Dodge Viper ACR

Dodge Viper ACR at a glance

The ACR is a road-legal car built for track days and club racing. Dodge's SRT division developed it on the VX I Viper, launched for the 2013 model year. It kept the formula of earlier ACRs: no extra power, but a lot more grip, downforce and braking. Compared with the standard Viper, it has stiffer, adjustable suspension, lighter components, carbon-ceramic brakes, special tyres and aerodynamic parts that turn speed into grip.

The racing background of the name is covered on the Dodge Viper GTS-R page: the GTS-R won its class at Le Mans three years running, in 1998, 1999 and 2000. The whole brand story is in the history of Dodge.

The 8.4 V10, gearbox and performance

The engine is an all-aluminium 8.4-litre V10 with pushrods and two valves per cylinder, assembled by hand. In the VX I it produced 477 kW (640 hp) at launch and 481 kW (645 hp) from 2015, with 813 Nm (600 lb-ft) of torque. Dodge called that the most torque of any naturally aspirated sports car engine of its day. The only gearbox is a Tremec TR6060 six-speed manual driving the rear wheels.

The ACR is not about top speed. Dodge quoted its downforce figures at 177 mph (285 km/h), and the drag of the wing and splitter limits the car to about that speed, well below the standard Viper. In return, it is much faster through corners: the ACR lapped Laguna Seca 5.27 seconds faster than the 2008 ACR.

Aerodynamics: wing, splitter and diffuser

The standard ACR has a front splitter, lower dive planes and a 1,776 mm-wide adjustable dual-element rear wing. It generates 1,101 lb (about 500 kg) of downforce at 150 mph and 1,533 lb (about 695 kg) at 177 mph.

The optional Extreme Aero Package adds a 1,876 mm wing with special end plates and a Gurney lip, plus a detachable splitter extension and four dive planes. A carbon-fibre diffuser starts ahead of the rear axle and carries six removable strakes. With the package, downforce rises to more than 1,200 lb at 150 mph and more than 1,700 lb at 177 mph, about 12% more on the straights and 21% more in fast corners. An SRT bonnet with removable louvres over the front wheels lowers pressure in the wheel arches.

The old 1cars text spoke of about a tonne of downforce at top speed. The factory figure at 177 mph is just over 770 kg.

Chassis, brakes and tyres

The suspension uses aluminium-bodied, double-adjustable Bilstein coil-over dampers with ten settings each for rebound and compression. The ride height can be changed by more than 75 mm (3 in). Spring rates are 600 lb/in at the front and 1,300 lb/in at the rear, and the wheels have 1.4 degrees more negative camber than an entry Viper SRT. The suspension is independent, with double wishbones and anti-roll bars at both ends.

Brembo carbon-ceramic brakes are standard: 390 mm two-piece discs with six-piston calipers at the front and 360 mm discs with four-piston calipers at the rear, cooled through detachable ducts. The Kumho Ecsta V720 tyres were developed for the car, with different tread patterns and compounds front and rear.

Inside the ACR

The cabin is the VX I Viper's, with a Uconnect touchscreen, a digital instrument cluster, a small steering wheel and supportive bucket seats. Air conditioning and audio remain, so the car can be driven to the circuit and home again.

Lap records and the Nürburgring

In 2015 the ACR set 13 lap records for production cars, certified by the SCCA. The best known is Randy Pobst's 1:28.65 at Laguna Seca, against 1:29.89 for a Porsche 918 Spyder and 1:30.71 for a McLaren P1 with the same driver.

An unofficial Nürburgring lap of 7:01.67 was reported for an ACR with the Extreme Aero Package in October 2015, but speed limits on the Nordschleife stopped an official attempt that year. In 2017 a crowdfunded team of owners tried to break seven minutes in a GTS-R Commemorative Edition ACR. It ran 7:01.3 on a warm-up lap, but a tyre failure and a crash ended the attempt without an official record.

End of production and value today

FCA announced in July 2017 that Conner Avenue Assembly would close on 31 August 2017. With it the Viper ended after about 32,000 cars over 26 years. The ACR therefore exists in only two model years, 2016 and 2017, including a limited GTS-R Commemorative Edition. No official euro price was published, as the car was sold only in North America, and late ACRs are now sought-after collector cars.

Rivals: how the Viper ACR compares

The Viper ACR stood out for its downforce and its manual gearbox. Check how its power compares with modern cars in the most powerful coupés ranking, or set it against a rival in the 1cars comparison tool.