Thanks to Chris the idea and to Brade for his input.

Spark Plug FAQ

Stock Heads also (Dart Windsor Jr & Sr)

Naturally Aspirated (non-projected tip)
NGK
Specifications:

Thread Size= 14mm
Hex Size= .625
Reach= .46
Seat Type= Tapered
Electrode= V-Power

NGK R5673-6 Stock Number 2405 (1 heat range hotter)
NGK R5673-7 Stock Number 2817 (Factory heat range)

Naturally Aspirated (non-projected tip)

Specifications:


Thread Size= 14mm
Hex Size= .625
Reach= .46
Seat Type= Tapered
Electrode= V-Power

NGK R5673-6 Stock Number 2405 (1 heat range hotter)
NGK R5673-7 Stock Number 2817 (Factory heat range)

Autolite Stock Heads

Autolite 25 Naturally Aspirated
Autolite 24 1 Heat Range Colder
Autolite 23 2 Heat Ranges Colder

Autolite Race Series for Stock Heads

Autolite AR135 Naturally Aspirated Only
Autolite AR134 1 Heat Range Colder
Autolite AR133 2 Heat Ranges Colder


NGK Forced Induction

NGK-Non Projected Electrode
Specifications:

Thread Size= 14mm
Hex Size= .625
Reach= .75
Seat Type=
Electrode= V-Power

R5673-8 Stock Number 3249
R5673–9 Stock Number 3442 for tons of boost and power.

Aftermarket aluminum heads (TFS, Edelbrock, AFR, Canfield, Brodix)

NGK Forced Induction

R5671-A8 Stock Number 4554, 1 heat range Colder (up to about 600rwhp)
R5671–A9 Stock Number 5238, for 18+psi, 2 heat ranges colder 650+ rwhp
R5671–A10 Stock Number 5820, for race cars.

Autolite Forced Induction and N/A

Autolite 3924's Naturally Aspirated Only
Autolite 3923’s 1 Heat Range Colder, good for approx 550rwhp
Autolite 3922’s 2 Heat Ranges Colder, good for approx 650rwhp

Autolie Race Series for aftermarket heads

Autolite AR3935 Naturally Aspirated Only
Autolite AR3934 1 Heat Range Colder
Autolite AR3933 2 Heat Ranges Colder

Plug Specs for GT-40 Iron, GT-40 Aluminum, GT-40X, & GT-40P Heads

Thread Size- 14mm
Hex Size- .625
Reach- .708
Seat type- Tapered
Electrode- Standard Nickel
Projected Tip

The stock equivalent replacement part numbers according to the Motorsport Catalog are:

Ford MotorSport Part Number AGSF-32C for the GT-40 Aluminum, and GT-40X
Ford MotorSport Part Number AWSF-32C for the GT-40P, and GT-40 Iron

These plugs cross to:

NGK - BPR6EFS Stock Number- 3623 (Stock Heat Range)

Autolite- 104

These are the NGK Race Series Part numbers and specs:

Thread Size- 14mm
Hex Size- .625
Reach- .708
Seat type- Tapered
Electrode- V-Power
Non-Projected Tip

NGK- R5724-8 Stock Number- 7317 (1 Heat Range Colder)
NGK- R5724-9 Stock Number- 7891 (2 Heat Ranges Colder)
NGK- R5724-10 Stock Number- 7993 (3 Heat Ranges Colder)

 

4.6 4v 96-2001

The stock equivalent replacement part numbers according to the Motorsport Catalog are:

Ford MotorSport Part Number AGSF-42C

These plugs cross to:

NGK - TR55 Stock heat range
NGK BP6EFS (one colder)
Motorcraft AGSF-32C(one colder)
NGK BP7EFS (two colder)
Motorcraft AGSF-22C (two colder)
Champion RS9YC (two colder)

These are the Race Series Part numbers and specs:

Thread Size- 14mm
Hex Size- .625
Reach- .708
Seat type- Tapered
Electrode- V-Power
Non-Projected Tip

NGK- R5724-8 Stock Number- 7317 (3 Heat Range Colder)
NGK- R5724-9 Stock Number- 7891 (4 Heat Ranges Colder)
NGK- R5724-10 Stock Number- 7993 (5 Heat Ranges Colder)

 

Well, I might as well put this here so the next time someone is looking it will all be in the same place'¦ WRT to NGK plugs:

I know that UR5 is the stock plug for my heads. U I believe is .460' reach/tapered seat. R is resistor, and 5 is the heat range. I'm fairly certain that a UR6 would be one full step cooler (like going from an AC 43 to a 41), and UR7 would be 2 full steps (like really cold, I'm not sure if anyone makes plugs that cold).

So how would I translate that same plug (say a UR6) to a non resistor plug with the same seat/reach?

