Emissions reduction at a stroke

Ricardo

is to develop a prototype engine capable of switching between two-stroke and four-stroke operation to reduce fuel consumption and emissions.

The company, which previously carried out a feasibility study to investigate the concept’s potential, will now build a prototype in a £1.9m project, partly funded by the DTI.

A petrol engine capable of switching between the two modes would be smaller and lighter, but with the same level of performance as a much larger power unit, the firm claims. The engine would also consume around 30 per cent less fuel and produce fewer emissions, with similar production costs to a conventional diesel engine.

The project will involve ‘a number’ of manufacturers, which Ricardo declined to name, although Ford took part in the original feasibility study. The consortium, which also includes automotive technology supplier Denso, valvetrain switching specialist Ma 2T4, and Brunel and Brighton universities, will build a 2 litre V6 research engine, which should have the performance of a 3–4 litre V8.

Ricardo believes the technology will be particularly attractive for premium cars and SUVs, as the 50 per cent extra torque produced during two-stroke operation would fit well with the typical driving characteristics associated with such vehicles. But the researchers will also study the potential cost and benefits of a 1 litre engine for use as a replacement for 1.8–2 litre engines in mid-sized family cars.

To switch from four to two-stroke operation, the speed of the valvetrain is doubled to produce twice the number of firing pulses per engine cycle, giving the engine its power boost.

The research engine will use an electro-hydraulic valvetrain to do this, although a cheaper mechanical system using an epicyclic gearset could also be used, and would be the company’s preferred option for the future if it proves as effective, said Dave Greenwood, chief engineer for advanced technology at Ricardo.

Once the prototype is built, the team hopes to integrate it into a vehicle and then optimise the performance of the complete system to get the best driveability, said Greenwood.