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Thread: Spark Plug Reference Chart

  1. #1
    Registered Newbie Harris Speed Works's Avatar

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    Spark Plug Reference Chart

    Hey guys, been working on this for a little while and finally have it ready to post. Maybe someone can sticky it to the top so that people can easily reference it? It's fairly hard to compare each manufacturers heat range since there are so many factors involved but this is, in my opinion, the closest match for NGK's heat range system, which was used in the chart. If you guys would like to see certain plug manufacturers added, let me know.



    Spark Plug Info

    **Note: Heat ranges are determined by NGK standards. Not all plug manufacturers follow the same guidelines.

    ***Note: List is intended for reference only. Please consult with head mfg. and ignition mfg. for proper gap.

    ****Note: NGK IX and Denso plugs are Iridium.


    LT1
    Thread 14mm
    Reach - .708
    Socket 5/8 hex
    Seat - Taper
    Stock Heat Range: 5
    Gap: .050
    Plug: NGK TR55 (stock number 3951); NGK TR55IX (stock number 7164); Autolite 764; Champion RS14YC6 (stock number 13); Denso IT-16 (stock number 5325)


    Nitrous (one step colder)
    Heat range: 6
    Gap: .035 - .038
    Plug: NGK TR6 (stock number 4177); NGK TR6IX (stock number 3689); Autolite 103; Denso IT-20 (stock number 5326)


    Nitrous (two steps colder)
    Heat Range: 7
    Gap: Consult
    Plug: NGK BR7EF (stock number 3346); NGK TR7IX (stock number 3690); Autolite AR94; Denso IT22 (stock number 5327)



    LT1 w/ AFR heads
    Thread 14mm
    Reach 3/4
    Socket 5/8 hex
    Seat Gasket
    Stock MFG Recommendations
    Heat Range: 9
    Gap: Consult ignition mfg.
    Plug: NGK 5672A-9 (stock number 7405); Autolite AR3910; Champion C59YC (stock number 792); Denso IQ27 (stock number 5315); Denso IQ01-27 (stock number 5708)(diagonal platinum ground); Denso IQ02-27 (stock number 5711)(horizontal platinum ground)


    Nitrous (one step colder)
    Heat Range: 10
    Gap: Consult ignition mfg.
    Plug: NGK 5672A-10 (stock number 7942); Autolite AR50; Denso IQ31 (stock number 5323)


    Nitrous (two steps colder)
    Heat Range: 11
    Gap: Consult ignition mfg.
    Plug: Denso IQ34 (stock number 5324)



    LT1 w/ Trick Flow & Edelbrock Heads
    Thread 14mm
    Reach 3/4
    Socket 5/8 hex
    Seat Gasket


    Stock MFG Recommendations: approx under 9:1 compression
    Heat Range: 4
    Gap: Consult ignition mfg.
    Plug: NGK FR4 (stock number 5155); NGK BKR5EIX (stock number 6341); Autolite 3926; Champion RC12YC (stock number 71); Denso IK16 (stock number 5303)

    MFG Recommendations: approx 10.5:1 compression
    Heat Range: 5
    Gap: Consult ignition mfg.
    Plug: NGK FR5 (stock number 7373); Autolite AR3924 (Racing Plug); Autolite 3924; Champion RC9YC (stock number 2075); Denso K20PR-U (stock number 3145); Denso IK20 (stock number 5304)

    MFG Recommendations: approx 11:1 compression
    Heat Range: 8
    Gap: Consult ignition mfg.
    Plug: NGK R5672A-8 (stock number 7173); Autolite AR3911; Champion C63YC (stock number 796); Denso IQ24 (stock number 5314)

    MFG Recommendations: approx 12:1 compression
    Heat Range: 9
    Gap: Consult ignition mfg.
    Plug: NGK R5672A-9 (stock number 7405); Autolite AR3910; Champion C61YC (stock number 785); Denso IQ27 (stock number 5315)

