Fiat’s latest revelation in engine design, UNIAIR, is undergoing fine-tuning at the Fiat Research Centre in preparation for commercialisation in 2007.

A red Alfa Romeo 147 2.0, complete with UNIAIR livery, has been used extensively as a test vehicle for this project  ever since it was first previewed at the 63rd Barcelona Motorshow in April 2003, where awards were handed out for the best technological innovations in the automotive field.

During this event, Centro Ricerche Fiat obtained one of the EUCAR prizes for their Alfa Romeo 147 UNIAIR prototype. The project led by Centro Ricerche Fiat has also been contributed to by Daimler Chrysler, PSA, and Magnetti Marelli.

The UNIAIR system will eventually feature on all Fiat Group automotive engines, due to be fitted across the entire range between 2007 and 2008. Early rumours suggested that the Alfa Romeo 148 would receive UNIAIR in October 2006, although this date is now considered as highly
improbable.

Patented by engineers Maira Massimiliano and Richard Francesco from Centro Ricerche Fiat, the UNIAIR system is the result of more than 10 years of extensive research and development. The innovative concept uses an electronically controlled hydraulic system to allow for variable operation of the inlet valves.

Traditional internal combustion engines use a butterfly throttle valve to mechanically control the volume of air that enters the engine.

As the operating cycles of each cylinder are out of phase, the induction phases occur at different times. As a result uneven quantities of air are sucked into the various cylinders. The UNIAIR project was based upon resolving this problem. 

 
In order to solve the problem, the inlet ports of the engines are fitted with air-feed flow sensors, which allow for the divergence of air flow between the different cylinders to be measured. This valuable data is subsequently filtered for the most significant values, and used as an input to control a hydraulic system for actuating the inlet valves, with the aim of obtaining an equal air-flow for each cylinder. CRF also had the option to develop an electromagnetic system, although the fact that such a system would not be compatible with diesel engines rendered it futile.

Extensive fluid dynamic analyses have been used to maximize the volumetric efficiency and performance of the UNIAIR engines. The higher volumetric efficiency of the engines, has direct and encouraging results on the reduction of fuel consumption, sound levels, and in particular with the diesel engines, emissions.

Reliability and life time of future Fiat group engines is also set to improve from an already good base, with new development technology in the areas of stress, vibration and temperature analysis. In addition, the robust electro hydraulic approach implemented by Fiat for the UNIAIR system has an intrinsic fail safe nature.

The results of the ten year project are stunning, with power output increasing by 10-15% on average, whilst fuel consumption drops by 8 to 10%. The latter improvement is mainly due to the elimination of the conventional butterfly throttle valve, a component that severely reduces the ability for air flow to be optimized. Consequently, UNIAIR technology allows for Euro 5 emissions standards to be met, and contributes to reducing the environmental foot print of modern day motoring.

One of the first engines to receive the UNIAIR treatment will be the 1.6 litre JTS engine, fitted to the Alfa Romeo 148. With UNIAIR technology, the 1.6 litre unit is expected to boast an output of 150 bhp. UNIAIR engines are also characterised by impressive low-end torque. 

Diesel engines fitted with the technology bear the MULTIAIR tag, and will also exude impressive power outputs per litre, and ultra-low consumption figures.

On the high performance side of the range, Alfa Romeo have been developing a 3.2 litre twin-turbo V6 UNIAIR JTS, with a power output of approximately 400 bhp. In this application, the benefits of the UNIAIR system are clearly evident, with the air-flow of the engine being far more substantial, and influential. The first application of UNIAIR for the Ferrari range of cars is expected to be with the 6.0 V12 direct injection engine, with an impressive 630 bhp.

by Patrick Granger