Underdrive pulleys

I have never done and underdrive pully. I wouldnt trust one. Seems you might over rev the engine or oil pump. Best bang for your buck, cat removal.

Your MPG goes up and so does ur HP. TQ might go down a bit.

Did i read that some of you are wanting to MAKE ur own? If it doesnt have a dampener in the pulley your going to get much more vibration while at idle and cruising.

-Ant.

 

I ran underdrive pulleys on my import racers. What it's doing is freeing up drag. Same concept as taking off the belt that turns your power steering pump. No power steering, but you will notice the motor will wind up quickly without it. I would definately run the Underdrive pulley for my truck. The amount of accelleration gained, compared to the lost of ie.. alternator charge, and power steering control, is well worth it. I do not however recommend trial and other. Let the pro's do their job and trial & era it for us. Then you can go out and purchase the finished proven product.

Oh... and the pulley on the crank is the way to go. All your center mass is there, so underdrivng will allow you to rev up quicker utilizing less horse, hense the term Underdrive=underworking your crankshaft. Less load = more power...

 

i saw something over at xr-underground.com that nonstoptuning is making a crank pulley for the 4.0, supposed to be half the weight, increase HP, MPG and torque. is this safe for your engine, is it worth the investment?

 

I don't know dude...I'm just posting to see if I have that little green dot under my name.

 

Yup! I got one!

 

http://www.marchperf.com/underdrive2.html

 

I just saw these...very tempting. Does the original crank pully act like a counterbalancer though ....where as a true underdrive pully is smaller but might weight the same. This one is the same size but lighter. I've never used one of these personally...so I don't know.

 

In theory you'll "free up" the horsepower absorbed by turning large pulleys- The gains will be limited without SERIOUS engine modifcations but doable.

I think that you will spend more money on other mods- but you'll get better gains out of those- without needing to daisy chain mods together.

I had a 5.2L supercharged engine on a 5 spd tranny with a corvette fuel system and some other treats- and even with all that work done- I still hadn't dropped an underdrive into it. (but that's just the Bruno Garage Magic)

 

Common mod on Nissan Frontier. I did it on my Frontier back in 2005. Worked great. Did make a difference, no Dyno data, but seemed significant.

 

Anyone know if an underdrive pulley ever came out for the 2nd gen Tacomas and how it has gone?

 

it's a pretty common performance mod. URD sells a ton of pulleys. I bet they have one that would work. a simpler mod would be to turn off the A/C. free HP.

 

Love my A/C. Need it here on the coast.

 

https://www.nonstoptuning.co/store/p90/2005-2015ToyotaFJTacomaXRunnerPulleyKitNST06150K.html

 

There was a groupbuy a while back for these. If you post in the magnuson supercharger thread you'll get good feedback.

 

This has got to be the oldest thread revival I've ever seen on here

Im curious, are we talking about UNDERdriving just the alternator or the entire accessory drive system (main pulley)?

 

The OP looks to be talking about underdrive pulleys, but the only ones available that I've found and linked a few posts above this, are not underdrive pulleys. They're just lightened versions of the OEM ones, which is what you want. I've ran underdrive pulleys before for awhile on an NA 4 cylinder, and while it definitely made the throttle response and power delivery quicker, I wouldn't use underdrive pulleys if I would do it again. Lightened pulleys do exactly the same thing and will get you the same results without sacrificing powering your accesories in the process.