    MFG Recommendations: approx 13:1 compression
    Heat Range: 9 - 10
    Gap: Consult ignition mfg.
    Plug: NGK R5671A-9 (stock number 5238); Autolite AR3933; Champion C59CX (stock number 296); Denso IK27 (stock number 5312)

    MFG Recommendations: approx 14:1 compression
    Heat Range: 10
    Gap: Consult ignition mfg.
    Plug: NGK R5671A-10 (stock number 5820); Autolite AR3932; Champion C57CX (stock number 295); Denso IK-31 (stock number 5321)


    **NOTE: Use chart for static compression and adjust heat range for nitrous use accordingly.



    LS1 Stock and AFR
    Thread 14mm
    Reach - .708
    Socket 5/8 hex
    Seat - Taper
    Stock Heat Range: 5
    Gap: .060
    Plug: NGK TR55 (stock number 3951); NGK TR55IX (stock number 7164); Autolite 764; Denso IT-16 (stock number 5325)


    Nitrous (one step colder)
    Heat Range: 6
    Gap: .035 - .038
    Plug: NGK TR6 (stock number 4177); NGK TR6IX (stock number 3689); Autolite 103; Denso IT-20 (stock number 5326)

    Nitrous (two steps colder)
    Heat Range: 7
    Gap: Consult
    Plug: NGK BR7EF (stock number 3346); NGK TR7IX (stock number 3690); Autolite AR94; Denso IT22 (stock number 5327)

    Nitrous (two and a half steps colder)
    Heat Range: 8
    Gap: Consult
    Plug: NGK R5724-8 (stock number 7317); NGK TR8IX (part number 3691); Denso IT-24 (stock number 5328)

    Nitrous (three steps colder)
    Heat Range: 9
    Gap: Consult
    Plug: NGK R5724-9 (stock number 7891); Autolite AR93; Denso IT-27

    Nitrous (four steps colder)
    Heat Range: 10
    Gap: Consult
    Plug: NGK R5724-10 (stock number 7993); Autolite AR92



    LS1 w/ Edelbrock and Dart Heads
    Thread 14mm
    Reach 3/4
    Socket 5/8 hex
    Seat Gasket

    Stock MFG Recommendations: approx under 9:1 compression
    Heat Range: 4
    Gap: Consult ignition mfg.
    Plug: NGK FR4 (stock number 5155); NGK BKR5EIX (stock number 6341); Autolite 3926; Champion RC12YC (stock number 71); Denso IK16 (stock number 5303)

    MFG Recommendations: approx 10.5:1 compression
    Heat Range: 5
    Gap: Consult ignition mfg.
    Plug: NGK FR5 (stock number 7373); Autolite AR3924 (Racing Plug); Autolite 3924; Champion RC9YC (stock number 2075); Denso K20PR-U (stock number 3145); Denso IK20 (stock number 5304)

    MFG Recommendations: approx 11:1 compression
    Heat Range: 8
    Gap: Consult ignition mfg.
    Plug: NGK R5672A-8 (stock number 7173); Autolite AR3911; Champion C63YC (stock number 796); Denso IQ24 (stock number 5314)

    MFG Recommendations: approx 12:1 compression
    Heat Range: 9
    Gap: Consult ignition mfg.
    Plug: NGK R5672A-9 (stock number 7405); Autolite AR3910; Champion C61YC (stock number 785); Denso IQ27 (stock number 5315)

    MFG Recommendations: approx 13:1 compression
    Heat Range: 9 - 10
    Gap: Consult ignition mfg.
    Plug: NGK R5671A-9 (stock number 5238); Autolite AR3933; Champion C59CX (stock number 296); Denso IK27 (stock number 5312)

    MFG Recommendations: approx 14:1 compression
    Heat Range: 10
    Gap: Consult ignition mfg.
    Plug: NGK R5671A-10 (stock number 5820); Autolite AR3932; Champion C57CX (stock number 295); Denso IK-31 (stock number 5321)

