what are these about???

http://www.jusnesmodified.com/store/...roducts_id=434

 

http://en.wikipedia.org/wiki/Underdrive_pulleys

Low cost way of boosting torque and horsepower.

 

so they're legit... Who runs em here?

 

Yeah there legit but don't expect much!
Probubly way less then an E fan.

Phil

 

the thing you need to remember with underdrive pullies is that your not adding any more power than the engine already produces, merely moving wasted power to the rear wheels. so you will not notice any HP with a seat of the pants test, but if you put it on a dyno, you should get 10-15HP at the wheels or notice a shorter 1/4 mile, depending on the variables involved. and yes they are worth it.

 

I wouldn't buy them because they turn the accessories slower, like the alternator, AC comp. They work well on smaller vehicles, but not so much on these bigger heavier trucks.

 

10 or 15 rwhp?

Phil

 

I would recommend doing efans first as you would have to remove the fan anyway to do the UDPs, plus they work in unison to free more horsepower.

And I've seen a few dynos with some trucks going up to 11 RWHP with a Troyer Kit.

 

I find that hard to believe.
Was it dynoed before and after on the same day,temp and all?

Phil

 

X2. I would not put them on anything I own.

 

If you look at the kit he posted a link to it says it has a bigger pulley for the alternator.

Phil

 

They are worth it for someone who is just wantin a little extra there will be a slight notice. and if you buy the right kit the accessories wont be slowed down you can buy just one pullies the kits with three keep them a stock specs. if you are going for a full bolt on truck you should try them.

 

only thing affected by turning slower is the alternator, with has an overdrive pulley for it so it evens out back to stock. a slower waterpump, compressor, or ps wont hurt it