Quote:
Originally Posted by theunchosen
...So RK you are right(at least I am pretty sure you are) that lean burn does go hotter, but that cat itself is no longer burning fuel onsite so its temperature will just be the exhaust temp(400 odd C).
The downside of keeping the cat ambiently that hot (without it burning HCs in regular stoich burn) is its going to be that hot when you are running in regular and its going to burn out sensors and unnecessarily heat the engine. My only beef with a hot engine is they don't usually last as long (something gets hot its elastic deformation range shrinks and you get close to plastic deformation and something messing up)...
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theunchosen, I follow your reasoning but there's a piece that I want to question.
First I have to say I don't have the background I should as far as typical temps for combustion, exhaust and cat operation. I tried doing some quick research but I'm not finding the data easily.
Anyway, normal stoich EGT at part throttle will be
x but in lean burn it will be 1.5
x or 2
x, I suppose? This hotter lean burn exhaust is likely not hotter than normal stoich cat operation??
If so, the hotter lean burn exhaust wouldn't damage the cat or oxy sensors BUT -
As you wrote it probably heats up the head more than usual. Would watching the ECT display on ScanGauge reflect this? - or would the high temps be local to the cylinder walls and not be reflected in the ECT data from the ECU?