Ford

What do Underdrive Pulleys do? Underdrive pulley systems increase engine horsepower by reducing the amount of power required to drive external engine accessories. For example, the alternator, power steering, water pump and air compressor rob horsepower from the engine. By replacing factory-sized crank and accessory drive pulleys with a resized pulley, the accessories are slowed, resulting in more horsepower available to the drive wheels. Typically, a set of Auto Specialties street pulleys will increase horsepower by 12-15, and increase mileage by 2 to 3 MPG. All pulleys are manufactured from Billet Steel or Aluminum, exceeding factory quality.

Nitride Overdrive Alternator Pulley

Nitride Overdrive Alternator Pulley

4.6L - 2 & 4 V, Ford Mustang Short Water Pump Pulley

Some street systems require the use of the short water pump pulley. Before ordering please check to see if your vehicle uses this design water pump pulley. Part # ASP520123 *
79-93
Underdrive Kit w/grooved WP
829125 ODG
79-93
Cobra WP
Year Engine Pulley Description Full Charge Info Image Nitride Zinc Hard Coat Black Alum Hard Coat Blue Alum Hard Coat Red Alum Hard Coat Clear Alum
05-07 4.6 L GT 25% HarmonicDampner
8% up 90
- - Image ASP527305
$244.95
- - - - -
01-04 4.6 GT 25% HarmonicDampner
26% Water Pump
8% Alternator
950 RPM Info - ASP522328
$244.95
- - - - -
99-01 4.6 Cobra 25% HarmonicDampner
26% Water Pump
10% Alternator
950 RPM Info Image ASP522375
$244.95
- - - - -
96-00 4.6 GT 25% HarmonicDampner
26% Water Pump
8% Alternator
950 RPM Info - ASP527328
$238.95
- - - - -
96-00 4.6 Cobra 25% HarmonicDampner
26% Water Pump
10% Alternator
950 RPM Info Image ASP527375
$238.95
- - - - -
96-00 4.6 GT 25% Alum Spacer
26% Water Pump
8% Alternator
950 RPM Info - ASP527728
$136.50
- - - - -
96-97 4.6 Cobra 25% Alum Spacer
26% Water Pump
8% Alternator
950 RPM Info Image ASP527775
$136.50
- - - - -
94-95 5.0 26% Crank 750 RPM Info - ASP523500
$55.00
- ASP823500*
$57.00
- - -
94-95 5.0 26% Crank
30% Water Pump
2 3/4" Alternator
950 RPM Info Image ASP525928
$109.95
- ASP825928*
$118.95
- - -
79-93 5.0 25% Crank 850 RPM Info - ASP520100
$59.00
- ASP820100*
$60.00
- - -
85-86 5.0S/Tran 25% Crank
2 3/4" Alternator
1100 RPM - - ASP520105
$74.95
- ASP820105*
$74.95
- - -
79-93 5.0 25% Crank
15% Water Pump
850 RPM Info - ASP520120
$89.95
- ASP820120*
$91.95
- - -
79-93 5.0 25% Crank
15% Water Pump
1 7/8" Alternator
700 RPM - - ASP520124
$101.95
- - - - -
79-93 5.0 25% Crank
15% Water Pump
2 1/2" Alternator
950 RPM - Image ASP520125
$101.95
- ASP820125
$112.95
ASP829125
$112.95
ASP822125
$112.95
ASP824125
$112.95
79-93 5.0 25% Crank
15% Water Pump
2 3/4" Alternator
1100 RPM - - ASP520128
$105.95
- ASP820128
$114.95
ASP829128
$114.95
ASP822128
$114.95
ASP824128
$114.95
79-93 5.0 25% Crank
15% Water Pump
3 1/2" Alternator
1500 RPM - - - - ASP820126*
$184.95
- - -
2001 4.6 GT 26% Water Pump Pulley
Short water pump
950 RPM - - - - ASP520123
$60.50
- - -
79-93 - Cobra WP Pulley - - Image - - ASP520141
$75.00
- - -

Mustang V6


1994-98 3.8 L Ford Mustang Crank Pulley

25% Reduction Crank and Alternator Pulley Kit,
This pulley kit will give you 9+ Rear wheel HP.
Part# ASP826308
Above images in order from left to right; 1999-00 3.8L V6 stock dampner / new stock dampner with factory pulley removed / new 25% reduction crank pulley and new harmonic dampner
All ASP 25% Underdrive Street System Harmonic Dampner Design add 10+ Rear wheel HP.
Part# ASP820117 & ASP820122 *




Year Engine Pulley Description Full Charge Info Image Nitride Zinc Hard Coat Black Alum
2011 3.7L 25% dampner 850RPM - - - - ASP520144**
$265.00
05-10 4.0L 25% dampner 850 RPM - - - - ASP526400**
$265.00
01-04 3.8/3.9 25% Dampner Crank Pulley 950 RPM Info - - - ASP820122
$318.00
99-00 3.8 25% Dampner Crank Pulley 950 RPM Info - - - ASP820117
$318.00
94-98 3.8 25% Crank 950 RPM Info - - - ASP826300
$109.95
94-98 3.8 25% Crank2 3/4" Alternator 950 RPM Info - - - ASP826308
$115.50
* Clear HC., Red and Blue also available.
** Will not work on LS Lincoln

Adjuster Bracket

84-93 5.0 Adjuster Bracket - - -  ASP020400*
DISCONTINUED
- -
* Allows you to retain factory belt with part no. 520100 & 520120.

