SavMan
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Pulley & Map – biggest bang for your buck
Firstly anyone that is about to embark on this consider yourself lucky less than two years ago the average price to supply and fit a crank pulley (the smaller SC pulley that most use now were only launched in March 2012) would have cost £2-3k most now pay less than a £1k including the remap.
There’s no doubt they work but there is a downside heat! Standard cars suffer even with new IC pumps and fully working stock cooling so adding a larger crank pulley or smaller supercharger pulley amplifies this so if this is your only modification expect to see a big variance between cold and hot days in performance.
Crank or Supercharger pulley and what size?
Crank pulley the larger the size the more boost, take longer to fit and need to be seated correctly and tightening them to the correct torque is vital. You have two main types those based on the OEM one’s with the same harmonic balance and solid one’s. My own preference was to stick with the OEM style but there are hundreds of cars running solid pulley’s without problems. So how big should you go well you have a lot of options starting at 168mm through to 200mm, 168/172 seems to be as far as necessary for a daily driver without having to consider far more serious cooling than just upgrading the heat exchanger or pump.
Don’t get me wrong you will still notice the additional torque from a larger crank pulley but the difference in power on hot and humid days versus cold will become greater. Anything above 180mm and you may find you need to get larger injectors to ensure you have complete control of your AFR, another area to consider is the additional rotating weight that is further away from the crank bolt and whether this puts any additional strain on the crank itself.
Larger sizes do not mean an equal increase in bhp but they will add substantial low down torque, take a look at some of the dyno graphs that were posted from the session in March and earlier this month.
The stock supercharger itself seems to have its optimum efficiency when the external SC clutch is spinning at approx 12500 rpm which would equate fairly closely to a 175mm crank pulley and stock SC pulley.
Supercharger Pulley - currently only one size which is 84mm and seems to give an equivalent boost level a little under a 168 crank pulley. Pretty easy to fit and requires no special tools, the early quality of these was an issue for many but they seem to be improving now, they are lighter typically made of aluminium but this seems to have little or no impact.
So crank or supercharger pulley? For a daily driver SC pulley seems to be the way to go but if you intend to build a high torque monster then crank pulley change is still needed.
For anyone considering fitting either I would also suggest you upgrade your cooling at the very minimum a larger heat exchanger and replace the IC pump.
Finally you can always top and tail for significant increased torque but your cooling and fuelling will need to be upgraded to match.
Firstly anyone that is about to embark on this consider yourself lucky less than two years ago the average price to supply and fit a crank pulley (the smaller SC pulley that most use now were only launched in March 2012) would have cost £2-3k most now pay less than a £1k including the remap.
There’s no doubt they work but there is a downside heat! Standard cars suffer even with new IC pumps and fully working stock cooling so adding a larger crank pulley or smaller supercharger pulley amplifies this so if this is your only modification expect to see a big variance between cold and hot days in performance.
Crank or Supercharger pulley and what size?
Crank pulley the larger the size the more boost, take longer to fit and need to be seated correctly and tightening them to the correct torque is vital. You have two main types those based on the OEM one’s with the same harmonic balance and solid one’s. My own preference was to stick with the OEM style but there are hundreds of cars running solid pulley’s without problems. So how big should you go well you have a lot of options starting at 168mm through to 200mm, 168/172 seems to be as far as necessary for a daily driver without having to consider far more serious cooling than just upgrading the heat exchanger or pump.
Don’t get me wrong you will still notice the additional torque from a larger crank pulley but the difference in power on hot and humid days versus cold will become greater. Anything above 180mm and you may find you need to get larger injectors to ensure you have complete control of your AFR, another area to consider is the additional rotating weight that is further away from the crank bolt and whether this puts any additional strain on the crank itself.
Larger sizes do not mean an equal increase in bhp but they will add substantial low down torque, take a look at some of the dyno graphs that were posted from the session in March and earlier this month.
The stock supercharger itself seems to have its optimum efficiency when the external SC clutch is spinning at approx 12500 rpm which would equate fairly closely to a 175mm crank pulley and stock SC pulley.
Supercharger Pulley - currently only one size which is 84mm and seems to give an equivalent boost level a little under a 168 crank pulley. Pretty easy to fit and requires no special tools, the early quality of these was an issue for many but they seem to be improving now, they are lighter typically made of aluminium but this seems to have little or no impact.
So crank or supercharger pulley? For a daily driver SC pulley seems to be the way to go but if you intend to build a high torque monster then crank pulley change is still needed.
For anyone considering fitting either I would also suggest you upgrade your cooling at the very minimum a larger heat exchanger and replace the IC pump.
Finally you can always top and tail for significant increased torque but your cooling and fuelling will need to be upgraded to match.
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