Forums
The Wilson R/C Modelers Association :: Forums :: Wilson R/C :: General Discussion
 
<< Previous thread | Next thread >>
Glow plugs
Moderators: Admin, Bob, Mike
Author Post
WILBOY64
Mon Nov 05 2007, 04:15PM
Registered Member #33
Joined: Tue Oct 09 2007, 04:18AM
Posts: 23
 Can anyone tell me what is called a hot glow plug or a cold glow plug?Does a hot plug burn hotter or does a cold plug burn hotter? I am a little confused.
Back to top
Bob
Mon Nov 05 2007, 09:57PM

Registered Member #4
Joined: Fri Mar 09 2007, 05:08PM
Posts: 11
 So what is a ‘hot’ plug, and how does it differ from a ‘cold’ plug? Naturally, a hot plug will heat up faster and stay hotter, but that’s not the whole story. When discussing this aspect of glow plugs, another very important aspect must be considered, the amount methanol in the fuel. The more methanol we’re using (i.e., less oil and less nitro), the hotter the plug we should use. Conversely, the more nitro and/or oil we use, the less methanol we’re using, so we use a cool(er) plug. An extreme example would be when using a very high nitro content fuel in a very high RPM engine (a typical ducted fan engine, for example). Here we’d use a very cold plug. For most sport pilots using fuel with just 5-15% nitro, however, a hotter plug would probably do well.

Probably? Yes, trial and error is often the best (and sometimes ‘only’) way to determine the right glow plug for your application. Most 4C engines need either high nitro or hot plugs to run at their best, since they have combustion strokes only half as often as 2C engines.

RULES OF THUMB TO LIVE BY

A. Use a hot plug with low nitro (less than 24%), and a cold plug with high nitro (more than 25%).

B. If you remove the glow starter from you idling engine, and notice an immediate drop in RPM, you may need a hotter plug or more nitro.

C. If your engine has a tendency to backfire a lot, you may be using a glow plug that’s too hot, or you may need fuel with less nitro.

D. Most hot plugs can take up to 2.0 volts starting power without burning up, while most cold plugs prefer 1.2 to 1.5 volts starting power.
The only limits are down!
Back to top
 

Jump:     Back to top
Syndicate this thread: rss 0.92 Syndicate this thread: rss 2.0 Syndicate this thread: RDF
Powered by e107 Forum System