How Radical revamped its record-breaking flagship model

Portimao – or, rather, the Algarve International Circuit – is an incredible track. It’s long, fast, undulating, challenging. Every time I drive it, I come away exhausted and exhilarated from the effort and the concentration. Hanging on to the steering (and you really are hanging on!) at more than 120mph around the right-hand parabolica that finishes the lap – unsighted through a plunging downhill entry, nasty bump on apex, trying not to bleed off the throttle too much, or at all if you dare… It never fails to take the breath away.

The first corner is a rapid right-hander, approached at well over 150mph, with a steep, downhill braking zone. There’s an apex over a steep rise at Turn 4, a blind exit at Turn 8, a blind entry at Turn 10. This circuit has ‘kinks’ that require driving rather than relaxing, corners that lead immediately into short, heavy braking zones. There’s uphill, downhill and gravel traps…

This place has everything. The perfect venue to drive high-performance racing cars. Beautiful Portuguese winter weather too – sun, and ambient temperatures above 16C even as Christmas fast approaches. The ideal way to escape dreary December in Britain.

I owe my brief extraction from cold winter’s nights to Radical Sportscars. Business in the world of low-volume, open-topped sports- prototypes is booming, and Radical naturally wants to shout about that. One year on from the launch of its newest model – the turbocharged SR10 – which Autosport was among the first anywhere in the world to drive, Radical has been busy selling cars, and upgrading them.

The SR10 I drove at Bedford Autodrome during the UK’s November 2020 lockdown was the very first of its kind. The 425bhp Ford EcoBoost-derived engine was impressive, but the power delivery was quite abrupt, and the car had only just rolled off the production line so had undergone absolutely no set-up work whatsoever. The result was something that felt short of its potential. Power-on understeer was the overriding impression.

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What a difference 12 months can make. In a record year for Radical – almost 200 cars produced – the SR10 has gone on to become the fastest-selling model in Radical history: 85 and counting at the time of writing, at a base cost of £109,500 (excluding VAT) each.

Radical SR10 has been updated for 2022 and is now a second per lap faster than before

Photo by: Radical

Radical is so sure it has penetrated the zeitgeist with this car that Autosport has been invited back for another test drive, to learn what 12 months of development can do. To see what the SR10 is really made of.

What’s changed exactly? Well, to start with, you can have the steering column raised on your 2022-spec SR10 – which is handy because the original position was much too low, making it near-impossible to read the flashy new AiM data display on the steering wheel while motoring. Radical’s engineers have also worked hard on the suspension geometry – to give the car better balance – while revising the mapping on that turbocharged engine to deliver more torque, and to make that torque delivery more linear, thus easier to handle.

Double SR1 Cup champion James Pinkerton, who is also Radical’s head of powertrains, says the SR10 in its revised 2022 spec is a “game changer” for Radical.

“Just the durability, the performance it delivers – straightline performance now is on par with a GT3 car,” he tells Autosport. “Our factory set-up was very safe, so we’ve refined that so it’s a little bit edgier now – you can put the car where you want it, so it’s a lot more satisfying to drive.”

The revised SR10 is now around a second quicker than the first iteration and, depending on circuit, somewhere between 0.5 and 1s quicker than an SR8, making it Radical’s fastest, as well as fastest-selling, model

Pinkerton says Radical found the chassis was capable of dealing with more torque than the original engine map produced, with the Hewland transmission initially designed for the FIA Formula 2 car. Therefore, he says with “a lot of trickery in the ECU – you know, pedal progression versus map targets, lots of graphs! – we’ve actually been able to increase the torque in the lower gears, but also through all the gears you have more torque earlier in the curve”.

“The [new] map really has just allowed us to deploy that torque and fire the car out of the corners,” Pinkerton adds. “Also, we found on downchanges it can lock the rear axle ever so slightly, so we refined that as well. It’s just small updates here and there put together to make quite a nice improvement from where we were.”

