In this episode, we bring you our report from a filming visit to County Kilkenny in August 2025, when we were invited by Alex Snr. and Alex Jnr. Wilsdon to see their Radical PR6 — an exceptionally fast purpose built single seater race car that handles with the sharpness of a go kart. Power comes from a 1,585 cc Suzuki Hayabusa engine, stroked and bored from 1,300 cc and built by Powertec, Radical’s own engine division.
To kick us off Alex Jnr. outlined his PR6; “it is the precision of the car on the track, between slick tyres, very firm suspension – it is a large go-kart”.
++
While Dennison Trailers kindly sponsors the website, all production costs, including travel, editing software, Meta verification, music licences and data storage are completely self-funded by Kevin Reid. All support for our work is greatly appreciated. Please click on red subscribe button.
++
SUPERBIKE-ENGINED CAR
When Radical Motorsport was founded in 1997, the brief they gave themselves was precise: build a lightweight sports racer powered by superbike technology.
What set Radical apart was a significant engineering first. Rather than simply installing a motorcycle engine into a car, the company developed a bespoke powertrain system specifically designed for a superbike-engined sports racer. The engine, gearbox and drivetrain were engineered as an integrated package, purpose-built for circuit use and hill climbs, delivering high-revving performance in a ultra lightweight chassis.
This approach created cars that were faster than many supercars of the era, yet intensely driver focused. By 2025, more than 3,000 Radical race cars had been built in Cambridgeshire, each car can be registered for road use and driven on track without modification retaining that original, uncompromising engineering philosophy.
POWERTEC ENGINE
At the heart of the Wilsdon’s car is a Suzuki Hayabusa engine, originally in 1,299 cc to 1,340 cc form and producing in the region of 175 to 197 horsepower. In most applications that would be ample. For the Wilsdon team, it was only a foundation.
The engine was removed and sent to Powertec in Lancashire — the specialist engineering arm established by Radical Motorsport to develop bespoke racing engines, including the V8 series used in the SR8 programme.
At Powertec, the engineers stroked and rebored the Hayabusa engine to 1,585 cc producing 200 hp, a significant increase in capacity that delivered a marked rise in power and torque with a sharpened throttle response and amplified straight-line urgency.
Complying with FIA and FIM regulations, the enlarged engine runs on 102 race fuel, a high octane, unleaded, oxygenated blend designed to deliver consistent performance and engine protection in high performance applications. A further rebuild was later completed by Mirage Engines, maintaining reliability while preserving the gains achieved through Powertec’s re-engineering works.
IRISH HILL CLIMBS
As Alex explained they have raced the car for the last eleven years in the hill climb championships in Ireland and also in the BOSS Series (Big Open Single Seater) across Ireland in locations like Mondello Park and Kirkistown Racing Circuit. In the BOSS Series the PR6 races against a variety of different machinery from Formula 3 cars, world series cars, Formula Renaults, Formula 3000s – anything goes!
Having previously raced a Caterham based car the PR6; “goes pretty well in a straight line and round the bends as well”.
Alex Jnr. regularly competes in the Irish Hillclimb Series and in 2025 took part in the Ballyvaughan Hillclimb Weekend placing 4th and 5th in the two races and was also a class leader in both races.
HANDLING
Handling is very sharp, you are on full slick tyres ultra soft Avon tyres (now unavailable) and the grip level is a real step up from the driving experience of a regular production car with superb steering feel. There is great pick-up-and-go due to the short gearing and an engine that revs to 10,500 rpm. Alex told us as the car is not very large on the track or in a hill climb scenario, it’s like driving something about three quarters scale and so is easy to place on the road and track and to squeeze through a gap and that makes it pretty interesting.
COCKPIT
Alex describes the cockpit as being a basic yet functional set up. A screen on the removable steering wheel holds all the dash information. There is 6-speed motorbike sequential gearbox with no reverse which can be problematic at times. The rest of the dash contains a gear indicator and assorted switches.
For a 2018 track day at the Nürburging a number of years ago and to comply with track regulations they fitted a full set of road legal lights including headlights (main beam and dip lights), indicators, brake lights and tail lights. In describing racing at the Nürburging Alex described one of the big pluses of a full bodied car over an open wheel car is that you can do a track day where you would not be permitted in an open wheel car. On their 2018 trip to the Nürburging they raced the PR6 against a variety of different machinery on the Nordschleife, a 20.8 km “North Loop” featuring over 170 corners and 300 meters of elevation change.
PLANNED UPGRADES
As the PR6 was designed originally for a standard 1,300cc Suzuki Hayabusa engine and is now running an aftermarket stroked and rebored 1,585 cc engine there will be a future requirement for upgraded brakes as the current system is undersized
Sources of Information, Video and Photo Credits:
Irish Hill Climb website
PowerTec website
Radical Website
