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.

79-93
Underdrive Kit w/grooved WP
829125 ODG

79-93
Cobra WP

Year	Engine	Pulley Description	Full Charge	Info	Image	Nitride	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	–	–		ASP527305 Discontinued	–	–	–	–
01-04	4.6 GT	25% HarmonicDampner 26% Water Pump 8% Alternator	950 RPM		–	ASP522328 $313.95	–	–	–	–
99-01	4.6 Cobra	25% HarmonicDampner 26% Water Pump 10% Alternator	950 RPM			ASP522375 $313.95	–	–	–	–
96-00	4.6 GT	25% HarmonicDampner 26% Water Pump 8% Alternator	950 RPM		–	ASP527328 $310.91	–	–	–	–
96-00	4.6 Cobra	25% HarmonicDampner 26% Water Pump 10% Alternator	950 RPM			ASP527375 $310.91	–	–	–	–
96-00	4.6 GT	25% Alum Spacer 26% Water Pump 8% Alternator	950 RPM		–	ASP527728 Discontinued	–	–	–	–
96-97	4.6 Cobra	25% Alum Spacer 26% Water Pump 8% Alternator	950 RPM			ASP527775 Discontinued	–	–	–	–
94-95	5.0	26% Crank	750 RPM	–	–	ASP523500 $68.80	ASP823500* $71.85	–	–	–
94-95	5.0	26% Crank 30% Water Pump 2 3/4″ Alternator	950 RPM			ASP525928 $140.55	ASP825928* $161.75	–	–	–
79-93	5.0	25% Crank	850 RPM		–	ASP520100 $74.00	ASP820100* $77.45	–	–	–
85-86	5.0S/Tran	25% Crank 2 3/4″ Alternator	1100 RPM	–	–	ASP520105 $120.00	ASP820105* $100.75	–	–	–
79-93	5.0	25% Crank 15% Water Pump	850 RPM		–	ASP520120 $139.65	ASP820120* $126.00	–	–	–
79-93	5.0	25% Crank 15% Water Pump 1 7/8″ Alternator	700 RPM	–	–	ASP520124 $150.25	–	–	–	–
79-93	5.0	25% Crank 15% Water Pump 2 1/2″ Alternator	950 RPM	–		ASP520125 $150.62	ASP820125 $157.32	ASP829125 $157.32	ASP822125 $157.32	ASP824125 $157.32
79-93	5.0	25% Crank 15% Water Pump 2 3/4″ Alternator	1100 RPM	–	–	ASP520128 $150.80	ASP820128 $157.32	ASP829128 $157.32	ASP822128 $157.32	ASP824128 $157.32

Mustang V6

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 *

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

Year	Engine	Pulley Description	Full Charge	Info	Image	Nitride	Zinc	Hard Coat Black Alum
2011	3.7L	25% dampner	850RPM	–	–	ASP520144** Call	–	–
05-10	4.0L	25% dampner	850 RPM	–	–	ASP526400 Discontinue	–	–
01-04	3.8/3.9	25% Dampner Crank Pulley	950 RPM		–	–	–	ASP820122 Call
99-00	3.8	25% Dampner Crank Pulley	950 RPM		–	–	–	ASP820117 Call
94-98	3.8	25% Crank	950 RPM		–	–	–	ASP826300 $136.82
94-98	3.8	25% Crank2 3/4″ Alternator	950 RPM		–	–	–	ASP826308 $143.65

* Clear HC., Red and Blue also available.
** Will not work on LS Lincoln

1989-94 Thunderbird Super Coupe 3.8L V6L

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
DISCONTINUED

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		–	ASP527328 $310.91	–
94-97	4.6	25% Crank 26% Water Pump 15% Alternator	900 RPM		–	ASP527728 Discontinued	–
89-95	3.8 SC	10% Blower Overdrive Adds 3 PSI Boost	950 RPM		–	ASP520009 $111.95	–
90-98	3.8	25% Crank 2 3/4″ Alternator	950 RPM		–	–	ASP826308 $143.65
90-93	5.0	25% Crank 29% Water Pump 2 3/4″ Alternator	950 RPM		–	ASP523528 $140.55	–

