Underdrive pulley's worth it ? really?
 

I'm sure this question has been run through the mill several hundred times.

So several hundred and one times now.

I have a 2001 F150 screw and I was looking to do some bolts ons.

Is the underdrive pulley setup any good for the 5.4 ltr?

I used to have a 95 5.0 and it pepped it up pretty good, but made the car run hot pulling hills. I changed the alternator pully back to stock and still felt gains.


What do you think. Is it worth the $50 for the new pulley setup?

I think a lot depends on what other bolt ons you are doing depending on which pulley's you go with. Here is a link I found for you.....

https://www.f150online.com/forums/19...lley-kits.html

ChrisT is right. According to Troyer there are only so many bolt on's you can do before you run out of injector capacity to make more HP. My 00 5.4 has a Troyer Tuner, Air Force Air Raid intake system, high flow cats & exhaust. Doug estimated the HP to be around 315 which is roughly the capacity of the stock injectors. If I want more ponies the injectors have to be changed.....

A electric fan setup would be a much better investment IMO.

Take a closer look at what happens when you slow down the water pump, the alternator as well as the power steering and the A/C compressor.
1. The water pump takes power away from the motor in an increasing amount as RPM rises.
2. Same for the alternator.
3. Same for the power steering pump as well as the A/C compressor.
The apparent power gains is the result of less loadng on the motor.
The consequences of doing this are less cooling capacity making the motor more load sensitive to heating.
Alternator does not charge enough 'at idle' after starting and with loads from the electrical system. The battery does not recharge as fast until the motor is at higher speeds.
Power steering pump slows down may cause a problem with increased drag when steering corrections are made.
A/C cpmpressor may not work well enough in slow traffic.
Some get away with 'accepting' some of these issue if they are present.
The min belt speed has been set up to provide the most reasonable performance without causeing issues the average owner would complain about.
Under drive pullies came from drag racing and is not meant for the street but any company will sell anything to make a buck at your expense.
It's your decision but do go into it knowing what happens/can happen when you do these things.
As a basis for compairison, you usually cannot feel less than 10 HP differences from any changes so the gains you might get from this will be about 10 or less along with one or more possible issues from doing so.

I ran underdrive pullleys for a while, e-fans would have been a better investment since i had to remove the u/d pulleys when I went supercharged...


if you have larger than stock tired (width) do not run u/d pulleys

Wow ,,,thanks guys for all the info. I wasnt sure if the fans would be a better bet , but it looks like I'm going that route.

Right now I have a K&N filter system with a 2 1/2" flowmaster exhaust from the cat back and have a poweraid throttle body spacer. I am running a diablo tuner as well. I havent re-geared yet, but was looking into the electric fans as well. I ran those on a 64 SS chevelle I restored and gained tons of power, so thats probably my next upgrade.

First off, take off that throttle body spacer. Sure it might have had gains on your carb'd Chevelle, but it actually hurts power for fuel injected vehicles.

Secondly, do the efans first. They work in conjunction with UDPs so you have more working space to do the UPDs later.

Lastly, if you do efans the compressor dosent have to work as hard, the water pump isnt a big issue as long as you have enough air going through the radiator (again, efans), and lastly that 130A alternator puts out plenty of power even if you slow it down. HOWEVER, if you run an aftermarket radio setup requiring lots of electrical loads, I would not do UDPs.

Food for thought.

i have been running UDP's on my truck for over a year now. I have 285 75 16 mud tires with a 400 watt stereo. If you have a decent battery it will be just fine. The only negative effect that I have had with mine is the power steering at idle in gear, about 590 rpm its a little tougher. In park or neutral the power steering is just fine and that is only about 700 rpm.

I like my pullies and will continue to run them. i will not hesitate to run them on other vehicles that i may own in the future as well.

Underdrive pulleys have nothing to do with fuel used. They only free up hp that have been used to turn the engine accessories for turning the rear wheels.

If a truck is used for a "truck" (hauling and towing), I think it would be a bad idea to slow down the water pump.

i have udp's and e-fans and tow all the time and never have had an issue with the temp

What? That's a pretty high estimate for the mods you have.

I'v gotten mixed input on underdrive pulleys, the guys who have talked em up run street performance cars or trucks. i havent met anyone yet who runs UDP's on a 4x4 truck who uses it off road. i'v never used them but i'v heard everything thats been writen on here before nd i'v used the e-fans a lot before on my 87 toyota 4x4, 83 elcamino, nd 73 Chevy custom 10. I'v got a flexalite dual efan setup waiting to be installed as soon as im stateside but personally i'd get a good efan setup before going to UDP's

I installed UD pulleys on my old 86 Monte Carlo SS. The alternator did not maintain voltage at idle if either the headlights were on or if the heater fan was on. That is the only symptom I noticed on that car. The power steering worked the same. Did not have any cooling problems but I was very careful about trying to avoid idling in heavy traffic. This was in NC in the summer. My MCSS came with 3.73 rear gears, so I thought it was a good candidate for UD pulleys.
I thought I noticed about a 5hp difference. It wasn't that much. The higher the engine revs the more they help.

It's been over two yrs since the mods on the truck, but I was just quoting what Doug Troyer told me when I ordered the tuner. It's not really out of the question when you think about it.

260 HP from the factory
025 HP from tuner
010 HP from air intake
025 HP from exhaust mods
___
320 HP

Again that's an estimate, but even if it's 10% too high that's still 314. If I ad it to do over again I would gear the truck lower. The 35's really dampen any seat of the pants that you would think you would get. I'm old school though, used to running big blocks. Part for part there is nothing like cubic inches, dollar for dollar is another story.