Moments later we hear the calmer sound of a printer producing a graph, whose scales must start at 223hp and 401lb ft to enable the peak outputs to fit on a sheet of A4. This is impressive proof of Viezu’s work, although “making Ford Transits go slower” in order to reduce their running costs is the usual fare of this Warwickshire-based engine management specialist, says CEO Paul Busby. “It’s not the most glamorous work,” he adds, “but it’s more profitable.” But Busby and Viezu have a distant history of tuning Jaguars and have recently rekindled the activity to spectacular effect. The company also offers more rampant XKs and Land Rovers, too, all sharing the same JLR V8.
In the days of the E-Type, it would have taken an extensive dissection of an engine to achieve power gains on this scale, with special components required to extricate the extra power. This F-Type, subtly named Predator, shares only a freer exhaust with these 20th century techniques, and mostly only for aural reasons.
To unleash the V8’s inner beast, you must undam the hidden torrent of extra power not by plunging in with a socket set but by manipulating the algorithms that make up the engine’s electronic marching orders. Viezu technical director Simon White explains that “the engine is actually more powerful” than in the form in which it is sold.
“We look at the parameters within the ECU for power and torque and see where it is being held back,” he says. “We try to limit the changes to the ECU and change more of the maps for the supercharger. We’re trying to get several parameters to work together and not stress the engine.”
To maintain reliability, Viezu doesn’t touch the temperature control maps (“They’re there for a reason”), although the intercooler is upgraded. “There are thousands of maps,” says White, “but we change only 50-60. There’s no change below 60% of total power on part-throttle. We try to retain a manufacturer feel to the driveability. It’s on a wide-open throttle that we make the changes.”
If you can sense this Jaguar straining when it’s lashed to a dyno, that’s nothing to the strain you feel with a wide-open throttle on the road as the F-Type tenses to deal with 687lb ft deluging through its driveline. And there’s a thrilling strain for the driver, too, as you try to find places where you might momentarily apply full throttle. It may be four-wheel drive, but the torque seems to compress the Jag’s spasming body as its rear wheels seemingly attempt to sledgehammer past the fronts. The last time I felt this sensation was aboard a Lamborghini Aventador. The word ‘quick’ barely begins to describe the experience.
And certainly not the noise. The Predator’s semi-free-flow exhaust sounds like King Kong with a headache even in Normal mode, while in Dynamic it’s like a small war on wheels.