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SR Performance Underdrive Pulleys - Polished (86-93 5.0L)

Market Price $119.99 You Save 25% ($30.00)
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$89.99

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  • Item 525568
  • MPN# 525568

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Features, Video & Details

  • Free Up Horsepower
  • Complete 3 Piece Kit
  • Durable, Lightweight Aluminum
  • Polished Finish
  • Premium Quality Construction
  • Fits 1986-1993 5.0L V8 Mustangs

Review & Installation Video

Review & Install Video

Hey guys, Adam here with americanmuscle.com. Today I'm bringing you a detailed overview and installation of the SR Performance Polished Underdrive Pulleys, fitting all '86 to '93 5 liter Mustangs. In this video I'll be going over exactly how underdrive pulleys work and what they are in regards to the benefits to your engine. I'll talk about the materials and construction, and I'll top the video off with the installation, which I'll let you know upfront here, underdrive pulleys are a very simple bolt-on mod, something that will get a one outta three wrenches on our difficulty meter. The SR Performance Underdrive Pulleys in the polished finish we have here today will be for any '86 to '93 5 liter Mustang owner who might be looking to free up some of the energy that the engine is using to power the factory pulleys in order to free up horsepower that can be used in other performance mods. Now on top of that, the installation is extremely simple, it's a very simple bolt-on mod here that we'll talk about a little later in the video, but upfront this is something that just allows you to pick up some horsepower in other areas instead of using that power for the factory pulleys. So the first thing I wanna touch on exactly is what are underdrive pulleys, what do they do, and what benefits do thy have for your engine. Now in a nutshell, underdrive pulleys basically cut down on parasitic drive train lost by reducing the amount of power it takes to run your accessories like the alternator, the AC compressor, and the water pump. So to explain that a little bit further, the engine basically uses it's own power to run all the pulleys together starting at the crankshaft pulley or the drive pulley. Now this particular pulley can actually be reduced in size to use less power which can eventually use less power on the engine and free up around 10 to 15 horsepower. So right here I wanna mention that freeing up 10 to 15 horsepower does not mean that you're gonna gain 10 to 15 horsepower from adding underdrive pulleys. What that basically means is now instead of using that extra power on the factory pulleys, you have underdrive pulleys in their place and that power can be redirected to other performance mods, such as the bolt-ons like a cold air intake, intake manifold, cylinder heads, cam, exhaust, things of that nature. Now you have the ability to add 10 to 15 horsepower with other mods such as those. Now another valid question you might be asking is, if you're reducing the size of the crankshaft pulley, wouldn't that mean that you're alternator isn't running at full capacity, which of course affects a lot of different things in the engine and the car alone? Now that's a valid question for sure, but of course when you're reducing the crankshaft pulley size, you're also gonna compensate by adding other pulley sizes as well. The changing in these sizes of the pulleys can actually reduce the amount of stress going on the engine and it'll run absolutely at maximum potential, of course. Now if you're running a smaller pulley for the alternator which we have here with the underdrive pulleys and you're running, like, a massive amplifier in your trunk, you might see a little less power, but of course it's nothing to really ruin any driveability, you just wanna make sure you're checking with your amperage and things of that nature with your alternator as well as your amp. So everything you can expect as far as pulleys are concerned, you can see right here on the table with me today. Everything you see here, you would get a crank pulley, an alternator pulley, and of course a water pump pulley. Now all these come in with SR Performance being one of the most budget-friendly options on the market. Now reducing the parasitic drive train loss is very simple with just shy of a hundred bucks. Now my personal opinion, it's not too bad of a price for this considering you'll be freeing up 10 to 15 horsepower. Now redirecting that power could definitely mean the w

Free Up Horsepower. A set of SR Performance Underdrive Pulleys reduce parasitic drivetrain loss by cutting down the amount of power your accessories take up, these underdrive pulleys will free up 10+ horsepower, without sacrificing cooling and charging functionality of your Pony.

Premium Quality Construction. CNC-machined from lightweight aircraft grade quality aluminum alloy for strength and durability, these SR Performance pulleys feature a bright polished finish that will give your engine bay an eye-catching high performance appearance.

Easy Installation. These SR Performance Mustang Underdrive Pulleys installs quickly and easily in under 2 hours with no modifications required.

Application. This SR Performance 3-Piece Aluminum Underdrive Pulley Kit is designed for use on 1986 to 1993 Ford Mustangs equipped with the iconic push rod 5.0L V8 engine, including the LX 5.0, GT and SVT Cobra models. Reuses stock belt.

