...Increase your fuel efficiency? With the $3/gallon price coming, I'm interested in that.

Also - are most 3pc. TBI U/D kits the same? By that I mean, I saw some for trucks that were a couple bucks cheaper than the Fbody's and the only difference I notice it the holes for the clutch fan bolts in the water pump pulley.... are they the same other than that?

 

pulleys are a waste of money. they don't add any distinguishable hp and they dont' do much if anyting for mileage.
if you want to free up resistance with a bolt on get an electric water pump. you eliminate teh mass of the pulley and the shorter belt is lighter, along with all the energy it takes to actually turn the pump.
most of the common lines are perfectly acceptable for years of street use and even have 3 or 5 year warranties.

later
tim

 

Okay, apparently, the pulleys topic is about the same as the spacer topics. Nobody likes them, but almost everyone has them for some reason....

Any other opinions?

 

yeah, save your money for the pump -- you'll need it

j/k - never used 'em, always interested though. But for a few more ponies (theoretically), is it really worth underdriving your electrical and cooling systems ?

 

Well, in theory, yes, I do think, if the reward was in fact improved efficiency, that it would be worth underdriving those systems at idle.

The Alt reaches peak output at around 1800-2000 RPM, and I don't know about the water pump - but I do know that bearings do not like being spun faster than they have to.....
... BUT if there was nothing to gain, then I don't see the point, your right.

 

I think the u-drives can save some power if your motor has to spin to 6k to make its peak power but the problems at idle wouldnt be worth it. The alt. wont be able to maintain much load and with all your accessories on youll be draining the battery at low speeds. In addition, youll also be pumping less coolant through the engine at idle, which means the possibility of hot spots and poor cooling. Even worse is if you have a belt driven fan, it too will turn slower and further impede the cooling systems ability to keep the motor from overheating at idle.

 

Then not to mention that the slower turning alternator and lack of an adequate charging voltage can confuse sensors or even turn the computer off. The ignition system will also recieve less voltage which in turn will hurt its ability to fire the plugs.

 

Well, thanks for the opinions guys, I guess I will forget about that mod, LOL.

 

People tend to buy them because they are a cheap inavasive mod that can be installed with hand tools and a 6 pack. Cheap and easy to install parts are more attrative to car modders than power gains.

 

I have underdrive pulleys on my 305 TBI, and I have had no problems with them at all.

I'm not sure if I've gained any performance from these or not, as I have no way of testing because I've never been to the track or to the dyno.

But in theory they should free up some extra ponies. And I'll take any extra power I can get.

 

I own the ASP Crank and Alternator underdrive pulleys on my 3.1.

Waste....I took the alternator pulley off the very first day because,I was actully afraid of the car stalling at a long light or in traffic.And I do like to warm up my car because I have a remote starter.Definatly not worth it for the $70 for pulleys and $20 for the belt.I felt no real increase after installing but I noticed the engine reved up easier if I were to put it in neutral and hit the gas.Other than that,their useless....

 

Case in point, underdrive pullies are proven to work. Period.
With that being said however, you need to look at your needs. In a daily driver, or even a second street car, you should stay away from the alternator pulley and water pump pulley. Only use a crank pulley. Install a cooler stat and a fan switch and you will be fine.

Also keep in mind that if you plan on removing the smog pump, install the underdrive crank at the same time. That way you only need to invest in a new belt once.

Then look at your money vs mods vs power output. Is $70 ($50 if you already plan on removing smog pump) worth the 10hp gain you may see at 5,000rpm?

Last but not least, keep in mind electric water pumps are pretty expensive to make work with our accesory brackets. So even if you buy a pump for $250, you need to either fab something up or purchase aftermarket brackets. Or you can go with the $450 pump for our cars......but then again you need to ask yourself if it is worth it at your current point in mods. Remember also electric water pumps will free up power on the same curve as the underdrive pulley.

So, would you rather spend $70 for roughly 10hp, or $450 for maybe 15hp if you are lucky.......

 

Also, I am sure someone will try to use the cooling aspect of electric water pumps in defense. But keep in mind that in most cases, modded L03s are still not going to see over 250hp, and the high flow rates offered from electric pumps are not going to benefit these engines. The stock pump with an underdrive crank works fine given a cooler stat and fan switch.