Here's A Challenge for Ya

[countryboy91]

I already downshift going up steep hills or hauling. I know how to drive a truck. Im just looking for tips to get me a few extra MPGs. as for a second car, that would be great. but like ive said a million times to everyone who says that: sure a $500 beater is a great deal, but its not just a $500 beater. its 500 for the car, 100 for registration/inspection, 35 for emissions, and who knows how much to maintain it. I bought a 1974 Valiant for 700 before I had this truck. great car. but after I sunk about 2 grand into it for purchasing and repairs, I gave up. then my uncle found me the Burb. only 1500 for a truck with freshly painted underbody and frame, spotless interior, and only 85K miles. on a 15 year old truck. easy to work on engine, new transmission, 4WD. I couldnt pass it up

[Jay2TheRescue]

I have tried windows up - A/C off and it does not make a noticeable difference in mileage. My theory behind it is that on large V-8's the a/c pulls a small % of the total engine output. On smaller engines the A/C is taking a larger % of total engine output.

Currently I have a "passive" warm air intake like you described. I took the lid off the air cleaner box, and I covered the original air intake from the fender with duct tape. This forces the engine to take warmer air from the engine bay, but its still not as hot as I'd like it to be. My intake air temperatures are running 10 - 20 degrees above ambient. I know I can do a lot better, but I've been lazy lately.

[trollbait]

Originally Posted by countryboy91

how bout A/C off, windows closed? lol. ill have to try to crush the egg this time. just filled up a few days ago, so I can check my mileage with using your tips. now as for warm air intake, I just flipped the air cleaner lid to allow more air in, and I removed the hose that goes from the fender intake to the snorkel. that way its surrounded my engine heated air. is that an ok intake? or can I do better?

The engine may warm up quicker with the snorkel removed, but the air temps where people report gains will take more effort. An aluminum dyer hose going from the airbox to the exhaust manifold seems to be the minimum needed for a WAI. Some pie and/or roaster pans may help. I didn't see a regular, high difference between ambient and intake temps until I packed some insulation around the airbox and duct hose this winter. Still need it to warm up outside before I'll see the 140 to 160F temps for the intake, where any benefit may be had.

WAI helping or not varies between models, but it's a cheap mod. Except for the dryer hose, I had the materials lying around.

[countryboy91]

so can someone explain to me how the warm air intake is different from the cold air. besides the obvious. I wanna know the science behind it

[Jay2TheRescue]

There are several theories behind it, but I believe that the most plausible reason for it to work on a V-8 is that warm air is less dense, so it virtually reduces the size of your engine. The engine computer will sense that the air is less dense, and inject less fuel into the engine. I had done the math some time ago in relation to a 5.7 liter V-8. This assumes that 100F is standard operating intake air temperature (For simplicity's sake in the math). By following the chart you can see that an increase of 80 degrees over ambient will virtually reduce the engine from a 350 (5.7 L) to a 305 (5.0 L). According to the EPA a 305 in my model year truck gets 1 MPG better, which equates to about an 8% increase in mileage.

[countryboy91]

hmm... very interesting. but doing a little research of my own, and relating to personal experiences, the denser the air, the more efficient it burns. thats why I get better MPG at sea level than in the mountains. the air is more dense, so the engine gets more air. i remember from automotive shop class that it takes something like 10,000 gallons of air to burn a gallon of fuel efficiently. so the denser the air, the less fuel burned. im not saying youre wrong, im just relating current knowledge to previous experiences. I might think about getting an engine block heater for the winter. what type should I get. and would it really make a difference?

[theholycow]

You need the same mass (not volume) of air to burn a given amount of fuel at stoichiometric ratio. Adjusting air density doesn't change that.

It takes more energy to push denser air around. Additionally, a WAI recycles heat energy that you'd otherwise be wasting by venting to the atmosphere. There may be an effect of the fact that the air/fuel is less but takes up more space and therefore pushes the piston the same as if it was denser.

Those are some ideas (some of which are half-baked) about how it may work. There is no shortage of theories about how a WAI may work or may not work, but there is a shortage of hard data. It's not a thoroughly researched science. All we know for sure is that it does work for some people and does not work for others. If a lot of people with the same vehicle have tried it and had consistent results then we can say it's likely to work for that vehicle, but in your case there's not that kind of data.

It may be worth an experiment. You'd have to be able to compare your driving habits to see if they were consistent, your intake air temperature, and your fuel economy over a relatively long term to properly declare it a success or failure.

It may also not be worth an experiment. The effort and potential risk to the vehicle (I've heard of nobody who has suffered damage but I'm still a bit intimidated) have not been worth it to me...mainly the effort, I'm pretty lazy.

[countryboy91]

what if I put a fan blowing in to the air cleaner snorkel? sort of to act as a vacuum to suck up hot air and also to boost total air volume forced into the combustion chamber. if I do this, should I also flip my air cleaner lid back over so all the air isnt just blowing back out?

[Jay2TheRescue]

What you're talking about already exists... Go to Ebay and search for "electric supercharger". There's problems with that as far as mileage is concerned.

1. The electricity to run it is not free. No matter how slight, the increased draw is an increased load on your alternator, which means you will burn slightly more fuel to generate this current.

2. Warm air is less dense, but you will be packing more of it in the engine. This means more oxygen, and the computer will inject more fuel to maintain the proper air/fuel ratio.

If you're looking for mileage gains you need to naturally aspirate warmer air, and make the engine behave as if its operating in a warmer environment.

[countryboy91]

how would I go about naturally aspirating it best then?