is there any relation between plug temp and outside temp? i have a feeling there is

[pelicanprentice]

i was bashing with my savage x 4.6 this weekend, and outside temps were about 60f. i am running 30% nitro. i decided to try a brand new mccoy mc9 however the truck didnt really seem to like it. it would sometimes shut off with throttle and it wasn't really reaching temp. so i threw in my traxxas 3232x and the truck seemed to like it better, it reached temps nicetly and seemed to shift into 2nd and had a good amount of smoke and it never shut off again.

i have done research and it seems like there isnt a correlation but i feel like if temps are hot u should use a cold plug and if there mediocre temps then a medium plug and cold temps a hot plug. is this actually factual or not really? i know 60f isnt that warm and it was windy so maybe that was causing the problem,?

thx!

 

[D3MON]

higher temps require cooler plug .cooler temps require hotter plug.. thats a fact .dont lets these guys tell you other cuz I posted this...

plug temperature dictates where in the compression cycle the engine will fire. plug temps have nothing to do with ambient temperatures.

Cold plugs fire later in the ignition cycle, they are used for high RPM situations because they are less likely to pre-detonate at high RPM, and are more stable at high RPMs, typically used for On-Road racing where the engines are going almost full throttle most of the time, and require every bit of response on the top end that you can possibly get, they make the engine run leaner comparatively as well, so running in hot weather where you have to run the engine leaner because less oxygen in the air causing even less fuel in the combustion chamber when it fires. they are typically a bit harder to start as well.

Hot plugs fire earlier, they are going to be more stable at idle, and have a better response low to mid throttle range. but if too hot of a plug, and not enough room in the combustion chamber (by lack of head shims) can cause pre-detonation, though typically not common unless its a high performance engine because of the loose tolerances on RTR engines.

why would it matter who posted it?

i was bashing with my savage x 4.6 this weekend, and outside temps were about 60f. i am running 30% nitro. i decided to try a brand new mccoy mc9 however the truck didnt really seem to like it. it would sometimes shut off with throttle and it wasn't really reaching temp. so i threw in my traxxas 3232x and the truck seemed to like it better, it reached temps nicetly and seemed to shift into 2nd and had a good amount of smoke and it never shut off again.

i have done research and it seems like there isnt a correlation but i feel like if temps are hot u should use a cold plug and if there mediocre temps then a medium plug and cold temps a hot plug. is this actually factual or not really? i know 60f isnt that warm and it was windy so maybe that was causing the problem,?

thx!

when you swapped the plugs, did you re-tune the engine? changing temperature plugs is a pretty significant change and will require change in tune to get to run correctly. for your engine id get a medium plug (MC8 if you have access to mccoy plugs) because that is what it is designed to run, you can run a Hot plug too (i run LC3 in my HPI F4.6)
very very minimal to non existent correlation from plug temp to ambient temperature.

 

[Greywolf74]

Glow plug temperature ranges are more about the % of nitro fuel you are running rather than the temperatures outside. The more nitro you are running the cooler the plug you want to use and the lower the Nitro% the hotter the plug. a medium plug like the traxxas one is generally a good middle ground.

When its super cold out it can be beneficial to up the heat range of your glow plug one level and in the summer when its 95F out you may benefit by steping your plugs heat level down one step but again the glow plug temp is more about Nitro% because untilmately what your trying to do if find the best ignition point for yhe engines air/fuel mixture.

One thing Though, The McCoy MC9 is a standard length plug and the traxxas one seems to be a long plug. I've never had any engines that used long plugs so I'm not sure if that matters or not.

 

[pelicanprentice]

plug temperature dictates where in the compression cycle the engine will fire. plug temps have nothing to do with ambient temperatures.

Cold plugs fire later in the ignition cycle, they are used for high RPM situations because they are less likely to pre-detonate at high RPM, and are more stable at high RPMs, typically used for On-Road racing where the engines are going almost full throttle most of the time, and require every bit of response on the top end that you can possibly get, they make the engine run leaner comparatively as well, so running in hot weather where you have to run the engine leaner because less oxygen in the air causing even less fuel in the combustion chamber when it fires. they are typically a bit harder to start as well.

