VNT turbos have been used by TT in competition for 20 years, starting with Geoff Kershaw’s Sierra 2.9 – 24V which produced 530 BHP with excellent torque and drivability.
Geoff’s car took many sprint and hillclimb records over the years, a number of which still stand, and won the BARC Speed Championship in 2009.
In 2007, Graham Beale was looking for an upgrade for his Cosworth YB-engined Ginetta G33 and settled on a TT VNT28 turbo – a hybrid between a Garrett T3 and a VNT25 with a TT wastegate incorporated. This was basically the same turbo as Geoff used on the Sierra (the Sierra had 2!). Graham used an electric actuator for the VNT mechanism which gave even better control, and mapping by Dave Walker gave 310 BHP with near full boost at 2500 r/m and very little lag, ideal for hillclimbing.