Plug temperature
 

When do you use a "hot" glow plug vs. a medium? This is a general question for my education, but specifically why I am asking is:

I have just ordered a Tower Hobbies .75 engine and they recommend either a Tower plug or OS #8. A search on RCU lead me to a specific thread that mentioned the Tower plug is "similar" to an A3, which is #6 or hot. If this is true, and Tower's recommendation of the type of plug to use is true, then this two-stroke works equally well on medium plugs as well as hot, which leads me to the original question: when do you use hot vs. medium.

The fuel I usually use is 10% Nitro, although I may occasionally buy 5%.

Thanks!

RE: Plug temperature
 

A practical suggestion: After testing and using about 50 plugs in the last several years I do not buy and use anymore
anyone else than the F type of OS. It is a 4 stroke plug which is similar to temperature to OS8 but the major difference
is that is very innert, meaning keeps its temperature longer due to the more massive spiral, as it should be for 4S.
This has many positive efffects and mainly: - more stable RPM at any fuel and as well much longer life although is
a bit more expensive. It is worth trying one prior buying many other types.
http://www3.towerhobbies.com/cgi-bin...&I=LXCB28&P=ML

RE: Plug temperature
 

In general, two stroke engines burning low nitro% prefer a hotter plug, while higher % and tuned pipe equiped engines will like a plug on the colder end of the scale. Most sport engines will like a plug in the hot to medium range, with the cold being prefered for car and boat racing.


You may want to start with a hot or med-hot plug with 5% fuel in your tower 75. If the engine runs hot, try a medium.

RE: Plug temperature
 

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

RE: Plug temperature
 

Originally the Tower Power plug was associated with an OS A-3 but it has been argued that the current ones are more like OS #8

I have a couple cards of the old ones so I havn't experienced the new Tower Power

Mine seem to work more like the old A3

RE: Plug temperature
 

Hi!
You choose the plug after what compression you have and what fuel (Nitro) you intend to use!
The more nitro... the cooler plug!
The more compression...the cooler plug!
Less compression...the warmer plug you use
Less nitro ...the warmer plug you use!

Simple?!
Well it is when you got the hang of it!
But remember that if you intend to use a pipe...then you automatically raise the compression inside the engine (By the function of the pipe) and have to use less nitro...or a cooler plug! Or both ...Your choice!


Remember! All European engines (MVVS, Rossi, Nova Rossi, Webra, OPS) are made to run well on 0-5 %nitro (some can handle 10-15%).
But all other engines can handle 0-15% (some even 20% nitro).
If you want to run these European engines on 10-15%nitro...you better add a 0,1mm aluminum head gasket (shim).
Or if you want to run the others (ASP, OS, Magnum,Tower, Enya) on 0-5% nitro... remove a head gasket!

A simple rule to follow!
All two stroke engines run well on OS 8 or Enya 3 plugs!
These plugs are not the best plugs to use if you want out most power from a Q-500 (424) .40 standard engine, but for a sport flier they are the best! For racing, a cooler plug like the Nova-Rossi 4 or 4A is better...or an even colder plug like the Nova-Rossi or Rossi 5, 6 or 7.
All Four strokes run best on the OS F plug!

Finally...Remember that choosing the right glow-plug and compression (head shim) isn't the only thing that govern how your engines is going to perform, the prop size is also a vital component in how the engines is going to perform.

RE: Plug temperature
 

In my Tower 75 I use the tower glow plug and 0% Nitro.

RE: Plug temperature
 

All - thanks for the responses, great information!

Nikolay - isn't the type F a little longer? If this is correct, wouldn't is potentially interfere with the piston head?

w8ye - this was my thought as well. The Tower site does call it "medium temperature", so it is probably an OS8 which is private labeled for Tower.

jaka - great info, I am going to print this one to refer to it later!


A question on ASP's: I realize we have been talking about two-strokes here, but I have two .61 4-stroke ASP's on the way. Do they run well on 5%-10% nitro, or do I need to do anything with the head gaskets?

Thanks again.

RE: Plug temperature
 

PPK your engine may also run without nitro...

Just give it a try, the engine will tell you if it does like what you give him!i

RE: Plug temperature
 

The ASP 61FS engines run just fine on 10%

They seem to like the OS "F" plug better than the plug that comes in them.

