Is there a true hp increase?
How do they increase HP?
http://cgi.ebay.com/ebaymotors/ws/eB...category=38656

 

They work because they change the speed at which they turn the belt driven accessories. They spin them at a rate in which it uses less horse power to turn them at upper rpms.

 

what is the hp gain?

 

Some info here: https://www.f150online.com/forums/sh...rdrive+pulleys

SL

 

I find the undrdrive pulley theory quite interesting.......
You put on a set of pulleys to slow down all the parasitic losses from the engine.

To get to the bottom of it you must take the system apart:

A/C compressor-if you are going to race that Hemi Dodge-turn off your A/C. That kind of eliminates that drag.


Alterrnator-the drag will change according to RPM-if it is turning slower(with underdrive pulley)it will require more torque to produce the same power. If no additional electricity is required there will be no drag on it anyways-The RPM does not matter here-it takes "X" hp to make "Y" amps at 12 volts- and your ignition system and computer requires "Y" amps.

Power steering-If you are not turning your steering wheel it takes very little power to turn the pump-the fluid is just going around in circles-it is a bypass hydraulic system.

Fan-you have a clutch fan or electric one(see alternator)-so it makes little difference.

Water pump-You have a cast iron block with aluminium heads-are you sure you want to slow that down??? It circulates the coolant to eliminate hots spots in your engine.

The 15 HP in dyno tests is with the A/C on full-the headlights on high beam, the steering wheel being cranked side to side and the fan clutch running-it is not a real world test

Just my thoughts.......John

 

get aluminum ones and u will get the most gain because it takes less force to spin that weight but on the F150's according to crash they saw 12-15rwhp gain

 

The electric fans only turn on when the coolant rises to a preset temp. or the A/C is turned on. When you're moving forward, they are normally off. The fan clutch spins ALL the time, and due to it's 10-11 pound weight, it does rob H.P. and gas mileage even when not engaged to pull max air.

The water pump pulley installed by Ford is actually OVER driven and spins the water pump faster than it needs to, so slowing it down doesn't put the motor in danger of overheating. BTW, I think we all knew that the water pump circulates coolant, but thanks just the same.

A/C on? High beams on? Steering wheel cranked side to side?? During a dyno run? Who dyno's their vehicle like that?

Bottom line is ANYTHING that turns, takes more power to turn faster than slower.

Welcome to the site. If you take the time to look through some previous posts on any given subject, you'll find that a TON of time, money and dyno runs have been poured into checking out most-if not all-the available upgrades for these trucks. Some things have come back with a negative impact, and many members of this site have been generous enough to share their findings. This particular mod is no different.

Maybe a phone call to Mike would clear things up better.

Mike Troyer
Troyer Performance/Performance Products, Inc.
Web Site: TroyerPerformance.com
(540) 862-9515
Email: Sales@TroyerPerformance.com

 

What is your personal experience?
If you do have them what did you do about the idle adjustment?

 

if u dont have a tuner u can juse port the throttle body near the flap so it raises the idle caur of increased air flow

 

No, I don't have them, YET. I have however spent hundreds of hours reading posts here about the Efans, tuners, cat-back systems and other mods that I want, but have yet to do.

Mike can make do a "custom tune" on a tuner for your truck. He can set it to raise the idle speed while doing so. You'd have to call him to set up something like that.

SL