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CAIs and Fuel Economy; what's the real truth?

Old 11-10-2009, 12:23 AM
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Location: Vancouver, WA
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Nice to see this discussion is still going!
Hah this has turned out to be quite interesting.

Shipo, you have made some very strong points, and to tell you the truth, I am mostly convinced. I do believe that CAI's don't always do good for a car. It takes a certain car, motor, driving, and CAI type combonation to show any improvement on a car. I think I got lucky with my car. I am not going to back down however. I have an intake in my car and I have improvement in horsepower, torque, and fuel economy. It doesn't always apply however. The horsepower and torque improvement is felt around 4500 rpms. As for fuel economy, I believe that driving style does affect it, but like I stated before, I tested out all driving styles on my long three hour drive. I did this several times, and did get an increase in gas mileage after the installation of the Cold Air Intake.

In conclusion, I believe that the CAI improves horsepower and torque around 4500 like the AEM intake claims.
I have experienced an increase in gas mileage, so, I can claim that the cold air intake does help fuel economy.

If any of you would like to read further on my statements that I have made before, Shipo has posted a link in his first post from our previous debate.
Old 11-11-2009, 10:17 AM
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I have finally taken the time to read the article and have came up with similar disagreements as shipo. The results are askew from those of a naturally aspirated engine.

The thing that I do have to say about the article is the gains due to tuning. I have seen first-hand the gains that you can get from a forced induction car by simply switching from conservative to agressive fuel maps. A friend of mine went from 525 to 610 hp just with a tune and no additional modification. Granted, that is only about 13-14 percent gain (on my mobile right now, so those numbers are estimated), but still more gain than you can get from any one bolt-on.
Old 11-19-2009, 10:27 PM
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pinned to the top for archive.
Old 12-22-2009, 10:01 PM
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You're right. the difference between a MAP and a MAF is that the MAP only measures pressure and assumes a fixed density, while the MAF actually measures the mass of the air-stream.

I understand how cold air injection could allow for the passage of a (slightly) greater number of air molecules through a given cross-section of plenum at a specific condition of negative pressure, but the loss of heat vaporization of the fuel mixture seems, at the same time, to be detrimental to creating optimum conditions for efficient combustion within the cylinder. With the counteracting aspects of CAI, I can't see how any efficiency gains could be very significant.
Old 01-17-2012, 09:25 PM
Join Date: Dec 2011
Location: Canada
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On my Mazda 6 2006 V6, I find the stock intake to be blah. The accordian tube cracks after time. I find the last set of turns before the throttle body to be quite sharp and not good for flow. My K&N has much better smoother and longer dimensions between the last 2 bends for better flow (along with it being a silicone piece). You really don't know the difference until you have it in your hands and you can feel the sharp bend in the stock one when you stick your fingers up it (accordian tube on throttle body side). Smoother bends are better for flow. The K&N filter also allows more air in for top end performance. I can't believe someone actually stickied this.
Another thing helpful is cutting the butterfly shaft allowing more air in: click on throttle bodies and scroll down.
I don't know about fuel mileage, but all what I said increases HP. Colder air is also better for your engine. I'd rather suck air from outside than air from behind the rad. Hot incoming air causes knock, so computer retards timing reducing your power, causing a stumble under open throttle. My set-up isn't the best looking but it does not get hot from the engine compartment and blocks air blown over by rad fan. Why do you think NITROUS works (very cold). Why do turbocharged engines have intercoolers?

Attached Thumbnails CAIs and Fuel Economy; what's the real truth?-winning.jpg   CAIs and Fuel Economy; what's the real truth?-wile-e-coyotehelp.jpg  

Last edited by UseYourNoggin; 03-27-2013 at 09:38 AM.
Old 01-18-2012, 10:23 AM
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Sorry, but I don't think I'd be wanting to cut my throttle shaft as they suggest in my daily driver. If it were a dedicated race car and I was trying to squeeze out every last ounce of power at all expense, then perhaps.
But frankly that mod looks dangerous to me. I have visions of throttle plates and screws coming loose finding their way down into the engine under vacuum.
Old 04-22-2012, 08:55 AM
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before reading this forum i dont know much about i know and very useful information.
Old 05-03-2013, 08:42 AM
Join Date: Dec 2011
Location: Canada
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This Video confirms CAI does increase HP due to denser colder air, but obviously negates fuel mileage? SRI's suck in heat for lack of HP. Best thing to do is SRI with a heat baffle (but maybe not as completely sealed as mine). I do remove the black painted fiber insulation behind the air filter in the winter!

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