RE: Plug temperature
 

Surely needs to be checked for every specific engine; there might be some bad surpirses.

RE: Plug temperature
 

Do any of you know who makes the “Hottest� hot glow plug?
Bob

RE: Plug temperature
 

If you have a power panel it is a simple matter and one Iuse to get the best power from my engines. Choose your prop and fuel , start the engine and get it warmed up, set your needles to best peak. Now add glow heat with the panel, check rpms if the rpms go up with heat added you can use a hotter plug if it goes down your plug is either hot enough or too hot.
Ialways use the hottest plug Ican in order to keep the idle and transition smooth.
Another thing about idle bar plugs. Some port designs cause the intake charge to be directed at the glow plug , this may have its advantages but it causes the plug to be washed with cold fuel at low rpm trying to "put out the flame" so to speak. An Idle bar plug can help prevent this and improve the idle as well as the transition. Although this is more common with baffle ported engines there are modern engines that also exhibit the problem.
Merlin Plugs seems to have the most comprehensive line Ihave seen.

RE: Plug temperature
 

Well, that is difficult question. In fact what I am doing when I have unknown engine and/or the air temperature
and humidity are unusual etc uncertainities, and if the nitro is below 5% in the fuel then I would start with A3
which seems hot, but if the nitro 5-10% then OS-8 and if nitro is more than 10% then A5. The temperature
of the plug is not so critical and if you do not have hot enough plug - then you can take away the shim
under he engine head - then check the RPM and if they are about 300-500 higher with the same propeller
then you need hotter plug or you need to add nitro in the fuel and then place the shim back and check.
You can check the OS web pages, I think there was a diagram which g-plug is for what.
Danger: - Some fuels have incompatibility of the synthetic oil to Castor. The TROUBLE is that
if you add Castor then the fuel which needs HOT plug will need very COLD plug because the
mix of synthetic(some types) and castor oil leads to detonation which in case of hot plug can
bust your engine in various ways (overheating etc.) Thus do not rely that all is done by the
Temperature of the plug...

RE: Plug temperature
 

But that is on the ground... I would go "one step back" to the colder one so to give some
"advance" to the ignition instance when the RPMs get higher in the air, of course if the
high-rpm is the goal. OK?

RE: Plug temperature
 

I have found that by using the hottest glow plug I can find and running the engine rich produces the most top end power in the air without hurting the engine. So far I have found the Merlin Hot Plug to be the hottest, but I wonder, is there another that is hotter?

Bob

RE: Plug temperature
 

Bob,


You are probably basing your last post on a misconception...

Using to hot a plug FORCES you to run the engine richer; perhaps much richer than ideal, so as to prevent the onset of detonation.
This will make the engine cooler than ideal, eventually causing wear to increase...

When an engine is running with sufficient lubricant, adding even more lubricant will not protect the engine better. It will not make the engine live any longer either.
Enough is enough and any more than enough, will just be a waste of fuel and a waste of lube.

Again; nothing but a waste of costly resources, which you have the honor of wasting a larger part of your pay-check to pay for.

What a great feeling? To carelessly waste stuff, like there's not tomorrow...

What kind of an education will your kids get from that?


For efficiency (and this also means longer flights), use the coldest glow-plug your engine will run reliably and consistently with.
This in combination with the lowest percentage of nitro that will serve the same purpose, unless you are competing and every last RPM counts.

RE: Plug temperature
 

Darzeelon; why is it you fail to answer, or even address my question, but rather choose to contribute nonsense? That must be a self portrait in the sidebar?

RE: Plug temperature
 

Quote:

---

ORIGINAL: Oldbob

I have found that by using the hottest glow plug I can find and running the engine rich produces the most top end power in the air without hurting the engine. So far I have found the Merlin Hot Plug to be the hottest, but I wonder, is there another that is hotter?

---

Bob,


What you wrote above is nonsense! Ask others, if you think I am wrong... I believe you will overwhelmed to find just how wrong you are!

And regarding that 'nonsense' that you claim I contribute, Mr Right; I suppose you are one of those people, who believe anyone who disagrees with what they write, is automatically wrong...

RE: Plug temperature
 

To borrow a phrase often used in another forum.....Irony meter pegged!

