Car Guides



Riley Daytona Prototype setups


Riley Technologies, LLC

Steel Tubeframe


Pontiac V8

5-Speed Xtrac transmission


2794 mm

2,275 lbs

Twin wishbones and pushrods



Riley Technologies is the most successful producer of cars for the Grand-Am’s Rolex Sportscar Series, and its new car, the Riley Mk XX, the latest in a championship-winning line-up, represents the company’s thinking on how to build the best possible Daytona Prototype racer.

The iRacing Riley Mk XX runs a Pontiac V8 and a five-speed Xtrac transmission, but Grand-Am rules permit a wide variety of engine brands and configurations, all of them limited in power output to about the same as the Pontiac’s – approximately 500 horsepower – which is plenty for a 2,275-pound, flat-bottomed car with limited downforce.

As a cost-containment measure, Grand-Am has published a tight set of specifications, and requires models from all manufacturers to use of a spec rear wing and Riley-designed and produced front and rear suspension uprights. The cockpit greenhouse’s minimum dimensions are also set by the rulebook, contributing to the distinctive look of these futuristic sports-racers.

But while the rulebook keeps all brands of Daytona Prototype more similar in appearance and performance than different, there is a wide range of aerodynamic and mechanical adjustment available to tailor the Riley’s handling characteristics to the needs of individual drivers on particular tracks. The angle of the rear spoiler is fully adjustable, and there are two choices of spoiler extensions and two of wickerbills. Front aero is adjustable through ride-height and the addition of small dive planes.

On the mechanical side, the suspension is fully adjustable and the drivetrain features a multitude of gear-ratio options for the transmission and three final-drive ratios. Everyone will find the Riley Mk XX an exciting car to drive, and experienced drivers will be able to use their knowledge of set-up to their advantage in extracting the maximum performance from this car.


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