Track & Race Cars Magazine Test Drive the All-New SR4

This is what they had to say...

Big Brother's Little Brother

It's new, it's small and it's perfectly formed, but will the new Radical SR4 cower behind the SR3, or break some records of it's own? Keith Wood tests the waters.

Cast your mind back to 1997...

If you need a little help then think of virtual pets named Tamagotchi, psychedelic Telly Tubbies, Tyson eating ear lobes and the birth of Dolly the sheep, the world's first cloned mammal. It was also the year that Radical produced its first extreme sports car, the 1100 Clubsport. It set the trend for endurance racing with cost-effective yet durable race cars which had a strong following, not only from the racers but the organisers and spectators as well.

After the introduction of the 1300 Hyabusa-engined 205 Prosport, basically a Clubsport with an advanced aero pack, and the 20bhp increase in power (from 185bhp to 205bhp), the Clubsport Biduro Championship still flew the flag well for Radical and the organising club, the BRSCC. Even with the introduction of the SR3 in 2002, last year's Biduro series still saw a keen interest from competitors. I doubt its attraction was just the fun handling characteristics though, it was probably down to the championship structure.

Last year saw 12 race meetings, each having two 40-kilometre races for a single driver and even one of the rounds at Pembrey saw four 40-kilometre races. Iron man challenge stuff, especially in a car which was now six years old and missing the aerodynamic aids of the Clubsport's younger counterparts. Okay, it was in a different championship but the Clubsport was a full three seconds slower at an early round at Snetterton with the pole position SR3 and the second-placed Prosport running within a few tenths of each other.

So taking Radical into 2004 is the new SR4 - the car to replace the 1100 Clubsport - and after our first drive I'm happy to report it's more than a match. So much so that I felt inclined to compare it more with the big brother SR3, it really is that good and my original plan to run the car alongside the company's founder model was put to one side. I'm not just talking about the aesthetics either; the whole driving experience was truly sensational.

The majority of the credit must go to Radical's chief designer, Nick Walford, who's still on board with Radical and many of the genius poured into the Clubsport, Prosport and SR3 has been carried on to the SR4 chassis. The suspension geometry stays the same and still retains the patented Nik-link suspension system, named after himself. Walford's cost-saving anti-roll bar system runs across the width of the front track (just over 1000 millimetres) and operates via a bellcrank at the top of each coilover mounting. Although cheap, the shock absorbers are run at such an angle that it creates more movement for any given suspension bounce.

Highly expensive remote reservoir and three-way adjustable suspension could have been used but all it would bring with the practice and race days was extra costs, advanced data-logging gear to get the most from the precise changes and lots of head scratching from team members and drivers. Now all of the Radical's racers run the 'Nik' rising-rate suspension and anti-roll system.

One thing the SR4 does carry over from the 1100 Clubsport though is the same basic shape and size. This is easily spotted when seating the car side-by-side with an original 1100 Clubsport or getting on to Radical's very own website and clicking on the pictures of the SR3 which was photographed with the SR4. You get a better idea of how much bigger the SR3 is over the SR4 and why I called this feature Big Brother's Little Brother.

The size and suspension setup is about where the similarities end as the chassis is truly unique and all new, as Mike Hyde from Radical was quick to point out: "The core criteria for the SR4 project was a cosy two-seater." With this in mind the overall width of the chassis has been widened by two inches for one reason - so the new Clubsport can take a passenger.

Those of you who have had experience with the original Clubsport will be familiar with the small surroundings inside the cockpit and will fully appreciate Radical's had work to make the extra space. One annoying thing that sometimes gets irritating, as with many a roll-caged racer, is the bar I normally smack my head on when entering and exiting the driver's compartment. However, these angled bars coming off the single rollover bar on the 1100 Clubsport haven't made an appearance on the SR4... so far.