All this means the revised SR10 is now around a second quicker than the first iteration and, depending on circuit, somewhere between 0.5 and 1s quicker than an SR8, making it Radical’s fastest, as well as fastest-selling, model. Radical’s group sales and marketing director, Dan Redpath, says the Peterborough factory has been working “full tilt” since launching the SR10 and, at the time of writing, has built around 70.

Anderson got to test the revised SR10 at the home of the Portuguese Grand Prix

Photo by: Radical

So popular is the new model that Radical sold as many units in SR10’s first four months as the venerable SR8 sold in its first four years.

“We’ve sold a lot of cars,” Redpath says. “When I first joined in January 2020, the portfolio was very heavy on SR3. Four out of five cars we were making at that time were SR3. SR10’s rebalanced that. SR3’s now one out of two. SR10 is just under 40% – 37/38% is SR10.”

Radical has also opened 12 new dealerships over the past 24 months, taking it to 32 in 21 countries. Redpath reckons the SR10 – which is eligible to race in the UK Radical Challenge – has hit a “sweet spot” with customers because, if you’re an SR3 owner, you can now get higher than SR8 levels of performance for what Redpath says are “comparable” running costs to a 1500cc-engined SR3. If you’re an SR8 owner, you can reduce your running costs substantially for no hit in performance. The SR10 will give you faster lap times, the same peak horsepower and double the torque, for double the SR8’s average engine rebuild time.

Extra durability is key for what is now Radical’s primary market in the United States. There, many owners do a UK season’s worth of running in a matter of months on private, country club-style racing ‘estates’ – which means SR8s will get very tired, very quickly.

“Two thirds of everything we make in Peterborough finds its way across the pond to the States,” explains Redpath. “The UK is probably about 6 or 7%. A race weekend at Silverstone, you could probably do three hours; as a private country club member with an open pitlane, five days a week… The 80 hours we think of as a season and a half in a European mindset, for them that’s ‘I’ve got a couple of months off work, I’ll do my 80 hours in those two months’.”

We won’t be doing quite that much running during my test, though Radical has generously arranged the timetable to mimic what a potential customer could expect to get during a typical sampler day. After consulting with Radical test drivers Michael Lyons (of Historic Formula 1 fame) and Sean Doyle, we tweak the programme slightly so I can lap solo for the duration, rather than beginning as a passenger.

First up is what you might call a warm-up outing in Radical’s entry-level SR1 model. I tried this car once before, on a cold and damp morning at Donington Park, and I didn’t really get on with it. The car had an unsettling tendency to snap straight into oversteer under braking, and I grossly underestimated the ability of the chassis, on grooved tyres, to hold on as gamely as it does in high-speed corners.

Anderson sits down with Redpath to get the lowdown on Radical's fastest-selling machine

Photo by: Radical

Lyons describes the car as “pitch sensitive” and compares the driving style required to Formula Ford but with more high-speed grip. That’s a pretty good summary. To cope with the quirks, you basically wind the brake bias as far forwards as possible, commit as much entry speed as the tyres and aero will allow, correct any snaps on the way in, then exercise patience to avoid inducing understeer with the throttle before you’re pointing correctly out of the corners.

I’m obviously not here to break down the nuances of an SR1, but three 20-minute runs in this car allow me to dial into the circuit in readiness for the main event. I experiment with my braking point at Turn 1, finding somewhere between 100m and 50m is the way to go. Fourth gear is better than fifth here. Second is fine for Turn 3, once you’ve got the car rotating on entry. Then it’s full gas through Turn 4, up to fourth gear on the blind exit; wait until 40m to brake for the downhill hairpin at Turn 5 – take second gear and nibble that apex kerb.

Climbing back up the hill, the Turn 7 kink turns out to be a lift in fourth, before braking down to third for Turn 8. This corner has a wide exit, so no need to worry too much about the apex kerb. Turn 10 is blind over a crest on approach, so the key is to wait as long as you dare before braking, while trying not to approach too wide, making the track no longer than it needs to be. Third gear is better than second, because again the wide angle of turn allows you to carry more speed.