How do you know exactly what he meant by "rich"? It's a known fact, although apparently not to you, that methanol, and particularly nitro, have a wide range of air/fuel ratio where they both deliver high power. So he likes to run it rich...more fuel to give more internal cooling to increase the density of the air in the crankcase which in turn will add some power. Works for me.

Making the engine cooler than ideal? Tell me what the ideal temperature is. Cooler than "ideal" eventually causing wear to increase? Why eventually? It either increases or it doesn't. How come I can run an engine in a 4 stroke and it'll last practically forever? It seems you don't know that there's very little difference in temperature from even the 4-2 break point to slightly rich of full peak.

RE: Plug temperature
 

Guys,
It seems Friday-night is getting to the "detonation" point ... and your "engines" get overheated ... [sm=punching.gif]
Maybe it is better go dancing in Friday night, please the girls and not take much "heavy" fuel...[sm=spinnyeyes.gif]
because the morning will be more painful ... Anyway Ethanol is not so bad for the health and
in good proportions cools the "engine" down ... I think ... you migth agree...[sm=thumbup.gif]
Proportions(!) are the essense of life ...

Back to topic please: There were in mid 60's (obviously I am getting older...) some Glow Plugs made
in the former East Germany which on the top were filied with transparent insulator so one can see the
COLOR, i.e. the temperature can be measured by some kind of pirometer. That time many were
runnig also with open exhaust so one can see how much "orange or red or yelow" the plug is...

So QUESTION: - How nowadays one measures the TEMPERATURE OF THE PLUG ? - please give some
Technical Details. Anyone have seen those Glow-plugs arround? - I have one somewhere in my storage
and if I find it I will light it for you and make a photo, but I would like to buy some more of those if
they are made somewhere; please advice.

After burning maybe some N x 10 plugs of different kind I use only F type and adjust the
rest to the plug, i.e. "manipulate" 1)The Fuel and 2)The Compression ratio(the shim).
And seems the Glow engines have pretty "flath" optimum of the set-up so they can take
a lot of unsuitable mix of "things" but seems the professionals make it always better
than the others... I wander How Many Super-Electronically Enhanced Engines OS managed
to sale; any idea ?

Thanks,
Nick

RE: Plug temperature
 

Bob, this may have worked on your engine(s), but you shouldn't make a "blanket statement" for others to follow.

Every engine and installation is a law unto itself. Glow plug selection depends on interacting factors of compression ratio, porting, exhaust scavenging, nitro content and engine load to name a few. The best analogy I can give you to think of, is to relate hot and cold glow plugs as to timing advance and retarding in a spark ignition engine. Hot= advance, cold=retard, realize this example is over simplified.

In most of my engines I have gone to colder than recommend plugs to gain performance when I push them to the limit.

Do I run rich, sure if the engine wants it. How about 8oz. of 30% fuel in three minutes in a 46 size DF engine. Or 16oz. of 30% in 5 minutes in a 70heli engine mounted in a full race WM P-51 mustang. A hot plug would last only seconds in those engines, the right one can last a gallon or so.

I now only use K&B brand glow plugs. HD type (like #8 but tougher ) or HP type (cool, high nitro) or Enya #5 in a pinch(cool).

RE: Plug temperature
 

Quote:

---

ORIGINAL: downunder

To borrow a phrase often used in another forum.....Irony meter pegged!

---

Brian,

If someone is wrong, I believe it must be stated in clear, unequivocal terms (I never use harsh language and profanity).
Trying to 'soften the blow' just won't have the right effect...

I 'tailor' my reply in such matters, in a way that should, at least in theory, make this wrong person "sit the next one out"...

...And I won't quote from Clint Eastwood's words; regarding what an opinion is like...


People can take different positions on matters and it is their choice...
But regarding physical, chemical, mechanical and biological FACTS; no one is entitled to have a different opinion of his own!

It is those members who have 'opinions' that contradict fact; that I am especially 'fond of'... [:@]


The two of us (you and I) have had conversation between us over the years and I believe we share facts, but sometimes don't fully agree on some things for which opinions can be considered legitimate.

And then we have our heated discussions; some of which make this forum much more interesting and enlightening.

RE: Plug temperature
 

The question was “is there a hotter glow plug than the Merlin?� I was looking for a yes or no answer and a brand name if the answer was yes. It appears that no one knows the answer.

