I have a Greddy pulley kit (waterpump and alternator) but I consider to add an idler pulley in the airpump position to upgrade the belt touching surface on the waterpump pulley... i just don't feel convinced right now.


The Greddy kit underdrives the stock pulleys, so does it makes sense to keep them when adding the idler pulley (fe. Pineapple racing item) and just resourcing a belt that's long enough?

 

I'm sure you've seen the thread by chadwick.

https://www.rx7club.com/forum/showthread.php?t=810990

I "spoke" with him about his idler pulley setup and pulley recommendations. In short, it probably doesn't really matter what pulley you're using if you add the idler pulley ... maybe in rotational mass but we didn't get THAT into it.

I reverted back from an aluminum underdrive to the OEM waterpump pulley with anticipation of purchasing an idler kit in the very near future.

In part because of howard's posting on aluminum underdrives: https://www.rx7club.com/showthread.p...capstan+effect

 

ok... but I guess waterpump speed will be higher with a smaller pulley (Greddy's waterpump pulley being bigger)

 

You are correct; there is a trade off when changing from a stock water pump pulley to an underdrive. The stock will move more coolant at idle and low speeds, but has the potential to cavitate at higher engine rpm. With an underdrive you have reduced the parasitic load and reduce the chance of cavitation, but also move less coolant at idle and lower engine rpm.

Dan

 

So Im thinking of removing my air pump. I have an N/A 89 FC gtus with an SAFC wired and tuned. The previous owner said it was straight piped, but I checked after buying it and it looks like it still has a cat. There are lines running to it and everything. Im hoping somone can post a couple links to the things I would need for a proper delete, so I dont have any problems with it. Im willing to take necessary steps to avoid them. Ive gone through threads and tried some of the thinks but alot of them dont work anymore. Hoping someone can help me out. Thanks

I just found this link. Says its for an 89 RX7. I looked around for this garfinkle company, couldnt find it. Looks like Pineapple sells one for the FD. But rescources for the FC seem limited on this one. think it would work? 89 1989 Mazda RX-7 Accessory Belt Idler Pulley - Engine Mechanical - Gates | Drivewire.com