WinSU is a computer program which contains information about SU carburettor needles. The taper of the needle inside an SU carburettor dictates how much fuel is delivered for a certain engine speed and load. It is vitally important that this taper is correct for the engine specification.
WinSU will suggest the best needle and dashpot spring for your engine specification and allows different needle profiles to be graphically compared. It will also estimate power, torque, and many other performance related values.