Jet Thrust Stoichiometric

JTS

These outstanding units take their name – Jet Thrust Stoichiometric – from its combustion system, an original Alfa Romeo concept that involves the high pressure injection of fuel directly into the combustion chamber with a stoichiometric mixture, optimised to increase engine power and torque – thus adapting this technology to the requirements of a sporting car – whilst adopting the stratified charge method to reduce fuel consumption in a limited engine speed range close to idle.

These engines operate with a lean burn system up to about 1500rpm which gives significant fuel savings. Above this engine speed, however, it burns a stoichiometric fuel-air mixture – i.e. with a conventional 14.7:1 ratio between the two components – thus guaranteeing performance superior to that achievable by a conventional, indirect injection unit.

Primarily, this is because fuel injected directly into the combustion chamber – instead of the intake ports – cools intake air, thus increasing the engines volumetric efficiency. As the temperature drops the gases increase in density and the volume therefore decreases, allowing more air into the combustion chamber. Cooling the chamber also reduces the risk of engine knock, allowing for an increase in compression ratio and a commensurate improvement in engine efficiency.

2.0 JTS

The 2.0 JTS is available in the Alfa GT.

With the arrival of the Alfa 159 and Brera, the JTS concept was taken a step further with the implementation of additional technology.

Accompanying the advanced injection technology from which the name is derived, these latest engines all feature light aluminium alloy cylinder heads with ‘Twin Phaser’ continuously variable valve timing – for both intake and exhaust camshafts. This system allows the phase angle of both inlet and exhaust cams to be varied by up to 50 degrees, optimising the volumetric efficiency of the engine at all engine speeds whilst reducing fuel consumption and emissions under lighter throttle settings.

They also feature maintenance free chain drives to the camshafts, aluminium cylinder blocks, and heads and the latest emissions reduction techniques.