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2006 BMW 320si

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Built by BMW Motorsport, the new race car based on a limited edition sports version of the road-going E90 3 Series to be known as the 320si, and uses a 2.0-litre four cylinder engine which maximum power conservatively listed at 275 bhp. Being shorter than the current six cylinder in-line engine, the four cylinder unit is expected further enhance the handling of the rear wheel drive 3 Series.

BMW announced a limited edition 320si sedan, a street version of the car Andy Priaulx drove to victory in the 2005 World Touring Car Championship. The car is being built in compliance with FIA homologation regulations, with a limited run of 2,600 cars beginning in March 2006. Essentially a 3-series M Sport, the unique feature of the car is its special version of the 2-liter 4-cylinder engine, with higher compression, a custom head with larger valves, and a large bore/short stroke engine block with aluminum-alloy cylinder liners replacing the stock cast-iron units. The engine is red-lined at 7,300 rpm, and puts out 173 hp at 7,000 rpm.

As an aside, Andy Priaulx is the first British FIA World Champion since Damon Hill in 1996. His 2005 championship win went right down to the wire in the last race of the WTCC season in Macau last weekend.

The new E90 320si itself is 45 mm longer and 36 mm wider than its E46 320i predecessor. It is the first time BMW has competed at the top level in saloon car racing with a four cylinder engine since the E30 3 Series which won the inaugural and short-lived World Touring Car Championship in 1997. Old model E46 3 Series cars were dominating the 2005 championship, with BMW regulars Dirk Muller, Jorg Muller, Andy Priaulx and Alex Zanardi sharing wins in the fiercely contested WTCC. In addition to running with all BMW national teams in the WTCC, motorsport kits will be sold to enable the 320si to compete in national championships around the world, including Denmark, Italy, Russia, Sweden and Asia. More than 100 such sports kits for the outgoing E46 3 series have been sold to motorsport teams by the BMW racing parts distributors, and this is expected to continue with the new model.

Though some media had speculated that the move to run its own F1 team might mean the demise of BMW’s involvement in touring car competition, BMW Motorsport Director Mario Theissen says the commitment to a new 3 Series underlines BMW’s passion for touring cars. "Touring cars without BMW i BMW i s unthinkable - and BMW is equally unthinkable without touring cars. This is what made the brand grow, and we will stick to this tradition. Apart from works support we have always been keen to keep racing affordable for our customers and at the same time offer a high-performance package. This tradition is now continued by the racing version of the new BMW 3 Series. I am sure that this model will write further chapters of BMW’s successful history."

Historically, Touring Cars has been BMW’s most successful racing category, with success in 24 FIA European Championships as well as the only previous World Touring Car Championship in 1987. The racing version of the BMW’s E30 M3 remains the most successful Touring Car ever, having won every official touring car championship in the world in the late 1980’s and early 1990’s.

Motorsport engineering

This high level of performance has been achieved using BMW’s motorsport technology. Compared with the ‘standard’ BMW 320i, the engine has been significantly modified with larger induction and exhaust valves to increase airflow. The cylinder bore has increased by 1mm to 85mm while the stroke has been reduced by 2mm to 88mm. The compression ratio of the engine has also been increased from 10.5:1 to 11.0:1, helping to boost power by 23hp over the 320i. Additionally, instead of running with grey-cast-iron cylinder liners, the pistons run in special aluminium-alloy liners in the cylinder block. Engineers have also decided to remove BMW’s patented VALVETRONIC induction system, reverting to a conventional throttle due to the higher engine speeds demanded by a racing engine.

All show and go

The new BMW 320si mates its high levels of performance with World Touring Car looks. The specification of the 320si is based on the 3 Series M Sport model that includes front and rear aerodynamic body styling, sports seats, sports suspension and aluminium interior trim. Additionally, the BMW 320si features Touring Car-style alloy wheels with BMW Motors W Motors port motif. The front wheels are 8J x 18 fitted with 225/40 R18 tyres while at the rear the 8.5J x 18 wheels are fitted with 255/35 R18 tyres. Finally, mirror caps finished in satin chrome differentiate the car from a standard 3 Series.



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