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View Full Version : cold air = more mileage?


intake
12-22-2008, 01:24 PM
do you think a CAI can improve mileage?

slvryaris
12-22-2008, 01:34 PM
I have been doing some experiments myself and have seen that with the stock air box and stock filter, Stock air box and a K&N drop in filter and an AEM CAI I get about the same gas mileage. The only difference is with the stock box and stock filter its a bit sluggish compared to the other two.

YarisSedan
12-22-2008, 04:16 PM
I dont like cold air. Whenever its cold i get less gas milage than when its hot =)

Red Horse
12-22-2008, 06:19 PM
I saw a 2 mpg increase when change mine to CAI last summer.

BailOut
12-22-2008, 06:39 PM
Red Horse,

Please post your mileage logs for a while before the CAI installation and for a while after it. I'm curious to see them because most folks either see no change, or more frequently decreased mileage, with a CAI.

Some hypermilers go the opposite direction, with a WAI, for this reason.

Red Horse
12-22-2008, 06:56 PM
I don't have a log or keeping a record of it but , I can tell you that since, I got my car i'm getting 35 mpg for 5 month,then I installed the Simota CAI, ever since my mpg went up to 37, is that good enough?

YarisSedan
12-22-2008, 07:12 PM
Technicially colder air is denser air which will result in slight increase in power. So say your car requires x amount of fuel to product y amount of horspower. And you need y amount of horpower to accelerate to C amount of speed on the freeway. Your vehicle will require less of X amount of fuel now to require the same amount of horsepower.

Most poeple tend to drive thier vehicle harder to enjoy the sound of increase of power which is why any increase in milage is negated by the increase of gas milage. Also keep in mind that our cars use dual filters. The regular stage filter with addition of carbon filtration. So you already have a restrictive system to begin with. The MAF filter is what directly controls the amount of fuel delivery. So by relocating the MAF filter closer to the throttle assembly and also switchign to aluminum tubing rather than the plastic one that has those ruffles that will slightly disrupt air flow. Top on a easier breathing filter. You will increase the amount of air flow going through the sensor thus increase your fuel consumption. So this could be the trade off why people are getting less gas milage as well.

justjesus
12-22-2008, 07:23 PM
We have done extensive R&D on mileage gains-oddly enough the most popualr mod (CAI) actually tends to reduce mileage. Hotter induction air improves mileage (but hurts power)...(I am speaking about cruise fuel economy as measured steady state on the freeway for instance). Light weight or synthetic oil improves mileage, a hotter thermostat improves mileage...

Hope this helps

BailOut
12-22-2008, 09:38 PM
I don't have a log or keeping a record of it but , I can tell you that since, I got my car i'm getting 35 mpg for 5 month,then I installed the Simota CAI, ever since my mpg went up to 37, is that good enough?

Unfortunately, no, that will not do. People tend to both overestimate and oversimplify everything from MPG calculations to the average speed of a trip. Without a detailed log no numbers can be trusted.

I encourage you to sign up at one of the sites that has easy-to-use MPG logging. One example of this kind of service can be found in my signature.

Kaotic Lazagna
12-22-2008, 10:41 PM
Two things I have to say:

1. On my NA (gen) Miata, I had a Racing Beat warm/hot air intake...and I gotta say is that it chugged down gas like a drunk in a bar.

2. On my MK3 GTI, I had a CAI, and when I switched back to the stock intake box, my gas mileage fell 1 or 2 mpg.

I haven't done anything to my sedan tho...don't have the funds...