Quick question about fuel economy.

Ok, I'm not doing too bad on fuel economy on my 95 Mustang 5.0L V8.

I am planning to do some upgrades to the car, the biggest one being to replace the Heads (thinking about Trick Flow Heads) and get a K & N Kit, including the Filter and Cold Air Intake.

How would this affect me as far as fuel economy? Would this upgrade use more fuel? use less? stay the same?

Thanks for the info guys.

any time horsepower increases, fuel consumption increases. there's even people who have figured this stuff out in equations. one popular estimate states that 1 HP = 1.5 CFM of air. you can help your fuel economy in little ways, like leaning out your mixture, but there you risk burning pistons and such. just be careful, do your research, and you'll be fine.

besides, when it comes to performance applications, who cares about fuel economy? if you really care that much, get an older Escort for a DD and go nuts on the Stang.

well, my question was becuase I know that Turbo Chargers tend to increase fuel economy in almost every engine where they are used. I would think a K & N kit would increase it slightly as well, but performance Heads would decrease it.

i know that when you increase air flow your fuel economy increases (new intakes, exhaust) but when you increase compression it decreases as in a supercharger or higher compression heads. usually the more air you're getting into the engine, the more efficient it is. i would guess your fuel economy would probably get better, though it might stay the same. I gained about 2 mpg from dual exhaust and intake.

yeah it might see a smidgen of better gas mileage in terms of a k&n kit, but with larger heads your gas mileage will decease... your air to fuel ratio has to be balanced...if you increase air flow you have got to increase fuel flow which equals less gas mileage...for example if you get bigger heads youve got to get bigger intake, injectors, cam, and maybe even a larger fuel pump, that is if you want to put the heasd to good use

any time horsepower increases, fuel consumption increases.

That is very un-true. lots of horsepower mods CAN help gas milage. take headers for example, they will help exhaust flow a lot better thus making hp and increasing gas milage. same with oil based airfilters. hell, even some intake can help gas milage.

now, in most cases you loose the milage because of the way you drive these mods. such as if you have a car with an intake, and headers this does not make it fast but i bet you sure will drive it a lot harder than if it was stock.

Great info so far guys! This is my only car, therefore I use it for everything, and nicer fuel economy would be nice, but I also want to start modding it. What are the best mods to increase fuel economy, with increased performance as a bonus benefit?