Running lean..
 

I was thinking about how you could tune the AFR of cars other than hondas in order to get better mileage. Is the only thing that would prevent running lean would be the risk of misfiring and knocking/pinging? If I was able to avoid these conditions, would running lean be an issue on cars not designed for lean burn?

What exactly besides the "swirl" the honda introduces into the cylinder would make running lean a bad idea? I figure the swirl idea could be introduced into vehicles with 4 valves by having just one valve open on one side which is what Vtec-E does. Correct?

Saturn VTEC
 

I just agreed to by a 2002 SC2 today. What a pretty car! I know it has the wrong transmission but it is so clean and cute.

I have not even taken possession of the car and I was already wondering the same thing. Could I turn this into a Saturn VTEC. I think it could be done and it might work. You would probably need to massage the O2 sensor signal for the lean burn. I don't think Honda disables the valve completely. At least I thought that it still moved a small amount so fuel did not collect in that port. I suppose it would take a modified camshaft and obviously would not switch back and forth like a Honda.

The Saturn Fuel injector looks like it splits the fuel between the two intake ports. If one port lets in less air than the other that port will be richer and the other port will be leaner. This is what we would be trying to accomplish.

The catalytic converter is not set up for this so there would be an environmental cost but the engine might run a bit leaner without missing.

The worry about detonation and high heat with running lean is usually overstated. In fairness I must admit to melting down a turbocharged engine once. After you get past stoichiometric temps start dropping again. If the exhaust valve cannot handle the excess oxygen it very well may burn but it probably isn't running much hotter than it was before. This may require an aftermarket exhaust valve. I am not sure.