Ford Performance has deployed a sizeable arsenal of clever technology on its most affordable offering – some of which are segment firsts, and all of which are designed to make the new ST the fastest Fiesta ever.
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- Three is better than four – The last Fiesta was propelled by a 1.6 litre turbocharged inline four-cylinder, but its replacement takes downsizing a step further. Displacing 1.5 litres and containing just three cylinders, the new Fiesta ST is the only B-segment hot hatch to have fewer than four cylinders. Not only that, but with an aluminium block instead of the cast-iron unit used in the previous car, the new ST’s powertrain isn’t just more compact – it’s significantly lighter as well.
- Power parity – Reductions in physical size haven’t come at the cost of performance. In fact, with outputs of 147kW and 290Nm, the new ST’s three-cylinder actually makes the same maximum power and torque figures as the four-cylinder it replaces – and it must be noted that the old engine could only achieve those numbers when in overboost, which only lasted for 20 seconds at a time. How does the three-pot do it? By using both port and direct injection, a short-runner exhaust manifold to minimise turbo lag, variable valve timing on both intake and exhaust cams, and optimised bore and stroke dimensions with a lower compression ratio allowing for more boost.
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- Fast, yet frugal – The downsizing story doesn’t end there. To help curb the Fiesta ST’s thirst for petrol even further, Ford’s engineers equipped the three-cylinder engine with cylinder deactivation technology. By decoupling the valves from the camshafts on one cylinder, the ST’s engine can run on just two cylinders – but only on light-throttle cruising.
- Use the force (vectoring) – At rear-end of the car, the new Fiesta ST flaunts more clever tech in the form of what Ford calls ‘force vectoring’ springs. Shaped like a banana rather than a straight cylinder and with the left coil wound in the opposite direction to the right, the Fiesta’s rear springs work to transfer more cornering force into the body while also resisting sideways movement from high lateral G loadings. Working in conjunction with an ultra-stiff torsion beam axle (the most rigid in Ford’s current stable), the clever spring design meant engineers could save 10kg by omitting a Watts linkage, without compromising ride comfort or handling.
- Best enjoyed with LSD – The Fiesta ST will be offered in Europe with an optional mechanical limited-slip differential. Sourced from Quaife and similar to the item used in the Ford Focus RS, the LSD limits wheelspin at the front and dramatically improves traction when accelerating and turning. It’s a rare thing to find in the world of budget hot hatches, and there isn’t currently one on sale in Australia that has one, which gives the Fiesta ST a critical advantage over its rivals.
- Vectored thrust – helping out the differential is brake torque vectoring, which plays little part in quelling wheelspin but instead serves to help direct the nose into turns with minimal steering input. By lightly braking one front wheel independently of the other, brake vectoring is designed to boost agility no matter whether power is going to the ground or not.
- Adjusting frequency – Poor ride comfort was a complaint of the outgoing model, but the new Fiesta ST aims to address that through advances in suspension hardware. Equipped with dampers that change their valving depending on the severity and frequency of bumps, Ford claims the 2019 ST has a more compliant ride without compromising handling.
- Knuckle technique – The Fiesta ST’s front suspension knuckles are unique to that model, with geometry and kinematics designed to minimise torque steer and enhance cornering grip. It’s married to a rapid 12:1 steering rack ratio for enhanced agility and responsiveness.
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- Exhaustive effort – Not every aspect of Ford Performance’s work on the Fiesta ST is concerned with making it faster. With the move to a three-cylinder engine there was concern that the resulting engine note wouldn’t sound sporty enough, but through careful exhaust tuning and the addition of a switchable exhaust bypass flap to increase decibels, Ford claims the Fiesta ST has the right soundtrack for a hot hatch. When put in Sport or Race mode the flap opens up and the audio system pipes in additional frequencies to enhance the in-car sound for an extra rorty experience.