___Increase M.P.G___

[89chevy]

My truck is going to be driven alot in the city and hiway. What should I do to get a noticable diff. in m.p.g. that is low cost? (89 Chevy, 350 TBI all stock)

Thanks.

[67malibu]

Get the engine to breathe better in and out. A K&N air filter and getting rid of the baffle in the line from the fender well helps the in. A cat back system is the best and easiest way to help the out and gain some torque. Headers can do good but the the shorty stock replacements (use factory Y-pipe) don't do much (in my experience.) More spark (better wires, platinum plugs, hotter coil, performance chip, etc) can do some good as well but it will take multiple changes to see a real difference at the pump (we're talking 2 to 3 mpg city here, don't expect huge gains from a 350.) Tires are also important(both style and air pressure.) If you're due for a set, do your homework. Some styles get better mileage. I'd start with the air filter and cat back system (~ $400 should do) 'cause you'll get a better sound as well. One word of caution: you can blow alot of money on upgrades to get better mileage but consider how much you're putting in versus how much you'll save over time at the pump.

[ChevyWonTon]

If your truck has an open pickup box, additional improvement might come from replacing the standard tailgate with a vented gate to lessen drag inside the pickup box. I've never seen actual data to prove this theory, but I've heard it from different sources. Anyone have additional thoughts on the benefit of a louvered tailgate?

An additional benefit is the cool look you get with the aftermarket style.

[67malibu]

The little bit of actual scientific data out there actually points to the opposite. Running with a solid tailgate up produces an area of high pressure behind the cab (open a sliding glass rear window while going down the road and air rushes in.) This high pressure pushes the air rushing over the truck up and over the bed allowing for better airodynamics. Mythbusters has actually done this one. They put it to the test with two identical new pickups with completely equal amounts of gas and did multiple highway drives. The tailgate up always made it farther on the same amount of gas. The word from some racing groups agrees with this.

[89chevy]

Thanks guys for your input. I wanted get some direction on a muffler, I read that dynomax does well... and if removing the cat and running true dual would show improvment? I was also considering an airaid spacer and cold air intake.(or K&N which I already have the filter itself installed) Would an electric fan do some good or a lightweight blade? Thanks Again!

[67malibu]

Mufflers are just personal preference. The best advice, find someone whose truck you really like the sound of and find out what their set up is. Flowmasters without a doubt give great gas mileage and torque increases but don't have the best sounds. I've run dual dynomaxs on a 327 and they sounded pretty good. Removing cats, although very illegal, does gain power and mileage. I know this from experience but I've put twin high flows back and only lost a hair of mileage from running just dual Flowmasters (moved to a location that has inspections, but it's still not good to advocate for the sake of the hobby.) If you still have the single pipe, keep it and go with a cat back. The bigger factory single can flow just as well as duals (seen several head to head comps),you'll avoid several issues and it'll be cheaper. An electric fan will save you some power but will cost you up front to get a proper setup for a V8 ($450+.) From what I've heard about the spacers and coldair intakes on trucks, I would save your money for something else.