information or disinformation?
one story says pneumatic is the direction Yam is headed in, then the next thing you read they have abandoned the valve train
WTF
The following is from
Mike Nicks blog during Sunday's Valencian Grand Prix (I'm not surprised by the V4 decision):
Yamaha Rejects Pneumatic Valves and V4 for 2008 ...
In its struggle to win back the MotoGP world championship, Yamaha will NOT build a V4 engine, will NOT adopt pneumatic valve gear, and will NOT copy Ducati's desmosdromic valve operation.
This extraordinary series of apparently negative decisions - which fly in the face of rival manufacturers' experiences - has been revealed at Valencia by Masao Furusawa, Yamaha's head of engineering.
Furusawa said that he has investigated alternatives for the YZR-M1, but will stick with an in-line four-cylinder layout, using traditional valve spring technology.
"We have made a lot of computer simulations of a V4 and we have found good and bad points," Furusawa said in a media presentation. Yamaha preferred the in-line four because it permits a more compact engine and a shorter wheelbase.
Furusawa admitted that valve springs had a ceiling of 19,000-20,000rpm. But he said: "Increasing the rpm increases the power, but at the same time you have more friction between the piston and the cylinder. And I don't think that over 20,000rpm is the way to go. I would like to make an engine that has lower rpm but good torque, one that makes a good 'conversation' between the rider and the tyre."
Yamaha has tested a pneumatic-valve engine this year, but Kouichi Tsuji, leader of the M1 project, said: "From the point of view of fuel efficiency and power, we have had no gain from it. If we find a benefit we would be ready to use it."
Kawasaki is currently proving that an in-line engine can match the V4s used by Ducati, Honda and Suzuki: in qualifying at Valencia Randy de Puniet was quickest through the speed trap at 300.8kph (186.796mph). But Valentino Rossi, the quickest Yamaha rider, hit only 293.5kph (182.263mph - 4.533mph slower).
Why is the Yamaha still lagging? "We are struggling to maintain horsepower and fuel efficiency," Furusawa admitted. "We always try to make a good engine, but the result isn't always the same as our plans."
Rossi will be hoping that Yamaha can recover power parity with other manufacturers during winter testing prior to the 2008 season.