We sometimes hear things like “My bike isn’t powerful enough,” followed by, “What should I do?” Dropping in a big bore piston kit, hot cams, bigger injectors, dumping the stock exhaust for a free-flowing unit, plugging in a racing ECU are some of the ways. But that is kind of meh, is it not? But one method that is now pretty much overlooked these days is a turbo kit, like this turbocharged Yamaha MT-10.
The stock MT-10 is already doing a healthy 158 hp. Let us see what the guys at Australia based Purpose Built Motor did to this one.
They began by bolting a turbo kit to a stock MT-10 engine which has a 12:1 compression ratio, with 7 psi of boost pressure. But as the host said, they found signs of overheating and undue stress on the pistons when they pulled the engine apart. Why? One simply does not run a turbo with 12:1 compression ratio! So in the end, they scaled it back to 9.5:1 by using a CP-Carillo pistons and conrods for better reliability.
They also asked a specialist to fabricate an custom intercooler to cool the boosted air down before it enters the engine. This creates two benefits: A cooler charge (fuel/air mixture) is denser and contains more oxygen molecules; and, keeps the engine from overheating. There are two fans, one large and the other smaller, behind that intercooler which the rider can switch on or off when he needs it.
Speaking of oxygen, ducting air from the airbox will not be enough, what more the plumbing to the turbo, so the guys installed an intake with a DNA filter right above the turbo’s compressor. It sits underneath the rider, between the swingarm and the rear seat’s underside.
The exhaust system is of course customized, with the turbo’s wastegate fitted externally. The main exhaust pipes lead from the turbo’s impeller to a silencer, while another shorter pipe is for the wastegate to dump overpressured gas.
Purpose Built Motor also installed a longer swingarm to keep the front end down, rather than having the turbocharged Yamaha MT-10 wheelie over backwards!
What does all this achieve? Dyno tests showed 230 bhp, running on 10 psi turbo boost pressure. Er… that was with the exhaust silencer’s baffles installed. It hit 260 bhp when they removed the baffles. And remember, virtually all manufacturers print their horsepower numbers by dyno’ing their engines at the crankshaft output shaft without the transmission, so this MT-10’s power output should be betwen 260 to 290 hp if printed on a brochure!
So, fast enough for you, sir?
