IndyCars cars noticeably quieter at Homestead

It was noticeably quieter with multiple cars on the Homestead-Miami Speedway oval. So much so that A.J. Foyt didn't have to raise his voice to speak with son Larry on pit lane.

The proposed 2009 exhaust system, which will reduce noise by about 9 decibels and temper the shrillness of the note, was further vetted during testing this week. The difference was especially noticeable when Vision Racing's No. 20 car driven by Ed Carpenter and A.J. Foyt Racing's No. 14 car driven by Vitor Meira (with the system installed) were being trailed by 2009 IndyCar Series rookie Raphael Matos in the No. 12 Luczo Dragon Racing car (without the system).

Cars driven by Tony Kanaan (Andretti Green Racing) and Scott Dixon (Target Chip Ganassi Racing) also were on the track, conducting a Firestone tire test.

"We ran the new exhaust system quite comprehensively on three or four cars during at Homestead this week to see what the initial effect of the new exhaust system is in terms of noise reduction and how it interacts with the car," said Les Mactaggart, senior technical director for the Indy Racing League. "Generally, the evaluation has gone extremely well; everybody seems to be very positive with it. There is a significant reduction in noise and the car is much less harsh."

Also tested was a carbon clutch, which was suggested during the season by several teams that had transitioned from Champ Car. It will be a team option for 2009.

"We've used a sintered (powder metal) clutch," Mactaggart said. "Some of the teams suggested if we used a full carbon clutch it might be more cost-effective mainly because the initial cost is higher but in terms of serviceability and cost of serviceability during the year it's much less. You compensate for wear on the clutch by replacing shims to restore the distance whereas a sintered clutch needs to be sent back for quite a significant rebuild every 1,200 miles or so.

"It gives you a much more progressive take-up in drive as well, so it's kinder on your gearbox components and your driveshafts. So there's potentially an added benefit in longevity of other transmission components.

"It's optional principally because it gives the teams the ability to run out their existing stock before they want to change over or continue where they are. It's not too much of a performance advantage because the mass of the components is very similar." IndyCar.com