Watch & enlighten
 

Hi
I came across this really informative video
Check it out

https://www.youtube.com/watch?v=YPd_2_IvKIw

that is a strange video to be putting on this site.

I don't think that most of us care about power and it has been proven that warmer/hotter air actually yields better MPG.

that is almost like trying to sell beef (at a good price) to vegetarians

btw: is this supposed to be spam?

If I don't see some useful commentary on this thread from the author within 24 hours, I'll consider it spam and delete it.

Otherwise, I'd like to hear the author discuss the relevance of this thread and how it pertains to increasing fuel economy.

-Bob C.

If it looks like a duck, walks like a duck, and quacks like a duck, it must be a duck.

https://myninjaplease.com/wp-content/...07/09/spam.gif

...or at least something vaguely avian.

Since we're talking about ducks, were you aware that they have evolved maze-shaped genitalia in an "evolutionary arms race"?

https://www.cosmosmagazine.com/node/1277

(It's not like we were going to talk about saving gas in this thread.)

this may be a case where there actually is a person out there that didn't know that cooler air and a freer flowing intake can produce better power. I guess they are assuming that this equates into less gas used.

silly teenagers.lol

in all honesty it is almost definitely spam and needs to be deleted even though they aren't going to make any sales or money from posting it on this forum.

Gah...specter. I hate that company with a passion.

While hot air intakes work by using less volume of oxygen per cubic foot of air the engine sucks, thus less fuel - the cold air one can work to save fuel as well if the driver is very easy on the foot.

In theory, they would use less throttle at the same RPM to produce the same power - while not as effective at fuel savings as the warm/hot air intake, there still is a bit of valid reasoning above it, but most people sink their foot into the throttle to enjoy the power or engine sounds - and there goes any potential gains right out the window.



Just a bit of sense in it - just a bit - if you've got discipline on your foot pushing.

at idle and with no throttle applied, the cold air intake is taking in more oxygen than with a warm air intake and thus needs more fuel to burn it. as a person that coasts quite a bit, I would put my WAI up agains anyones CAI for better FE any day of the week.

also, my WAI was around $10 in parts and I have almost enough left over for another vehicle. CAI actually cost quite a bit (most of which is the free flowing filter which allows all kinds of crap into your engine).

That would reduce efficiency by forcing the engine to suck air through a smaller throttle opening.
https://www.google.com/search?q=%22pumping+losses%22

Beef - I agree with you completely. Notice I said WAI has less O2 to burn per cubic foot, and nothing about idle consumption for a CAI (of course it will be worse - same RPM and load, more O2 per cubic foot = more fuel required to keep from going lean).

I'm going to be doing the warm air route here on the next fill up, along with relocating the IAT - it's not that I disbelieve the fuel economy benefits of making an engine produce less power at a given RPM, it's just that you can get an improvement over stock with a cold air - IF you're very careful on the throttle.

Agreed - but having had one when I was younger, thinking my little Saturn was a hot rod, and noticing that I did get better mileage with the cold air compared to the stock one when I watched my throttle for a tank - I do believe that the reduced throttle requirement outweighs the 3% smaller opening into the intake manifold, since a 20*F decrease in temperature yields about 3.5% more oxygen per cubic meter.

Like I said - if you're very careful on the throttle, you can see a benefit - but not as good as a warm air.

to be completely honest, before I did my WAI, I could tell you what the outside temps were within about 3 degrees just by looking at my IAT reading. maybe my intake is designed better than most. the only benefit to a CAI that I can see is a freer flowing intake witout the baffles of some intake boxes (which mine doesn't have) and a less restrictive filter (there again, crud in the engine).

I also remember hearing somewhere that a less restrictive intake and exhaust will actually push your torque peak farther up in the RPM range which will hurt your FE. not sure about that one but if it did reduce your torque in lower RPMs then you would definitely get worse economy.

I've had a philosophical problem with the WAI idea for a long time, but have held my tongue. Correct me if I'm wrong but you're saying that the primary gain in efficiency is through a decrease in air density, right?

If decreased density improved efficiency, then it would follow that you'd get better fuel economy at high altitude. In my life I have lived primarily at two altitudes; 1000' asl, and 7000' asl, and I've owned the same vehicles in both locations. I can tell you for a fact that I get an average of 2-4 mpg lower gas mileage at 7000 ft than at 1000 ft. I've kept paper gas logs on my vehicles for the last 17 years, so my degree of confidence in this statement is very high.

Unless you can describe some other reason that a warm air intake will increase FE, I'll remain unconvinced. The one thing that I am convinced of with the WAI is that you'll decrease your warmup time which would probably yield a noticeable difference in your MPG on short drives and in cold weather.

