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

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.

The engine brace damper is already under production. I already presold a few. I have about 4 sets unspoken for. If you want it, just go to http://www.rotaryextreme.com/enginebrace and you can preorder one. It will be done in about 10 days.



20rwhp from a pulley kit is unrealistic. Even if it were true, mine will outperform those simply because it's lighter. To be realistic, you should gain about 10-12 rwhp depending on the engine load.



I am going to dyno tune a car in 2-3 weeks. I will slap on the pulley kit and get some dyno numbers for you.



Chuck

Since the pulley is already smaller, it will make it worse if your belt is already slipping with the stock pulley.



I am going to do some size measurement on all those pulleys so I can determine how much it's going to underdrive if you use this one with the Greddy pulley kit.



Chuck

Yeah, I can make it but the only problem is that I need to make at least 10 at a time or it's going to cost too much. If we have 10 people prepaid on the stock size aluminum one, I can do $175+shipping for the pulley only. Since it's the stock size, you are keeping the belt from the greddy pulley kit.



Chuck

The power steering pulley is hard to make due to those spines in the middle. It will be more cost effective to buy the RE Amemiya one. They probably make a bunch of them to reduce the cost.



Chuck

The engine brace damper is already under production. I already presold a few. I have about 4 sets unspoken for. If you want it, just go to http://www.rotaryextreme.com/enginebrace and you can preorder one. It will be done in about 10 days.



20rwhp from a pulley kit is unrealistic. Even if it were true, mine will outperform those simply because it's lighter. To be realistic, you should gain about 10-12 rwhp depending on the engine load.



I am going to dyno tune a car in 2-3 weeks. I will slap on the pulley kit and get some dyno numbers for you.



Chuck [/quote]

thanks Chuck,



is the $220 forum discount still in effect for the powerpulley? if so how do we go about ording?

The engine brace damper is already under production. I already presold a few. I have about 4 sets unspoken for. If you want it, just go to http://www.rotaryextreme.com/enginebrace and you can preorder one. It will be done in about 10 days.



20rwhp from a pulley kit is unrealistic. Even if it were true, mine will outperform those simply because it's lighter. To be realistic, you should gain about 10-12 rwhp depending on the engine load.



I am going to dyno tune a car in 2-3 weeks. I will slap on the pulley kit and get some dyno numbers for you.



Chuck [/quote]

thanks Chuck,



is the $220 forum discount still in effect for the powerpulley? if so how do we go about ording? [/quote]

Yeah, the $220 discounted price still applies. The pulley kits will be done in about a week along with the engine brace dampers. You can just paypal $220 to rotaryextreme@aol.com and mark the subject as " light weight pulley kit" and I will get it out to you once it's done. Thanks.



Chuck Huang

Chuck,



are the belts for the pulley easily replaceable and findable???

im guessing not since this isnt a part of the intake or exhaust but would the ECU need to be reprogrammed in any way for the pulley?

kris

nah, that wouldn't be enough of a change to do anything, it'll just create less load on the engine and the computer will then look at a diffrent block of information.. Much diffrent to changing the air flow in and out of the engine... No problemo...

Those belts are regular goodyear belts. You can get them from your local auto part store.



The pulley kit does come with belts if you are wondering.



Chuck

Like dragon said, you don't need to tune the ecu. It's just like shaving some weight off your car or rims to make your car go faster. You don't have to retune the ecu for that. Adding a pulley kit will not change the fuel or ignition setting.



Chuck

is this yours chuck? i see that the bolts are not Al, but it looks similar. are people biting you already? i know you and jason are pretty good business partners though

http://66.216.67.51/product.asp?0=209&1=249&3=765

kris

Nah, that's not mine. Mine has a different design that reduces weight by 33%. He actually has those before mine came out. BTW, the bolts I use are stainless steel. Not aluminum. =)



Chuck

id hope theyre not aluminum. . . that might prove to be a problem. haha.



paul

doh, thats what i meant:):)honestly. i was just reading about uh...Aluminum and stuff. okay, honest mistake...lash me now

kris