IF YOU AIN’ T CHEATING, YOU AIN’ T TRYING
Volvo 850 BTCC
Race teams have been pushing the boundaries of the rules since the dawn of motorsport. Volvo’ s Nineties touring car was an example of just how far some regulations could be stretched
One of motorsport’ s greatest examples of misinterpreting the motorsport rule book was when TWR, Tom Walkinshaw Racing, created the Super Touring Volvo 850 for the 1994 British Touring Car Championship.
The car is most famous for its estate body. Rumour suggests TWR, who built and ran the cars for the BTCC, made a mistake when ordering the bodies. Whatever the truth, it was a genius marketing ploy. It grabbed the viewers’ attention because an estate was so distinctly Volvo and it highlighted the Swedish company’ s rarely-seen silly side.
But the estate body couldn’ t be a joke at Volvo’ s expense. The 850 couldn’ t trundle around at the back being slow, safe and steady in typical Volvo estate fashion. It had to shatter the stereotype and be properly fast.
Reworked in a conventional competition manner, the 850’ s transversely-mounted five-cylinder 2-litre engine wasn’ t powerful enough. Early race versions by Ricardo and Volvo made around 260hp, while other BTCC cars had approximately 285hp.
The issue was the Volvo’ s head. The angle between the inlet and exhaust valves totalled 58 °. A decision not created for improved power or even efficiency, but because of Volvo’ s engine production line. A narrower angle would have meant the plant’ s machining tools would clash if two heads were machined together. Volvo chose the more cost-effective production process of wide-angled valves and two heads at a time. Plus the cam carriers cast into the head limited the amount of lift valve that could be achieved.
The championship’ s rule book stated that the head had to be the factory unit. It had to retain the same valve angle, the same inlet port in the same position and, while items could be bolted on, nothing could be welded to it. But inlet and exhaust ports could be fettled, big valves could be added, basically material could be removed.
So that’ s what TWR did. Firstly, it removed the top section of the head and bolted on new cam carriers that allowed high-lift cams.
The next step is where the real genius comes in. TWR machined the head’ s mounting face at an angle so the whole head would sit on the block with the exhaust side pointing down a little. While this didn’ t circumvent the rules by altering the valve angles in relation to one another, it did make for a steeper and more optimum inlet valve.
The combination of the new cams and the angled head helped TWR realise 325bhp from the five-cylinder, giving the Volvo one of the fastest top speeds in BTCC at the time. That’ s despite its boxy shape and relatively big frontal area.
The chopped-up and cock-eyed head was questioned at every race. It wasn’ t in the spirit of the rules, that’ s for sure. The amount of machining required to produce it meant that it was wildly expensive when the organisers were trying to make Super Touring more affordable. But like the very best cheats, this one was technically legal. At the start of every race, the officials deemed the sliver of original Volvo metal in the head was enough to satisfy the rules.
Volvo 850 Estate: pushing the boundaries of speed and style in the BTCC
66 The Engine Rebuilder Issue 01