Crown Victoria / Grand Marquis

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

Contour / Cougar with SVT Duratec

Year	Engine	Pulley Description	Full Charge	Info	Image	Clear HardCoat Alum
95-99	2.0L	15% Reduction	800 RPM	Auto Specialties recommends these pulleys be installed by a qualified mechanic. 1. JACK UP FRONT OF CAR, PLACE JACK STANDS UNDER PASSENGER SIDE FRAME. PLACE BLOCKS BEHIND REAR WHEELS TO PREVENT CAR FROM ROLLING BACK. 2. REMOVE RIGHR WHEEL. 3. REMOVE UNDERSIDE PLASTIC BODT PIECE. 4. REMOVE CRANK BOLT. LOOSEN BELT AND REMOVE CRANK PULLEY. 5. REMOVE LOWER TIMING DUST COVER. YOU WILL NOT NEED TO PUT IT BACK ON. PLACE SCREWS BACK INTO HOLES TO PREVENT BLOCKAGE. 6. PUT ON NEW ASP CRANK PULLEY. APPLY LOCTITE #242 OR EQUIVALENT TO SECURE BOLT. TIGHTEN BOLT TO 80-100 FT/LBS. 7. FOR ESCORT INSTALL NEW GATES BELT K060845. REPLACE ALL PARTS IN REVERSE ORDER. TURN ON VEHICLE AND INSPECT FOR PROPER BELT ALIGNMENT AND INSURING THAT THE NEW INSTALLED PULLEY DOES NOT WOBBLE. BELTS 3.0L ESCAPE , K060810 CONTOUR 95-99 K060721 W/O A/C K060670 FOCUS ZX2 00 K060825		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		–	ASP527374 $299.91	–	–
97-01	4.6, 5.4	25% Harmonic Dampner26% Water Pump	850 RPM		–	ASP528774 $299.91	–	–
01-07	4.2	Harmonic Dampner25% Crank Pulley	850 RPM		–	–	–	ASP820130 Call
99-00	4.2	Harmonic Dampner25% Crank Pulley	850 RPM		–	–	–	ASP820129 Call
97-98	4.2	25% Crank Pulley	850 RPM		–	–	–	ASP826300 $136.82
92-08	3.0L Ranger	20% Crank Pulley	850 RPM		–	–	–	ASP821120 $126.20
90-03	4.0L Ranger/Explorer	25% Dampner	900 RPM	–		ASP526400 Discontinued	–	–
80-86	5.0, 5.8	30% Crank	800 RPM		–	ASP523000 Call	–	–
80-86	5.0, 5.8	30% Crank3″ Alternator	1000 RPM		–	ASP523003 Call	–	–
87-97	5.0, 5.8	30% Crank	850 RPM		–	–	–	ASP820100 $77.45
87-97	5.0, 5.8	30% Crank15% Water Pump	1100 RPM		–	ASP520120 $139.65	–	–
93-94	2.3	25% Crank	1000 RPM		–	–	–	ASP926500 Call

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(+2 to 3″psi)		–	ASP520002 $111.95	–
99-04	5.4	Blower Compressor Overdrive Pulley 2.80″ Diameter(+3 to 4″psi)		–	ASP520003 $111.95	–
99-00	5.4	Blower Crank Pulley 8.40″ Diameter (+4″psi)	–	–	–	ASP820116ps $265.00
01-04	5.4	Blower Crank Pulley 8.40″ Diameter (+4″psi lightning +2″psi harley)	–	–	–	ASP820116aps $265.00
99-00	5.4	Blower Crank Pulley 9.00″ Diameter (+6″psi)	–	–	–	ASP820116ps9 $275.00
01-04	5.4	Blower Crank Pulley 9.00″ Diameter (+6″psi lightning +4″psi harley)	–	–	–	ASP820116aps9 $275.00

Early Model Crank Pulleys

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

Alternator Pulleys

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 Discontinued
79-95	5.0	1 7/8″ Alternator	–	–	ASP520004 $32.65	–	–
79-93	5.0	2 1/2″ Alternator	–	–	ASP520005 $39.00	–	ASP820005 $35.35
79-95	5.0	2 3/4″ Alternator	–	–	ASP520080 $26.95	–	ASP820080 $35.81
79-93	5.0	3 1/2″ Alternator	–	–	–	–	ASP820006 Call