needed the length for aerodynamics, and weight for traction. So we de- cided to use two engines of 1500cc each. Bob Carpen- ter has a lot of experience building sportbike engines, and he makes 500 bhp with a GSX-R motor all the time, but they're like glass. Reli- ability is a huge issue. "To reach the three-liter capacity Bob's retained the stock engine block and the stock cylinder head, which he has CNC-ported and gas-flowed, and stock valves. He then de-stroked the billet crankshaft made by Marine in Los Angeles with very long Crower titanium conrods carry- ing custom pistons made by Carrillo, using a stock 101.6mm bore and a shorter 60.96mm stroke to get 1485cc on each engine, times two. They each pro- duce over 500 bhp, and we run to about 9000 rpm, a lot higher than stock [peak is 5750 rpm on a stock Rocket III]. This is a short- stroke motor, but Bob can run the stock long-stroke engine at 9000 rpm with modified valve springs and titanium retainers, like those he has on these motors of ours. After looking at it, it's clear that the Triumph fac- tory developed the Rocket III motor to give a lot more than the 146 bhp that it has on the street! New valve springs get another 3-4000 rpm, then Bob does a little port work, he makes some new cams and better fueling, and he can make 280 bhp with that thing, still naturally aspirated without compromising reliability, and still using the standard throttle bodies and injec- tors. But we then add a turbo system designed by Carpenter Racing and fabri- cated by Precision Chassis, which gives each engine its own Garrett AiResearch GT2876R liquid-cooled tur- bocharger running around 21 psi of boost." (Left) Two engines are fed by twin turbochargers to pump out 1000 bhp but remain under the 3000cc limit. (Below) A MoTeC dash is just one part of the huge collaboration between the U.S arm of the Australian company.