Downunder is correct about keeping the engine cool. I have found that a head temperature of about 225 to 250 F) on the ground and 250 to 275 in the air works best for maximum in flight power. I used an infrared meter. By running rich on the ground there is enough fuel for the engine during high G maneuvers such as a high speed pylon turn so the engine will NOT overheat.

Here is how I determine that one glow plug is hotter that another. I used an OS-F plug as my base line. 15% nitro fuel, 10X4 APC prop, engine either a TT PRO 40 or a GMS 40. The RPM should be around 16,500 peek when you pinch the fuel line. Set the needle valve to achieve 15.500 RPM or 1000 RPM rich from peek.

Now let the engine cool and change the glow plug, make NO other changes i.e. do not touch the needle valve. Start the engine and let it worm up then go to WOT. If the RPM is greater than 15,500 and somewhat rich, the plug under test is hotter than the OS-F; if the RPM is less than 15,500, and very rich, than the plug under test is colder than the OS-F.

Remember this test must be performed with the same fuel, prop and the same engine, and on the same day within 15 to 20 minutes apart.

This works for me.

Bob

RE: Plug temperature
 

Head temps are notoriously inaccurate.

RE: Plug temperature
 

Bob,

I imagine (but it is your jusdgement) that you can increase pretty much the precision of your
measurements in the following manner:
1. Get a stroboscop from the car guys which is used to see the ignition instance, or use a photo-flash.
2. Drill and place a nipple beside the glow plug and use that pressure to trigger the stroboscope.
3. Then instead of propeller place a heavy wheel like those used for the boar engines. Behind or in front of it
place a disk on which outer surface you mark every 1mm axial line for about one half inch distance.
So the idea is pretty classic one: - when the pressure in the head chamber triggers the flash then you will see
which mark on the disk is seen due to the stroboscopic effect. With different plugs you should be able to see
different mark on the disk and from there you will find which plug is hotter = it should flash the earlier
mark on the disk, isn't it.

Check also my post earlier today. Using that old DDR-idea you can install second plug on the head of your
engine, drill it trough and fill it with transparent material, like melted quartz. Then you will see what is going
on inside of the head-chamber of your engine... It is amazing thing ...

Of course the professional laboratories for engine research have much more precise instruments.

For example, why not visiting the nearest University, I believe that is University of Dallas or Texas A&M
university and ask if they have some lab where the undergrad students will enjoy having a course project
and measure some bunch of glow plugs for you. For sure in those Universities there are many who are
at least interested also in RC flying.

Cheers,
Nick

RE: Plug temperature
 

Quote:

---

ORIGINAL: Oldbob

The question was; “Is there a hotter glow-plug than the Merlin?� I was looking for a yes or no answer and a brand name if the answer was yes. It appears that no one knows the answer.

---

Bob,


And it seems it is either that there isn't one, or that if there is such a plug, it is so rare that no-one knows about its existence...

The hottest glow-plug made in large numbers is the OS A3/#6...
A close second is the Enya #3, which has a desirable trait... It 'behaves' colder, when installed in mid-size engines.

The Novarrossi C-5S is also close...

I believe the [link=http://shop.vendio.com/RossiEnginesUSA/item/2019666765/index.html]Rossi R1[/link] may even be hotter than the Merlin, which I have never seen.


Most people have probably not heard of hotter glow-plugs, simply because no-one ever asked, or needed his/her plug to be any hotter...
...Until you came along, that is.[>:]

RE: Plug temperature
 

Which Merlin plug (they have a full range) are we talking about?

I've tried their 1/2a ones but it seemed a little cold to me. The Rossi R1 might well be the hottest, but the OS#8 usually does the job well enough...

RE: Plug temperature
 

Heavy Duty Hot, #HD2003

RE: Plug temperature
 

It 'behaves' colder.....? :D

Bob, I suggest you ask this question in the Jett Engine forum. Bob Brassel should be able to give you the answer you’re looking for. I buy Merlin Plugs from Dubb Jett.

RE: Plug temperature
 

Oldbob, seems that Merlin has changed their range, I think I have had the 2003 but not the HD2003.
They list the 2003 as being similar to Enya#3 so the HD2003, being hotter, may then correspond to a Rossi R2... (only guessing though)

RE: Plug temperature
 

Quote:

---

ORIGINAL: Broken Wings

It 'behaves' colder.....? :D

---

BW,


Yes.

