German aftermarket tuning specialists, skilled in the art of direct-injection forced-induction tuning, must have a jolly old guffaw at some of the US-sourced performance cars rolling around the fatherland.

In general the Corvettes, Camaros and Mustangs are hardly the last word in cutting-edge, high-revving automotive technology.

Fortunately a few Ford GTs (perhaps Dearborn’s greatest car ever) did make it to Germany before production ceased.

It's a rather contemporary supercar (especially by American standards) which means German tuning specialist (and American car fanatic) Carl Geiger simply had to modify it…

The renowned Bavarian tuner, who has been dutifully fettling American performance cars for nearly three decades, has unveiled perhaps his most ambitious project yet – the Geiger HP 790.

It might be green, but it's a rather quick version of Ford’s GT - a car which already possessed validated supercar status.


Carl Geiger has this thing for Shrek green US performance cars. Must be wathcing too much cartoon network with his kids or something...

In principle there is an issue with modifying the GT. It's such a limited production series vehicle (a little over 4 000 were made) in the first place and much coveted by collectors.

Not that Carl Geiger cares much for the collector's market or residual values. His guiding principle in life is extracting power, power and more power from American V8s. Bless him…

Big bad blower

For his HP 790 project Carl binned the stock 5.4l V8’s supercharger for a larger capacity one that increases boost pressure to 1.25bar.

Larger throttle valves are augmented by a less restrictive performance air filter, which greatly increases flow to the cylinders.


High-capacity supercharger does alarming things to the 5.4l V8's output graphs.

The increase in supercharger capacity from 2.3- to 4l obviously exerts greater strain on the V8’s moving parts. To counter these forces the GT’s mid-engined temperature regulating regime has been shored up with addtional geared cooling.

A recalibrated ECU ensures perfect harmonisation of all the modifications, whilst dual 110mm diameter performance exhausts providing a pitch perfect acoustic signature. 

Geiger’s GT modifications ramp up power output alarmingly, from 410- to 581kW. Peak rotational force swells from 677- to 836Nm, which means the 1.6t Geiger HP 790 does shift quite a bit.

Certified supercar numbers

Rolling Dunlop SP Sport Maxx tyres (instead of the original Goodyear Eagle F1s) Carl Geiger claims his Shrek green GT will clip 200km/h from standstill in 9.6 seconds, and power onto 300km/h only 13.2 seconds later.

Find an appropriate stretch of road and the Geiger HP 790 is geared (and tyre equipped, perhaps more importantly) to run a top end of 360km/h… Sensational stuff.

Additional stability (which is a Godsend considering the performance potential) is providing courtesy of a 60mm ride height reduction.

This leaves the Geiger HP 790 with only 67mm worth of ground clearance, which is rather distressing if one lives in one of those speed-bump invested security estates…