what gives the good gas mileage-tq?

[no_doz]

if i were to take a light car & swap a 3100 or so & a 4t60e out of a lumina & used it in conjunction with wheels that are a good deal smaller (13" rims rather than 16 or 17")-if i wanted to cam my engine for best gas mileage at 60-70 & maybe in 4th gear the engine wanted to cruise at around 1500-2k rpms-would i want to cam it for tq at that rpm in order to achieve the best gas mileage? also is it possible to cam/build these engines for high rpm hp & low rpm tq (like 5-6k rpm hp & 1.5-2.5k or 3k rpm tq)??

[Azrael]

Tall gearing and torque is a winning combination for fuel mileage. My grand am used to have the same gearing as the 99+ GTP's (2.93:1 FDR) but I was always a few mpg behind them without the torque to back it up. A slightly lower stall torque convertor might help as well. Particularly with stop and go driving.

[johnnymossville]

To get good mileage requires a few different things. Some of which are: close to stock height and width tires on aluminum wheels properly inflated, a good tune-up including air filter and most of all proper driving technique. My wife averages 30-32 mpg in her '93 Lumina 3.1 in a mix of city/highway driving while when she lets me drive her car I get only 25-26 mpg. Hmmm, makes you wonder doesn't it. The only mods to her car are a K&N drop-in air filter and a Z34 single to dual exh. with Dynomax Super Turbo muffs, a cat delete, and 16/7" American Racing Avenger wheels with 235/55-16 tires. It looks good, runs good and sounds great.

Now if you want to build an engine it should to be close to stock but you can add a short duration higher lift cam to get good torque and good mileage. Some people on this site have built their engine fairly radical but yet get good mileage. I think Superdave said that he gets close to 30 with his 3500, onefastv6 said that his mpg went from ~30 to 33-34 when he modded his engine if I remember correctly. I was getting upper 20s with my build, not completely tuned yet and I drive for fun.LOL

Remember the single most important thing to good mileage is driving technique. It doesn't matter what you drive, if you drive it right you'll get the best mpg that your car is capable of achieving.

[IsaacHayes]

Weight and engine efficiency play a role. As well as RPMs.

The ford tore-ass wagon I'm driving gets 13-14 with some hwy. It's trans slips like a mofo though, but my moms sedan tore-ass gets 15 so not far off. The engine is a 3.0 and only 140 hp in a heavier car than my beretta. The intake manifold is horrible on them. The runners are not equal length at all. One side is super short, one side is super long. It isn't very efficient. Upgrade the intake/etc to make more power and it would be more efficient and get better mpg.

[no_doz]

those cars are crap but my mom insisted on getting another one after the first ones trans went out-the first had a 3.0 and got like 26-27mpg hwy & the other was a 3.8 that got like 16-17 mpg hwy lol

[carbon]

Weight and engine efficiency play a role. As well as RPMs.

The ford tore-ass wagon I'm driving gets 13-14 with some hwy. It's trans slips like a mofo though, but my moms sedan tore-ass gets 15 so not far off. The engine is a 3.0 and only 140 hp in a heavier car than my beretta. The intake manifold is horrible on them. The runners are not equal length at all. One side is super short, one side is super long. It isn't very efficient. Upgrade the intake/etc to make more power and it would be more efficient and get better mpg.

Yeah... it amazes me what Ford as gotten away with over the years with engine output... most of the reason that people think that they will get 20-25HP out of intake in exhaust mods is the fox body 5.0s. Even the new 4.0 Mustang... 4 liters gets you 210 horsepower? Really? The 4.6 will get you over 300HP? GM has been doing that with the Northstar since the 90s...