Can anyone tell me what "underdrive" pullies are and what is bad about it? and are all of the sold lightened pully sets underdrive?

 

If you put 'underdrive' pulleys on, the accessories (alternator, a/c, water pump) will turn slower, robbing less power from the wheels and making quite a difference at high revs.

HOWEVER, the alternator will be real slow at idle, lights may flicker at a stop sign.

The a/c is only marginal at full speed, if you slow it down anymore.......

The water pump is kind of important, if you slow it down, you will PROBABLY be o.k., you just won't be circulating the amount of coolant Madza intended, but if you ever have a warranty claim that involves any kind of overheat situation, you are toast.

So for a couple of peak horsepower, you have voided the warranty on the aircon, the engine, and anything electrical.

But they come in some really nice colors....

S

 

I agree with Stealth, except that it needs to be pointed out that not all underdrive pulley sets cause problems. A well designed set that only underdrives a small amount (say, 20% or less) will probably be fine.

 

Would just a underdrive pulley have problems? Not wonting to change alt, and water pump at this time.

 

How about same size pulleys, but just lighter. Would that make a difference?

 

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/new-rx8-owner-faq-1-25-09-a-163824/

 

thanks that helped.

 

We ran a test and my AC was a consistent 2 to 4 degrees cooler than the RX 8 with an under drive pully.

 

Shouldnt it be the opossite.