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shoota0075 01-14-2013 07:25 PM

what glow plug
is recommended for the .28 4.6 k or the f engine (hpi) ?

JoeMaxx 01-19-2013 03:27 PM

RE: what glow plug
The Medium Heat Glow plugs are the best all around for most engines when the outdoor temps are above 75 Degrees outside running 20 to 33 percent Nitro. Colder outdoor temps I would suggest a hot glow plug or less than 20 percent nitro content.

Now this is only my personal opinion and there are more expensive and less expensive Glow plugs out there then I have alsoused some of them in the past. I buy these in bulk 6 at a time and can get about of gallon of fuel running them in an engine unless I run my engines too hot one day. Running a lean mix will fry any glow plug fairly quick and as long as you keep the engine in the 260 to 200 range most glow plugs will last a long time. Yes I have hit 300 degrees a few times and fryed a glow plug when I got carried away and did not tune properly for the day. A temp guage is suggested when you run but not a guage for determining the best tuning. Always make sure you have a good smoke trail and you can never hurt an engine by running a little rich.

I have been using Fox Glug Plugs for about 9 years now in my enginesand they seem to last as long as the more expensive plugs on the market. They were originally designed for use in Air Planes. In my Turbo Plug engines I stick with O.S. Medium Heat Turbo Plugs because they are the easy to find.



FrickenJoey 01-19-2013 08:54 PM

RE: what glow plug
The heat rating of a plug is what helps control the ignition timing of the engine not for the outside air temp. A hot plug ignites the mixture more easily than a cold plug so the hotter the plug the more the ignition point is advanced. In a way it works something like the distributor in a car, if you advance it too far you can get per-detonation. There are other things that control the ignition point as well, like compression ratio of the engine and the type of fuel and nitro content. Typically the higher the nitro content the cooler the plug you would want to run.
If the air temp mattered to which plug you used you still have it backwards since cold air is denser. Since it is denser it contains more oxygen. Since it contains more oxygen it burns more readily. Now considering you have a more volatile mixture that ignites easier than normal a hot plug is not recommended. Essentially cooler plug is better to use in cooler weather since a hot plug can run the risk of per-detonation especially when using higher nitro content fuel.

I would run a cold to medium plug depending on you fuel, what fuel are you running?

JoeMaxx 01-21-2013 09:08 PM

RE: what glow plug
Since most forums are open source of information and there was no disclaimer saying I could not repost this information I figured I would share a little of my research ;) So I admit I am a little wrong in my assesment to run hotter plugs in the winter but as these guys say it will idle better and stay running longer at Idle because in colder temps you will need to run a richer mix.

The words below are not mine and borrowed from sitelink to a Forum down in South Africa then repost what there suggestion are on Glow Plugs ;)

I hope this additonal information helps you guys out ;)

http://www.oneten.co.za/showthread.p...lugs-explained I will provide a link to a Forum down in South Africa then repost what their moderatorssuggestions are on Glow Plugs ;)

But a rule of thumb you can all follow is the following

less nitro = Hotter Plug
More Nitro = Cooler Plug

So lets look at the Rossi range of plugs, because they are easy to follow... with low nitro you would use a # 5 plug say 15% 15 to 20% use a #6 (slightly warmer) 25 to 30 % nitro use a #7.. Besides the cooler plug retarding the ignition slightly it also has another purpose. Cooler plugs generally have a thicker element; the thicker element is also more resilient to higher impact explosions made by higher nitro. But in my opinion I always like to use a med to hot plug no matter what, cool plugs just don’t work for me... some people do like them but i dont.

Advantages of warmer plugs are they idle better and are harder to flame out.

Disadvantage they are a little more fragile...

Does the heat range of the plug make the engine run at a different temp? No it makes no difference except for one thing, a hotter plug will in most cases let an engine run harder therefore running hotter. It would seem the plug makes the engine hotter but its not, its like running a body without ventilation, it makes the engine run hotter but the body causes the symptom because it has changed a determining parameter... (I hope that makes sense http://www.oneten.co.za/images/smilies/icon_smile.gif

Ok now long body and short body plugs.

