| Alfa Romeo JTS engine | |
| Manufacturer: | Alfa Romeo (2002-2011) |
| Configuration: | Straight-4, 60° V6 |
| Production: | 2002 - 2011 |
| Predecessor: | Alfa Romeo Twin Spark Alfa Romeo V6 engine |
| Successor: | FCA Global Medium Engine (I4) Alfa Romeo 690T engine (V6) |
| Bore: | 83mm 86mm 89mm |
| Stroke: | 91mm 80mm 94.6mm 85.6mm |
| Displacement: | 1970cc 1859cc 2198cc 3195cc |
| Weight: | 1680NaN0 (3.6 V6 High Feature engine)[1] |
| Block: | aluminium alloy cast-iron (2.0 JTS) |
| Head: | Aluminium alloy |
| Valvetrain: | DOHC 4-valve with VVT |
| Fuelsystem: | Direct injection |
| Fueltype: | Petrol |
| Coolingsystem: | Water-cooled |
| Power: | NaN0NaN0 |
| Torque: | NaN0NaN0 |
| Compression: | 11.25:1 |
The JTS engine (Jet Thrust Stoichiometric) is a gasoline direct injection engine produced by Alfa Romeo. It exists in two forms, straight-4 and V6, and was introduced into the Alfa lineup in 2002.[2]
The JTS engine debuted in 2002 in the Alfa Romeo 156.[3] The engine was based on the 2.0 Twin Spark (itself a variant of the Pratola Serra engine family), replacing Twin Spark with direct injection, dubbed "Jet Thrust Stoichiometric". This improved power from 1140NaN0 to 1210NaN0, but more importantly, torque climbed from 1870NaN0 to 2060NaN0. In 2003, this engine was introduced to the GTV/Spider coupé and roadster and it was fitted to the GT from launch.In spite of its benefits to power, torque and economy, the JTS was not used in the smaller 147 or the larger 166, and much less in other models from the Fiat Group. This was allegedly because the JTS engine cost a lot more to produce than the Twin Spark.
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It was only in 2005, with the arrival of the 159, that more variants of the JTS were produced. The 2.0 JTS gave way to a 1.9 L variant with 1600NaN0 and a 2.2 L version with 1850NaN0. The 1.9 JTS and 2.2 JTS form part of a new engine family and are completely different from the 2.0 JTS. Both 1.9 L and 2.2 L have chain driven camshafts and variable valve timing on both inlet and exhaust camshafts. Both 1.9 and 2.2 JTS engine blocks were supplied by GM to the Fiat group and belong to the GM Ecotec engine family. Both models are mapped to either a six-speed manual gearbox plus a reverse gear, or a Formula One inspired sequential gearbox also having six gears and reverse.
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With the arrival of 159, a 2.2 JTS was also introduced. The engine block is sourced from GM (Ecotec L61).
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The JTS direct injection system was first used in a V6 engine in 2005 with the introduction of the Alfa 159 and Brera. This is not related to the Alfa Romeo V6 engine, but is instead a derivation of the GM High Feature engine; built in Australia by GM Holden. While it retains the High Feature engine's NaN2NaN2 bore x stroke and chain driven camshafts, it is modified by Alfa for their performance, fuel economy and sound characteristics. These modifications include: "TwinPhaser" variable valve timing (cam-phasing on both inlet and exhaust cams, thus the name), gasoline direct injection and a higher compression ratio of 11.25:1. It also operates with a lean burn system up to about 1500 rpm,[4] as on many other engines from the company and is capable of generating 1910NaN0,[5] a number matching the larger LY7 3.6 L variant used by GM. Alfa Romeo stopped using the V6 JTS engine in 2010.
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