Radical Performance Engines (RPE) V8 Engine


Steve Prentice Design Limited designed this engine for Radical Sportscars and their in-house engine builder RPE (formrly Powertec).  It is used in the Radical SR8 sportscar and RXC racing coupe.  It is also available to purchase as engine only and gives exceptionally good value per horsepower.   The original design brief from Radical was to design a 2.0 litre V8 engine to give 300hp using parts from the Suzuki Hayabusa 1300cc bike engine and to use as many Suzuki parts as possible to keep costs down to make the engine affordable for club racers.


At the first design discussions with Radical in 2002 I suggested that the capacity should be 2.6 litres to commonise on parts and set ups with the 1300cc bike engine that Radical would continue to use in their SR3 model, which meant that the V8 would make more horsepower than Radical had asked for.  We kept the brief to keep the manufacturing costs down and use as many proprietary parts as possible and the package had to be lightweight and compact to fit the Radical chassis.  The bank angle of 72 degrees is the minimum that the liners can be nestled together to make the most compact engine package.


  • RPE V8 engine to power Radical SR8 sports prototype road and race cars.

  • 2,6 litre V8 - 380 bhp, 10500rpm with 6 speed sequential transaxle transmission.

  • 2,0 litre, 2,5 litre, 2,7 litre, 2,9 litre and 3,2 litre variants are now available, producing up to 480 bhp.

  • 88 kg mass basic engine.

The RPE engine uses cylinder heads from Suzuki GSXR1300/1340 motorcycle. The rest of the engine has been purpose designed for this project.


Quaife & Hewland have each produced 6 speed transaxle transmissions to suit this engine.




Design started in December 2002 and the first engine ran on dyno in September 2004. The RPE engine was launched in USA at Performance Racing Industry Show in Indianapolis on 9 December 2004, and in UK at Autosport International at NEC Birmingham on 13 January 2005.



It won its first races in UK and USA and has gone on to win most of the events it has competed in and set the outright fastest laps at Brands Hatch and Cadwell Park.


Radical SR8 has set prestigious ‘lap record for a road legal car’ around Nurburgring Nordschleife in 2005 and again in 2009, driven by Michael Vergers in 6 minutes 48 seconds.


Radicals compete in support races for European LeMans Series. SR8 lap times are only 10% slower than LeMans prototype lap records set by Audi and Peugeot 5.5 litre turbo diesels.

Check out these links to RadicalAutosport


RPE V8 Race Engine Tech magazine 2009.pd[...]
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