CAI/intake impact on mpg

[speed3-10]

I live near Boston area which means more than 7/12 months we get cold weather and I have noticed the impact on my mpg. I have been keeping track of per tank mpg and with 70/30 highway I get around 26 mpg during warmer months and around 23 mpg in colder months. I am thinking about getting a CAI and wondering if I will get any additional drops in mpg after install. I am assuming that the ECU will adjust the fuel level up to compensate for all the additional colder denser air coming in.

For those of you with any kind of CAI or other intake install - was there any impact to mpg and by how much?

 

[Russm]

MSCAI I get about 27MPG in the cold(WI) and 30-32 in heat Hwy., Mine improved in the cold about 1-2 MPG

 

[speed3-10]

Did you have other mods and an ECU programing to go with it? Your numbers look awesome but if you go to Fuelly http://www.fuelly.com/car/mazda/speed%203 most of our cars don't do nearly as good as you. What is your secret

 

[MSMS3]

It's all related to the application of the right foot to the "go" pedal. More horsepower will consume more fuel. But the extent in which you dip into the power of the engine, even in a lower horsepower car can have a dramatic effect on mileage. If vehicle weight remains the same, then changes in intake and exhaust, and there increases in absolute power, have little effect on mileage unless the driver modifies driving style.

Which gets better fuel mileage, a new turbo V8 BMW M3, or a lowly Toyota Prius? Well, depends on how you drive. There is a hilarious episode of the TV show "Top Gear' in which the British car nut hosts had a BMW M3 follow a Toyota Prius around a their closed road course that they use to test Ferraris, Lambos and other such exotic rides. The goal was for the Prius to go flat out within the limits of the driver and the car to try to get the best lap time. The M3 driver was instructed to drive as hard as necessary to stay with the Prius, but that he could not pass the Prius.

At the end of the lap, they measured fuel consumption. The Prius had far worse fuel mileage than the M3. Yes, the M3 got better fuel economy under those conditions. That was because the Prius had to run flat out and the M3 driver could be much lighter on the gas pedal, mostly just cruising, and still stay on the rear bumper of the Prius.

It's all in how you use the right foot.

 

[speed3-10]

Cool story and good point. I notice you have Mazdaspeed CAI and Hypertech tune. From your experience if you did a virtual identical runs - similar to the top gear story - with stock air box vs. CAI and everything else be the same in your car - would you say your car with the CAI would give more, less or the same mpg. I know that is a subjective call but what heck what would be your impression?

 

[MSMS3]

I couldn't tell any change in fuel ecomomy. But I have a pretty heavy right foot, lol. Also, I had not had the car very long, maybe only a couple months when I put on the MSCAI, so I was really not trying to make that kind of comparison.

My guess, and it would be just that, is that as long as the intake is providing air mass at a particular flow rate and the ECU is directing the injectors to match that mass with fuel at the correct AFR at a given power level, the fuel consumption is going to be the same regardless of the intake design or filter material. The difference would come in, IMHO, when air flow demands are increased under load (WOT or close to WOT situations), and the aftermarket intake is called upon to provide greater air mass than stock. When this happens, the ECU lets the injectors spray more fuel to maintain its designed AFR, up to the limits of the fuel pump. You get more power. but fuel economy would go down with the CAI compared to stock.

I really can't see that an aftermarket intake is going to make this car more fuel efficient under any operating conditions. Should be exactly the same under almost all operating conditions, except you'll be able to burn more fuel and produce more power at WOT with the better intake. Just an opinion . . .

 

[sick_role]

Cobb SRI (w/ AP OTS Map). improved roughly 4 MPG generally speaking (same driving habbits, 60/40 city/hwy). will get at or over 30 mpg on an all hwy tank.

 

[speed3-10]

Thanks MSMS3 - my thinking is also is along the same but here is where I am wondering if we can have our cake and eat it too. The community that goes with CAI and other mods in all likelihood care less for fuel economy than the WOT fun they can have. But as a daily driver when a good portion of driving is dictated by traffic speed in front of you I believe with a gentle go pedal modulation under 3K RPM I can imagine a higher natural (non turbo) airflow with the CAI and with a good ECU adjustment one can provide a bit more HP / Torque so that the same driving routine and practice would yield in a slightly better gas millage (2-3 mpg?) - in theory. I am hoping others can share their experiences as well so we all may get a better understanding of the real world CAI user impact to mpg.

 

[speed3-10]

Cobb SRI (w/ AP OTS Map). improved roughly 4 MPG generally speaking (same driving habbits, 60/40 city/hwy). will get at or over 30 mpg on an all hwy tank.

Which map the economy?

 

[MSMS3]

Cobb SRI (w/ AP OTS Map). improved roughly 4 MPG generally speaking (same driving habbits, 60/40 city/hwy). will get at or over 30 mpg on an all hwy tank.

What highway speed to you drive? I do have a heavy foot and typically drive in the 75-80 mph range when cruising on long trips on the highway. I think the best mpg I've ever gotton on sustained highway driving under those conditions is 27 and a fraction.

