or many years, a V8 built from a pair of motorbike engines has been a tantalising dream. The potential of two powerful, in-line fours spliced to a common crankshaft is obvious and very appealing; low weight, high output and, importantly compared with four-cylinder 'bike engines so far installed in cars, much more torque. Yet despite the first prototype appearing the best part of ten years ago, nobody has been confident enough to put one into production. Until now. This Caterham is fitted with a 2-litre V8 that weighs a mere 74kg yet develops a stonking 340bhp backed up by 190lb ft of torque. And it's very compact, too, measuring 19in long, 19in high and 19in wide. There are plenty of clues that this wide-bodied 'SV' Seven isn't standard, principally the bonnet scoop but also the many extra louvered vents let into the bonnet and sides. However, it's when the bonnet is lifted off that your pulse picks up. The tiny V8 is buried down between the chassis tubes, almost impossibly low - the tops of the eight carbonfibre throttle trumpets have a good couple of inches of headroom to the underside of the aluminium bonnet. Think what that does for the centre of gravity. When it fires up, this compact V8 - dubbed the RST V8 - sounds urgent and inertia-less, like a four-cylinder bike engine but with an extra undercurrent of bass. It throttle-blips hungrily, the revs soaring and falling very rapidly, the blat of the twin exhaust pipes overridden by the staccato, machine-gun-like bark of the eight throttles gulping air. This isn't a woofly V8. Like the V8 in the Ferrari 360, it has a flat-plane crank that synchronises firing pulses in opposing banks of cylinders so that it remains balanced at very high revs. While the 360 goes to 9000rpm, this pocket-sized V8 breaks through the 10K barrier. It would go to 15,000rpm(!) but in this application it's capped at 10,250rpm, partly because 340bhp is more than enough. The car's geared for 148mph in top and it has attained this speed on more than a few occasions during the engine validation process. Without a windscreen it would run to 160mph. We're lucky enough to try the engine and the Seven before they're fully signed-off, so you'll have to excuse the temporary louvres, the extra sensors and wiring and the braided hoses that snake spaghetti-like around the engine bay. The question is, why has it taken so long to get to get a 'bike-derived V8 into production? The man who knows better than anyone is Russell Savory, boss of Moto Power, which built this car, and also designer of the RST V8. 'Getting to the stage where you have an engine running on the dyno feels like 90 per cent there,' he says. 'In fact, you're only about 40 per cent of the way.' The original prototype V8 that he built ten years ago was a pair of Yamaha EXUP 1000 motors spliced together. Individually they made about 130bhp but together they made 302bhp - even Savory was surprised. The reason, it transpired, was the dry sump lubrication system fitted to the V8. 'We hadn't realised how much power was sapped by the crankshaft churning the oil in the sump,' he says. A flying start, then? Not exactly. There was interest in the engine back in the mid-Nineties, principally from Chris Craft who, with McLaren designer Gordon Murray, had created the Rocket, the first serious bike-engined road car. Craft's Light Car Company built the Rocket and a proposed second model, the Lightning, was designed with the new V8 in mind. That project didn't progress, though, and as Savory was being kept plenty busy enough running successful bike racing teams, the V8 was put on hold. In the intervening years a whole host of bike-engined cars have appeared, driven partly by the increasing popularity of trackdays. Caterham, Westfield et al have developed and marketed bike-engined cars, and Radical's whole range is powered by developments of motors from two-wheelers. Interest in the V8 was picking up again, so Savory found an enthusiastic backer and 18 months ago rejuvenated the project. From experience with that first V8, Savory knew there were still many design issues to be resolved before the new unit was a reliable, consistently potent engine. There are a number of other parties working on their own V8s so he's canny about certain details, but the RST V8 shares only its cylinder heads with the EXUP engine that spawned it. In time they will be replaced by bespoke items.