I make no apologies whatsoever for being a terrible Ford Sierra Fanboy, and I was duly excited to see a Sierra Cosworth darting purposefully up the track at the Crystal Palace Hillclimb, followed closely by its later, more practical,  three-box, four-door Sapphire Cosworth successor. What I didn’t expect to see was a crazily be-winged family car cleaving its way around every hairpin while shouting with a voice I didn’t quite recognise.
Of course, we all know that the only five-door Sierra hatchback with any claim to sporting credentials was the XR4x4. Well, this used to be one of those. A long time ago.


In 1986 Ford of Europe got serious and moved their high performance game up a notch. In tandem with a hugely successful attack on motorsport, civilian versions of the 204hp Sierra Cosworth were released and a legend was immediately born. To make space for this leviathan, the former champion of speedy Sierras, the 130mph XR4i was quietly dropped from the price-lists. However, it morphed into a car which was actually far more useable in the real world.
The Sierra XR4x4 used the same Cologne V6 power plant as the XR4x4, but allied it with permanent four wheel drive. Although the extra transmission losses blunted the performance ever so slightly, the XR4x4 was quickly seen to be something of an all-weather performance hero, and it was a far more useful car, too, having gained a pair of rear doors.

Always living in the shadow of the Cosworth, the XR4x4 took a long time before it became recognised as worth preserving. Countless examples were driven to destruction and thrown away as just another consumer durable. Good ones, though, are now well worth hanging onto. And this one? Well, feel free to decide for yourself.
In 1990 the true potential of that Cologne engine became truly apparent when a 24 valve version of it became available in the Ford Granada Scorpio. Normally aspirated, it pumped out an easy 195hp, rising to 204bhp on later models. And it was courtesy of those clever blokes at Cosworth.
Crashed Scorpio 24vs were much sought after during the ’90s, their engines being transplanted into everything from Caterhams to Transits. Any car which had space for a Cologne could take the 24v version, named Cosworth BOA. For installation into the XR4x4 it required the sump from the old engine to be transferred, as this was shaped to allow the front driveshafts to pass through it. If you were willing to make the effort, an easy 50hp or so gain was there for the taking.

But why stop there? Many specialists could turn their hand to extracting further power from these engines, usually with recourse to forced induction. Turbo Technics, for example, were profligate in their creation of twin-turbo Sierra Ghia 4×4 Estates; the five-door, station wagon version of the XR4x4 and a pretty astonishing piece of kit. But the conversions were always a bit quick ‘n dirty.
Not so what we have here. The owner of this particular BOA has chosen the supercharger route, constantly driven and explaining why I couldn’t quite get my head around the noise the car was making. He explained that he chose a setup which didn’t produce an overwhelming amount of power- he mentioned 280bhp, but offered power throughout the rev range allied to “big gobfuls of torque”.
Sounds good to me. Looks good, too. The installation has been quite artful and would look factory if it wasn’t so damn shiny. My favourite piece of attention to detail is seeing how the intake duct passes through the inner wing and then back out again to keep the duct the right length and free of power-sapping changes in direction. It is a fantastically clean installation, and one which seems to suit the car perfectly.

Of course, the extra power has been joined by appropriate upgrades to the running gear, bigger and wider wheels and tyres live under widened arches in the style of the much missed Thundersaloon series, where pretty much anything went so long as the silhouette was the same as on the production vehicle.
Alas, during the race-car conversion the rear doors have become non-functional, which is a shame as it means this can never be the all-slaying family runabout I’d love it to be. But it certainly hasn’t done my unconditional love for Uwe Bahnsen’s Jelly Mould masterpiece.
(All images copyright Chris Haining / Hooniverse 2016)