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Old 10-10-2012, 01:25 AM   #1
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Default CAI mpg debate...my mind is blown

I own a 2007 Mazda CX-7. It's AWD, with a 2.3 liter 4 cylinder, intercooled turbo.
I want to do some mods to it to hopefully better the fuel mileage, but because of what I've been reading on the internetz...my mind is blown.
My theory is simple, "remove factory implemented restrictions, and volumetric efficiency should improve."
When I say: "I don't want it to be faster, I want it to have better fuel economy."
I mean: "The increased power due to less restrictions, should also provide better fuel economy."
Same reason that my stock '99 Miata got 26mpg, and now turbo'd and megasquirted it get 29mpg's.
I was thinking about getting a better flowing intake, thinking, "the less restrictive design of the CAI should provide better airflow making it easier for the turbo to move air, which should increase efficiency".
However, I read this, "CAI will end up increasing fuel consumption not decreasing it. Colder air will be metered by the MAF and fuel will be ADDED to keep the ratio right. You'll get more sound and maybe a little more power, but not less fuel."
How is that?? I'm thinking that response means, "since my CAI makes so much noise, I spend more time on the throttle". That's why the fuel economy decreases.

I also thought about tuning software for it, so I read this:
"An ECU reflash like MazdaEdit or piggyback controller like the Standback from CPE can adjust fuel pressure to decrease the flow of fuel and increase MPGs. However, with DISI motors they run rich on purpose because the added fuel is used to cool the combustion chambers. Make it too lean and you get dangerously hot."
The added fuel that the quote was referring to is like 9.7:1. To me, that is disgustingly rich. This turbo spools stupidly fast and supposedly makes the torque at low RPM's, like 2600 or something. Why should a daily driver be designed to run this rich? Does my thinking about less restrictions/ improving efficiencies make sense or am I losing it?
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Old 10-10-2012, 02:17 AM   #2
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Too drunk to understand you r post right now, but IIRC *(disclaimerrunk) the hotter air causes better efficiency due to less pumping losses in the same way as EGR causes less pumping losses. Less oxygen=less power=more throttle=less pumping losses. Don't quote me on this.
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Old 10-10-2012, 02:18 AM   #3
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Lots of variables here. Pick your constants and do a little research yourself.
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Old 10-10-2012, 02:21 AM   #4
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yeah I read somewhere that hot air can actually have gains in fuel economy

here's a hot air intake, for example
Warm air intake on a Focus.... - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com
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Old 10-10-2012, 02:21 AM   #5
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Driving the same as current (light on the pedal), + cooler/ less turbulent airflow, minus restriction= more efficiency IMO.
Or is my opinion cracked like a taco taco manifold?
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Old 10-10-2012, 02:23 AM   #6
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Quote:
Originally Posted by thirdgen View Post
Driving the same as current (light on the pedal), + cooler/ less turbulent airflow, minus restriction= more efficiency IMO.
Or is my opinion cracked like a taco taco manifold?
it is cracked. Hot air is the way for MPG. I gained 2 mpg going from fender air intake to engine bay intake.
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Old 10-10-2012, 02:27 AM   #7
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I like tacos.


Except the tacos at Jack in the Box.


Those suck.
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Old 10-10-2012, 02:28 AM   #8
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Dude, I don't understand that at all...how can you get a gain from hotter air?
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Old 10-10-2012, 02:28 AM   #9
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Quote:
Originally Posted by Joe Perez View Post
I like tacos.
All of a sudden, I have a craving for tacos.
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Old 10-10-2012, 02:29 AM   #10
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Quote:
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Dude, I don't understand that at all...how can you get a gain from hotter air?
Especially in a forced induction application?
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Old 10-10-2012, 02:32 AM   #11
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From all of my research, its about pumping losses. Hotter air, less pumping losses. Same goes for EGR. Basically, you're intentionally depowering the motor, thus for a higher throttle percentage to maintain cruise speed.
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Old 10-10-2012, 03:10 AM   #12
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I always thought it was pretty basic. Cooler air is more dense, aka, more oxygen. If your engine is trying to maintain a certain air fuel ratio, if you give it more air, it'll give you more fuel.
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Old 10-10-2012, 03:24 AM   #13
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bald taco bistro

yummm......
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Old 10-10-2012, 03:44 AM   #14
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For the cost of the CAI (or parts to make one), how much gas could you buy?
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Old 10-10-2012, 03:46 AM   #15
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...Which then gives more power, meaning to cruise at the same speed will then require less throttle, therefore using the same amount of fuel.... but the throttle is closed more so you get greater pumping loses.

Dann
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Old 10-10-2012, 09:18 AM   #16
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Bottom line = new modern cars are nothing like your 30 year old BP. They are already efficient and very economical. Stop effing around and don't touch that car.
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Old 10-10-2012, 09:48 AM   #17
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Or drill a large hole in the exhaust mani heatshield and plumb the airbox inlet to that large hole. Get super trick with a valve (cheap exhaust cutout style? old throttle body?) that you can flip so you can HAVE THE POWA when you need it.

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Old 10-10-2012, 09:50 AM   #18
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lolol

DEI y0
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Old 10-10-2012, 11:00 AM   #19
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Quote:
Originally Posted by thirdgen View Post
Dude, I don't understand that at all...how can you get a gain from hotter air?
Fuel on dem walls?
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Old 10-10-2012, 11:13 AM   #20
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There was a thread here a while back on smokey yunick's hot vapor(?) hypermile setup that used really high IAT's as part of it. And a turbo to mix the air/fuel, not pressurize.
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