Hot plugs fire earlier, they are going to be more stable at idle, and have a better response low to mid throttle range. but if too hot of a plug, and not enough room in the combustion chamber (by lack of head shims) can cause pre-detonation, though typically not common unless its a high performance engine because of the loose tolerances on RTR engines.

why would it matter who posted it?

when you swapped the plugs, did you re-tune the engine? changing temperature plugs is a pretty significant change and will require change in tune to get to run correctly. for your engine id get a medium plug (MC8 if you have access to mccoy plugs) because that is what it is designed to run, you can run a Hot plug too (i run LC3 in my HPI F4.6)
very very minimal to non existent correlation from plug temp to ambient temperature.

thanks for reply! when i put in the mc9 to start the day, i reset the tune and i got the temps ranging between 220-240, it was super good but i really couldnt give it because the truck would shut off. i fiddled with the needles a bunch and probably restarted the truck 10 times. it did run moderately, but i think the motor wasn't staying hot since it was also windy out. when i put the traxxas 3232x in the truck came alive but the motor started getting hot, like between 260 and 280. i tried to richen it a smidge to lower the temp but it would get too rich and would feel sluggish.

the reason i picked up the mccoy is i always hear people saying to run a cold plug in a savage running 30% nitro, but maybe the mc9 is too cold?

 

[Blitz987]

Glow plug temperature ranges are more about the % of nitro fuel you are running rather than the temperatures outside. The more nitro you are running the cooler the plug you want to use and the lower the Nitro% the hotter the plug. a medium plug like the traxxas one is generally a good middle ground.

When its super cold out it can be beneficial to up the heat range of your glow plug one level and in the summer when its 95F out you may benefit by steping your plugs heat level down one step but again the glow plug temp is more about Nitro% because untilmately what your trying to do if find the best ignition point for yhe engines air/fuel mixture.

One thing Though, The McCoy MC9 is a standard length plug and the traxxas one seems to be a long plug. I've never had any engines that used long plugs so I'm not sure if that matters or not.

the plug length matters. usually short plugs like the Os #8 is about 2mm shorter than standard. long plugs can sometimes be misleading. the best standard plugs rn are the Lrp R5/R6 and the O.S Lc4

 

[Blitz987]

thanks for reply! when i put in the mc9 to start the day, i reset the tune and i got the temps ranging between 220-240, it was super good but i really couldnt give it because the truck would shut off. i fiddled with the needles a bunch and probably restarted the truck 10 times. it did run moderately, but i think the motor wasn't staying hot since it was also windy out. when i put the traxxas 3232x in the truck came alive but the motor started getting hot, like between 260 and 280. i tried to richen it a smidge to lower the temp but it would get too rich and would feel sluggish.

the reason i picked up the mccoy is i always hear people saying to run a cold plug in a savage running 30% nitro, but maybe the mc9 is too cold?

the plug length matters. usually short plugs like the Os #8 is about 2mm shorter than standard. long plugs can sometimes be misleading. the best standard plugs rn are the Lrp R5/R6 and the O.S Lc4. make sure ur running the same length plug. the length slightly changes the compression ratio and cause delay ignition or preignition. O.S shorts are 2mm shorter than standard and O.S longs like the LC4 are the same as standard. some Mccoys have the same issue.

 

[Blitz987]

sorry but there is no way to retard the plug firing.. like I said can't wait to see the reply's.

i was more or less refering to the issue that running a short plug. not necesarily delaying/pre. just wanted to point out the 2mm difference in the O.s short plugs vs standard so lenght of the plug could cause issue

 

[D3MON]

sorry but there is no way to retard the plug firing.. like I said can't wait to see the reply's.

yes, yes there is.
diameter of filament wire will affect heat retention and the amount of platinum in the plug filament and surface area of platinum will also affect the reactivity to the methanol in the fuel to change ignition timing.

out of curiousity... what do you think changes in heat range from plug to plug? why do you think ambient temperatures changes the plug temp and how and why does it affect it? or just is because thats what some people say?

 

[cbaker65]