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Engines at Indy - at the max for 22 seconds 16 Jun 2004

Jarno Trulli (ITA) Renault R23B.
Formula One World Championship, Rd15, United States Grand Prix, Race Day, Indianapolis, USA, 28 September 2003

The long main straight at Indianapolis presents one of the toughest tests of the year for a Formula One engine. From the time a driver exits Turn 11 to head onto the banking until the time he brakes for Turn 1, his foot will be flat on the throttle for around 22 seconds – longer than anywhere else on the calendar.

Other circuits may feature a greater percentage of the lap at full throttle – Montreal, for example, is higher at around 56.6 per cent – but it is that long single period at Indianapolis that makes it so particularly punishing on the engine.

“The challenge is essentially one of heat evacuation, and the area of the engine on which it has the biggest impact is the pistons,” explains Renault’s Head of Engine Operations, Denis Chevrier. “When a driver is accelerating through the gears, the engine is not actually at maximum revs for very long, and braking means that the moving parts are given respite from the load they are under, and heat is evacuated. However, for a continuous period at full throttle, there is no respite, and no opportunity for this energy to be lost.

“The best analogy is if you imagine an oven at 60°C, and then asking a person to go inside. Asking somebody to do so ten times, for one second at a time, would not harm them. However, asking them to do so once, for a continuous ten-second period, could have much more serious consequences. Furthermore, the relationship between the challenge of dealing with an extended period at full throttle, and the time this involves, is not linear: in other words, if you double the time spent at full throttle, this more than doubles the challenge.”

This single extended period of maximum acceleration is what distinguishes Indianapolis (along with Belgium’s Spa circuit) from most other venues on the Formula One calendar. Even new circuits such as Sepang and Bahrain with their long straights only see maximum throttle for around 13 to 14 seconds.