1989-94 Thunderbird Super Coupe 3.8L V6L V6

1989-94 3.8L S/C Blower Pulley

10% Blower Overdrive Pulley Adds 3 PSI Boost,
Adds 12+ HP Part# ASP52009

1989-94 3.8L S/C Street Pulley Kit

Street Pulley Kit 25% Reduction Crank Pulley,
29% Water Pump, 3" Alt.Part# ASP520425
Year Engine Pulley Description Full Charge Info Image Nitride Hard Coat Black Alum
94-97 4.6 25% Harmonic Dampner 26% Water Pump 15% Alternator 900 RPM Info - ASP527328
$238.95
-
94-97 4.6 25% Crank 26% Water Pump 15% Alternator 900 RPM Info - ASP527728
$136.50
-
89-95 3.8 SC 10% Blower Overdrive Adds 3 PSI Boost 950 RPM Info - ASP520009
$79.95
-
90-98 3.8 25% Crank 2 3/4" Alternator 950 RPM Info - - ASP826308
$115.50
90-93 5.0 25% Crank 29% Water Pump 2 3/4" Alternator 950 RPM Info - ASP523528
$119.95
-

Crown Victoria / Grand Marquis

Year Engine Pulley Description Full Charge Info Image Steel
81-89 5.0, 351W 25% Crank 850 RPM - - ASP928900
$150.00

Contour / Cougar with SVT Duratec

Year Engine Pulley Description Full Charge Info Image Clear HardCoat Alum
95-99 2.0L 15% Reduction 800 RPM Info Image ASP840110
$124.95

Ford Truck

Year Engine Pulley Description Full Charge Info Image Nitride Zinc Hard Coat Black Alum
02-09 4.6, 5.4 25% Harmonic Dampner26% Water Pump 850 RPM Info - ASP527374
$227.95
- -
97-01 4.6, 5.4 25% Harmonic Dampner26% Water Pump 850 RPM Info - ASP528774
$227.95
- -
01-07 4.2 Harmonic Dampner25% Crank Pulley 850 RPM Info - - - ASP820130
$318.00
99-00 4.2 Harmonic Dampner25% Crank Pulley 850 RPM Info - - - ASP820129
$318.00
97-98 4.2 25% Crank Pulley 850 RPM Info - - - ASP826300
$109.95
92-08 3.0L Ranger 20% Crank Pulley 850 RPM Info - - - ASP821120
$109.95
90-03 4.0L Ranger/Explorer 25% Dampner 900 RPM - Image - - ASP526400
$265.00
80-86 5.0, 5.8 30% Crank 800 RPM Info - ASP523000
$130.00
- -
80-86 5.0, 5.8 30% Crank3" Alternator 1000 RPM Info - ASP523003
$150.00
- -
87-97 5.0, 5.8 30% Crank 850 RPM Info - - - ASP820100
$60.00
87-97 5.0, 5.8 30% Crank15% Water Pump 1100 RPM Info - ASP520120
$89.95
- -
93-94 2.3 25% Crank 1000 RPM Info - - - ASP926500
$175.00

1999-2004 SVT Lightning Truck

1999-2004 5.4L Blower Pulley

1999-04, - 5.4 L Ligntning Truck Blower Pulley, 2.80", adds 3 psi to engine and 23.2 extra hp,
Part# ASP520003 *
Year Engine Pulley Description Info Image Nitride Hard Coat Black Alum
99-04 5.4 Blower Compressor Overdrive Pulley 2.93" Diameter(+3 to 4"psi) Info - ASP520002
$109.95
-
99-04 5.4 Blower Compressor Overdrive Pulley 2.80" Diameter(+2 to 3"psi) Info - ASP520003
$109.95
-
99-00 5.4 Blower Crank Pulley 8.40" Diameter (+4"psi)
Info - - ASP820116ps
$200.00
01-04 5.4 Blower Crank Pulley 8.40" Diameter (+4"psi lightning +2"psi harley)
Info - - ASP820116aps
$200.00
99-00 5.4 Blower Crank Pulley 9.00" Diameter (+6"psi)
Info - - ASP820116ps9
$200.00
01-04 5.4 Blower Crank Pulley 9.00" Diameter (+6"psi lightning +4"psi harley) Info - - ASP820116aps9
$200.00
How to install the ASP Blower Crank Pulley in just 1 hour! Click-Here for more info.
How to install the ASP Blower Pulley in just 1/2 hour! Click-Here for more info.

Early Model Crank Pulleys

Year Engine Pulley Description Info Image Steel
65-69 289 (3 Bolt) 25% Reduction - 1 V-Groove - - ASP922900
$125.00
65-69 289 (3 Bolt) 2 V Grooves - - ASP924200
$150.00
70-78 302, 351 W 25% Reduction - 1 V Grooves - - ASP924000
$125.00
70-78 302, 351 W 2 V Grooves - - ASP924100
$150.00
68-87 429, 460 25% Reduction - 3 V Grooves - - ASP925600
$150.00

Alternator Pulleys

Nitride Overdrive Alternator Pulley
For Serpentine Belt Systems
32% overdrive alternator pulley.
Increased charging capacity.
CNC -machined billet steel nitride coated.
Year Engine Pulley Description Info Image Nitride Zinc Hard Coat Black Alum
- Early Model 3 1/4" 1 V-Groove - - - - ASP820003
$80.00
79-95 5.0 1 7/8" Alternator - - ASP520004
$26.50
- -
79-93 5.0 2 1/2" Alternator - - ASP520005
$26.50
- ASP820005
$26.50
79-95 5.0 2 3/4" Alternator - - ASP520080
$26.95
- ASP820080
$26.95
79-93 5.0 3 1/2" Alternator - - - - ASP820006
$95.00