The OS F plug is hot.
It is intended exclusively for four-stroke engines; to retain the glow over the exhaust period, so it is capable of igniting the mixture, during the engine's next revolution...

Large engines need to use colder glow-plugs and smaller engines need hotter glow-plugs; yet the F plug behaves very nicely in large engines, like the ST 2000-2300 and many others.
It does this, despite being hot and it is not necessary to richen the mixture, beyond the cold plug setting for the same engine...

...Hence; 'acting' colder in some engines...


The Enya #3 is the only plug they specify for four-stroke engines; despite not having the 'protruding snout', Ã* la OS F...

Like the OS F, it also 'behaves' like a cold plug, under certain circumstances.

RE: Plug temperature
 

Dar,

Is it F so hot or it is massive to retain the temperature, or both ? - please specify.

Nick

RE: Plug temperature
 

My oh my, I didn`t know until now how difficult and complex it is to choose a plug for my engines, it is almost rocketscience it seems[sm=lol.gif]

I run OS F in all my fourstrokes, they might cost a $ more than others but so what? they last forever, I think I have never blown one of those.
In my twostrokes I use whatever I have at hand, mostly OS 8, 5, 3,also the F, Towerplug, Sirio`s, Rossi`s, Mc Coy 59, ASP, and propably lots of others. After a needle tuneup I can hardly tell the difference between them in the air or on the ground (car, boat)

I did some peak rpm testing a couple of years ago and in my engines rpm never varied more than max 300 rpm peak no matter what plug I used, so I think for casual sportflying it really doesn`t matter that much;)

RE: Plug temperature
 

Quote:

---

ORIGINAL: NikolayTT

Is it F so hot, or it is massive to retain the temperature, or both? - Please specify.

---

Nick,


A "hot" glow-plug's element, does not necessarily glow any hotter than a 'cold' one's.


What differentiates a hot plug from a cold one, is its heat retention.

This could be achieved by using a heavier gauge platinum wire (which takes longer to cool off) for the glow-element, but it can also be achieved by better 'insulating' the element, against heat-loss.
It is all in the time it takes the glow to cease - a hotter plug glows for a longer period.


Regarding the OS F; I can not sure if its glow element has a heavier gauge than, say, an OS #8.
But with its longer 'nose', the element does not lose its glow quite as quickly.

RE: Plug temperature
 

That should clearly indicate that with the approaching winter most of us have got more on the talking than on the
building and flying side of the life. At least frankly I feel so... and I fully agree that in many cases it is very
hard to tell which plug is used if the fuel and the engine are having some kind of "common sense set-up" proportions,
i.e. if we stay away of the extreems... It might be good to agree with some of the earlier posts about What
each type of enigne wants, i.e. to pay some respect to those who built the engines and wrote the manuals...
I am afraid some of them are looking with pitty at some of the statements at RCU and let us talking endlessly
here without even writing a single word (at least I know one guy like that from a very advanced RC engine
making company; he is even wandering how we can spend so much time & money to re-discover the Universe ...

How is the weather in Norway ? Here we got already the first snow flakes but still is above the freesing
point and ... I keep writing instead of flying ....

Nick

RE: Plug temperature
 

A question: - How Hot are the Non-RC plugs when compared to the RC types ?
Anybody has tried some of them for RC flying, please share your observations.
Thanks,
Nick

RE: Plug temperature
 

Pretty bad around here now, not too cold but lots of wind and rain, snow in the mountains though. I write more than I fly too these days:)

RE: Plug temperature
 

There aren't any non-RC plugs, actually there aren't any RC plugs either....there's just glow plugs :). Choosing a plug for an unthrottled engine is much the same as choosing one for an RC engine, apart from not having to worry about how it idles or transitions. Although come to think of it, I guess you could say they transition from not running to flat out as soon as you give them a flick. Most of the time you can barely detect the time it takes to reach full speed :). My favourite plug for engines that I run 4 stroking rich is the Taipan red (hot) plug. There's no discernible rev drop when the glow igniter is removed. This is with zero nitro fuel so it could possibly be too hot for nitro.