Brake just after the surface change and drop down to second for the tight left at Turn 13, then up to third just before the Luffield-esque double right at Turn 14. Short shift to fourth on exit then grab fifth just before the entry to that parabolica. This can be done full throttle, but you need to be careful of the bump at the apex and the wind trying to blow you sideways. This is where you really feel the physicality of the circuit on your neck, so I’m already wondering about the extra severity of this in SR10…

“The feedback we get from professional drivers is that the [Radical] chassis is very intuitive. They can really feel what the car is doing in terms of weight transfer and dynamics and the way it moves through a corner” Dan Redpath, Radical’s group sales and marketing director

As it turns out, I needn’t have worried. Trading what Redpath calls “slightly quicker than a GT4 car” in SR1 for SR10 also means a slightly different driving style. The SR10 I drive for my two runs doesn’t yet have the benefit of 2022’s revised brake package – bigger discs, bigger calipers, plus additional cooling – so you can feel the extra weight of that Ford-inspired drivetrain still pushing you along whenever you try to decelerate quickly.

Otherwise, the car is absolutely nailed on – fantastic stability through the high-speed corners (which are all arriving much faster now!) and tremendous acceleration. Portimao has an impossibly long main straight, with a bit of uphill after you come off that parabolica, and often cars will run out of steam quite early before Turn 1. This thing feels like it can go on and on.

The direction of travel in this market seems to be carbon chassis, but Redpath reiterates Radical’s commitment to spaceframe design – comparing it to the “special” characteristics of old Lotus cars, and the need to be “careful custodians of that”.

SR10 chassis was capable of dealing with more torque than the original engine map produced, with the Hewland transmission initially designed for the FIA Formula 2 car

Photo by: Radical

“The feedback we get from professional drivers is that the [Radical] chassis is very intuitive,” he adds. “They can really feel what the car is doing in terms of weight transfer and dynamics and the way it moves through a corner. It’s protecting that sort of feel.”

Driving carbon cars like the Praga R1, in the wet especially, the grip can be difficult to sense precisely. SR10 telegraphs everything through your backside, and if you do overstep the mark – as I do once or twice at Turn 1 – the chassis is forgiving enough to allow you to bring it back.

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During my first run, I work down to a 1m47.65s best, against a reference lap of 1m43.77s set by Doyle. He suggests the extra physicality needed through the final corner here transfers from neck to arms in the SR10, and he is right. Handily, Radical will now offer a power steering module as part of the upgrade package.

A quick review of the data shows nothing too surprising – my basic driving style is about right, but I’m 8mph down through Turn 1, and arriving at some other corners a little too slowly – making them go on a bit too long. Before my second run is curtailed by unexpected rain(!), I refine my driving well enough to post a 1m46.223s best – not quite breaking into the 1m45s as the dashboard several times predicts, thanks to traffic and some scruffiness on my part.

The data shows I’m mainly losing time through a slight lack of confidence through the blind uphill kink at Turn 4, and also through the slower corners in the second half of the lap – braking at about the right point but bleeding off the pedal a bit too quickly, rolling speed in the style of the SR1, which is then delaying the point at which I can get properly back on the gas to take full advantage of all that extra torque.

This shows how easy one can transfer habits from one car to the next. But I’m encouraged when Doyle and Lyons tell me: “many guys we coach wouldn’t get down to that lap time”. To be within 2.5s after two short runs in a car I’ve barely driven is a pleasing outcome. And I’ve thoroughly enjoyed myself, lapping what must be said at one of Europe’s finest circuits.

As I depart, Radical is gearing up for another full day of play – messing around with race formats for the coming season, looking forward to celebrating its 25th anniversary in 2022, and surely a bright future led by this fantastic new car.

Anderson came away impressed with the tweaks to revamped Radical SR10

Photo by: Radical