Fiat Chrysler has revealed an upgraded Pentastar V6 engine, which will debut later this year in the US under the bonnet of the revised Jeep Grand Cherokee.
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For the updated 3.6-litre motor, the company has added a new intake manifold with longer runners, increased the compression ratio to 11.3:1 from 10.2:1, installed new eight-hole fuel injectors and high-tumble intake ports, and reduced friction.

Coupled to this, the V6 now features a modified variable valve timing setup that improves the operating range and smoothness of the automatic engine stop/start system.

Despite roughly six kilograms of new equipment, the revised Pentastar V6 actually weighs around 1.8 kilograms less than before. At its lightest, the new 3.6-litre engine tips the scales just shy of 148kg.

Power has been raised slightly in US trim from 216kW to 220kW, but the company has yet to reveal torque output for the heavily upgraded engine. Fiat Chrysler does state, though, that the revised Pentastar V6 now develops 14.9 percent more torque at engine speeds below 3000rpm.

Above: The current Jeep Grand Cherokee.

According to Fiat Chrysler, the new V6 engine is over six percent more fuel efficient. If this number is carried over to the all-wheel drive Grand Cherokee, its use will see fuel consumption drop from 10.4L/100km to around 9.8L/100km under the Australia testing regime.

Direct-injection is not part of this engine's upgrade package, though. Steve Gorgas, chief engineer of Pentastar engine programme, explained to AutoGuide that for a naturally aspirated engine "parasitic losses that come from driving the high-pressure fuel pump are quite high".

He also noted that direct-injection engines tend to be noisier than their port-injected brethren, and given "the market this engine competes in" cost was also an important consideration for the company.