Here's a link that gives the RSRs specs
flat six-cylinder boxer engine, water-cooled
3.598 cc, stroke 76.4 mm, bore 99.99 mm dia.
max. torque: 405 Nm at 7.200 rpm
max. power: 327 kW (445 BHP) at 8.250 rpm
with 2 x 30.8 mm dia. restrictors in FIA version (2 x 29.2 mm dia. in ACO version; power ratings in ACO version at request)
max. rpm: 8.500 rpm
four-valve technology
oil-cooler (oil-water heat exchanger)
dry-sump lubrication
oil and cooling water quick refilling system
intake manifold with single throttle valve
electronic engine management system MS 3.1
Bosch MS 3.1 fuel injection with ignition control
required fuel quality: 98 octane ROZ, unleaded
race exhaust: multiple pipe manifold, open exhaust
no catalytic converter (rear exhaust muffler retrofit)