And yes, as another poster inquired, are you running an economy AP map? That would probably make a huge difference.

I'm tuned for power. In daily drive cycle, probably about half stop and go and half highway driving I'm getting 24-25. Just around town, it's more like 22-23. Again, I blame the heavy foot. That's good enough for me.

My other ride is a big full sized Nissan Armada, which weighs close to 6,000 pounds, has a high output V8 and low gearing for towing. Around town it gets . . . 10 mph. On the highway, if not towing it gets 13-14. Lol. Towing an 8,000 pound trailer - well, you really don't want to even ask! Oh, and it does have a K&N Air Charger CAI intake. Didn't help with mileage one bit.

It's all relative.

 

[Russm]

I got 1 $175 speeding ticket 1 month after I got the car (2008 Mar), I try to stay a lot closer to the speed limit since then than 20 MPH!
I got 44K miles of a set of Yokohama Ws4 tires, 24 out of the OEM's, I just changed out the front BP at 68K miles and still had 1/4 " on them!
I drive easy most of the time, shifting at 3K keeping out of boost! I only took it to dragstrip 1 time this year! I act like an old man until the time is right! (58)
But smile when I don't keep to this!!!!!!!!!!!

MSCAI and MSCBE and the fear of the Law & Insurance!

Did you have other mods and an ECU programing to go with it? Your numbers look awesome but if you go to Fuelly http://www.fuelly.com/car/mazda/speed%203 most of our cars don't do nearly as good as you. What is your secret

 

[speed3-10]

I got 1 $175 speeding ticket 1 month after I got the car (2008 Mar), I try to stay a lot closer to the speed limit since then than 20 MPH!
I got 44K miles of a set of Yokohama Ws4 tires, 24 out of the OEM's, I just changed out the front BP at 68K miles and still had 1/4 " on them!
I drive easy most of the time, shifting at 3K keeping out of boost! I only took it to dragstrip 1 time this year! I act like an old man until the time is right! (58)
But smile when I don't keep to this!!!!!!!!!!!

MSCAI and MSCBE and the fear of the Law & Insurance!

If I read your original post correctly that means in WI weather even before CAI you were getting around 26 mpg per tank in cold season. That is awesome. The best I have done is around 24 cheating with rounding the numbers up - tops - and with NE weather not being probably as cold as WI.

 

[sick_role]

What highway speed to you drive? I do have a heavy foot and typically drive in the 75-80 mph range when cruising on long trips on the highway. I think the best mpg I've ever gotton on sustained highway driving under those conditions is 27 and a fraction.

And yes, as another poster inquired, are you running an economy AP map? That would probably make a huge difference.

I'm tuned for power. In daily drive cycle, probably about half stop and go and half highway driving I'm getting 24-25. Just around town, it's more like 22-23. Again, I blame the heavy foot. That's good enough for me.

My other ride is a big full sized Nissan Armada, which weighs close to 6,000 pounds, has a high output V8 and low gearing for towing. Around town it gets . . . 10 mph. On the highway, if not towing it gets 13-14. Lol. Towing an 8,000 pound trailer - well, you really don't want to even ask! Oh, and it does have a K&N Air Charger CAI intake. Didn't help with mileage one bit.

It's all relative.

I am running the Stage 1 SRI SF+93 (or however it is arranged, alphanumerically; can't recall of the top of my head). def not economy mode. I stick to around 75 if I can. cops are ruthless on the insterstate throughought my route and have already learned me a lesson...I travel a bit on side roads as well and a heavy right foot is present for many blasts through the gears or at least a quick 40-80. Winter I get much worse mpg but the factors for that are many.

 

[speed3-10]

So what is your winter mpg per tank?

 

[sick_role]

I rarely keep track in the winter, simply because I know it's crap. I'd guess close to either side of 20mpg. I'll check next tank.

 

[Russm]

Pretend you have an egg under you accelerator foot.

If I read your original post correctly that means in WI weather even before CAI you were getting around 26 mpg per tank in cold season. That is awesome. The best I have done is around 24 cheating with rounding the numbers up - tops - and with NE weather not being probably as cold as WI.

 

[speed3-10]

It is hard for me to envision a mpg improvement with just CAI or intake without some sort of added ECU economy programming to keep the mixture lean at reasonable RPMs - which would certainly hamper any high HP/torque performance in the same program map. So my thinking is that CAI/Intake even with Hypertech and other performance (AP) maps will not yield any more mpg unless one babies the modded car like a granny.

This said I gather adding a CAI and or intake without the appropriate ECU programming will more likely yield in worse mpg numbers under similar driving conditions and driving practices. That is based on the understanding that ECU will compensate for the added incoming air with more fuel to keep the AFR mixture the same as stock map. My guess is that the mpg loss with CAI - without some sort of economy map - would be similar to the mpg drop we see from going from warm weather to cold.

So far, I haven't seen any clear evidence from the replies to this post - as well as other posts/forums I have been finding - that CAI improves mpg. Can anyone turn my theory up-side-down with some good support data?