Honda's Indy Car Engine Evolves Yet Again.

3/27/2007 3:31:00 PM

The evolution of Honda's Indy Car engine is state-of-the-art, but it certainly isn't a typical progression in motorsports.

In 2003, Honda Performance Development unveiled its initial 3.5-liter engine for the Indy Racing League - a powerplant that would go on to dominate the Indianapolis 500 and IRL series in 2004 and 2005.

In 2004, engine displacement was dropped from 3.5 to 3.0 liters, in order to help contain accelerating speeds at the Indianapolis Motor Speedway. Then, in 2006, Honda accepted the daunting task of
supplying every IRL team with engines.

But, last year, when the Indy Racing League announced it would be the first sanctioning body to race with 100 percent ethanol in 2007, it was 'back to the drawing board' again for HPD - and back to a 3.5-liter engine.

"It's been an interesting period," says Roger Griffiths, Race Team Technical Leader for HPD, who joined the company in 2003 after a career in Formula One and sports cars. "When the IRL announced it was going to one hundred percent ethanol and added more road courses, we knew we needed to react.

"We could either increase the RPM limit of the engine or the increase the engine's displacement capacity. We opted for the latter because it offers some additional benefits."

Among those are performance and endurance.

"Straight away, we knew the performance of the engine would be different with ethanol compared to ethanol, but our concern wasn't so much for the ovals, it was the road and street circuits we had to focus
on," said Griffiths.

"This 3.5 liter version of the Honda Indy V8 engine will give us more midrange torque and better driveability. In other words, we'll increase the range of the power band, which makes the engine less peaky and much better suited for road racing.

"It will also be less stressed, so that will be good for reliability, and that's good for the teams. With increased engine life, we should be able to get an additional race out of an engine, and engines that ran two races between rebuilds should now last for at least three.

"That helps reduce costs to the teams."

The layman might think this is an easy fix, to just go back to the old 3.5 liter model.

"It's not the same engine," explains Griffiths, "but we did learn a lot previously going from three and a half to three liters. Therefore, increasing the displacement was easy enough. We just changed the connecting rods and crankshaft and maintained the same bore.

"There were also some minor revisions to the intake system, but in doing so, I think we've improved the overall durability." Roger wants to make sure everyone understands it's a community effort.

"We work in conjunction with Ilmor Engineering in the U.K. and Detroit because we each have specific strengths, whether it's engine mapping, performance or durability."

It's a different challenge nowadays for HPD. Instead of concentrating on defeating manufacturing rivals, there's a different mindset.

"Our primary purpose is not to affect the outcome of the championship with an engine failure, and to keep the playing field for the entire series as level as we possibly can," said Griffiths.

"After last season, we sent out a survey to all the teams and asked them what they thought of the product. And the universal response was that Honda supplied an equal footing and that made us feel good.

"That's what we want to do, and let them fight it out on the track."