Fitment: 1986 1987 1988 1989 1990 1991 1992 1993 Details

What's in the Box
  • (1) water pump pulley
  • (1) alternator pulley
  • (1) crank pulley
  • (4) bolts
Installation Info
Tech Specs
UnderDrive Pulley Specifications
Year/Model: 1986-1993 5.0L V8  Manufacture: SR Performance
Material: Aluminum  Finish: Polished
Crank Pulley: Piggyback SFI Certified: No
Will it fit my Mustang?
  • Foxbody - 86, 87, 88, 89, 90, 91, 92, 93
  • Cobra - 93

Fits 5.0L V8's Only

People Who Bought This Item Also Bought

Most Helpful Reviews

4/5
underdrive pulley install

Pulleys are as described, only problem is wrong size bolts for the crank pulley had to source locally, that is why the install took all afternoon

Helpful (2)

4/5
Worth every penny spent!!!

Quick and simple installation, got them on Black Friday , worth the wait !

Helpful (2)

Overall Rating 4.6 out of 5 stars
Read All 43 Reviews

Customer Photos (4) Submit Your Photo

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3 Questions / 3 Answers

Ask a Question

Has the issue with the crank bolts been resolved yet? I want to order this kit, but with the complaints about the crank bolts being the wrong size has put me off. The last thing I want to do after I get everything apart is to have to stop what I'm doing and go buy the correct ones.

RonL

  • The SR Performance Underdrive Pulleys have been corrected in all of our recent batches received from the manufacturer.

    Rob D

Helpful (0)

Can you use the stock size serpentine belt? A different review said the belt needs to be an inch bigger, is this true?

Dmass

  • The SR Performance Underdrive Pulleys are designed for use with a stock belt length.

    Rob D

Helpful (0)

What are the dimensions of the pulleys? Diameter specifically

Chris

  • The alternator pulley will be about 2.5" in diameter, the crank pulley will be about 4 3/4" in diameter, and lastly, the water pump pulley will be about 5 1/4" in diameter.

    Ricky36

Helpful (0)

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Customer Reviews (43) Write a Review

Overall Rating 4.6

out of 5 stars

Installation Time:Less than 1 Hour

  • Performance Gain 4.432433 4.4
  • Fit 4.810811 4.8



  • 4/5

    Installation Time: Afternoon

    December 11, 2015

    underdrive pulley install

    Pulleys are as described, only problem is wrong size bolts for the crank pulley had to source locally, that is why the install took all afternoon

    scooter

    Year: 1989 Submodel: Other Alvin TEXAS

    Helpful (2)

  • 4/5

    Installation Time: Less than 1 Hour

    December 10, 2015

    Worth every penny spent!!!

    Quick and simple installation, got them on Black Friday , worth the wait !

    Luigi2707

    Year: 1986 Submodel: GT Atlanta ga

    Helpful (2)

  • 5/5

    Installation Time: Afternoon

    January 19, 2017

    Pulleys

    It was very easy to install and matches my engine dress

    Jay

    Year: 1991 Submodel: Other

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    December 12, 2016

    Fit and look great

    Went right on no problems, great product for the money

    Tolli21

    Year: 1988 Submodel: GT

    Helpful (1)

  • 5/5

    December 12, 2016

    Great Product

    Easy fit and look great same problem with underdrive pulley bolts tho

    B

    Year: 1987 Submodel: Other

    Helpful (1)

  • 5/5

    August 14, 2016

    Review from SR Performance Underdrive Pulleys - Black Aluminum (86-93 5.0L)

    Underdrive pulleys

    Great product. Light weight yet still strong. Durable paint with a great finish. Match my steel bbk underdriver pulleys and are 25 of the weight.

    Stangman351

    Year: 1991 Submodel: Other

    Helpful (1)

  • 4/5

    July 21, 2016

    Looks good, but wrong bolts

    Bought these while they were on sale a few months back. The kit includes 4 bolts that appear to be crank pulley bolts, but they're far too small, and they're also too big for the water pump pulley. The heads on the bolts I already had on my stock crank pulley were too large and interfered with the wall of the underdrive pulley, due to its much smaller diameter. So because my original bolts (possibly not factory as the car has a previous owner) had heads that were too large, and the provided bolts were too small, I chose to purchase a set of ARP's. Smaller bolt heads, better clearance, better quality. BE WARNED As the description states, these pulleys are designed to work with fox's with factory pulley accessories. My car had the AC and smog pump removed many moons ago before it was mine, and so I had to shop around for a bit to find a belt that would fit. Finally got it all together and so far I'm happy. Slightly quicker throttle response, and the engine bay just looks that much prettier. I've also been told that underdrive pulleys frequently result in the engine running hot due to the fan and water pump running slower-than-stock with the pulley ratio change. I have yet to run it in any weather over 80 degrees F, but I haven't seen any cooling issues yet.

