Power and Efficiency

[novaderrik]

you need to think of the car as a combination, and you don't need to go with modern engines with a lot of expensive and complicated electronics to do it, either. back in '93, i had a 76 Monte Carlo that would get an honest 30mpg if i drove it nice.. and there was nothing special about the car- i threw a $159 Northern rebuild kit into the stock 350 with the smallest cam they had.. it had an old WEIAND dual plane intake with the stock quadrajet bolted to it with an adapter plate.. stock 882 heads.. it had some crusty old headers and 4 feet of 2.5" pipe with Super Turbo mufflers stuck on the ends.. it was fed cool air from the front of the car with a home made dual snorkel air cleaner hooked up with some dryer duct- the carb was actually extremely cold to the touch and had water running off it after running for a few miles down the highway on humid 100 degree days. the exhaust crossover was left open in the intake to help heat up the air/fuel mixture after it left the carb and the stock TH350 trans and 2.56 gears were in the car. the car weighed 4200 pounds on the local grain scale, however accurate that was..
it wasn't a race car by any means, but it did put a friend's 351W powered 79 Mustang and my cousin's late 70's 280Z to shame a few times and would light up the right rear tire for as long as i wanted it to.. and with gas being right around $1 a gallon at the time, $5 was enough to drive all weekend.

the first thing you need to do before doing anything to the car is learn how to drive for efficiency. get a vacuum gauge and mount it in the car where you can see it out of the corner of your eye at all times.. every little twitch of your foot will move the needle- and every time the vacuum reading goes down, you are using extra fuel.
once you've got yourself trained to drive smoothly, then you can start experimenting with the car. a tuneup and playing with the timing and carb mixture screws will get you a long ways.
if you've got a small block Chevy, a set of vortec heads with flat top pistons and thin head gaskets would be a good place to start when planning the engine rebuild.

you need to know what rpm it will spend it's most time at and build for that- an engine that makes max torque at 4500 rpm will not get great mileage if you have it geared for 1700 rpm at 60mph, and an engine that makes max torque at 2500 rpm's won't be very efficient if you gear it to cruise at 3500rpm's.
the aero of the car is free mileage- block off as much of the grill as it will take before running hot and seal up all gaps behind the headlights and around the radiator itself- make sure that any air that gets into the engine bay goes thru the radiator core.
overdrive transmissions can sometimes help, but they might also hurt economy or not even change it at all- how much money are you willing to spend and how much effort are you willing to exert for $20 a year in gas savings? an overdrive trans might be worth it just to make the car more comfortable and quiet at highway speeds, even if it doesn't help mileage.. but that's a personal judgement call on your part..

all that being said- the newer LS series of engines are really tempting.. www.car-part.com has 80,000ish mile 5.3's listed for as low as $350 (only $100 more than a set of used Vortec heads).. it wouldn't be that hard to put one in almost anything and tweak it for efficiency and power.. you could get a 5.3, a brand new carb intake, and a few odds and ends to swap it into any older GM vehicle for about $1000..