 

The E6SE Head has the following plug requirements, which can/should first be verified by the OEM plug requirements.

This is the factory plug I've crossed for specification:
Motorcraft P/N AGSF32C, Motorcraft Stock Number 32

14mm Thread
.708" Reach
5/8" Hex
Tapered seat

I've researched this head's plug requirements and have concluded with the following part numbers and IMEP ratings:

NGK Race Series Number (shielded V-Power electrode)
NGK R5724-8 Stock Number 7317 (2-3 heat range colder)

NGK Standard Series (Nickel Electrode, Projected tip)
NGK BPR6EFS Stock Number 3623 (1 heat range colder)
NGK BP7EFS Stock Number 3526 (2 heat range colder)
NGK BR7EF Stock Number 3346 (2-3 heat range colder) Non-Projected Tip V-Power Electrode
NGK TR6 Stock Number 4177 (1 heat range colder, V-Power Electrode)

Autolite Race Series
AR94 (1 heat range colder) Power Tip, Copper Core, Nickel Plated
AR93 (2 heat range colder) Power Tip, Copper Core, Nickel Plated

Autolite Standard Series
Autolite 2544 (1 heat range colder) (Projected Tip)
Autolite 2543 (2 heat range colder) (Projected Tip)

When using the aforementioned specifications, additional variations can be found here:
http://www.sparkplugs.com/search_ch...manufacturerID=

Just insure you completely understand the different manufactures IMEP ratings.

I also suggest you read this thread:
--- dead link -

 

Doesn't seem like anybody comes to the FAQ section.

 

I ran the NGK TR6's (R5673'“9 Stock Number 3442 for tons of boost and power) in my stock 150,xxx mile motor with a Paxton SN2000...and they worked just fine at 9 - 11lbs of boost. This was at 330rwhp and stock ignition...so they should work just fine for you.

 

I have 93 Cobra GT40 irons on my car. Stock heat range plug as listed by NGK is the TR55. Autolite says 764, which is what I run N/A right now. When I ran the nitrous I used an NGK TR6 or Autolite 103, which are both supposed to be 1 range colder than stock.

 

I currently use one step colder NGK V power on my 89 Twin Turbo. I will soon run the TR6 or TR7 on my 03 cobra

 

i forgot what plugs im runin but there gaped at .32

 

Great info!

Anybody have similar chart for the big plugs? I'm using Autolite 45's right now would like to go colder.

 

anyone else have problems with NGK plugs fouling prematurely?

i had NGKs TR6s in my incon car and they would foul on startup (seriously!) i went through 3 sets of plugs then finally decided to switch to autolite 103s and never had a problem again

 

anyone using autolite 3924's ( naturally asp. ) on 8 to 10 pounds of boost?

 

Hello guys,

I am the technical support representative for NGK Spark Plugs (USA) and being a fellow mustang enthusiast I just wanted to clear up some of these recommendations I have found on here.

For most all 5.0l engines ngk recommends a UR4 or UR45 (.460" reach) on a stock engine. The 5.0L cobra heads did take the colder TR5 with a longer reach (.708" reach).

remember that the higher the number the colder the plug (which is oppositie to most other manufacturers), our range goes from 2 (hot) - 11 (cold)

So
one step colder is a UR5
two step colder is a UR6

to go three steps we will have to go to the R5674 race plug series that will not have a built in resistor, so you may experience RFI static and EMI that will interfere with your onboard electronics such as the fuel injection system or datalogging equipment.

R5674-7 (projected series same as original plug, good for boost, bad for nitrous) three steps colder
R5674-8 four steps colder
R5674-9 five steps colder
R5674-10 six steps colder

we also have the non projected version which is good for large amounts of boost and or nitrous, it still has NO resistor
R5674-7 three steps colder
R5674-8 four steps colder
R5674-9 five steps colder
R5674-10 six steps colder



Now getting into the 4.6 liter engines they require a longer reach .708" and a 5 heat range for a stock engine. The TR55 is what is recommended.

One step colder is TR6
two steps colder is only available as an iridium IX series TR7IX
three steps colder is the iridium TR8IX


The iridium plugs work very well with Nitrous and with boost contrary to popular belief! Platinum though is still not suggested at least not with nitrous.

Now the only way to go colder than an 8 is to go with a non resistor plug which again will cause problems (possibly) with your radio and computer system. That series is the

R5724-8 three colder
R5724-9 four colder
R5724-10 five colder

If you have an aftermarket head that requires a .750" reach with a gasket seat you will want to run the BKR series if your car is fuel injected because this series has a resistor.

