The TDCi Conversion

Summary

Ford’s 1·4 litre TDCi engine is licensed from the PSA Group - in other words, it’s a Peugeot / Citroën donk. This is currently available in two versions - one with eight valves and the other with sixteen valves. At the time of writing, Ford only use the eight valve version, so despite the much reduced power and torque, this would be my preferred engine. The eight valve version omits the intercooler and, in Ford tune, produces 67 PS and 159 Nm of torque. For academic purposes, the sixteen valve, intercooled version produces 92 PS and 199 Nm of torque - but for various reasons this engine is not wholly suitable for the Ka.

A Ka TDCi is one of my dream cars.

Performance & Economy

In the heavier Fiesta and on paper, the TDCi engine produced broadly comparable performance to that of the Endura-E equipped Ka. The Ka is some 100 kg lighter than the Fiesta and this should certainly help performance and fuel consumption. Everything being equal - and of course it will not be - a Ka TDCi should be able to reach 62 mph in approximately 13 seconds and on to somewhere around 100 mph.

In terms of fuel consumption, a realistic everyday figure is 60 mpg.

Weight

Comparing the 1·3 Duratec and TDCi Fiestas side by side, there is almost no weight difference between the two models. This is good news since it means that the Ka TDCi will be of around the same weight.

Suspension & Braking

Given that the Ka TDCi’s performance and weight are broadly similar to that of the Endura-E equipped model, there will be no pressing need to uprate the suspension and braking systems of the Ka.

Servicing

Quite how difficult the TDCi donk will be to service once in place in the Ka remains to be seen.

Cooling

Diesel engines, especially those turbocharged, are capable of producing immense quantities of heat and almost all production turbodiesels have large, high capacity cooling systems. Given the relatively cramped underbonnet area of the Ka, and the comparatively small frontal area available for a radiator, this will entail some special considerations. Some form of bonnet ventilation may well be a prudent measure, depending on the alignment of the engine and manifold.

Example Fuel Costs

The above spreadsheet shows that with an assumed petrol fuel consumption figure of 40 mpg (at the time of writing, Kermit’s fuel consumption average is just 38·3 mpg, however most of our mileage will be on a run so I can reasonably extrapolate his fuel consumption to reduce), and that after the conversion we’ll manage 60 mpg – but that diesel will cost approximately a penny per litre more than petrol.

The above shows that we will recoup the estimated £3,000 outlay in just under 106,000 miles.