I've been reading some of the great ideas from this site off and on and its time to get contributing. I'm concerned with carbon emissions and dislike driving culture in general. I currently live in Atlanta where public transport is terrible, people leave cyclists meager space for survival and all places seem far apart.
I have owned a 96 Accord with a
F22B2 gas engine for a while and when some repair needs came up, I began to wonder about making the car more efficient. Its not terrible to begin with, and is rated 22/29mpg stock (although this seems a little conservative).
Its a Canadian car and the exhaust rotted out, so I replaced it with 3" stainless steel pipe (with little resonating chambers, and one of those N1 "mufflers", but basically its a large, unrestricted pipe) from the catalytic converter back. The kit was on ebay, like many other "cat backs" and costs about $130 delivered (vs $350+ for a stock replacement). It took about 2 hours to change with hand tools and a little elbow grease. Its certainly louder now, and I keep a silencer on the tip, but on a recent drive from Georgia to Ontario I filled up the gas and realized i'd made 41mpg (I tend to do a lot of coasting and follow others when possible, but this was a steady 75mph even on heavy climbs). On a subsequent trip I was averaging 85mph for a couple hours and still achieved 38mpg.
I'm impressed with the new economy of this car, and want to stretch things farther.
I am interested in other refinements I can make which give it high efficiency at 'flow of traffic' highway speeds. I'm concerned that ram air and cold air intakes may increase fuel consumption, but I feel that a better aspirated engine could increase efficiency.