BKR5E (stock or one heat range colder depending on year and engine)
BKR6E two colder
BKR7E three colder
BKR8EIX four colder and only comes in iridium

For race cars and carberated engines you can also run the projected series:

R5672A-8 ( Basically same plug as a BKRxE series just without a resistor and offered in colder versions)
R5672A-9
R5672A-10
R5672A-11

or the non projected series (good for high boost racing applications and or nitrous applications.
R5671A-7
R5671A-8
R5671A-9
R5671A-10
R5671A-11


Everyone please keep in mind that NGK does not recommend gapping a plug more than about .008" from where the plug comes factory gapped to as this will cause the inner surfaces of the electrodes to not be parallel which will lead to the plug fialing prematurely and can also cause misfires, poor performance etc. The use of circular coin style gappers are not recommended either as they aren't very accurate and if used to pry between the electrodes to adjust gap can cause damage to the center firing electrode and or insulator especially on precious metal plugs.

I'd also like to clear up the misconception of what guys commonly call "copper plugs".

There is no such thing! Copper is way too soft of a material to be in a combustion chamber and would literally melt!

ALL of NGK's plugs and most all manufacturers that are worth a lick have COPPER CORED plugs. Standard plugs and V-power plugs have nickel alloy electrodes with a copper core. Our iridium, platinum, tungsten, gold paladium, etc all have the same copper core just a different central eletrode material and or ground electrode to help with wear and or to increase perofrmance.

Iridium has about a 2000 degree F higher melting temp than nickel alloy and is nearly twice as strong and even has less electrical resistance. it also has a much higher oxidation point which is directly related to plug wear. These benefits are what make this materialmuch better suited for the enviromenment a spark plug sees. It also lets us make a tip diameter that is much smaller to aid in ignitiability, reduce quenching and lowers the required voltage to fire the plug while still maintaing a life expectancy longer than a standard v-power plug. The IX series also goes a step beyond this and feautures a tapered ground electrode which helps reduce quenching, and allows the flame kernel to grow faster and larger, hence increasing ignitability and efficiency. This simply translates to improved torque and throttle response and an increase to fouling reisistance.

certainly this can't cover all the heads and setups that are out there. So if you have any additonal questions or concerns please contact me at my desk at 248 926 6315 or you can call tech support at 877-473-6767 option 2 or shoot me a PM Hope this helps, Thanks

Brandon Peeler
Technical Support Representative
Aftermarket Division
NGK Spark Plugs (U.S.A.), INC.
46929 Magellan Dr.
Wixom, MI 48393

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great info. thanks!
what are the advantages/disadvantages of running a projected/nonprojected plugs in boosted applications?

also, does e-85 fule require a different heat range?

 

The theory is that typically for street driven applications a projected insulator will be beneficial as it positions the spark farther into the combustion chamber promoting better ignitiability as it will be closer to the densest part of the mixture. at low speeds it also helps keep the firing end of the plug hotter preventing fouling. This is helpful in high power cars that run very cold plugs on the street. Also as the intake valve opens and the fuel charge rushes in the plug has a greater area being exposed so as to cool down more.

The only downside is that by putting the plug into a higher turbulence area you may also raise the required voltage needed to fire the plug. In very high boost cars this can lead to misfire (spark blowout), especailly with a weak stock type ignition system or over heating of the ground electrode at high rpms (because the ground path is longer), especailly with a weak stock type ignition system. This can sometimes be helped by switching to a fine wire type iriidum plug which reduces that voltage requirement back down and also lowering the plug gaps.

I have also heard from drag racers on a couple applications that they were able to run a non-projected plug and add in a degreee or two of spark timing and pick up some substantial horsepower increases.

So really I would say if it is a street driven vehicle try to run a projected plug. If it is a all out race car you may benefit from a non projected type plug (or if running nitrous). Of course this rule is not always valid as cylinder head turbulence, quench area, etc can sometimes change this recommendation.


Generally alchohals require a colder heat range to be fitted because they do not absorb as much heat when evaporating, causing higher cylinder temps. With E-85 though we have seen most applications requiring the same heat range. Just run the original heat range plug and be sure to check the appearance of the firing end after 50 miles street use or a couple drag passes. Hope this helps, thank you.

 

i run/ran only ngk's in my 2.3t and now my 5.0.

22psi on ethanol.

 

You might add the AUTOLITE 144 in your list. This fits stock heads as well as the other heads that use stock plugs.

It is 3 heat ranges colder than stock, and is designed just like the racing series plug (non-projection tipped plug.)


This is the plug we used when spraying the nitrous and with our turbo @ 15 psi. The plug works damn well

 

95 Cobra 5.0L T70 turbo 10 psi probably 400 WHP
Eldrebrock heads

So I need eather NGK r5671-a8 or Autolike 3933's ? ?? ? ?

 

Great Info! Will come in handy!

 

crap, why did I assume Autolite 3924's were a 1 step colder plug, OR ARE THEY ?

so really I want eather 3923's ( 450 HP)

or AR3934's ? ?? ( Eldebrock heads) ??????