Powertec RPA

Powertec RPA is the name of a V8 engine developed by Radical Sportscars in Peterborough England for use in the SR8 sportscar. The design is loosely-based on the 1.3 liter I4 engine produced by Suzuki for their Hayabusa motorcycle. The company have designed their own engine block and use existing Suzuki cylinder heads. The two heads are joined at a 72-degree angle. Lubrication is provided by a dry sump system. The engine is mated to a purpose-build transaxle designed by Quaife.

Ultimately, three versions of the engine are planned: the original 2.6 liter model which retains the original bore and stroke of the Hayabusa design, a de-stroked 2.0 liter for higher peak output and a stroked 3.0 liter which sacrifices peak power for higher torque at low revs.

pecifications

(from Radical Sportscars)

*72° V8 cylinder
*32 valve quadcam
*Power 350 to 400 bhp (260 to 300 kW)
*Maximum revs 10,500 rpm (2.6 litre) / 12,500 rpm (2.0 litre)
*Bore 81 mm
*Stoke 63 mm (2.6 litre) / 48 mm (2.0 litre)
*Compression ratio 11.0:1
*Steel flat-plane crankshaft
*Twin counter-rotating balance shafts
*Twin pump lubrication system
*Four scavenge pump dry sump system
*Rotary vane coolant pump
*Pre-engage starter motor
*Belt-driven 45 amp alternator

Dimensions

*Length: 546 mm
*Width: 513 mm
*Height: 440 mm
*Dry weight: 88 kg -

Bellhousing/clutch

*Single plate dry clutch
*Optional twin plate dry clutch
*Integral oil tank capacity 9 litre
*Integral rear engine mount
*Engine - gearbox spacing 126 mm
*Dry weight 13.7 kg

Transaxle

*Six-speed constant mesh
*Sequential shift 5 forward, 1 back
*Gear ratios
*1st 2.615
*2nd 1.937
*3rd 1.526
*4th 1.285
*5th 1.136
*6th 1.043
*Overall reduction ratio 3.400:1 to 5.670:1
*Reverse gear ratio 3.000:1
*Torque biased limited-slip differential
*Integral oil cooling pump
*Pressure fed lubrication system
*Dry weight 36.3 kg

Dimensions

*Length: 393 mm
*Width: 300 mm
*Height: 365 mm
*Dimensions from mounting face to drive shaft centre: 128 mm
*Dimensions from front of engine to drive shaft centre: 800 mm