The M7 Speed 4% oversize - speed increasing crankshaft pulley will add power, acceleration and performance to your MINI. Speeding up your supercharger safely adds "low end" boost and torque which gets your MINI Cooper going. Weighing in at a scant 13 ounces, (an amazing 88.5% less than factory) the lightweight M7 Speed 4% Crank Pulley reduces crankshaft rotational mass which equals additional increased horsepower, torque and throttle response.
This beautiful design is a result of advanced computer modeling and high precision CNC machining. Made in the USA from billet 6061-T6 aerospace grade aluminum alloy and finished with a deep black anodized coating and laser etching. The Micro V-Belt grooves are machined to exacting SAE J1459 specifications for minimum belt slippage at maximum boost. Use this in combination with the M7 Speed 16% Supercharger Technology Pulley for maximum performance and boost yourself to the next level of MINI tuning and performance.
From the factory, the MINI suffers from no positive drive key on the crankshaft snout to drive the lower pulley. The factory pulley is press fit onto the crank. All aftermarket pulleys are slip fit at best and rely on the bolt to provide adequate clamp force to prevent the pulley from slipping. The M7 Speed crank pulley is engineered with an interference fit onto the crankshaft eliminating pulley slippage on the crankshaft.
Simple to install. Heat the pulley to 275/300oF (135/150oC) in your kitchen oven or using a small propane torch and heat gun and the pulley will drop straight onto the crank. When it cools it will be super tight onto the crank. Finish the installation with the supplied ARP bolt and precision flat washer and presto...more power, more reliability and more overall performance for your supercharged MINI Cooper.