Monday 6th June 2016

Secrets of Subaru's IoM TT record car

Mark Higgins has smashed the car lap record around the TT; PH goes behind the scenes to find out how

---

Those glued to the action from the Isle of Man TT will likely already know but on Saturday Mark Higgins smashed is own lap record for cars around the 37-mile course by a huge margin, clocking 17min 49.7sec and an average speed of 126.971mph on his first run. How huge? The last time he did it he recorded 19min 15.8sec and a 117.5mph average. From the teaser pics we shared the other week we knew the highly modified Subaru WRX STI he was driving was something special. Now, after a sneak preview at Prodrive, we can reveal exactly how special...

Despite still being cagey on a full specification, those numbers that we do have are extremely exciting. Using a development of the 2.0-litre boxer turbo previously seen in the WRC cars, power is said to be around 600hp. Six hundred. Principally this comes about through revving the engine higher - a WRC car is typically limited to 6,500, this one goes to about 8,500 - but also by fitting a larger turbo and removing the rally restrictor. Weight is "11 something" according to David Lapworth, responsible for every Subaru WRC car and a key figure in this project. Those numbers give it comparable performance to a GT3 car. On the Isle of Man!

As the pictures should make clear, this car is a far more specialist build than the production-derived previous attempts. It's a bespoke build using Prodrive's nous with making swift Subarus and Subaru America's desire to promote the model with this, er, unique publicity stunt. Where they will go from here is anybody's guess...

Underneath this STI is a lot of old WRC stuff; not only does this cut down on costs and development time, but it's also extremely useful for the challenge this car will face. While the Isle of Man has similarities with other tarmac rallies, it's of course much faster than any WRC event. A car going for the record must be fast but also capable of dealing with bumps at high speed plus the odd low speed sections of the TT course as well.

To that end, the car is low but not to the levels of a circuit car - notice the gap between wheelarch and tyre as well as the fresh air between front splitter and tarmac. There is said to be tangible downforce but, with outright speed such a priority, this couldn't be at the expense of aero drag. So the underfloor isn't flat but the big spoiler plonked on the back has a DRS system. Having originally tried a P1-style system - Prodrive helped McLaren develop that - the team used a simple device that uses Prodrive's experience with the Aston GT cars. It's manually deployable but will retract on its own if the speed drops, and aims to help the compromise between aero stability and minimising drag. It's also pneumatic and sounds like an air rife when it's deployed - very cool.

This STI uses Dunlop slicks from a BTCC car and the gearbox from a WRC Impreza, the latter able to change gears in eight milliseconds. Over the previous record holder, this car has a longer fourth, fifth and sixth gear and a theoretical top speed of approximately 180mph.

There was no chance of hitting that around the Bicester Heritage test track, but there is enough space to confirm this is one seriously rapid Subaru. From both inside and out there are familiar (and fantastic) Subaru rallying noises but everything is happening faster. So much faster. The brakes are staggering too, but it's the way this STI handles that's most interesting. It looks like a circuit racer but pitches and moves like a rally car, a result of the softer set-up needed for the TT. At Bicester it's not especially happy, understeering at the slower corners that it simply isn't built for. But when it's out the other side... Wow. The aim for a 120mph average looks extremely pessimistic.

Higgins is aware of the understeer too, but understandably states that it's a worthwhile compromise for the high-speed stability. Inevitably that video comes up in discussion, which he is keen to avoid repeating. "I'm getting older; my hands won't catch up!" he says.

Now while a few commenters have already taken issue with Subaru attempting a record with no competition, the car itself is excellent. We've been clamouring to see a four-door Impreza (allow us one slip of the tongue...) on a rally stage again, and now we have it. Sort of. And with 600hp. The record attempts are due in the following days and we'll be flying out today to catch up with Higgins and the team and find out more. For his part Higgins has already Tweeted "Great first lap ... a bit more to come!" We look forward to seeing it for ourselves!

 

 

[finnie]

I find it notable that this car is not slammed. So many people lower a car to the floor, wheels up in the arches for example. Yet here is a team striving for a fast time on a real road course who actually leave some suspension travel in the car. Surely proves that all the boy racers weren't right at all!