Air Filter Question
 

I noticed yesterday before i started doing routine maintenance on the civic, to prepare for a long trip (Vegas and back), that while changing out the stock air filter, that the air intake hose, just before the air box had a circular opening roughly 2 3/4". Is there a fuel efficiency advantage to removing all that BS for the stock air filter housing and adapting a cone filter to fit that opening? anyone done with the stock intake tube and not that long chrome intake tube?

I've not seen any documented cases here of unwanted results due to air flow restriction, when driving for mpg with a fuel injected engine.

Running at 5000-8000 rpm at WOT or with a turbo added you probably would not realize full possible power without modding the intake. But if you're here, I suspect that's not how you're driving.

The amounts of fuel (and thus air) we are putting through our engines is less, if anything, than what the designers planned for, not more. Even unplanned added restrictions like a dirty filter has been tested to show near zero effect. The air flow sensor detects the net air going through the pipe and that's all the computer really needs to know.

Take a look at the "65 proven mods" thread sticky at the top of the EcoModding Central forum. You will find stuff on warm air intake and hot air intake (I'm pretty sure) but nothing on unrestricted intake or cold air intake. I use a WAI in winter.

Check out this test:
http://ecomodder.com/forum/showthrea...est-19054.html

...with a carburettor the answer is YES, but with todays Fuel Injection Systems the answer is NO, because the computer automatically adjusts the A/F to compensate for airflow restriction.

i know it automatically adjusts the ratio, but would the cone filter make for less restriction, the easier it is to suck the air in, the less the engine has to work for it, I just want to know if the mpg gain is significant or slight.

Try non-existent.

Yeah I've read the 65 proven mods before , that was another thought I had with the cone, was that it would be closer to the exhaust manifold heat.

The stock intake tends to be designed to help maintain momentum in the air intake as it's drawing air in in pulses, one of the things that I've seen with a cone air filter will make your engine louder because the intake is pulsing again and there is no sustained momentum, it would be kind of like removing your fly wheel with the idea of saving weight.

No gain in MPG. Some folks come up with anecdotes otherwise. The plural of anecdote is not data.

If it takes 20% throttle opening to cruse at 50mph with the stock intake. Then we add fancy filter and now it takes 15% throttle to cruse at 50mph. All we have done is moved the location of that intake restriction. The same number of air molecules (and therefore fuel molecules) are going through the engine.

With a carbed engine intake restriction can reduce mileage but it is not so much the restriction as what it does to the fuel mixture. Fuel is forced into the airflow by a pressure differential at a venturi in the carb. By increasing the amount of vacuum before the venturi more fuel is forced through the jet per unit of air that goes through the venturi making the mixture richer. The choke on a carburetor does the same thing.

There is also math to back up the intake designs that have "restrictions" compared to a simple duct that gets air from one location to another location.
Sure math is based off mathematical theory, so not everyone believes in it, but there are a lot of well written books on intake design that use math and when those intakes are put on engines that they are designed for they work better and you can design that intake to work well at high revs so you produce more power or at low revs, but a poorly designed intake will make the engine work harder to produce the same amount of power.
But some don't like to pay attention to complex things like math and instead like the simple "less restriction is better" idea instead of designing something that really is better.