[foggyMCS]

Hey guys, im pretty new here and not a machanic so i have a question regarding pulleys.

We see advertised everywhere differant size superchrager pulleys and also oversized lightened crank pulleys. Can someone with good knowhow explain for me which combinations are good for the engine without having to replace lots of other parts due to strain.

What ive read is that a lot of folk choose the 15% supercharger option with no change to the crank pulley. why is this.

From what i think i read on the web, is that the standard crank pulley is very heavy and replacing it with a lightened version can give great improvements because of reduced rotational mass (its like removing 100lb from a cars weight it said).

Would it not be better to just change the crank and not the supercharger pulley or does it make sence to change both wether it a lightened standard size crank or oversized.

If im talking rubbish plaese just explain for me, i cant be the only person that doesnt totally understand this.

Surely!

[3rdpillar]

good question.. id like to know the answer as 2008 will bring the 2nd phonse of my modding now I have a JanSpeed manifold and Milltek catBack. More grunt to go with the glorious sound.

[Richard Crofts]

15-17% supercharger is considered one of the better option in UK. This is due to the ambient temps and the fact that these size pulleys are within the usual tolerences that the stock cars IC and other parts can just about cope with safely. Some cars will cope better than others. If you were in a colder climate then larger pulleys could be used as the higher temps created by the higher compressed air are offset by the colder intake air and the ability of the IC to have colder air washing over it. The reduced SC pulley is chosen because it allows the supercharger to compress more air faster (but remember the more you compress the air (smaller the pulley) the higher the temp gets)

The crank pulley is usually dependant on the supercharger pulley. It is advised that anything over 3% enlarged is not good. Depending on your choice of SC pulley you should pick a different crank. Eg a 15% reduced pulley will probably be pretty OK with a 2-3% oversize crank. However if you have a 17% pulley its generally thought you should stick to about 1% maybe a 2% at max. The crank pulley allows the engine to spin up faster so letting the engine rev freeer and faster, thus delivering the power from the charger faster (or thats how my limited knowledge of engines thinks)

Most folks go for a 15% or 17% with nothing but colder plugs as it is the fastest and cheapest way to get more power on the MINI. These mods also require little else to make them work safely. The crank is a bit harder to fit and once you add this you do really need to consider upgrading your intercooler as the boost pressures and so temps are usually raised to a level where its better for power and safety of the engine to consider a better IC.

Hope that helps explain why many dont go above 15% SC pulley