ta3mo3

hi all


how are you doing?



i just watn to ask you what is the diffrent between the hot glow plug and the cold glow plug?

what will do for the engine?


examples plz



thanx

thedub88

a hot plug makes your engine run hot - for cold weather
a cold plug makes your engine run cold - for hot weather


if your temps are too high put in a colder plug, and if your temps are too low put in a hotter plug

Philster

Wow - a glow plug IS NOT for weather management! One could be exchanged for the other if the conditions are so different that the engine fires differently and can't ignite fuel with the right timing, but a glow plug is not a thermostat!

A glow plug coil (whether it is hot, medium, cold, etc) determines when it will ignite the fuel -- during which exact moment of compression. Engine size and nitro % are the biggest drivers.

A thin coil gets hotter and ignited fuel a little earlier compared to a thicker 'cooler' coil on a cold plug. It is the combo that is important.

For example, a .21 mid-performance engine running 20% nitro would probably run a medium to cold plug. One might be a touch better than the other, but both would probably work great.

A multi-ported modded motor running 33% nitro would probably run a hot plug.

Usually, if you are not running extreme nitro% or you have a fairly 'normal' motor, you have room for error and can run a medium cold plug w/out any issues and you'll get a good tune. As engine size shrinks or grows and nitro limits are pushed, you probably need to make a glow plug change. Little motors that spool up fast and have vicious RPM redlines might devour a cold plug. These are just examples. Run what the manufacturer recommends, and if you race, ask local racers, because it comes down to the conditions you live in.

However, the 'glow-plug-as-thermostat' rule has always been a joke to me.

ta3mo3

Thanx all

thedub88

last summer (80 -95 degrees) my car was running way too hot 280 - 300+ with the stock plug. I posted this problem and someone told me to put in a colder plug, temps went down. As soon as the winter came, (30 - 40 degrees) my car wouldn't get up over 220. Again I posted this problem and someone told me to put in a hotter plug. I did, then temp went up

why did it work for me if it's not supposed to?

125cchyperman

Glow plugs do make a factor but not a huge factor as in lowering or raising temps. The glow plug's are meant for more or less retarding the ignition or advancing the ignition. A cold plug will retard the ignition and the hotter plug will advance the ignition. When you retatd the ignition you tend to see a little hotter running engine but not by a huge amount. And vise versa. If you advance the timing the temps should go down but not by a huge number though.

The cooling action all is all done by the advacing and retarding of the ignition. The temps that it changes are not big enough to fo from running extremely hot like 300 degree's and slap in a medium or cold plug and have the numbers then be at 250 degrees.

But what you said makes no sence you said that it was running 280 to 300 with stock plug. Ok tahts fine then you put in a cold plug (which retard the ignition and makes temps go up) and the temp went down. Then summer came around and you slapped in a hot plug and the temps went up. Now you might have typo and just said you put the wrong plug in at the wrong time. Thats ok everyone makes mistakes. But he way you have it now it doesnt make any sence yo have it backwards. So you had to have messed with the neeldes to see those results.

thedub88

ya, I 'm was having an over heating problem in the summer. The way I just said it helped, but didn't completely fix it. Mabee it only ran colder is because the temp went down. It still over heats after a while. I must have been misiformed. I'l try a hotter plug then adjust the needles and see what happens

thedub88

by the way I'm running 10% nitro in a HPI .18 engine with a medium plug

SManMTB

Duude!
No.... that's about 163% wrong.


Heat range of the plug effectively sets the ignition timing (to use a spark ignition term) on the engine.
Hot plug - advance timing
Cold plug - retards timimg

What to use depends on how much nitro you run and what compression you're running, to name a few things.

125cchyperman

Yeah try a hot plug. I always say if your using 10% fuel then use a hot plug. I would never use a cold plug with 10% as this just wont cut it. This is probably your problem for overheating as your timing is so retarded that is cant dissipate the heat which means that your engine is over heating and which is bad. You could also go up in nitro percentage as the higher the nitro percentage the cooler it tend to run. But you may not want to do that so Just do what I said and you should be fine. If you have any question just get back.

Sorry for kinda taking over the thread.