I keep reading that running too rich and too lean will cause your exhaust system to glow. I can understand too rich, but it is the too lean that I am missing something. Is it that the combustion process on a lean mixture is hotter than normal? That so far is the only theory I can come up with.

 

lean means more air, and more air (the oxygen) makes it burn hotter. Look at an oxy/acetalyne torch, the more oxy you add the hotter it gets. Same with an engine, thats why the guys who run huge boost are always worried about fuel starvation, cause it'll get hot as hell if it leans out.

 

Ok, on the turbo subject, is it only draw-through carb setups that use the fuel to cool the turbo? Or would the turbo be oil-cooled? Or a mix of both?

[edit] Sorry about the hijack, figured I would go ahead and keep my question to this thread since his question was already answered.

 

No, that isn't the issue, turbos are cooled by oil and/or coolant, but what I was refferring to was the internals of the engine. Running large boost and then leaning out (from fuel starvation etc) is really bad because it can heat up the engine, but as I understand it the bigger issue is predetination, which can cause the engine to "explode" and in a rotary that would destroy the apex seals. So I guess I should have specified that earlier, its more an issue of detination, not really cooling per say, but what i said about lean running hotter still applies.

 

Lean = hot and burns cleaner

Rich = cooler and burns black smoke and burns your eyes

With my experience, on my setup, my engine likes to be on the rich side with headers only, then it would scream . . .

You must find the happy medium, being as lean as possible with out being too lean, becuase leaner is faster!

Thats what they say!

 

yea, too rich and it'll bog, too lean it'll burn up, you gotta find that magic spot, cause as you said, the leaner it is the more power it will make (within reason of course)