On our shoot the SR4 was still having a lot of development work completed so the twin rollover tubing was exposed and for all to see. It also showcased the neatly welded double cross section (from the rollover bar into the chassis behind the driver's head), taking the responsibility of not only bringing extra strength into the chassis but acts as the holding point for the driver's and passenger's headrests.

Strength and safety has been a key issue of the Radical and the SR4 was no exception. As you now know, the driver's cell isn't just keeping the pilot in one piece, it's got two to think of so higher side rails with strengthened crash bars have been cleverly designed and secured on the SR4 chassis. A two-seater moulded seat has been fixed to the floor with wide strapped six-point harnesses, making the driver and passenger feel at one with the car, although the crotch strap will do its best to make you think otherwise.

Unlike it's predecessor, the SR4 will be able to take passengers and the extra-width all round has created a wider foot box, but who cares? For those of you who race it will mean very little but for those after a hot track day/road car you won't find anything quite like the SR4. The SR3-inspired plush carbon fibre dash with Radical's own control box featuring all the relevant information from oil pressure to revs per minute is enough to win you over, even if the looks don't.

However, styling is neither here nor there at 140mph, because it's been designed for one purpose - to create downforce. What's good enough for the Le Mans-winning Bentley is good enough for Radical but is hasn't just nicked styling cues. It has an SR3-style lighting system with the central nose creating high downforce and forcing airflow up and into the cooling ducts, through the rads and exited back out and once again pushed up over the rear engine cover and on to the rear wing.

The Controlled rear wing looks highly similar to the one seen on the Supersport but will be slightly more limited to the amount of downforce freely available to the driver. The Tracksport version will feature smaller end pieces to comply with the SVA test and will probably be constructed using carbon fibre. Although weight-saving isn't really an issue, a smaller-engined, 1000cc lighter version is intended for the US market.

I'm glad I'm English though because powering the UK-spec SR4 Clubsport is the Powertec Kawasaki 1200cc, normally in between the legs of an owner mounted on top of a ZZR sports tourer. Powertec enlightened me of the basic changes, which include the long stroke crank and rods and baffled sump. During the time I was at our Bruntingthorpe test track I was spoilt with having two SR4s to play with, one with the normal dry sump setup and a cheaper wet sump version.

Over the original 1100 ZZR engine used in the original Clubsport, the stroked 190bhp 1200cc version found in the SR4 boasts all new internals, CV flat slide carbs, a new carbon fibre air box and stiffer springs fitted into the clutch for improved pedal feel. As well as the conventional six-speed sequential gearbox, the Radical still retains the chain drive setup and an easier, adjustable mechanism has been designed with the overall weight being kept a lot lower just by keeping this tried and tested route.

Drive is via the Quaife limited-slip differential system to the rear wheels and also comes equipped with the Radical-designed reverse system, eliminating the need for the electrical reverse found on early Clubsports. While the engine's reliability is the main priority, other power units are being considered for use in non-championship races like the 1300 and 1500 Powertec Suzuki.

Early indications look highly likely that the SR4 Clubsport won't take any nonsense from its elder brothers. A lap around our test track has highlighted how much the SR4 means business (see The Drive) by squashing the Clubsport's attempt by a full four seconds. What's more impressive though is that the SR3 and Prosport on average normally lap around three seconds quicker than the 1100 Clubsport depending on the circuit.

So will the SR4 be just as quick as its big brothers? I'm not sure if Radical had planned for this or not, but it will certainly be very close, especially with that 1500 power plant...

The Driver
It's like I said in the main feature; the SR4 is a dominating form to look at and it's no different in the driving seat. To compare the ride to something completely different is very hard because its SR3 looks also transfer to the handling department too. It's a rock solid performance straight out of the box and there's still plenty of development work to be completed by the bosses, Phil Abbott and Mick Hyde, and of course, the rapid Michael Vergers.

