The four-door Jeep Wrangler is one of the most competent off-road vehicles on the planet but, never mind what it says on the tin, Unlimited it ain't.
The current 3.6-litre V6 Pentastar engine is a huge improvement on the 3.8-litre lump it replaced, pushing out a decent 209kW at a surprisingly high 6350rpm, but the longer Wrangler is no lightweight and it has the aerodynamic efficiency of a gothic cathedral.
Long gearing doesn't help and neither does the 17 percent power penalty incurred by living 1500m closer to the ionosphere in Gauteng.
Randburg tuning house RG Motorsport recorded a 17.9-second quarter-mile time with a disappointing 125.5km/h terminal speed. Worse still, the big workhorse took 8.3 seconds to kick down and giddy-up from 80-120km/h.
BEEF INJECTION
At that point the Wrangler disappeared behind the locked doors of the RGM skunk works, emerging several weeks later with a Vortech supercharger, a Unichip Q engine management piggyback computer, a serviceable free-flow air filter element and a Techniflow exhaust system, designed and made by RGM.
Unfortunately, direct performance comparisons were impossible because the backroom boys had also bolted on more than 200kg of accessories, including a high-ride suspension kit, a winch/bumper kit, and an aftermarket rear bumper with spare wheel carrier.
But even with the extra load the 'blown' Wrangler was good for 0-100km/h in 8.7 seconds, 0 - 120km/h in 12.2 (four seconds quicker than standard) and a quarter-mile time of 16.5 seconds (a 1.4 second improvement) at 136km/h. It also knocked 1.4 seconds off the 80 - 120km/h kickdown.
REAL GAINS
On RGM's rolling-road dyno it posted 215kW at 6500rpm (that's six kilowatts more at the rear wheels than the stock engine makes at the flywheel!) but the real gains are in the torque output.
At just 2000rpm the supercharged Jeep matched the standard version's best of 347Nm; at 4300rpm, where the standard engine peaks out, it was making 475Nm and it went on to record 517Nm at 5500rpm.
Trailer - what trailer?
The RGM engine kit (supercharger, Unichip computer, air filter and auspuff) costs R105 000 fitted; whatever exterior kit you hang on your Wrangler is up to you and bank manager.