St. Pete Grand Prix To Be Easier On The Ears

This weekend's Honda Grand Prix of St. Petersburg will be gentler on the ears.

Honda, the sole engine supplier to the featured Indy Racing League, made a modification to its 3.5-liter power plants that softened the harsh sound from the 650-horsepower engines.

The change also reduced decibel levels by an average of 10 decibels to about 95 decibels.

"I think it's a big improvement - not necessarily in overall decibel level, although it's a decent reduction there - but it has really changed the tone and the pitch of the engines," IRL president for operations Brian Barnhart said. "It's certainly more appealing and pleasant to the fans."

Honda accomplished the improvement with a revised exhaust system routed to exit at the top rear of the side pod rather than at the back of the chassis. A canister with steel baffles functions as a muffler.

"The new sound is much less raspy," said Honda spokesman Day Layton. "The best way I can explain it is, you know there's this nerve that runs up the back of your jawbone behind your ear? The old motor seemed to irritate that nerve, and the new one doesn't."

Honda created a similar "180-degree header" exhaust system for its Acura prototypes in the America Le Mans Series, which also is running at St. Petersburg. Trans-Am Series cars used the system in the 1990s to increase top-end power.

The most offensive sounding engines at the grand prix belong to the Indy Lights support series cars, but the IRL has improved those, too. A 180-degree "flat" crankshaft rather than the old 90-degree crank has made them sound more like Indy car engines.

ALMS, which sanctions the sports car half of the event, has a rule limiting its cars to 112 decibels at 50 meters from the edge of the track. A few of the ALMS cars are turbocharged, and as such, they're quieter than anything else on the track.

Decibel levels vary at different locations of the track, depending on RPMs and surrounding structures, such as concrete buildings.

The grand prix runs Friday through Sunday in downtown St. Petersburg.