Hey all

which would be the better option?

1) 15%pulley with 2% crank; or
2) 17% pulley?>

Thanks.\

 

All other things being equal, you'll achieve the same level of boost with either one. Advantages of the 15+2 is you can use the stock belt, the overall tension seen on the belt is less than if you went with 17% (mechanical advantage plays in here) and the reduction of crank pulley weight allows for quicker throttle response. Disadvantages are the fact the jury seems to still be out regarding the long-term durability factors with lightened crank pulleys and the slight increase in drag by all the engine accessories being driven at a higher speed (the latter is negligible IMO).

 

Great question My plan is to someday augment my M7 -16% SC pulley with a Alta +3% Crank pulley to "equal" 19%. I'm in no hurry, waiting to get concrete answers about which approach puts more area "under the curve". I think Jeff @ Alta may have done some testing that would help with this, but I haven't taken time to follow up.

 

Ah - more or less thought so , but didnt know the reason why people wouldnt opt for the 2% crank pulley. but makes sense now - thanks!

 

i dunno about the lightened crank pulley because steve at dinan had an article that goes with greatbear's mention about the disadvantages. you can check it out at the dinan site under technical/forums if your pondering about it.