Ford SIERRA – 2.3 DOHC Conversion

The 'I4' DOHC engine first introduced in the Ford Sierra and Granada models of late 1989 was only available in the Sierra in 2.0-litre 8-valve form. While power output improvements can be made to the stock 2.0 8v engine, as documented in a separate article entitled 'DOHC tuning', the engine output is ultimately limited by the availability and cost-effectiveness of off-the-shelf tuning parts.
For ultimate power output of a 2.0 8v engine, it is necessary to involve some form of customized engine management system and forced induction, either through turbo- or supercharging. Both of which are expensive and relatively complicated to sort out – necessitating exotic or rare kits (in the case of turbocharging, Turbo Technics used to sell an aftermarket kit for the DOHC engine. Although rare with a handful believed to remain in operational condition, they do occasionally come up second hand - though prices are at a premium. At time of writing, there is no known supercharging kit for the DOHC commercially available)
As discussed in the 'DOHC Tuning guide', beyond gasflowing, camshafts, exhaust, air filter and chip the next stages for improving the output of the DOHC engine 'in a cost effective manner' were to either fit the cylinder head from the 16-valve version of the same 2.0-litre engine found in a 1990's Escort RS2000, or fit the 2.3- litre variant found in a Ford Scorpio from the late 1990's. While the 2.3 DOHC was also used in the Ford Galaxy MPV, it is used in front-wheel-drive format and as such is not as easily mountable into the Sierra's rear-wheel-drive chassis – engine mount and ancillary positions having been modified for the FWD package.
The Ford Scorpio was a RWD car, and as such the 2.3 engine is almost a straightforward 'slot in' upgrade for the Sierra.

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