I noticed that I used to get 20-21 MPG consistently with the stock airbox and 87 octane on my 07 Mustang GT manual.

After the Steeda cold air intake and 93 octane tune, I am getting consistently 18-19 MPG readings.

I thought it was just me getting on the throttle more, but thinking about it more closely, wouldn't more air mean more fuel is being used?

 

Yes the more air you flow the more fuel you have to put into the system as well to keep the AFR at 14.7:1

 

Also bear in mind that 91 and 93 octane fuel burns faster than 87-89 to begin with as well..

Consider using an 87 octane tune for your Steeda as an alternative and see if you notice a difference in fuel economy..

 

You need to take off more slowly or hit the go Pendle lighter than you would without the tune

 

I drive mostly on the highway and get about 24-28MPG with a Bamma 93 hybrid tune. I switched it back to stock for a couple of days and noticed that my MPG went down to 20-22mPG... Ive had my tunes for awhile now so I'm probably not as enthusiastic as when they were new.

 

Hi Mark ! I get between 19-20 MPG highway with my Airaid CAI and stock programming so if your able to get 24-28 MPG with your Bama 93 hybrid tune then perhaps I should look into this.. I do have one question for you through, can you tell me exactly what your Bama 93 hybrid tune is.. Is it like a 93 economy tune ?

 

Not true .... 91 and 93 are simply more resistant to preignition caused by compression / heat .... they are "less volatile". 87 is less resistant to preignition, it is more volatile .... but all three grades, everything else being equal, have same energy in a given volume .... but the 91 or 93 will burn in a more controlled rate, slower even.

You can make more HP and Torque with the 91 and 93 if the engine is designed / setup with higher compression (tighter squeeze) or more spark lead (start the burn sooner before TDC) .... but the power is there because you are squeezing the charge more.

If the engine is built / tuned to run 87 octane fuel, likely that's where the best mileage is.

 

So in other words, when running a larger air intake it doesn't matter whether you run 87 or 93 octane, it's not the fuel itself burning faster it's actually the increased amount of airflow from the intake which in turn requires more fuel is that correct ?

 

My JTL3 with Bama 93 race tune was getting almost 23 on the way to Mustang Week. Once I hit Myrtle Beach & show traffic, fuel economy went right out the window.

 

Yeah, If all you change is air intake, using the same fuel will not help or hurt .... the computer will try to adjust to maintain proper mixture.

Too large of increase in intake air or a change in MAF location may result in the computer (and fuel system) being unable to compensate and then it goes some lean and often burnt valves result.

Where higher octane fuel (formulated to resist preignition due to heat) is needed is when a tuner or other mod results in more ignition lead that starts the burn earlier in the compression stroke which itself results in higher combustion pressures and heat that result in more power as long as it's a controlled burn. Tuners don't change actual compression ratios, but an increase there through shaved heads or a piston change or .... by packing it in with a blower .... or even a short overlap cam that raises compression pressures will change octane requirements.

Problem with low octane fuel isn't that it has less "energy" in it, it's that it tends to explode easier under less heat / pressure than higher octane fuel .... and those "uncontrolled explosions" hammer pistons and try to drive them back down just like hitting them with a hammer before TDC while they are still coming up and rods and rod bearings can even be damaged .... as well as upper ring lands.

That's a short version.

 

One of my reasons for switching over from my Steeda 90mm intake to my current Airaid CAI is pretty much that I'm still running stock and was concerned about using custom mail order tuners/tunes while running 87 octane with a larger MAF intake and until I'm able to get my car dyno tuned on an actual dyno, I felt it was in my best interest to purchase an air intake that can run off the factory calibration programming and also able to run on 87 octane as well..

I also chose the Airaid intake over the other non tuning kits such as K&N, BBK and SR Performance because the Airaid intake in my opinion has a much better design, better materials, has great fit and finish and my main reason is it also includes a non tune insert which reduces it's 100mm MAF intake tube around the same size as the factory airbox 80mm MAF housing and then when you decide your ready for future mod upgrades, you simply remove the non tune insert, re-flash your ECM with the required calibration tuning and your all set to go.. Plus you won't need to upgrade to a larger intake down the road..

At any rate, I believe the Airaid CAI offers the end user the best of both worlds IMHO

 

Sorry for not getting back to you for so long... The "hybrid" tune is a tune that Bamma made that kinda smooshes the good parts of their Race tune and Street tune together. I was ( and still am) running a K&N CAI that required no tune. I saved up and got a tuner and some tunes. Works great. My tunes are sent to me from Bamma via E-mail and I have had NO problems AT ALL with the tunes or customer service. Hope this info helps.

 

Thanks for getting back to me Mark, and yes the info you provided has addressed all my concerns and I'm very pleased that everything is going well with your tunes from AM/BAMA..

BTW: are you running 87 or 93 octane with your BAMA hybrid tunes ?

 

All my tunes are 93 octane. No problem

 

Sounds great Mark, and thanks once again