It's now 15 years since the Ford Sigma engine replaced the Rover K Series in the Caterham Seven, which is a long time for any engine to remain in service. Especially when it wasn't new in 2006. But all good things must come to an end, and with Sigma production now wound up, with it go the 1.6-litre Caterham models: the Super 1600, 270 and 310. The Caterham website no longer lists them for sale.
Losing any Sevens from the line-up is bad news, but the demise of these three will be especially keenly felt given how well the engine suited the car. Faster and more responsive than the turbocharged Sevens yet less intimidating than the Duratec-engined models, the 1.6-litres were as much Caterham as a lot of customers needed. "If Caterham was only going to make one car for the rest of its days, this would be it", was how the 310 was announced in 2016, for some idea of just what a cohesive experience the smaller Ford engine delivered. Moreover the Sigma served as the engine for a lot of the Caterham race cars (an arrangement that will continue for 2022) further proving its suitability for the Seven package.
All is not lost, however. Those after a circa 150hp Caterham Seven need only wait until next year, when Autocar suggests that a detuned version of the 2.0-litre Duratec will fill the void left by the 1.6-litre cars. At the moment that has a minimum of 183hp in the 360 models. Something like 150hp would mean a power-to-weight in the region of 300hp per tonne - which is obviously the same sweet spot that the 310R hit. PH has since learnt that the 1.5-litre SkyActiv-G unit currently powering the entry-level Mazda MX-5 has also been considered as a possible replacement.
Until that point, the Seven range will consist of the just-launched 660cc 170 model and the 2.0-litre 360, 420 and 620 cars at the top of the range. But if you have missed the boat on Sigma Sevens, don't panic, as the PH classifieds are chock full of them. Set the search criteria to 1.6-litre models from 2006 and there are almost 50 cars available, starting from this £15k Supersport. There are race cars, road cars, wide ones, narrow ones, never seen rain ones and those with 20k under their wheels - you're covered for a Sigma Seven. We'd take this one - an S3 310R in Exocet Red, with a white decal pack and fewer than 3,000 miles. It's yours for £32,495...
Image credit | Harry Rudd
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