sorry guys. but you are mistaken. the acceleration pulley IS larger than stock.
this is coming straight from KDMguy:
in this thread:
http://www.newtiburon.com/forums/showthread.php?t=126043&highlight=acceleration+pulley
he said:
"it is larger and lighter than stock.
because it is larger your throttle cable attactched to your gas pedal is tighter you get better response .. understandable? "
:gotsearch:
Sorry bro... and excuse me Kdmguy
I agree with the result = faster throttle response with SFR acceleration pulley.
BUT, I disagree on size relation, I know SFR and Kdmguy are great with performance tuning expertise, but may be Kdmguy had just made a mistake in writing or something and here is my argument.
(1) Geometry:
(sorry for bad post image)
For any given angle a2=a1, X2 is absolutely smaller than X1 where X2 and X1 are proportional to respective pulley diameter.
That is to say, in the case of smaller pulley, you need to pull at P a length X2 only less than length X1 at P1 if you want to get the same turning angel. Less pull equal of the cable at P equals less push at the pedal.
(2) There might be little slackness coming from putting in a smaller pulley, but this is totally negligible compared to the slackness we already have in the TB (after all the cable isn't wrapped around the pulley and just holds to pulley close to the top). And once the TB cable gets stretched, the relation described above holds. (you can always adjust the slackness if you want)
(3) SFR website doesn't say anything about relation of stock size to this aftermarket accl. pulley.
Note that the same geometry principle is applied with underdrive pulleys. Smaller cranck pulley yield less linear speed of belt (
less distance per given time), and that lower linear speed of the belt is translated at the other pulley as lower rpm of the driven pulley (water, alternator,..)
