Glow Plug heat range - modern plugs

[Dennis Toth]

Guys,
Has anyone done a Glow Plug heat range chart for the currently available plugs? I have an old one the has K&B, OK, Gold Seal and Fox.

Also, with the muffler holding in heat do we still favor using idle bar plugs for stunt?

Best,      DennisT

[Steve Helmick]

I don't know of a modern chart, but various manufacturers (McCoy and Merlin, at least) kinda list the sort of stuff that each specific glowplug is useful for. Tower Hobby sells/sold McCoy glowplugs, and listed their suggested uses. I think CL may even have been mentioned.

What makes for a cold or hot glowplug is apparently alloy and size of wire, and the coil size (length of the wire used to make the coil, I suppose). It would be a great Winter project for an affluent engineering type to gather all the typically used glowplugs and do whatever it would take to make a modern chart. I'm curious about the brands of glowplugs they use in Europe, also. We just don't see many European brands over here, while all the Asian stuff is pretty easily available.

FWIW, I think everybody I know uses Thunderbolt idle bar or 4-Cycle plugs, except Dirt, who used SIG for years...and no idle bar. I've used both the T-bolt idle bar and 4 cycle glowplugs in my engines for years, and haven't seen any difference, good or bad. OS .46LA, ST G.51, 2Star .60bb on mufflers, and OS .46VF & PA .51 on pipe. I think the reason Dirt didn't like idle bars was that he had one come adrift in an R/C engine (years ago) and it ate the piston. If that worries you, use one of the 4-cycle plugs...no idle bar.  Steve

[Dennis Toth]

I found this web site that had information on plug heat range rating:

http://www.rcuniverse.com/forum/beginners-85/8376353-good-guide-selecting-correct-glow-plug.html

General Glow Plug Information - Consolidated
 By James McCarty, Brian Cooper, and Brian Gardner

 OS Glow Plug Information
 # 8 Hot Recommended for most current O.S. (and other) 2-stroke engines
 Type F Mildly Hot Special long-reach plug recommended exclusively for O.S (and other) 4-stroke engines
 Type RE Hot Special long-reach plug designed exclusively for O.S. Wankel rotary engine
 A5 Cold Recommended for most current O.S. (and many other) 2-stroke engines particularly for 1/10th & 1/8th scale off-road car engines
 A3 Hot Dependable O.S. quality makes A3 the most durable and longest-lasting glow plug available at an economical price
 R5 Very Cold Recommended for high-nitro fuel and high r.p.m. engines, particularly 1/8th track racing car engines

 ENYA Glow Plug Information
 # 3 Hot All Enya engines such as TV & four cycle engines
 # 4 Mildly hot All Enya engines, especially those used with 10%or greater nitromethane fuel
 # 5 Medium All Enya engines, especially the .40CX, .45CX and high nitro methane fuel
 # 6 Cold High compression engines and high niro methane fuel used in racing.

 Fox Glow Plug Information
 All 1. 5 Volt Plugs are Dry Cell or Ni-Cad All 2 Volt Plugs are Lead Acid Battery

 Standard Short Hot 1.5 Volt, Standard Short Hot 2 Volt
 Standard Long Hot 1.5 Volt, Standard Long Hot 2 Volt
 Gold STD Long Plug Hot 1.5 Volt, RC Short Mildly Hot 2 Volt
 Gold RC Long Hot 1.5 Volt, RC Long Mildly Hot 2 Volt
 RC Short Mildly Hot 1.5 Volt
 RC Long Mildly Hot 1.5 Volt
 Miracle Plug Hot 1.5 Volt
 Pro 8 Short Cold 1.5 Volt
 Pro 8 Long Cold 1.5 Volt

 McCoy Glow Plugs with OS Equivalent
 MC-8 Medium Hot #8 (thanks for correction, mvbashers.org)
 MC-9 Cold A5, R5 (thanks for correction, mvbashers.org)
 MC-50 Hot IDLE BAR - LONG
 MC-55 Medium Hot A3, #8
 MC-59 Hot

Hope I gave proper credits to the original authors.

Best,          DennisT

[Allan Perret]

So what is it about the design of a plug that determines the heat range ?

[Curare]

I was under the impression it was the diameter of the coil wire? Thicker being colder, and thinner being hotter?

Of course that could be complete bunk.

Just as an aside, OS do a long hot plug, (for RC cars but who cares) known as an LC3, I'm currently testing them to see how well they work.


Thunderbolt plugs aren't easy to come by in australia, whereas OS is available at virtually every hobby shop.

[John Leidle]

  A while back a kid at the hobby shop told me a hot plug has more space between the filament & the housing. I'm having a time explaining what I mean.  They bore a hole in the housing for the filament and the bigger the bore the hotter the plug...I consider the housing the threaded section that screws into the head.  I don't really know .   I just work here.   John

[Lauri Malila]

Hi.
Many things affect the heat range;

-Filament diameter
-Filament lenght
-Coil diameter & pitch
-Cavity dimensions & coil position in cavity
-Coil alloy

I'm just making some heads for Nelson type plug, I want to see if it brings any more stability to the system. With the thinnest, 0,16mm filament the important dimensions are quite close to Enya #3 which I have used lately. It will be interesting to learn the results. My guess is that Nelson plug with same dimensions will in reality be slightly colder than Enya. Time will tell. L

[Dick Pacini]

I have always wondered about the difference between a long and a short plug, in the case that the original paperwork that would identify the plug required on the particular engine isn't available.

[Dennis Toth]

Dick,
Generally, the short plugs fit in engines 15 and smaller. The idea is that the threads of the plug should end at the inside surface of the head. If you use a long plug in an engine meant for a short it can sometimes hit the top of the piston (particularly if it has a idle bar). This also has a effect on ignition timing, if you use the short plug in an engine set for a long you will retard the timing slightly.

Best,     DennisT

[John Leidle]

   Cavity dimension, I like that term. Much more descriptive.

[Curare]

Ugh, makes me think I have to go to the dentist 

[Terry Caron]

I don't remember where i got this list:

GLOW PLUG SELECTION:

    HOT GLOW PLUGS (Low nitro and FAI fuels)
        Enya #3
        Fox: Miracle, Standard, and R/C Long (2 Volt)
        Fireball: Hot(1.2 - 3.0 Volt) and S-20 R/C Long
        Fire Power: F6 (Warm) and F7 (Hot)
        K&B: 1L
        McCoy: MC55 R/C Long, MC59, and MC14 (Very Hot)
        OS Engines: #0, #1, and #5
        Rossi: R1 (Extra Hot)
        Sonic Tronics: Glow Devil #300
        Thunderbolt: R/C Long

    MEDIUM GLOW PLUGS (10 - 15% nitro fuels)
        Enya #4 (Medium Hot) and #5 (Medium Cold)
        Fox: R/C Long (1.2 - 1.5 Volt) and Gold
        Fireball: Standard (1.2 - 2.0 Volt)
        Fire Power: F5 (Medium) and F6 (Warm)
        Hangar 9: Sport Long
        McCoy: MC50 and MC8
        OS Engines: #A3, #8, #9, #7 (with idle bar)
        Rossi: Medium and R3
        Sonic Tronics: Glow Devil Standard
        Tower Hobbies: Tower Power Performance plug and Regular (with idle bar)

Terry Caron

[Akihiro Danjo]

I don't remember where i got this list:

Maybe here.
http://www.scootworks.com/rdrc/gloplugs.html

I've found 2 mistakes.
OS Engines: #5 is (was, it's too old) not HOT but COLD.
OS Engines: #A3 (now #6) is not MED but HOT. Old OS #3 was MED.

Aki