Thermal Imaging for engine tuning and troubleshooting

[Fuelie Fan]

In the combustion chamber leaner mixtures are hotter.

But I have seen a way too-rich mixture create horrible amounts of header heat. My theory is the extra fuel is not burned, so it enters the exhaust and burns there, perhaps aided by oxygen from excessive overlap of the cam. This was on a race car with roller camshaft and Weber carbs.

So much heat was generated at idle (1200rpm) that a coolant hose 1.5 foot away was smoldering! It radiated heat like a furnace.

Individual header temp probes or wideband oxygen sensors would tell a lot.
David

1. Hottest in-cylinder temps are at stoichiometric, not lean.
2. Sounds totally plausible. It's not too far removed from an anti-lag system, when you think about it.