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Sunday, September 21, 2014

How Audi turns a stock R8 into a race-winning monster


 at  Motoramic
Click for R8 photo gallery
You may assume that the production-based GT race cars you see at professional sports car events around the world are as close to stock as a slice of bacon is to a pig. If you place both race and street-going machines on track together, the race car will lap the off-the-shelf production car in a handful of minutes.

And yet, the two aren’t as dissimilar as you might think.
Audi campaigns its R8 LMS ultra in various race series and marque events around the world—including the 24 Hours of Daytona and the Nürburgring 24 Hours. It’s entered in the GT3 category, meaning it must begin life as an actual production Audi R8.
It must also use a production engine, which due to restrictors meant to level the field among automakers, the R8 LMS ultra pushes a smidge less power than the stock 550-hp R8 V-10 Plus.
It also comes with stock suspension, a stock chassis and, in the case of CRP Racing’s Hawk Performance R8 competing in the Pirelli World Challenge, the stock indicator column behind the steering wheel.
 The $400,000 R8 LMS ultra bares many of the same genes as the $153,900 R8 V-10 production car, with 52 percent of the car remaining untouched.

So how, then, is the race car that much faster? The simple answer is weight, stiffness and tires — and getting thousands of small details correct.
All of the V-10 engines in stock form are tested on the dyno, with the ones boasting the best power curves set aside for potential motorsport use. The leading candidates then undergo strength tests, followed by switching out two ECUs for remapped versions that have the typical road-car alarms and features removed, and a small increase in power to roughly 570 hp, pre-restrictor.
 Next some of the fittings are switched, like the oil lines, to ensure the engines are compatible with the race car’s needs. And then the restrictor gets affixed for the specific championship in which it will be raced, such as the 49mm restrictor mandated for R8s in the Pirelli World Challenge.

That engine is still located in the same mid-chassis location, only the all-wheel drive system is removed in favor of rear-wheel drive.
This is required by regulations, although Audi admits that an AWD R8 LMS might be preferable from a branding perspective; let’s not forget that Audi remains famous for revolutionizing rallying with the introduction of the Quattro AWD system.

A racing traction control unit allows drivers 12 setting — from fully on to fully off — and a launch control system is optional for series that adopt standing starts. Since 2013, the exhaust system has been slightly rerouted, and gone are the exhaust tips that could swallow a small child.
One of the few aspects of the car that transforms dramatically is the gearbox. The 7-speed S-tronic dual clutch transmission from the production R8 gets junked in favor of a 3-plate, 6-speed sequential racing gearbox.
 The drivers shift via paddles on the steering wheel, but a dip of the clutch pedal is required to leave pit lane. After that, the clutch is obsolete, and shift times are dramatically improved. The exact gear ratios will be adjusted from track to track as race teams fine tune the car for each event.


The Audi “ultra” aluminum space frame chassis saves weight over a comparable steel frame. This technology isn’t exclusive to the R8, though, as even the A8 receives the same treatment.
 The chassis is unchanged in the R8 LMS ultra race car, with the only form of additional stiffness deriving from the mandatory steel roll cage (more on that later).


The body is effectively the same as the production car, although it’s dressed in carbon fiber. It has an enhanced hood with a large vent, carbon wheel arch, bumper (which is the same shape as stock, bar its carbon construction) and splitter.
 A spec aero package, approved by the FIA at the beginning of the season and locked down to prevent further development, gets bolted on. Those aero upgrades include a big rear wing, protruding front splitter, diffuser and various downforce-producing louvers, primarily located on the front bumper.

To homologate the car for GT3 racing, the FIA has a power-to-weight-to-downforce ratio that it imposes to ensure all automakers submit machines that will remain close to one another on track. That figure is not released by the FIA for public consumption, nor is Audi willing to share the exact amount of downforce the car produces.
Click photo to view R8 slideshow


The suspension components on the front, such as the uprights and double wishbones, are all production quality, down to the road-going Bilstein dampers.
 On the rear, due to the new gearbox and the removing of the AWD system, packaging requirements mean that the uprights and tie rods need tweaking to fit. Naturally, the spring rates, damper settings and anti-roll bars are stiffened up significantly.


