http://www.rotaryextreme.com/powerpulley.jpg



The power pulley is made from CNC machined 6061 T6 billet aluminum. It under-drives all the acc. by 25% and on top of that, it's super light weight to reduce the rotational inertia so you can have more power to the rear wheel. The kit comes with two belts and stainless steel bolts for a bolt on installation. I retail it for $250 but for you nopistons member, $220 shipped.



Chuck Huang

will this cause the lights and stuff to flutter at idle?

Nope, it won't.



It will if you use it with other underdrive pulley for the water pump and alternator such as the Greddy pulley kit.



More pix



http://www.rotaryextreme.com/powerpulley-2.jpg



http://www.rotaryextreme.com/powerpulley-1.jpg



Notice the belts are not on there because using this with the Greddy pulley will underdrive the alternator and water pump too much. The customer has no stock pulleys so I can only take pix with just the crank pulley bolted on without belts.



Chuck Huang

well this looks really neat. i have a few questions and one was already answered. 1)is it worth changing out the ACC pulleys in the first place?

ive looked at the pulleys several time and actually had teh WP pulley off, it didnt weigh much. i know everything adds up.

2)what are the TQ specs of the bolts that hold the pulley on. i have never had any luck with the hex bolts

3)err...i read the answer to this above EDIT

4)uhhh...thats all i can think of. ill post more

kris

Looks great Chuck....I am interested also but, i have never looked into them enough. What is the difference of getting the full set like the GReddy, or just the one pulley??

1. You will notice some differnce but for the money, it will not be worth it to change the ACC pulleys. Besides that, the ACC pulleys are bigger than stock ones to serve the underdrive purpose so you are not going to get that kind of weight saving even though they are made of aluminum. The power pulley has a smaller diameter and it weights less so it's a better way to underdrive the ACC vs using the ACC underdrive pulleys.



2. The bolts are stainless steel so it's stronger than those steel ones. It can withstand a lot more torque. As long as you you use the wrench that's long enough to get the leverage, that will have enough torque. Besides that, the belts provide the tension so it's not going to come off.



Chuck Huang

If you get the Greddy pulley kit, it only underdrives the alternator and the water pump. Besides that, the Greddy pulley kit isn't that much lighter than the stock one and since it's bigger, it has more rotational inertia so more power is needed to drive it.



The power pulley is smaller than stock, made of aluminum, and lighter so it has less rotational inertia and then again it underdrives all the ACC such as air pump, alternator, water pump, power steering pump and A/C. You will notice more hp gain with the power pulley.



Chuck Huang

okay now what would be the difference of the UR pulley kit vs. just your pulley. well apples to apples, your pulley vs. UR main drive pully. seems like yours is much lighter. what is the stock weight of the pulley.

is underdriving the WP a good idea. right now im trying to figure out how the hell to keep the temps down with the freakin heat.

kris

meant to put this too...chuck you are the man.

OT if you dont mind...do you have an intercooler like ricks(or did you help build that one?). i love how its drop in and dont worry about moving the radiator.

kris

The UR pulley requires you to take out the eccentric shaft bolt which is very hard to take out and a lot of times, you will damage the engine. A while ago a guy on the rx7 mailing list installed the UR crank pulley and damaged the engine.



I will weigh the stock pulley and post the info.



It's ok to underdrive the water pump pulley by 25%. If you have cooling problems right now, you should get a larger radiator or an aftermarket bumper with larger opening to help cooling. If your water seals on the engine are blown, the exhaust gas will heat up the water. Overdriver or underdrive the water pump will not make any significant difference.



Chuck Huang