Simple really a short body plug increases geometric dome size reducing compression. A long body does the opposite; it reduces geometric dome size increasing compression.

So long body = better power = hotter engine
Short body = Less performance = cooler engine

Ahaaaa! You said the plug makes no difference to the temps! Well the heat range of the plug doesn’t but the physicality of its dimensions does. Its + or - a determining factor of how the engine runs. But all this is untrue really...... WHAT? ....

What’s really happening is a higher geometric compression will increase heat conductivity to the head button and release heat transfer via the heat sink more efficiently thus giving the impression the engine is running hotter for all you temp gun freaks out there... The reverse is true when you decrease geometric compression. This also applies to reducing head clearance; the engine will transfer more to the head as opposed to through the side walls and pipe. Remember the head button is aluminium and ally likes to absorb heat and dissipate it usually toward a cooler direction, towards a cooling head...

Glowplugs are common to all "glow" engines and are used with methanol-based fuels. The glow plug itself is made up of a steel "plug" with a platinum wound wire element that when inserted into the head of the engine forms the uppermost portion of the combustion chamber. In operation, there is a catalytic reaction between the alcohol and the platinum element that, when combined with the right compression, causes the alcohol to burn. We initially attached a 0.5-1.2V battery to the glow plug to cause it to glow, and remove this battery once the engine is running and the element continues to glow through the catalytic reaction.

You will hear of glow plugs being referred to as "hot" or "cold" plugs. Both of these terms refer to the heat range of a glow plug, and it is easiest to notice the difference at an idle. In general, the "hotter" the plug, the richer the mixture can be at idle and the engine will continue to operate. The "colder" the plug, the mixture will need to be leaned out in order to operate properly.

Assessing the Condition of Your Glow Plug
The glow plugs on the market today are designed to provide good service to the user and may last a long time or a short time, all dependent upon the way you choose to operate your engine.

Physical indications that you might need to change the glow plug are:
a. Twisted or mangled glow plug element. (This is usually caused by too high a compression ratio.)
b. Small "bumps" are attached to the glow plug element (This will generally be most noticeable during the break-in process. These are actually tiny pieces of aluminum that have attached to the element and these will severely hinder the operation of the glow plug.)
c. The glow plug element is no longer shiny but is dull, almost a white powder color. (This just comes with age and is a by product of the catalytic reaction. The shinier the wire, the better the catalytic reaction can be.)

Operating indications that you need to change your glow plug are:
a. The glow element will not light with a charged glow igniter. (This indicates that there is a physical short or breakage in the element wire itself)
b. Glow plug lights but the engine will not stay running once the battery is disconnected. (This is usually an indication if the microscopic particles we discussed earlier)
c. Glow plug lights, engine runs but there is a perceptible loss of rpm at full throttle when the battery is disconnected. (This is a typical indication that the white powder residue is building to the point that the catalytic reaction of the glow plug is no longer anywhere close to being optimum.)


GLOWPLUG #1 = The engine was set too lean, this glowplug is overheated you can see the spiral is going inwards and the worst case scenario is that the spiral brakes and drops in your engine!!

GLOWPLUG #2 = This glowplug is from a good working engine with a perfect fuel micture.

GLOWPLUG #3 = The engine was set too rich, the spiral is black due to the excessive fuel in the chamber, this engine will start very hard and does not run smooth.

GLOWPLUG #4 = This one is old and used alot, time for a new one, the extra thing you can see is that the spiral is rather white, this means that the setup of the engine fuel mixture was ok

A very important thing for a long lasting engine: regulary check your glowplug and the engine temperature!

Borneoben 01-21-2013 10:23 PM

RE: what glow plug
</div><div>Great information Thanks very much for sharing.</div><div>
</div><div>I will print most of it and keep in my tool box for reference.</div><div>

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