There's a bit more involved than just that. With the intake temp, primarily where the source of air is, and where the sensor is, is of primary concern. My little saturn sucks it from behind the driver's headlight, and has an IAT a few inches downstream. How much that air is heated up as it travels down the tube, I've no clue. I'm sure it's under 10 degrees, but it's an unkown in the equation.

The exhaust design considerations has a much bigger impact than the tube going to the intake manifold does on where the powerband is. When I was doing Formula SAE, we would dyno the piss out of the header design to tune the torque curve. We went through about 12 header concepts. We went through 3 intake manifold concepts, with the biggest changes being throttle response and intake temperature. Scavenging, exhaust temperatures, and exhaust velocity all had huge roles in the torque curve.

The intake tract, especially without access to a dyno, fluid flow analysis software, and a lot of patience, will only effect the intake temps and oxygen consumption - not the shape of the torque curve itself.

The effect on torque isn't about how restricted the intake and exhaust are. It's about the length the air has to travel between the throttle and the valves, and EGV.

Restriction wouldn't matter to most hypermilers anyway; if the stock system can flow (somewhat restrictedly) enough to make three or four (or more!) times as much horsepower as you'll be using, it's got to flow completely freely under the conditions in which we use it. For us, and probably for most others, the throttle is the biggest restriction and everything else flows freely to and from the throttle.

Not only is there the decreased volume of oxygen going into the engine, and reduced warmup times but the gasoline should vaporize better in warm air than in cold promoting more complete combustion.
I'm sure there are other factors at work here as well.
-Jay

This is DEFINATELY true. Take a peek under the hood of any C/K chassis, R/V chassis, or any muscle car and look for the thermo tube going from the carb hat to the exhaust manifold, as well as the flapper valve for it.

However, the decrease in oxygen content from 6000 feet of elevation difference tosses another player into the role - barometric pressure. At lower outside pressures the engine has to work harder to create a vacuum to keep going given the same air intake (least this is according to my thermodynamics professor - I haven't taken the time to do the math, nor do I really care enough to do so).

So the difference may very well have to do in your case with not only the decrease in oxygen per cubic meter, but also in the decrease in air pressure. Just something to think about.

That heat-scavenging effect maybe also increases efficiency after warmup -- instead of discarding that heat energy, it's put back into the engine. Additionally, the warmer air may enhance fuel vaporization.

Just a couple guesses.

There could also be other factors at work for your high-altitude observations -- for example, the lower pressure air outside the engine would increase pumping losses effectively nullifying the WAI's density advantage. Hills could cause you to drive less efficiently, climate might require the fan to be used a lot, etc

Edit: D'oh, I was too slow. :)

It's not the restrictive part of the intake and exhaust that moves power around. It's all in the velocities. Smaller pipes yield higher velocities and more low-end torque at the expense of top-end power. Exactly the opposite of large pipes.

I have to agree with the altitude statement. I lived in San Antonio at 650ft and my best tank using coasting and such was 33.8 mpg all city. Here, forget it. My best in town tank so far here at 5800ft has been MAYBE 27. And that's because 1/2 of my drive to work can be spent in neutral with the engine shut off. I have to press the gas down more here to get the same power I would need to use at 650. According to the WCF on the dyno i'm down 20% of the power at sea level as is.

If you had two engines, one here and one at the coast, and ran them both WOT the engine here would use 20% less fuel and make 20% less power.

And this is exactly why Willies used engines with .2 higher c/r for high altitude dealerships than those closer to sea level. :D

Also why we run 86 octane fuel instead of 87 like they have at the coast.

Everything I read points to us supposedly having better mileage up here but it doesn't happen.

On the motorcycle i do though, it tops out about 75-80 (top speed doesn't change with altitude, just how fast you get to it does) and at seal level it gets about 60mpg at those speeds while up here i'm getting around 70-75 mpg.

Another thing to consider at high altitude... The air is less dense so in theory your areo drag should be less...

-Jay

jeep45238,

you can see the IAT reading via your scangauge. as for the arguement about the altitude. I understand the theory that you are using but obviously there are more affects to high altitude than just thinner air.

my drive is 20 miles one way (40 per day) also of note is that my instantaneous MPG were lower before the WAI. I can't explain the altitude arguement but with the WAI you are just changing one variable, not the entire environment of the car.

Beef - I'm aware I can see the IAT reading - but that sensor is about 8 inches away from ambient air, right behind the headlight - and the air has to go through about 2.5 feet worth of black plastic that's heated by an engine bay for a whole drive. That's my only point - without relocating it toward the throttle body, it's not accurate - the air is warmer than where the IAT is, but by how much is unknown.

my incoming air moves pretty fast, I don't think you can heat soak air but so much. in the same respect, I run my air along side my header for the heat which is much hotter than the IAT is saying that it is. the air comes by the header so fast that the temp difference has to be substantial to get the air to increase in temp enough to matter.

good luck to you in your choice but a lot of saturn guys on here have seen pretty good gains from a WAI. that is your choice.

also, you know that it isn't that hard to relocate. if you care that much

It is possible that GM took that into account and the sensor or the way the ecu reads it is offset from the factory to compensate for that.

