How to build a BTCC race engine

At the start of each British Touring Car Championship race, something like 13,000bhp is unleashed before an excited crowd. Engine builders, although quietly confident, may admit to the odd flutter of butterflies, too, because their efforts are vital to every driver’s chances of success. Since 2011, when BTCC organiser TOCA established the New Generating Touring Car (NGTC) rules, teams have been able to use a race-prepared factory engine or a generic TOCA unit supplied by Swindon Powertrain. All use an Xtrac six-speed sequential gearbox no matter their engine choice.

The ‘unbranded’ TOCA engine is based on a standard 2.0-litre, direct-injection, 16-valve, turbocharged four-cylinder engine purchased from a major road car maker. Swindon has built nearly 200 examples since 2011, each one taking around 45 hours to complete. The race engines are equipped with ‘drive-by-wire’ electronic throttles under the control of a Cosworth ECU that every car must use, although engine builders can modify the mapping.

Power is quoted by TOCA as 350bhp-plus, but Swindon says they’re technically capable of 400bhp and Maxed Racing gives the output of its Vauxhall Astras as ‘around 380bhp’. The engines have a life of 5000km (3100 miles) between services and will cover 3500km (2174 miles) in a season. Installation in the car can be either transverse or longitudinal in order to suit both front-wheel drive and rear-wheel drive.

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Regenerative braking is adjustable by the drivers, who will have an extra 40bhp or so available to aid overtaking or defending for up to 15 seconds per lap once the first lap has been completed. Pit-lane driving will be under electric power only and the hybrid system’s performance can be calibrated to suit wet conditions.

The system has been developed by Cosworth, which says the main benefit to drivers will be at lower revs, bringing the engine up into the ‘turbo window’ more quickly. Simulation shows that with two cars accelerating out of Copse at Silverstone, a hybrid would gain eight metres using hybrid drive before they reach the braking zone.

The new units will also change the shape of the racing. BTCC bosses will stop using success ballast, instead using the hybrid units to reduce boost levels for successful machines.

The units can be leased from Cosworth for £20,500 per season, making the hybridisation cost-effective for teams that won’t need whole new powertrains. Track testing is due to begin at some point this year.