what plug

[Andy from Sandy]

Too fast and you risk damage to the engine if fuel starts to burn as the piston is still coming up, too slow and not all the fuel will burn and the engine may not idle reliably, so it's a balance of those two extremes.

The fuel needs to start burning as the piston is travelling up so that it reaches its maximum intensity as the piston just goes over TDC and then driven down with the fuel producing its maximum pressure.

The temperature of the plug is a very technical area. One that I have not had much dealing with. Just because one plug works for person A doesn't mean it will work for person B. All factors have to be taken into account: The engine's compression ratio; the amount of nitro in the fuel; the type of exhaust; the density of the air; the ratio of fuel to air mixture and maybe some others.

What I do know though is if the selected plug is too hot you will almost certainly damage the engine due to the firing of the fuel not being clean and controlled.

[brin]

Also bear in mind that Higher nitro contents usually require a cooler plug. Conversly lower nitro content require hotter plugs.

i shall be using 20% optifuel in both helis the raptor has the os 32 and the 600 has the os 50 will the same plug suit both.

[Steve]

i shall be using 20% optifuel in both helis the raptor has the os 32 and the 600 has the os 50 will the same plug suit both.

I'm currently using MT 20% fuel and now have OS No8's in all my helis - 1 x OS37, 2 x OS50 and 1 x YS91 engines. Works fine.

[oneandonlyian]

Enya 4 in my o.s carbed redline engine on 20% opti fuel and its running sweet not much power difference between 30% either. the plugs seem to last a lot longer for me than than the o.s8.

[trillian]

The fuel needs to start burning as the piston is travelling up so that it reaches its maximum intensity as the piston just goes over TDC and then driven down with the fuel producing its maximum pressure.

Yeah, I was trying to keep my explanation as simple and concise as possible, the point being you don't want that max intensity to be reached too soon

[Rotorhead]

Ian, if you're running 20% nitro or more you may want to look at the enya #4 rather than the 3.

Its a bit cooler than the #3 which will counter the advance in combustion that higher nitro causes so you may find that with higher nitro contents it runs better and develops more power.

[machasm]

Found this tech article
http://www.iroquois.free-online.co.uk/gloplug.htm
Although a little old I think the theory is still the same.
Ade.

[oneandonlyian]

my bad just checked im on enya 4 thanks

[brin]

thanks once again for all the input .now where do you all get your plugs?

[Steve]

thanks once again for all the input .now where do you all get your plugs?

From a model shop.

[brin]

From a model shop.

always a smart one lol but which one(shop i mean)