Lust for power
Inside Mountune’s engine room
Squeezing more power from production engines for racing is an art that requires a lot more than a few bolton goodies. Essex-based Mountune has been refining that art since it was founded by David Mountain in 1980. Today the company produces the only tuning packages for the Focus ST and RS, Fiesta ST and Mustang that don’t invalidate Ford’s warranty. It also builds the direct injection, 2.0-litre Ford Ecoboost engines for the Motorbase British Touring Car Championship Focus, and even more potent versions for rallycross.
The British Touring Car Championship almost imploded in the Super Touring Car era towards the end of the 1990s when budgets became too big for manufacturers to swallow. When the BTCC’S New Generation Touring Cars (NGTC) regulations were phased in from 2011, they aimed to slash costs by limiting the specification of both cars and engines. Teams (which today are mostly private) can use an unbranded 2.0-litre turbocharged NGTC engine or build their own to the rules. Only two engines are allowed each season without penalty, so they must be reliable as well as powerful. Once built, both engines are sealed by the Motor Sports Association scrutineer at the first race of the season.
The NGTC rules control engine cost by restricting modifications and placing an emphasis on keeping key components standard. Inlet and exhaust ports must remain untouched. The governing body measures the gas flow through standard cylinder heads for comparison with race engines, so there’s little room for bending the rules. Reshaping the internal dimensions of a cylinder head is usually the first thing a tuner would do, but in this case the narrower, unmodified ports are not so bad.
“Direct-injection engines like this need high air speed into the engine and good tumble in the cylinder to make them work,” says Mountain. “So we can run higher boost while still meeting the regulations.”
The inlet manifold, which takes air from the turbo to the cylinder head, must also remain standard, but there’s no restriction on the design of the exhaust manifold. Mountune starts with a standard ‘crate’ engine from Ford and opts for the ‘classic Ecoboost’ with a traditional bolton exhaust manifold, rather than the latest ‘value Ecoboost’ with an integral manifold cast with the cylinder. Although excellent for controlling emissions on the production engine, a specially designed exhaust manifold is worth around 35bhp in race tune.
Fuel injectors can also be changed, explains the Mountune boss. “Any type can be used as long as it’s an off-the-shelf item.” Mountune looked at several options, settling on an injector with “spray targeting” to complement the forged pistons designed in-house to maximise performance. Competitors must all use the same Cosworth SQ6 ECU, but teams can edit the software maps to suit their own engine. The aim is to get to maximum boost as soon as possible when the driver floors the throttle. “Some drivers like a more aggressive transition than others,” says Mountain. BARC (TOCA) Ltd, which controls the BTCC, closely monitors the performance of competitors’ engines by logging the data from each individual ECU.
Modifying the internals of turbochargers is a quick way to gain more power but is against the rules, so all teams must use a sealed unit supplied by Owen Developments. To gain extra power, race engines still run much higher boost than standard. “They’re closer to diesels than naturally aspirated petrol engines in a way,” explains Mountain. “The cylinder pressures are so high and they rev more slowly.” With engines spinning to a maximum of around 7000rpm, pressures in the cylinders reach around 185bar, close to that of a diesel at 200bar. Specially designed studs are used to bolt the cylinder head to the block with a 30% higher clamp load than standard. Even so, the heads lift fractionally each time the engine fires so a specially designed fivelayer head gasket is used to absorb the movement and prevent fatal leakage.
‘I’-section connecting rods attach pistons to an almost standard cast iron Ford cranskshaft rather than forged steel ones found in naturally aspirated race engines. Regulations forbid the dry sump lubrication favoured in racing, so engines retain a road car-style ‘wet’ sump. Mountune has installed baffles and flaps to stop the oil sloshing around, plus a ‘floating’ oil pick-up to ensure contact with the reservoir of oil at all times.
In that form, power is up from the standard 237bhp to 350-380bhp using 102-octane racing fuel. Power is transmitted via an AP Racing triple-plate carbon clutch and X-trac six-speed sequential gearbox common to all cars in the BTCC. In 2021 the game is due to move on again with the introduction of hybrid technology, but the form that will take – a 48V low-voltage system or a 400V high-voltage system – is still under discussion.
A decision is expected at the end of this year but Mountain thinks a lowvoltage system may take the form of either a belt-driven or crankshaftmounted electric motor, producing around 50kw. The motor could also be integrated into the X-trac control transmission. It’s likely to be a ‘push to pass’ set-up, giving a brief power boost for overtaking, and with the number of hybrid boosts used in each race being limited by the ECU. As ever in the newer, more affordable BTCC, the final specification is likely to be governed by cost – which can only be good news for what is a hugely popular race series.