By David Emmett
You would think that the secrets of how to make a MotoGP bike go faster would be kept under lock and key at all times. Not so if you're Yamaha: On Friday night, Yamaha's technical leaders Masao Furusawa and Masahiko Nakajima gave their annual presentation on what they did to the YZR-M1 to ensure that they won the championship again in 2009.
The first thing they did was identify the changes to the 2009 regulations that would be key to the development direction. They highlighted three rule changes they needed to deal with to maximize the performance of the bike:
* The tire restrictions, with just 20 slicks in two compounds and 8 wets available at each race;
* The reduction in practice, with the Friday morning session scrapped;
* The engine limits, with just 5 engines available for the final 7 races of the season.
They then pinpointed three goals that would allow Yamaha to adapt to these rule changes, and get the best out of the 2009 bike. An improvement in the chassis, to allow them to get the maximum performance out of the tires; increased reliability, while sacrificing as little performance as possible; and a refinement in the engine management system, to allow them to control what they called the vehicle dynamics.
The chassis was the first port of call in optimizing tire performance. The bike was made longer and lower, lowering the center of gravity for both bike and rider. Though they lost some of the benefits in weight transfer, this reduced the tendency of the bike to wheelie and made it easier to get the power down. At the same time, the rigidity of the chassis was tweaked, adding yet more vertical rigidity and a fraction more lateral stiffness, while allowing the chassis to twist slightly more. These changes in stiffness gave more control for the rider, making the bike both better under braking and easier to turn.
Making the bike longer and lower had another benefit. The improved rider position, together with a few aerodynamic tweaks, gave a 5% improvement in CdA (basically, aerodynamic drag) which provided a 1% top speed boost basically for free. At the same time, the improved aerodynamics did not adversely affect the ability of the bike to turn.
The airbox and engine were also modified: A heavily revised airbox combined with increased fuel pressure and altered injector position aided combustion, as did revisions to the pistons and combustion chambers. Altering the surface treatment of the engine internals and modifying the crankcases reduced friction yet more, an area which had seen huge improvement in 2008. Altogether, these changes provided a 4% power boost and a 3% boost in maximum torque. Most importantly, though, torque was increased throughout most of the rev range, improving driveability and acceleration.
Those torque improvements were achieved by burning less fuel. Yamaha's design team, Nakajima said, had focused on performance at partial throttle openings, improving combustion by tweaking the ignition system and modifying the combustion chamber. The changes had provided 10% more torque with the same airflow, and could run leaner without sacrificing torque. All of these changes allowed the riders to open the throttle 3-5 meters earlier than 2008, helping the M1 accelerate much better. In practical terms, this meant that the bike was coming out of the final corner at Laguna Seca some 3 km/h faster than in 2008.
The improvements to combustion had not just been about improved throttle response, however. The changes to the combustion chamber and piston had also been aimed at making the heat profile of the piston more even, with added piston cooling reducing piston temperatures by 30 degrees, increasing engine mileage without drastically increasing piston weight (the usual way of smoothing out piston temperatures) and sacrificing less than 1% peak power.
These changes had been a key part of increasing engine durability, upping engine life to around 2200 kilometers and surviving the engine limits with ease. Crucially, this also leaves them not far off the target of 2400 kilometers per engine which Nakajima and Furusawa believe necessary if they are to run the 2010 season on just 6 engines.
Illustrating the gains that had been made, Nakajima said that the engines the team had run prior to the limits introduced at Brno had been capable of just 1000 kilometers between rebuilds, and those engines were getting tired after just 600 kilometers. He also underlined that these limits were very interesting to Yamaha in terms of R&D, as it gave them data they could use to eventually improve their road bikes.
But the biggest improvement according to Yamaha's chief engineers had been in the field of wheelie control, and the changes had been as devastatingly simple as they were effective. Instead of using fork extension to measure whether the bike was wheelying, they used the gyroscope to measure the pitch of the bike (i.e. the angle at which the bike was) to see if the front wheel was in the air.
The change meant that instead of having to wait until the front wheel was back on the ground and the fork was being compressed again before the power could be reapplied, the ECU would start feeding in the power more gradually as the front wheel started to lower, greatly increasing the amount of acceleration and improving driveability. No changes had to be made in software, the same algorithms were being used, just the data being used to feed to those algorithms. As Julian Ryder put it afterwards, they are actually using less electronics to go faster, rather than more.
Valentino Rossi's 7th MotoGP title was testament enough to the success of the program of modifications the Yamaha MotoGP project team had undertaken, but titles alone were not enough. Nakajima also laid out the results in numbers of podiums to demonstrate the improvements: In 2008, Yamaha had 10 wins, 8 second places and 6 thirds; in 2009, they scored 10 wins, 10 seconds and 4 thirds, one step higher in two races.
Yamaha's openness in discussing this kind of data is both a testament to the culture inside the company, but also highlights the strength of their racing department. Nakajima was open not just to pointing to their strengths, but also freely admitting their weakness, and highlighting what the company needed to work on for next year. Dani Pedrosa kept getting the holeshot, it was pointed out to Nakajima, to which he replied that yes, that was something that Yamaha needed to work on. Expect the 2010 Yamaha YZR-M1 to get off the line a good deal quicker than the 2009 version.