Beef,
I've already said I'm going to do it. Remove the airbox silencer, enlarge the hole a small amount, toss in a piece of exhaust flex pipe, it's done on that front.

I'd solder in a wire extension for the IAT to relocate the sensor at the throttle body. Yes, I am that finiky.

The only fault with that is the readings would not be consistent on a summer day with a warm engine and a winter day with a warm engine.

one more thing, if you are planning on doing it, you may want to fabricate some sort of heat shield to go between the front of the car and the header. I have a pic in my garage. you can't see my IAT sensor in the pic but it is just in front of the throttle body (also not in the pic).

I used metal flasing from lowes to do this.

on a side note: how did this spam thread turn into a full blown discussion about the WAI vs CAI. I think we have already had this arguement too many times in the past.

I've got some scrap 22 gauge sheet I was planning on using for that. Interestingly enough, there's a psuedo grill block on the saturns - the radiator is not exposed to the air from the grill directly. Pretty slick if you ask me.

It wasn't an argument - just saying in theory both can give better mileage, but that warm air gives bigger gains. :confused:

I can almost buy most of these arguments, but not quite... Maybe it's just because I'm coming from a skeptical point of view.

The heat aiding vaporization probably works in a physics classroom, but this weekend, why don't you go for a drive, then open your hood and put your hand on your intake manifold or the side of your cylinder head when you stop. I'm going to go out on a limb and say those parts will be too hot to touch (the head especially). They add enough heat to the air to vaporize the fuel and then some by the time the fuel hits the back of the valves, and if there is any unvaporized fuel at that point, the valves will be hot enough to finish the job for sure. An extra 30 degrees of IAT isn't going to make or break that equation, especially on an engine with throttle body injection where the fuel has a relatively long time to vaporize before it enters the CC.

Recycling heat energy? The percentage of heat energy in the intake air compared to what the engine producing is probably to infinitesimal to measure.

Lower barometric pressure? Nope, that's a zero sum equation as far as I can tell. Keep in mind that the air pressure is lower on both sides of the engine (intake and exhaust that is), so any differences in the amount of energy necessary to pull the air in would be nullified by the lower amount of energy needed to force the air back out.
The only thing I can say about this one is that less dense air will reduce your dynamic compression. That'll translate to lower FE every time I think.

Is anybody on this forum a pilot? I'm guessing that pilots can teach us a thing or two about altitude and FE....

Hal, keep in mind a pump works off of differences in pressures from it's outlet to it's inlet. On an engine, this is from the intake tract to the compression stroke of a 4 cylinder engine. The compression is the same, but the difference in pressure is less the higher the altitude you go, and the engine has to work harder for the same amount of air movement.

Don't blame me, I tried to make it about avian genitalia.

This effect will be the same no matter if the air density decrease is caused by altitude or temp. Increasing temp will attenuate the effect somewhat, but to overcome the decrease in efficiency caused by air density, the positive effect of temp alone would have to be substantial to say the least. The 6K ft elevation change that I'm used equates to a roughly 15-20% (depending on who's numbers you believe) change in air density. That usually changes my MPG by about 3 mpg on my 20 mpg=/- Ranger.

If memory serves me correctly (from my turbocharger design calcs) the effect of air temp on density is more substantial than altitude by a fair margin. So you'd need to overcome some pretty substantial losses before you saw any gains at all. I just can't find any proof that's the case. It's easier for me to believe that people with WAI's live in cooler climates and are seeing gains during warmup averaged over short drives.

Does anybody with a WAI live in the southwest or do nothing but highway driving? I'd love to see those fuel logs? Have Semi drivers switched over to WAI's I still the external air filter intakes on lots of the rigs I see on the highway, and those guys go to great lengths to save on gas.

I've seen a very modest gain on my truck, but my IA really doesn't start to rise until the thermostat opens up. I'm thinking about some ducting to suck air from around the manifold.

-Jay

that is what I did. I am still getting air from under my bumper (which is good because I don't overheat). this causes my temps under the hood to be low so I set up a WAI with a heat shield to deflect the cool air away from the intake. take a look at my pics.

$10 bucks and a little time will prove/disprove the theory behind it...if anyone was having issues with whether it worked or not. there are several DIY threads on the WAI.

Hal9000: Intake Air temp works much different on a Diesel than a gas engine. They dont have to maintain a specific air/fuel ratio to operate.