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BMW’s BTCC winner

BMW’s B48 engine was a new addition for 2017 at West Surrey Racing, along with the Bavarian marque’s direct backing as a Manufacturer. With competition more intense than ever in the Dunlop MSA British Touring Car Championship this past season, the squad were able to double up with Manufacturers’/Constructors’ and Teams’ honours to go with the same accolades last year – quite the two-season spell for the 125i M Sport.

RACE TECH featured the B48 in its most recent issue – in shops now – analysing in great depth just how the titles were won, with the help of the new unit. Here’s an excerpt:

It’s been 21 years since BMW last had a manufacturer entry in the British Touring Car Championship (BTCC). But this season the German company has returned, through BMW UK, with a three-car team run by championship stalwarts West Surrey Racing (WSR) and its BMW M125i M Sports for Colin Turkington, Rob Collard and Andrew Jordan have proved competitive right from the start.

To many, this won’t have come as a great surprise. After all, WSR has been running BMWs independently in the series since 2007. But it’s more than just a rebranding exercise. Along with the investment comes some technical support from the factory and most importantly a new engine developed by one of WSR’s longstanding partners, Neil Brown Engineering (NBE).

The B48 – as the production engine is known in BMW-speak – is a 2-litre, turbocharged inline four with direct injection (DI) and variable valve timing (VVT). It’s used in a huge variety of BMW Group applications from the MINI Cooper S to the long-wheelbase 7-Series. And it also makes an ideal base for the BTCC engine regulations.

“The B48 is a very good starting point,” comments Neil Brown, managing director of NBE. “It’s a good strong unit, and it’s been designed for turbocharging from the outset. The block is a closed deck design, which greatly aids its rigidity.”

The team’s previous engine was turbocharged under the BTCC rules, but it was based on the naturally aspirated BMW N43 unit. Like most older production engines this was an open deck design, which provides limited support for the top of the cylinder liners. However, with the B48 the engineers found they had a ready-made solution.

“It’s generally easier starting with a turbocharged base engine,” comments NBE design engineer Tom Morris. “Most OEM engines are now designed specifically for forced induction, so they put a lot of effort into things like cylinder head sealing. It means that there’s a lot of good components in there that we can continue to use. The boost pressures encountered in the BTCC aren’t greatly dissimilar to those on the road car – we’ve done the calculations to check, but in the end we could use stock parts for cylinder head fasteners, for instance.”

The BTCC regulations carefully control the modifications that can be carried out. Teams can use any engine within the road car manufacturer’s family that satisfies the basic requirements: two litres, four cylinders and a maximum engine speed of 7,000 rpm. Substantial portions of the base engine have to be retained, though. The block and cylinder head castings have to be carried across essentially unmodified, as does the crankshaft unless a waiver is issued on the grounds of durability…

Read the rest in the magazine!

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