Dewalt17

Which glow plug should I use a A8 or A3?? Which is better? I assume the A8 is a better plug since its a bit more expensive.
What is the difference between the two? Is one just a hotter plug than the other? Does one last longer than the other??
Any other suggestions of a different glow plug that may work better than the ones mentioned above?

Im not having a problem or anything but i feel knowledge is power. Power over the LHS who wants to sell you the most expensive stuff they got and you may not need it!!!

Thanks,

Sean

3DFanatic

My Feedback: (5)

The 8 is a hotter plug then the A3. The 46FX runs great on an A3. No need to spend the extra $3 on an 8 (even though fanatics like me do).

Imac Kiwi

OS no 8 is the recommended plug for this engine

MikeL

My Feedback: (3)

Of course they recommend the more expensive plug!

I use the A3s. If you're careful about how you run your engine they seem to last quite a while. Try a #8 if you want, but you won't notice any performance difference between it at the A3.

Tired Old Man

My Feedback: (1)

Any RC Long glow plug will work in your engine. It never hurts to experiment a little to find out what works best for your engine. OS does seem to make the best plugs on the market, but there have been instances where other manufacturer plugs have worked better. You will probably not want to try idle bar plugs.

Yub, yub, cmdr!

YNot idle bar plugs, like Thunderbolt and Fox?

I have an A8 plug, never used, on magnum .46XLS. I'm gonna get a backup plug and probably will buy a Fox plug, just to see.

PS will APC 10x7 ruin my Magnum when the magnum suggests 10x6 prop for breakin?

3DFanatic

My Feedback: (5)

Lots of guys use Fox Miracle plugs (intended as a 4-stroke plug) in their 2 strokes and like them better then the OS 8! I just seem to have a surplus of A3s around here and am burning them off...

FunXtra

3DFanatic, u stole the keys from my board...
yeah miracle plugs are the best thing that happened to me since i switched to powermaster 15%!!!!
idle and output RPM are great--no need for idle bars with these!!! let's face it: bars DO come off sometimes (more often than i expected, which is never and it happened ONCE to a FRIEND and i havent bought em since), and they somewhat limit top RPM.
this is not necessarily true about the RPM, but i noticed a tiny bit more power from plugs w/o bars

ifixairplanes

My Feedback: (9)

I have always used the OS8's with good luck. last summer 1 plug lasted the whole summer. I just recently had to put in a new one (last week) but i got my $8 bucks worth. I have never had a problem with them. But this is just my preference, i havent used any other plug so find what you like!

sean

pinkertonfloyd

I just use the Tower Power Plugs... cheap, made in Japan (look exactly like an OS A3), and never had an issue with them.

3DFanatic

My Feedback: (5)

Made in Japan? Wow. Don't see that much anymore. It's all shifted to even farther away places

Xtra, gimmie your address and I'll send your keys back

I'm personally sold on the OS8s. But I'm gonna have to try a Miracle just to see.

Montague

I've been running K&B 1L plugs in most of my engines for quite a while, and they work just fine. I used to use the Fox Miracle, but I have no idea why I don't now. I'll have to get some to find out.

However, the K&B and Fox plugs are slightly longer than an OS 8. Not long enough to hurt anything, but I've seen some new OS FX engines that wouldn't run right with the longer, hotter plugs until broken in. Too much compression I guess.

There are lots of good plugs out there. OS are good, but expensive.

Espen K

OS #3 is a plug for engine up to .40 size. Bigger engine as the .46 needs OS #8 or equal from other brands.

Have used both of them in OS and SC engines (.40 and .46) and I think I got a better throttle response and safer idle by using #8. I'm using Cool Power (15%nitro) or a Norwegian brand named JeRo fuel (5% nitro).

DeepSpace

We usually use a Rossi 4.

MikeL

My Feedback: (3)

Sorry, but that's just not true. The A3 is just OS's less expensive plug. Engine displacement isn't a factor.

DeepSpace

No that's not true. Now i'll quote for rossi. OS has a simular thing.

R1 - Very hot - From 0.8 to 2 cc
R2 - hot -From 2 to 3.5 cc
R3 - Med - From 3.5 to 6 cc
R4 - Cold - From 6 to 10 cc

Montague

Engine displacement alone does not determine how hot or cold of a plug you need. In fact, it's one of the less important factors. The compression, fuel, exhaust system, and expected RPM of the engine matter more.

Most sport engines like the OS FX line do pretty well with a wide selection of plugs, espeically after a little run time. Higher RPM, high performance engines with high compressions frequently need colder plugs to avoid pre-ignition. Man 4-strokes need a hotter plug to help maintain combustion at lower RPMS with combustion every other rotation.

It is quite possible that Rossi engines are set up such that the chart you quote works for Rossi engines. If we all ran Rossi's that would be fine. But Rossi is a fairly odd-bird, not what I would consider typical of your average sport engine in the .25-.61 range. I don't know if they still are, but if I recall Rossi was one of those Eurpoean engines that was tuned for 0% nitro and could become quite the firebreathing monster when sone nitro was added. Very high compression ratios. I could be mis-remembering, and it's been awhile, I haven't seen a Rossi in person in years.

MikeL

My Feedback: (3)

Heat range isn't always linked to displacement.

http://www.osengines.com/accys/glowplugs.html

Also take a look at Tower's tech notes for the two plugs:

http://www2.towerhobbies.com/cgi-bin...?&I=LXCB26&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXCB27&P=V

Espen K

The dealer of OS in Norway has made a list of engine size/nitro rate and recommend the following:

OS#3 Hot plug for 0-15 nitro, .12 - .15 size car, and all kind of 2 stroke engine less than . 46.

OS#8 Medium plug for 0-15%nitro for 2 stroke engine.

3DFanatic

My Feedback: (5)

The #8 is the hot plug. The A3 is a cooler plug.

Espen K

Sorry 3DFanatic you are wrong, follow the string and see how OS has classified plugs:

http://www.os-engines.co.jp/english/...g/pluindex.htm

MikeL

My Feedback: (3)

Dealers often prefer it when people believe that the more expensive product leads to better performance.