You can only feel the short wheelbase with the power firmly planted while attacking a high-speed bumpy curve. The nose dips while the rear follows, resulting in the rear becoming light, forcing a little opposite lock while the Nik suspension works its wonders ironing out the curve. It would be a rare action on a super smooth race circuit but around Bruntingthorpe's bottom loop, just before the run along the two-mile straight, it's an all-too-common sensation.

However, around our test track the SR4 was in its element. The huge power kick the Powertec 1200 engine gives is nothing short of breathtaking and the push doesn't just give up, well, until you haul the car down from speeds such as 140mph using the ultra sensitive brake pedal which clamps four-piston calipers all round on to the discs.

Imagine a car with zero body roll; that means the horizon stays the same level left to right, and every bit of your steering input is equalled by pinpoint accuracy from the steering rack to the Matador slicks.

These are the Radical characteristics and the SR4 inherits them and learns from the best of the bunch, the SR3 Supersport. That's impressive, even though the wheelbase is nowhere near the footprint of the SR3 and comes equipped with smaller 13-inch three-piece rims.

In the hands of Michael Vergers, the 1100 Clubsport managed an impressive 1 minute 15.21 seconds around our test track, proving the Radicals are the cars to beat and even more so after the time came home from the SR4 Clubsport: 1min 11.58secs. It's quite amazing how far Radical has come after six years of building extreme sports cars; in fact almost a second for every year.

2004 Matador Biduro Championship
So far the 2004 Biduro Championship is shaping up to be one of the best years so far. A few of the 1100 Clubsport drivers have updated to an SR3 and stepped up into the Enduro Championship, leaving plenty of spaces to be filled by SR4s. So far Radical has taken 15 orders for the SR4 so there's a good chance next season's grids will be oversubscribed. "We don't want to run four different championships with small grid numbers," commented Mick Hyde.

"I'm certain the Radical Enduro Championship will stay strong for years to come and I'm also just as confident the Radical Biduro Championship will, too. My only worry is what happens to all the old 1100 Clubsports? "This year we'll be running two classes in the Biduro series, one for the SR4 and one for the old-spec 1100 Clubsport," Mick Hyde answered.

This year sees a new championship sponsor, Matador Tyres. The Slovakian tyre manufacturer has developed a tyre just for Radical and will be providing 'Driver of the Day' awards, a prize trip to Prague and a VIP visit to Matador's Slovakian factory for the class championship winners. I have it on good recommendation that Prague is the place to be.

However, take a look at some of the race weekends in the championship calendar to see where else is worth a visit. There are some fantastic races planned at the world's best race circuits for both the Biduro and Enduro Championships, which I'm sure is a big attraction with drivers lucky enough to have a healthy budget burning a hole in their pockets. I know I wouldn't pass up on the opportunity...

SPECIFICATION - RADICAL SR4 CLUBSPORT

ENGINE
Power-unit: 1200cc Powertec Kawasaki, four-cylinder, 16-valve, CV flat slide carburettors, Radical exhaust system

Power: 190bhp
Transmission: Rear-wheel drive, six-speed sequential, Quaife LSD, integral Radical reverse system

CHASSIS
Clubsport SR4: Tubular spaceframe chassis with integral FIA/MSA Blue Book roll-cage
Minimum Weight: 530kg including driver

BRAKES
Front & rear: Radical four-piston calipers, 300mm discs

SUSPENSION
Front & rear: Double wishbones, Nik-link rising rate suspension anti-roll bar system, coilovers

WHEELS
Front: 7x13" Image three-piece, centre locking
Rear: 8x13" Image three-piece, centre locking

TYRES
Front: 6.0/21.0 Matador slicks and wets
Rear: 7.0/22.0 Matador slicks and wets

AERODYNAMICS
Front splitter: Controlled
Rear wing: Controlled, adjustable
Diffuser: Controlled

HOW MUCH?
Price: Expected cost from £22,000 plus VAT

CONTACT: - Tel: 01733 331616