By Peter McLaren
Yamaha has extracted five more horsepower - or 'ponies' as engineering general manager Masao Furusawa calls them - from its YZR-M1 since the end of last season, but believes another three or four will be needed for the 2008 Qatar season opener.
After witnessing an impressive test for star rider
Valentino Rossi at Sepang last week, Furusawa spoke exclusively to
Crash.net about Yamaha's progress since last season.
"So far, so good. The bike has changed very much since the Valencia race and it looks like Valentino is very happy - especially with the pneumatic-valve engine, new electronic control system and new tyres," said Furusawa.
Rossi's two main 'problems' last season, as he fought in vain to prevent Ducati's
Casey Stoner lifting the world championship, were tyre and engine related.
The response has been a switch by the Italian to Bridgestones and a decision by Yamaha to concentrate on the pneumatic-valve engine, seen on and off during the closing rounds of 2007.
"Last year I would say we had too many engine options - mechanical springs and pneumatic springs - so this year we have just focused on the pneumatic-valve engine and this means we have more spare time to set-up the bike," admitted Furusawa.
But he also confessed that the use of pneumatic-valves is far from an obvious engineering choice.
"From the theoretical point of view we don't need to use the pneumatic valves, because the rev limit is around 19,000 rpm [achievable with valve-springs]," he declared.
"Basically the engine shape is also still the same and, even though we changed the cylinder head, the centre of gravity location is almost the same as well. Of course some of the internal parts are different, because otherwise we cannot increase the horsepower."
And just how much has the horsepower been increased?
"I would say we have added five 'ponies' compared to last year's engine, but we will need another three or four by the first race," he explained.
