Watch a 600-hp Subaru Tackle Isle of Man TT Course For New Record
Mark Higgins puts car to the test against motorcycle racing’s most radical circuit
ISLE OF MAN—If you've seen videos of the Isle of Man TT, you know about the 1,000-cc, 200-horsepower, 200-mph Superbikes. About how they come leaping off a descending road surface, straight-line a squiggling street lined with cottages, and lean their way through a hairpin corner.
Now imagine rally driver Mark Higgins cutting a lap of the daunting 37.7-mile open-road circuit in a car, though certainly not your average carriage. Instead, Higgins pilots a 600-hp, 2,590-pound Subaru WRX STI.
Banbury, England, home to Prodrive, is where the car was created. Building both pro rally cars and Aston Martin road racers meant the company could develop a machine that has to be a bit of both. At first glance, the WRX STI looks like a rally car, but then you notice the tires are Dunlop racing slicks that fill the flared wheel wells. The four-door sedan looks to sit a bit lower than a rally car—and is that an articulated wing out back?
Prodrive began with a WRX STI, stripped it and fitted the expected safety cage. The suspension is based on World Rally Championship links, struts, and dampers. There's a low front spoiler (made of wood of all things) that likely wouldn't last long on a rough rally stage.
Where the Subaru TT Challenge Car diverts wildly from rally cars is up front. WRC racers have 1.6-liter turbo engines with about 318 hp and about 317 lb-ft of torque, crucial for squirting out of corners.
By contrast, the flat-four engine in the WRX needed high rpm for the TT course. Displacement is 2.0 liters, and the block and heads are production-derived. Everything else is, as the Brits say, bespoke: crank, rods, pistons, gaskets, etc. There's a single Garrett turbo and custom radiator and intercooler designed to allow for cooling on the slow corners, but minimal drag at high speed. Horsepower comes out to 600 with a redline of 8,500, though for reliability Higgins was shifting at 7,750 (about 550 hp).
Richard Thompson, a rally engineer guru from Prodrive, explains, "Around 600 horsepower the big problem is keeping the heads on the block. What we see is the heads lifting due to cylinder pressure. We don't have a head gasket but two Wills compression rings, which is a very effective means of sealing the head on the block." The team can read the pressure between the rings to know when the heads are lifting, which tells it to back off slightly on the turbo's speed to settle the heads back down. And to think of all those Offy Indy engines and Testa Fissa Alfas in which the block and head were one piece to prevent blown head gaskets. Ain't progress wonderful?
Prodrive took an unusual approach to the transmission, which works like a sequential gearbox but isn't one. Instead it is an H-pattern 'box by Prodrive Xtrac with left-right, fore-aft actuators to do the shifting. And still manage 24-25-millisecond shifts via a paddle.
That's the hardware side of the WRX STI TT Challenge Car, while the human factor is an Isle of Man native. Higgins is a three-time British Rally champ, and he sat in for James Bond being chased through Rome in his Aston Martin DB10 in Spectre. Higgins explains there was a time when racing around the TT circuit was for motorcycles only.
"We'd been told by the government that categorically there will never be a car on the TT course. It just wouldn't happen," he said. "It's a bike event and we don't need the hassle of it all. But then Subaru came along and made it happen. We probably upset a few people, but I think we've now established a nice relationship with the organizers, which has allowed us to go to the next level of car."
He points out that this WRX "is similar to rally cars I've driven before apart from the power, which changes everything. The big thing here is the speed. I rally at 120-130 mph and that's no problem. You don't even think about it. But when you start to get into the 150s-160s-170s, there's no way to prepare for that on any course other than here."
That's because there is no other circuit like the 37.7-mile TT track. Subaru was allowed three laps to go for a record, but weather plays a big factor, with no racing when it's wet or even if the fog keeps the rescue helicopters from landing. So, Higgins explains, "You always have to go for it because you might not get another run.
"At that speed, when you turn-in [to a corner], is it flat or is it not flat? You've got two chances. You get around it or you don't. And that's the reality of it. And when you're given three laps in total to get around the course you've got to take calculated risks because you haven't got the time to build up to it. On a racetrack you can go around 10 times, but you'd never get around here 10 times."
He continues, "The car is just beautiful to drive. The first time I got out all I could say was, 'wow.' It does everything I want it to do, it feels like it's part of me. I don't steer it around corners, I think it around corners because there's that much movement going on. The pedals, the braking … a total pleasure to drive."
As for that articulated wing, "I've a little blister on my finger because I've been using it so much, getting braver and using it more. When I get out of a corner, just getting on the exit and I know the car is stable, I hit the button to reduce the drag. When the wing flattens you can feel the car move a little bit, but it's not dramatic."
He can then hit the button again to deploy the wing for added downforce, but a hard stab on the brakes will also change the wing's angle. But really, what's the most difficult part of driving the WRX around the TT circuit?
"I think getting used to the speed and focus," Higgins replies. "Where the bikes are able to go flat because they've got more road to choose from, I'm pretty restricted. I have to be on line and there are certain bumps I'm hitting which the bikes can avoid." And there's also the crown of the road to consider.
"It's like driving down a tunnel, you're looking so far ahead and thinking about the ballsy corners. There's probably about six of those around the circuit."
So is driving the super Subaru on the TT course scary? Higgins smiles again. "It's not scary when you're doing it … you're in the zone," he says.
Being in the zone got Higgins around the circuit at and average speed of 128.73 mph on his second run this year. Weather scrubbed the third run, but that speed put him in the top 10 of the fastest motorcycles in the real TT, the Superbikes.
Just wait until next year.
Photos courtesy of Marc Urbano