I founded RX-7 Fashion, owned it for 2 years and I sold it to Rick's Rotary about 4 years ago. I sold him the right to make that APEX GTR core custom intercooler so I don't make or sell them anymore. If you need one, you will have to talk to Rick's Rotary. Sorry that I can't help you on this one.



Chuck Huang

When I make a product, I will look around to see what's out there. I will look at their product design flaws and see what I can do to improve the design.



On the power pulley, there are two kinds on the market right now: the UR one and the other one that uses very long bolts.



1. UR one requires you to remove the eccentric shaft bolt. VERY BAD idea. It's heavier as well.



2. The other kind uses very long bolts. The pulley is a lot heavier. It's 560 grams (1.2 lbs) so it has more rotational inertia and takes more power from the engine just to turn it. It uses very long bolts so that will create a lot of stress on the bolt itself. Now we have to talk about concept of torque. Torque = force x distance. The A/C and power steering pump belt is on the very outside of the pulley. Since the bolt is so long, the tension from the belt exerts a lot of torque on the very end of the bolt where the bolts screw on. If the bolt is not strong enough, it will snap at where the bolts screw in. If the bolt is pretty thick, it might be ok but then the bolt is only 6mm in diameter. It's just not a very good idea to use such a long and thin bolt.



If you look at my power pulley, I machine out the center part more to reduce weight and I also use the counter sunk so I can reduce the length of the bolt to the same length as the stock one to reduce the torque stress on the bolts and any kind of vibration. I believe my power pulley is the best one on the market at this time and also the easiest one to install.



If you have any idea that can improve the design of my power pulley, please let me know. Thank you.



Chuck Huang

I took some pix of the stock pulleys on scale:



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



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



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



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



Stock crank pulley: 860 gm, 1.89 lbs

stock water pulley 270 gm, 0.59 lbs

stock alternator pulley: 170gm, 0.37 lbs

stock power steering pulley: 270gm, 0.59 lbs



After I get the prototype pulley back from the CNC machine shop, I will put it on the scale and take a pic of that as well. I will borrow another brand of aftermarket pulley and put it on scale for comparision.



Chuck Huang

Can we do something like this for the FC????

Chuck, seen many threads, very interested in this, as well as the engine brace you spoke of that is in development. When are these ready for sale?



BTW what is a realistic HP gain from the power pulley? The 20 HP numbers by some just seem unrealistic.

I gotta see how the market is for the FC before I have it made. If you can go to the FC section and gather some interest, that will be great.



Chuck

Is your pulley going to work with no air pump? I had to go with the larger Greddy pulleys because the belt was not getting good enough contact on the water pump pulley. It seems to me that your pulley would just make the problem worse.

Now can you make a stock sized one for us guys that already have the greddy kit, but want the weight reduction.. https://www.nopistons.com/forums/pub...#>/biggrin.png a nice power steering pully would be nice too..

ditto...minus the power steering pulley

Yeah. What they said.