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

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.

Engine:

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.

Gearbox:

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.

Chassis:

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).

Bodywork:

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.