Car engines have been designed and built on the same basic principles since the 1880s, but thanks to the work of ingenious people across the world the details have changed to an enormous extent. One brilliant and fascinating example of this is Fiat’s MultiAir system, which allows one engine to behave in several different ways depending on what the driver needs.
To understand MultiAir you need to understand what an engine is like without it. Fuel and air are allowed to enter, and exhaust gases to exit, by the opening of valves, which consist of a circular head and a long stem. The valves are operated by a camshaft, which has what is known as a ‘profile’. Although there are many other factors, the performance or economy of an engine is largely determined by this profile. Systems such as variable valve timing or Honda’s VTEC get round this to some extent, but Fiat’s solution was a lot more radical.
How MultiAir works
A MultiAir engine has normal exhaust valves, but the inlet valves are different. They have a head but no conventional stem. The job of the stem is done by high-pressure oil, which is allowed in or out of a column by solenoids. There is still a camshaft profile, designed for maximum performance, but control of the oil column means that the valves do not necessarily behave the way the camshaft wants them to. It is therefore possible for the engine to run far more economically than it would if the camshaft had its way.
Although it had been developed several years previously, MultiAir did not become available to customers until the near the end of this century’s first decade. It was applied retrospectively to the 1.4-litre turbo version of Fiat’s FIRE (Fully Integrated Robotised Engine) unit which was fitted in this form to the Punto Evo.
Another early MultiAir car was the Alfa Romeo MiTo (named after the Italian cities of Milan and Torino, known to us as Turin). Power outputs in this and other models ranged from 85bhp to 168bhp. Although not exactly brand new, the MultiAir was voted best new engine in the 2010 International Engine of the Year awards.
The 875cc two-cylinder TwinAir was the first engine intended from the start of its design process to use the MultiAir system. In 2010 it made its debut in the Fiat 500, which became the first mainstream two-cylinder car to go on sale for many years. Already arguably the cutest car on the market, the 500 seemed even cuter when the TwinAir was purring away at tickover.
The TwinAir went several steps better than the 1.4 MultiAir in the 2011 International Engine of the Year awards, winning the overall title and the New, Green and up to 1 Litre categories. At around the same time it became available in the Fiat Panda.
Delightful as it was in many ways, the TwinAir was criticised for feeling too rough, a common problem in engines with very few cylinders. Fiat got round this by fitting a dual-mass flywheel to its TwinAir cars, starting with the 2012 Punto. Explaining what a dual-mass flywheel is and how it works would take too long, but the effect was that it reduced vibration inside the car.
Beware of spiders
The Fiat 124 Spider and its Abarth equivalent are both closely related to the Mazda MX-5 but use the 1.4 MultiAir engine, and are the only rear-wheel drive cars to do so. The Abarth was the most powerful car in the family until quite recently, when Mazda fitted an even stronger two-litre engine to the MX-5.
MultiAir in the UK
Fiat licensed MultiAir technology to German company Schaeffler, which calls it UniAir and has in turn licensed it to Jaguar Land Rover for petrol engines in the Ingenium range. The company’s Engine Manufacturing Centre in Wolverhampton began production of these units in April 2017.
The Ingenium petrol engine fitted to the F-Type is a two-litre turbo producing 297bhp. It is the most powerful four-cylinder engine ever fitted to a production Jaguar.
The same engine also appears in Land Rover products including the Velar. In P300 form it gives this two-tonne SUV an impressive 0-62mph time of around six seconds.