For racing, 370 mm Brembo brakes arrive on the front, slightly bigger than the production V-10’s 365 mm but smaller than the V-10 Plus’ 380 mm.
 The rotors are mandated to be constructed of steel, not carbon as is becoming customary on most road cars, and a racing ABS system allows the drivers to chose the level of intervention they desire.


When Audi’s factory drivers stepped behind the wheel at this year’s Nürburgring 24 Hours, a race they won, the steering column could be adjusted forward, back, up and down, just like in the production car.
It is, in fact, the exact same rack and column, with the addition of a cooler to keep it fuctional under race conditions. Of course, the steering wheel has changed, and the wiring is different to incorporate the various motorsports functions, such as the radio. The hydraulic power steering is also production spec.
While cooling has been increased in the race car, it’s not as dramatic as you might think. Part of that is because the engine is straight off the production line and raced with a restrictor, so it’s never at max capacity.
 Larger cooling ducts for the brakes, the hood vent and a more open grille all contribute, and additional cooling fans for things like the aforementioned power steering unit help keep things in check. But by motorsports standards, the updates are relatively minor.
In the Pirelli World Challenge, the R8 LMS ultra can weigh no less than 2,843 lbs. Compare that to the 3,660 lb. curb weight of the production R8 V-10 Plus, and that gives you a pretty clear idea of how much more nimble the LMS car is.
It also ensures a far greater power-to-weight ratio, making the race car considerably quicker in acceleration when compared to the 3.3 second 0-60 mph street car.
The 817 lb. weight loss comes from the use of carbon fiber in the body, the removal of the AWD system, and of course the stripping of all superfluous interior bits: air conditioning, radio, navigation, power seats and switching out the glass for a plexiglass-like material.
Wheels and tires:
Aftermarket wheels, with 12-by-18 inch fronts and 13-by-18 inch rears, arrive on the R8 LMS, and the track increases from 1638 mm/1595 mm to 1670 mm/1650 mm. In World Challenge, the R8 LMS ultra races sticky Pirelli P Zero Racing Slick tires, a huge contributor to lap time.

It’s here we return to the roll cage, something Audi spent much time and effort developing. Not only must it be incredibly strong and offer a safety-cell for the driver, it also stiffens the car’s chassis.
And while a percentage telling how much it does that cannot be offered, it’s fair to say that the cage itself delivers much of the race car’s inherent stiffness.

Audi is particularly proud of the R8 LMS ulta’s removable door and its integrated impact system. Here, within the carbon door, a high-density foam helps protect the driver.
 Unlike some race cars, having the foam within the door is far cleaner than it lying externally next to the driver, bolting it directly to the cage—like Chevy does with its Corvette C7.R. This allows for a more compact package, and gives the drivers better maneuverability during driver changes.

Audi also says its PS1 Protection Seat, which took five months to develop, is one of the safest in the business. Top surgeons consulted with the German automaker to build a seat that minimizes the risk of back issues, compression fractures, neck injuries and more. This, according to Audi, is causing the FIA to potentially ban some aftermarket seats in GT3 unless they can up their game to a similar level.
In all, it’s amazing how similar the R8 LMS race car is to the machine on a dealer's lot, and that’s the beauty of GT3-spec race cars — you can watch them tear up the racetrack, then pass you on the freeway knowing that the core fundamentals are the same.

But from a driver’s standpoint, a lightweight, stiff, slick-tired super car makes the driving experience seem like a different universe, and lap times prove that point further (I'd guess the LMS ultra is roughly 15 seconds per lap faster on track than an R8 Plus production car, maybe even faster).

I’ll be racing the Hawk Performance Audi R8 LMS ultra you see pictured above in November, so check back soon for more on how it drives. If Audi’s performance as the leading GT3-spec racer in the Pirelli World Challenge is anything to go by, it won't lack for speed.