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Old 10-10-2012, 09:17 AM   #1
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Default Gas Mileage Mods

I know this is a little bit off the typical goal around here, but I was curious to see opinions or personal experience relating to modifications increasing gas mileage.

It seems pretty common to see intakes claiming to increase gas mileage by XXX and I've seen arguments go both ways as far as their positive and negative affects on gas mileage. It seems like similar arguments with a more free flowing exhaust. Assuming identical conditions and driving habits, would these changes typically improve gas mileage?

I know there is a lot of gain to be had by leaning out a tune, and changes in gearing, improving aero, and reducing weight will have positive results as well, but specifically curious about I/E modifications. Hopefully some chemical/mechanical engineer or Joe Perez will jump in here and explain it all to me.
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Old 10-10-2012, 10:10 AM   #2
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I regularly track my mileage. Doesn't make much difference if I honk on it or drive like an old man. Right around 29MPG all summer long. Biggest change was when it started getting dark in the mornings, and I have to drive with headlights (popups) on, which dropped it by about 2 MPG. I can't imagine much would change that significantly.

Car is stock.
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Old 10-10-2012, 10:11 AM   #3
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Apparently adding hotter air to the intake will better fuel economy...
See this thread: https://www.miataturbo.net/insert-bs...72/#post937709
My mind is still blown.
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Old 10-10-2012, 10:34 AM   #4
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The tune is where you're going to find a lot of it. Get on the dyno (load varying) and find Mean Best Torque timing (MBT) in every cell. If you are at MBT and cruising you need less air and fuel to maintain the same speed opposed to someone who's 5* off of MBT since you are making more torque with that same amount of fuel and air.

You don't want to say maximize VE, since that means more air and fuel are getting into the combustion chambers. You more want to say, reduce pumping losses (will normally increase VE). Semantics, but its important in regards to how you approach the problem.
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Old 10-10-2012, 10:37 AM   #5
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Quote:
Originally Posted by Leafy View Post
The tune is where you're going to find a lot of it. Get on the dyno (load varying) and find Mean Best Torque timing (MBT) in every cell. If you are at MBT and cruising you need less air and fuel to maintain the same speed opposed to someone who's 5* off of MBT since you are making more torque with that same amount of fuel and air.

You don't want to say maximize VE, since that means more air and fuel are getting into the combustion chambers. You more want to say, reduce pumping losses (will normally increase VE). Semantics, but its important in regards to how you approach the problem.
STOP POSTING!!!

Holy ****, can someone please ban this tool?
He has yet to post anything even remotely non retarded since he started posting on this forum.
OMFG
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Old 10-10-2012, 10:58 AM   #6
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Quote:
Originally Posted by 18psi View Post
STOP POSTING!!!

Holy ****, can someone please ban this tool?
He has yet to post anything even remotely non retarded since he started posting on this forum.
OMFG
Formula ASE is a mental illness.
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Old 10-10-2012, 11:09 AM   #7
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Quote:
Originally Posted by Leafy View Post
The tune is where you're going to find a lot of it. Get on the dyno (load varying) and find Mean Best Torque timing (MBT) in every cell. If you are at MBT and cruising you need less air and fuel to maintain the same speed opposed to someone who's 5* off of MBT since you are making more torque with that same amount of fuel and air.

You don't want to say maximize VE, since that means more air and fuel are getting into the combustion chambers. You more want to say, reduce pumping losses (will normally increase VE). Semantics, but its important in regards to how you approach the problem.
Just for clarification.

Can someone explain why what he said is not correct? This is a tad over my head.

And if I know this guy, he's gonna post another "fabelesqe" rebuttal providing "evidence" to his cause. Of course, this is me assuming he's wrong.

Anyway, explanation please. want more brain
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Old 10-10-2012, 11:23 AM   #8
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Its just a semantics of forming a good problem statement. You can increase VE in ways that decrease mileage, but you have to do something really strange to decrease pumping losses and decrease mileage. Does that make sense? Like you shouldn't say, "create a better lawn mower", you should say, "create a better way of cutting grass."
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Old 10-10-2012, 11:28 AM   #9
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Quote:
Originally Posted by Leafy View Post
Its just a semantics of forming a good problem statement. You can increase VE in ways that decrease mileage, but you have to do something really strange to decrease pumping losses and decrease mileage. Does that make sense? Like you shouldn't say, "create a better lawn mower", you should say, "create a better way of cutting grass."


Please don't reproduce..
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Old 10-10-2012, 11:32 AM   #10
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The lawn mower analogy is a little.... abstract, and still don't follow.

Someone explain this so it's "Army-Proof"
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Old 10-10-2012, 12:03 PM   #11
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So, if I put an intake on my daily, will I be able to drive it more farther before it runs out of gas?
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Old 10-10-2012, 12:13 PM   #12
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^ This is what I am trying to answer too.
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Old 10-10-2012, 12:29 PM   #13
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What is your daily?
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Old 10-10-2012, 12:32 PM   #14
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You're better off checking the basics first and exhausting the features your car already has to get the best mileage.

New spark plugs and wires
New fuel filter
Check tire pressure
Check engine timing
Check all fuel lines
Check fuel pump (rust? tank contamination?)
Make sure all of your fluids are clean and topped up (engine/tranny/diff/etc)

I'm a firm believer your alignment over the course of time will also effect gas mileage. If your alignment is off badly and you are constantly over steering to compensate, or your tires are shredding rubber rolling down the road, that is resistance/friction that equeates to drivetrain power loss. Maybe not an appreciable amount, but over the course of 1,000 miles, 10,000 miles, or more it can add up! Not to mention, your wasting rubber and your car is not driving as well as it could be.

I'm also a big fan of Barryman's B12 Chemtool Fuel Treatment. It pretty much brought my Miata "back to life" after it sat for about 5 months. I put in fresh gas and new spark plugs and the engine just bogged under throttle and missed at idle.
I put a can of B12 in with a full tank of gas and drove the car around. Probably halfway through the tank the engine kicked back to life, the miss at idle disappeared, and it really felt like I gained a ton of power (read; restored all my stock power). I've since used B12 in my motorcycle to clean my carbs and in my roommates car both with phenomenal results; engine ran better, gas mileage improved, and idle improved. Just make sure you read the can and the hazards/instructions. If used wrong you could hurt your car too.

I can not comment on the intake. My car came with a big cone filter but still uses the OEM intake tube and AFM and an 'Ice Box' brand heat shield. I do not believe this setup is ideal for performance or gas mileage, but it looks/sounds cool? I think the OEM filter would do just as good for gas mileage.
Now, if you could get a TRUE CAI installed that might make a difference.
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