    ManBearPig

    Year: 1986 Submodel: Other

    Helpful (1)

  • 4/5

    July 20, 2016

    Review from SR Performance Underdrive Pulleys - Black Aluminum (86-93 5.0L)

    They look like a quality product

    I haven't installed them it ran into issues with bolts

    oxford1970

    Year: 1989 Submodel: GT

    Helpful (1)

  • 4/5

    Installation Time: Less than 1 Hour

    June 20, 2016

    Fantastic to a certain extent!

    Is it all in my head or does every little bit help because now i can't hardly take off with out spinning the tires. The pulleys are top quality and a beautiful finish. They do come with new allen head bolts because the crank pulley is going to be so much smaller that the original bolts will not work. You will not get a regular socket on them. They give you new bolts but you might as well just throw them a way. I've read so many reviews where other people say the same thing and you would think they would get it right after awhile but on my 1988 fox they did not. You will be going up to the hardware store to finish this project. The job is simple but could be do much more if you just got the right parts!

    Richard

    Year: 1988 Submodel: GT

    Helpful (1)

  • 4/5

    Installation Time: Less than 1 Hour

    December 14, 2015

    Crank bolt issue

    Having an issue, the 4 crank pulley bolts that were sent with the pulleys do not fit. The diameter is off. The original crank bolts will not work because you cannot tighten them with the smaller pulley.

    Adam

    Year: 1987 Submodel: GT

    Helpful (1)

  • 4/5

    Installation Time: Less than 1 Hour

    December 10, 2015

    Nice product nice price

    Quick install. They look great shame you have to put a belt over them. Not a huge performance upgrade...but it all adds up.

    VEGASbabyVEGAS

    Year: 1989 Submodel: Other Reno, nv

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    December 10, 2015

    Good Value

    Good bang for the buck, easy installation. Overall good product for the money.

    JDC

    Year: 1989 Submodel: Other Benson, NC

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    November 13, 2015

    Great throttle response

    Good looks and great throttle response with a little bump in power

    Rocket

    Year: 1988 Submodel: GT Piedmont SC

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    September 18, 2015

    Review from SR Performance Underdrive Pulleys - Black Aluminum (86-93 5.0L)

    Amazing power gain!

    The pulleys were super easy to install the only took roughly 20 mins!! You will feel the power gain it was really noticeable specially enough to get a speeding ticket, but on a side note your stock serp belt will not fit with the new pulleys. I went an inch and half smaller and it fit perfect!!

    Foxmonster86

    Year: 1986 Submodel: GT Post Falls, ID

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    May 29, 2015

    Warranty- Quality - Technical Support Managerial @ Blue Giant Equipment Corp, Loading Dock and Material Handling Equipment

    Excellent product, Overall, outstanding performance and looks. Strongly recommend it.

    UHURT

    Year: 1989 Submodel: Other Atlanta, GA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    December 11, 2014

    Review from SR Performance Underdrive Pulleys - Black Aluminum (86-93 5.0L)

    more horses

    Easy to install less than an hour. Great upgrade for your mustang.

    Erikkk30

    Year: 1988 Submodel: GT San Benito, TX, USA

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    September 06, 2017

    Review from SR Performance Underdrive Pulleys - Black Aluminum (86-93 5.0L)

    Five thumbs up

    Beautiful pieces and fit as they should! Lightweight and strong

    Rogerb2

    Year: 1987 Submodel: GT

    Helpful (0)

  • 5/5

    July 15, 2017

    Review from SR Performance Underdrive Pulleys - Black Aluminum (86-93 5.0L)

    Great product

    Good quality pulleys, easy to install and new hardware

    Ironreaper

    Year: 1993 Submodel: LX

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    June 30, 2017

    Review from SR Performance Underdrive Pulleys - Black Aluminum (86-93 5.0L)

    Easy bolt on

    These pulleys look great and are easy to bolt on. Engine revs faster

    danield

    Year: 1979 Submodel: Other

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    June 28, 2017

    Review from SR Performance Underdrive Pulleys - Black Aluminum (86-93 5.0L)

    The perfect underdrives

    Clean and accurate. No wobble. A good powder coat.

    dnstommy

    Year: 1993 Submodel: LX

    Helpful (0)

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