    **NOTE: Use chart for static compression and adjust heat range for nitrous use accordingly.




    4.6 Mustang GT
    Thread 14mm
    Reach - .708
    Socket 5/8 hex
    Seat - Taper
    Stock Heat Range: 5
    Gap: .054
    Plug: NGK TR55 (stock number 3951); NGK TR55IX (stock number 7164); Motorcraft AWSF-32C (copper); Autolite 764; Denso IT-16 (stock number 5325)

    Nitrous (one step colder)
    Heat Range: 6
    Gap: .035 - .038
    Plug: NGK TR6 (stock number 4177); NGK TR6IX (stock number 3689); Motorcraft AWSF-22C (copper); Autolite 103; Denso IT-20 (stock number 5326)

    Nitrous (two steps colder)
    Heat Range: 7
    Gap: Consult
    Plug: NGK BR7EF (stock number 3346); NGK TR7IX (stock number 3690); Motorcraft AWSFA-12C (copper); Autolite AR94; Denso IT-22 (stock number 5327)

    Nitrous (two and a half steps colder)
    Heat Range: 8
    Gap: Consult
    Plug: NGK R5724-8 (stock number 7317); NGK TR8IX (part number 3691); Denso IT-24 (stock number 5328)

    Nitrous (three steps colder)
    Heat Range: 9
    Gap: Consult
    Plug: NGK R5724-9 (stock number 7891); Autolite AR93; Denso IT-27

    Nitrous (four steps colder)
    Heat Range: 10
    Gap: Consult
    Plug: NGK R5724-10 (stock number 7993); Autolite AR92




    4.6 Mustang Cobra (96-01)
    Thread 14mm
    Reach - .708
    Socket 5/8 hex
    Seat - Taper
    Stock Heat Range: 5
    Gap: .054
    Plug: NGK TR55 (stock number 3951); NGK TR55IX (stock number 7164); Autolite 764; Denso IT-16 (stock number 5325)

    Nitrous (one step colder)
    Heat Range: 6
    Gap: .035 - .038
    Plug: NGK TR6 (stock number 4177); NGK TR6IX (stock number 3689); Motorcraft AWSF-22C (copper); Autolite 103; Denso IT-20 (stock number 5326)

    Nitrous (two steps colder)
    Heat Range: 7
    Gap: Consult
    Plug: NGK BR7EF (stock number 3346); NGK TR7IX (stock number 3690); Motorcraft AWSFA-12C (copper); Autolite AR94; Denso IT22 (stock number 5327)

    Nitrous (two and a half steps colder)
    Heat Range: 8
    Gap: Consult
    Plug: NGK R5724-8 (stock number 7317); NGK TR8IX (part number 3691); Denso IT-24 (stock number 5328)

    Nitrous (three steps colder)
    Heat Range: 9
    Gap: Consult
    Plug: NGK R5724-9 (stock number 7891); Autolite AR93; Denso IT-27

    Nitrous (four steps colder)
    Heat Range: 10
    Gap: Consult
    Plug: NGK R5724-10 (stock number 7993); Autolite AR92




    4.6 Mustang Cobra (03-04)
    Thread 14mm
    Reach - .708
    Socket 5/8 hex
    Seat - Taper
    Stock Heat Range: 6
    Gap: .049 - .052 (have had better results with tighter gap)
    Plug: NGK TR6 (stock number 4177); NGK TR6IX (stock number 3689); Motorcraft AWSF-22C (copper); Autolite 103; Denso IT-20 (stock number 5326)

    Nitrous (one step colder)
    Heat Range: 7
    Gap: .035 - .038
    Plug: NGK BR7EF (stock number 3346); NGK TR7IX (stock number 3690); Motorcraft AWSFA-12C (copper); Autolite AR94; Denso IT-22 (stock number 5327)

    Nitrous (two steps colder)
    Heat Range: 8
    Gap: Consult
    Plug: NGK R5724-8 (stock number 7317); NGK TR8IX (stock number 3691); Denso IT-24 (stock number 5328)

