Jeep Grand Cherokee Trackhawk for Oz

Officially, Jeep Australia is yet to confirm the local release of the new Grand Cherokee Trackhawk, saying it's yet to establish a business case.

It must have forgotten to tell its parent company, however, because senior Fiat Chrysler Automobiles executives make no secret of their plans to export the hammer-fisted super-SUV.

Touted as the most potent production SUV ever, Jeep says the 527kW Trackhawk can hit 100km/h in a mere 3.6 seconds, cover the quarter-mile in only 11.6 seconds and runs out to a top speed of 290km/h.

When it arrives and at what price are two important points yet to be confirmed, however, Jeep executives at the Trackhawk reveal at last week's New York motor show clearly dismissed any doubt that the Trackhawk is only for the US market.

Creating the Trackhawk has been an exercise of power management. Jeep engineers basically took the supercharged 6.2-litre V8 from the Challenger SRT Hellcat and wedged it into the family-oriented Grand Cherokee. Dad’s new toy will make mother pucker.

In the Hellcat, the V8 develops peak torque of 881Nm. In the Trackhawk, engineers had to change exhaust manifolds and induction system, which explains why Jeep claims a 6Nm drop in peak torque to a mere 875Nm. You’ll learn to live with the loss.

Street and Racing Technology — SRT — is Chrysler’s wouldn’t-it-be-cool-if department and the head of Advanced & SRT Powertrain Chris Cowland says SRT has completed Trackhawk testing for NAFTA countries and is now working on Australia tuning.

Australia is officially classified as a ‘hot’ country by the world’s car-makers, and because of our excessive ambient temperatures there are specific adjustments SRT engineers have made to the Hellcat engine for Australia.

“One of the requirements we have as part of SRT is that you can drive in extremely hot ambient conditions and not suffer a D-rate on racetrack,” said Cowland.

“A D-rate is basically when we get problems with the cooling system not keeping up with heat rejection or we get issues with ignition knock caused by spark timing and hot ambient temperature coming into the engine.”

SRT tests for D-rate with a rather unique test. “We test on a racetrack flat-out for 20 laps at ambient temperatures above 30 degrees C,” explains Cowland.

Those exhaust changes for Trackhawk extend to specific tuning for Australia to pass drive-by noise requirements.

“Sometimes we have to do a little bit of different tuning on the exhaust system for Australia which can result in higher back pressure which also influence the power output of the engine.

"We also have to tune for intake noise,” mentioned Cowland.

Fuel quality in Australia is another critical issue to consider, claims Cowland.

“One of the tests we’ll do is test right down to 82-83 octane petrol. We want to make sure the knock system is robust against these fuel grades and no damage will happen to the engine.

"We also have to be very careful of higher levels of sulfur in the fuel.”

SRT also tests engines including the Trackhawk’s supercharged V8 to run on ethanol levels up to E27.