What plug do you run for the Axial .28.

[NITRONUT]

so different amounts of fuel burn at different temps?

Absolutely they do.
The temp of the burning fuel/air charge will vary because of the amount of oxygen in the charge.
That is why your engine will run hotter when its lean than when its rich. The best way to look at it is like this.

First thing you have to remember is your engine can only draw a certain amount of fuel and air into the combustion chamber. This is set by a whole host of things like the # of ports, port timing, crank timing and so forth but that isn't important right now.

Now with that said, if you have more fuel going into the combustion that will leave less room for air making the fuel burn slower and not as hot, hence a cooler running engine making less power.

If you have less fuel going into the combustion chamber that will leave more room for air and will make the fuel burn faster and hotter, hence a hotter running engine making more power.

I hope this answers your question.

 

[NITRONUT]

The plug does in fact have a bearing on the engine temp for the fact that if ignition timing is advanced the combustion temps will be slightly higher due to the fuel burning more completely during combustion process. In reality its only going to be a few degrees if your running rich but you in fact could run into problems when tunning for utmost performance.

The rule is
High nitro content ( over 20% )= cold to medium plug on a typical big block at air temps over 60F.
Med nitro content (15-20%)= medium plug at the same temp.
Low nitro content (below 15%)= hot plug at same temps.

If the temp outside is below 60F you could go ! step hotter or allow the engine to warm up for a longer period of time.

Hope this helps. This info was what I was taught from MANY engine manufactures.

I just read the Febuary issue of R/C CAR ACTION magazine and on page 173 there is a great article on "Understanding Glow Plugs". It says allot of what I have posted here on this thread and is good to read. Check it out if you have the magazine.