Quote:Thanks all,

David, I did rejet the carb for the hotter summer air and ended up with running between 14.8 to 15.4 to 1 A/F. That's fairly lean for this old technology. The lean burn systems that Honda employs use specific cylinder head chamber shapes and phasing of the cams via the vtec-e system. Here's a quote from Wiki:

Honda uses one of the newest lean-burn technologies available in automobiles currently in production uses very precise control of fuel injection, a strong air-fuel swirl created in the combustion chamber, a new linear air-fuel sensor (LAF type O2 sensor) and a lean-burn NOx catalyst to further reduce the resulting NOx emissions that increase under "lean-burn" conditions and meet NOx emissions requirements.

This stratified-charge approach to lean-burn combustion means that the air-fuel ratio isn't equal throughout the cylinder. Instead, precise control over fuel injection and intake flow dynamics allows a greater concentration of fuel closer to the spark plug tip (richer), which is required for successful ignition and flame spread for complete combustion. The remainder of the cylinders' intake charge is progressively leaner with an overall average air:fuel ratio falling into the lean-burn category of up to 22:1.

If I were to try running much leaner my guess is that I would lose power and raise fuel consumtion. I am running somewhat of a temp controlled air cleaner right now. I've sealed off all openings to the stock air cleaner except for the heat riser tube and main snorkel. Both are plumbed to the back of the radiator, to draw warm air only.

I think any future gains might come from more aero work. The wind noise on the road tells me the car is not nearly slippery enough. I plan to do some front and rear end aero mods in the future to see if we can reach the 80's.