3.8l underdrive pulleys

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3.8l underdrive pulleys

January 07, 2009, 12:03:47 PM

hi i have an 86 élan with the 3,8l engine and i am intersted in underdrive pulleys i need a little bit of education on them as to will those made for 5.0l be good wich company makes the pullies for the 3,8 and all the info i should be aware of thanx everyone happy new year!

3.8l underdrive pulleys

Reply #1 – January 07, 2009, 09:43:07 PM

here is what underdrive pulleys do. An Underdrive pulley refers to an aftermarket crankshaft or accessory pulley (such as an alternator pulley) that is designed to drive a vehicle's accessories at a slower rate than stock. Underdrive from the crankshaft pulley means the pulley is smaller than the original pulley it replaces. Overdrive from the accessory pulley means the pulley is smaller than the original pulley it replaces. Originally they were invented for race cars in the 1950s and 60s, whose engines had been modified and ran at higher RPMs for longer periods of time than the manufacturers had intended. It was therefore necessary to underdrive the belt-driven accessories (among other things like the water pump) to keep the accessories from burning out and the engines running reliably. Underdrive pulleys did not become mainstream until the mid to late 1980's with their introduction from March Performance for fuel injected 5.0L Mustangs, Camaros & Trans Ams. They also appeared for small displacement engines in the mid-nineties with the entry into the market of Unorthodox Racing. These pulleys are marketed as performance enhancers that actually net additional engine torque and horsepower by reducing parasitic drag caused by belt-driven accessories, but more importantly by being lighter and reducing rotational mass. Horsepower gains from underdriving alone are usually minimal, 2-3 wheel horsepower depending on the engine. HP gains from being lighter can be significant, from 4-14 HP for normally aspirated engines and 12-25 HP for forced induction engines. These are some of the best HP improvements enthusiasts can find for their money. Be careful if your car is driven on the street to not have more than 15-20% underdrive. Some companies also offer stock diameter crankshaft and accessory pulleys. Poorly designed cheap pulleys or copies and knock-offs of major brands can have severe side effects because of too much underdrive of the alternator, power steering, and/or air conditioning units, which are not spinning fast enough. These lead to dips in alternator voltage, power assist, and air conditioning effectiveness may be noticeable, especially at idle. The headlights may dim when coming to a stop, or the stereo may lower in volume, for instance. Too much underdrive for a race car, this is not of concern, but for a daily driven vehicle it can be a major annoyance.
Changing the original crankshaft pulley can have negative effects if the replacement pulley is not manufactured properly. A crankshaft or accessory pulley that is not machined or balanced properly can cause severe damage. For most domestic V8s a harmonic damper is necessary to absorb crankshaft vibrations. Early to mid-year V8's kept the pulley and damper as separate components. Most late model V8s now integrate the damper and the pulley into one part. For small displacement engines found in many import and domestic vehicles (4.0L and under) the original crankshaft pulley only serves to quiet noise vibration and harshness (NVH) you hear in the occupant compartment. Although it may look like a damper on V8's engines it serves no protection function to the engine. It is the same as the baffles and resonators found in the intakes and exhausts systems of most cars today that serve to make the engine as quiet as feasibly possible. The first things most enthusiasts do is install high flow intakes and exhausts; the quieting function is eliminated. also the ones i use are from a 94-98 mustang v6 here is a link of the ones i used.http://www.speedconcepts.net/product_info.php?products_id=52

3.8l underdrive pulleys

Reply #2 – January 10, 2009, 05:24:24 PM

thanx alot black cougar but i was wondering if you had any ideas on eliminating the ac on my v6 i wonder if can just bolt in the power sterring pump where the ac compressor is then use underdrive pullies and find a belt with the right size whaat do you think?

3.8l underdrive pulleys

Reply #3 – January 12, 2009, 03:25:53 PM

that what i have done on my car. i will get some good pictures later.

3.8l underdrive pulleys

Reply #4 – January 13, 2009, 08:34:39 AM

thank you!!

3.8l underdrive pulleys

Reply #5 – January 13, 2009, 09:28:43 PM

I had a 87 cat with a 3.8, and the belt was just off on it. They have several v belts if I remember right.

3.8l underdrive pulleys

Reply #6 – January 18, 2009, 04:44:03 PM

if you remove the ac compressor and ac componments you would get rid of the second belt that goes around the power steering pulley and ac compressor. here is some pictures of my underdrive setup.

3.8l underdrive pulleys

Reply #7 – January 18, 2009, 04:46:35 PM

the powercoated pulley are the underdrive pulleys which are the alternator pulley and crankshaft pulley.

3.8l underdrive pulleys

Reply #8 – January 18, 2009, 08:18:13 PM

but did you get a new bracket for the power steering pump or u just bolted it where th ac compressor was also with that setup wich lenght of belt are you using?

3.8l underdrive pulleys

Reply #9 – January 19, 2009, 04:03:25 PM

in the first too pictures you see the power steering bracket well on my car it went power steering pump then in the empty spot next to it was the ac compressor was. i dont know the length but i do know the part number of the belt from advanced auto is (5060780) since they were the only people that had that belt.