one of the "standard" mods that people with 300zx's perform is to install a set of Unorthodox Racing Underdrive Pulleys, they free up about 15-20rwHP...

is there some reason why an underdrive pulley install would NOT be a good idea on a 13B?

an easy gain of 20HP or so seems an appealing prospect, yet i don't see anyone mentioning UD pulleys for rotaries. Why aren't they a common upgrade item for rotary owners?

if they are a viable option, mechanically & financially, where is the best place to get a set for an FC?

Thanks!
Perry Gehenna
www.AusRotary.com

 

I had a Unorthadox Racing Underdrive pulley for my MR2 before, it kinda became a hassle because my alternator belt would become loose always.... makinig that terrible sound.. ack..
But then the MR2 alternator is much harder to get to than the RX7 alternator!
It's ur call tho!

 

I put on a dual Alt. pully on my T2 after I removed the air pump. It does help free up some pw and equals out the balance for the belts while saving some weight as well (Without the air pump) I doubt if this mod is worth that much HP, it might not be what you mean?

 

The drawback of the UR pulley is you have to take out the eccentric shaft nut . Then when they go to install the UR, the thrust washer falls out of place inside the shaft itself, causing oil leakage. With that said, I bought one before I knew about it and had our local Mazda performance shop install and have no problem with it. I couldn't really tell any HP difference but when we installed it my wife was driving it daily, not me so my butt dyno was calibrated Wife said she thought it felt faster when she would gun it in traffic. I think RX-7.com has one that you don't have to take out the eccentric shaft nut.

Tim Benton

 

hmm.how could that be?the eccentric shatf bolt holds on the front hub..i dont have a ud pulley,but the stock one bolts to the hub with 4 small bolts,you never have yo touch the eccentric shaft bolt to get it off or on.i would think that a aftermarket unit would have to be mounted in the same manner...

 

UD pulleys are for high-rpm engines, where they are necessary to keep the water pump from cavatating and your accessories from burning up. If you are running at high rpm's, then you will need the pulleys. Otherwise, I would stick with the stock pulleys, and just remove any accessories that you don't need. Removal is free, saves weight, and eliminates belt friction, while UD pulleys cost $ and just make your accessories run worse. Would you really want to run your water pump and alternator slower in city traffic? Besides, I don't see where you would get much of a HP increase with the UD pulleys, because completely removing the air pump, for example, only gains about 1 HP. I think that the best thing to remove would be the PS pump, and then just go with a manual steering rack, which performs much better IMO.