Swiftune has developed a radical new crankshaft, connecting rod and piston assembly to eliminate the A series’ power sapping vibration at high revs caused by off-set con-rods and lack of crankshaft counterbalance.
Starting with a clean sheet of paper we have designed the new DC5 crankshaft with five main bearings, instead of three, so creating two “false” journals which enables the counterbalance to be doubled. Just as important the new design allows straight, no-off set con rods to be adopted – a first for an A series engine. They save weight and reduce the longitudinal side thrust on the piston. The DC5 con-rods are ¼ in longer than standard with the benefit that the reduced angularity at the small end reduces lateral friction losses on the piston under power.
The straight, longer DC5 connecting rod is fitted to a modern, short-height slipper piston; ¼ in shorter between the gudgeon pin and top face. The high-tech piston is CNC machined from solid billet for higher rigidity and coated in molyslip for the ultimate in low friction performance. The slipper piston is a key part of the DC5 design, saving 25 per cent of the weight of a conventional forged piston and enabling the longer con-rod to be used. At 8000rpm the lighter piston massively reduces the bottom-end loads.
The DC5 engine has already been used in anger, powering the Mini-based DART to a win in the Fordwater Trophy at Goodwood in September. Nick Swift says,” The double counterbalance engine revved easily to 8400rpm and the traditional harsh harmonic vibration which saps the power at the top end is gone, it is brilliantly smooth.”
For the conventional crankshaft we are now developing a slipper piston and longer connecting rod assembly. The DC5 assembly CANNOT be used in Appendix K FIA engines as it is ineligible.
For more information, give us a call on (01233)850843 or email info@swiftune.co.uk
15 February 2011