I ordered a Cobb Lightweight Main Power Pulley and a Perrin Crank Pulley and i know they increase performance a little bit but was wondering exactly how much? discuss?
Just from what I've read.... it improves throttle response a little(no actual hp gain), but are not worth it over all... I know its a popular mod because they are not expensive but I have heard much positive feedback at all.......... Happened across this thread on IWSTI.. not much in it now but you could follow it as more people answer.. http://www.iwsti.com/forums/engine-power-performance/115788-pulleys-worth.html
It removes rotational mass. When things of a certain weight spin faster and faster they seem heavier and heavier. So if you lighten a few pounds off of something, when it is spinning really fast it becomes a loss of a lot of mass. The pulley's are worth it if you are all about acceleration in 1st and 2nd gears (i.e. autox and drag). No other gears will you notice the difference due to the engine load being higher. This works in the same way as a lightened flywheel, except without all the slow speed drive problems. Inertia and momentum... You don't actually gain hp, but free up engine resistance. I guess your hp to the wheels might improve, but the hp at the crank will still be the same. This should be in the performance section, not off-topic.
I have a lightweight crank, alt, and ac pulley and lighweight flywheel. I love it. Immediately I noticed it drove a lil snappier. Rev matching was amazing. The rpm's do fall faster inbetween shifts so you have to shift quicker to keep it smooth. The car is peppier but it does require a lil more attention to drive it smoothly.
I assume that they do not make more power but just remove a little bit of drain on the power so to speak.