  2. #2
    Registered Newbie Harris Speed Works's Avatar

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    5.0 Mustang 87-95
    Thread 14mm
    Reach - .460
    Socket 5/8 hex
    Seat Taper
    Stock Heat Range: 4
    Gap: .054
    Plug: NGK UR45 (stock number 6945); NGK UR45IX (stock number 3207)

    Nitrous (one step colder)
    Heat Range: 5
    Gap: .035 - .038
    Plug: NGK UR5 (stock number 2771); NGK UR5IX (stock number 7177)

    Nitrous (two steps colder)
    Heat Range: 6
    Gap: Consult
    Plug: NGK UR6 (stock number 7773); NGK UR6IX (stock number 7348)




    5.0 Mustang Cobra 93-95 w/ GT-40 Heads
    Thread 14mm
    Reach - .708
    Socket 5/8 hex
    Seat - Taper
    Stock Heat Range: 5
    Gap: .054
    Plug: NGK TR55 (stock number 3951); NGK TR55IX (stock number 7164); Autolite 764 or 104; Denso IT-16 (stock number 5325)

    Nitrous (one step colder)
    Heat Range: 6
    Gap: .035 - .038
    Plug: NGK TR6 (stock number 4177); NGK TR6IX (stock number 3689); Motorcraft AWSF-22C (copper); Autolite 103; Denso IT-20 (stock number 5326)

    Nitrous (two steps colder)
    Heat Range: 7
    Gap: Consult
    Plug: NGK BR7EF (stock number 3346); NGK TR7IX (stock number 3690); Motorcraft AWSFA-12C (copper); Autolite AR94; Denso IT-22 (stock number 5327)

    Nitrous (three steps colder)
    Heat Range: 8
    Gap: Consult
    Plug: NGK R5724-8 (stock number 7317); NGK TR8IX (stock number 3691); Denso IT-24 (stock number 5328)




    Ford F-150 Lightning (99-04)
    Thread 14mm
    Reach - .708
    Socket 5/8 hex
    Seat - Taper
    Stock Heat Range: 6
    Gap: .049 - .052
    Plug: NGK TR6 (stock number 4177); NGK TR6IX (stock number 3689); Motorcraft AWSF-22C (copper); Autolite 103; Denso IT-20 (stock number 5326)

    Nitrous (one step colder)
    Heat Range: 7
    Gap: .035 - .038
    Plug: NGK BR7EF (stock number 3346); NGK TR7IX (stock number 3690); Motorcraft AWSFA-12C (copper); Autolite AR94; Denso IT-22 (stock number 5327)

    Nitrous (two steps colder)
    Heat Range: 8
    Gap: .033 - .036
    Plug: NGK R5724-8 (stock number 7317); NGK TR8IX (stock number 3691); Denso IT-24 (stock number 5328)

    Nitrous (three steps colder)
    Heat Range: 9
    Gap: Consult
    Plug: NGK R5724-9 (stock number 7891); Autolite AR93; Denso IT-27 (stock number 5329)

  3. #3
    LS2.Com Moderator
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    Nice work, Matt!
    Steve - NJ State Trooper #3936 (retired)
    Life Member: VFW & Vietnam Vets of America
    2000 Millennium Yellow Corvette Convertible
    Mods: Hurricane intake, Halltech Cobra air bridge, LS6 intake manifold, XTrooper Cam (223/227 .566/.567 112), Rapid Motorsports Stage II LS1 heads, Crane 1.80 Quick-Lift rockers & dual valve springs, ATI Super Damper, Rollmaster double roller timing chain, TTS headers, MagnaFlow exhaust/x-pipe, QTEC electric cutouts, NX/Nitrous Outlet wet kit, Yank SY3500, 3.73 gears, Baer EradiSpeed rotors, Z06 chrome wheels, Nitto drag radials
    441 rwhp/418 rwtq
    11.478@121.55 60'=1.696

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