Hopefully this is posted in the right area. if not, maybe a moderator will just move it and not delete it...<o></o>

Disclaimer:
I have seen various postson here asking about how mods effect gas mileage. with this in mind I figured id try to do a little study to see if changing out my exhaust and intakeshad an effect (good or bad) on gas mileage. There are likely flaws with my "testing" but take it forwhatever its worth. these are just my results for these specific modswith these specific brands. I tried to drive the same during the wholetime and in general drive the same places so hopefully it was a fairlyconstant control input.<o></o>

My "Study":
my car wasstock at the start of this study. every time I put gas in my car I filled the tank until the auto shut stopped the pump then gave one more full squeeze till it shut off again(retrospectively I probably should have not added the last squeeze because thepump pressure varied likely allowing different amounts of gas to go in). Ikept track of MPG per tank by dividing miles driven on each tank by the gallonsrefueled. I did not go by the mpg calculated by the car's computer. I continued this process after adding an injen ram air intake and magnaflowcat-back exhaust.

Results:
tank mileage per tank at stock - 20.18; 19.96; 20.23; 20.24
tank mileage with injen ram airintake - 15.06
tank mileage with injen ram air and magnaflow cat back - 21.06; 19.64; 19.33; 20.66; 20.00; 20.37

im not sure this proves or disproves anything, just information that I found. mods didnt seem to have an effect on mpg. either way car seems to have a little more pep to it and definitely sounds better!

 

Thank you for your findings. I will take them into consideration when installing my next mods.

 

Seems like some decent real world testing. Even though there are a lot of factors that changed the result, it's still better than "Injen claims 15 HP and 2-3 mpg", which a lot of manufacturers do without any real data. Interesting that MPG is decreased with just the intake (in your case) and then went back to normal with the exhaust. But like you said already, take it FWIW.

 

My milage went up with my mods. Of course when u first install ur gonna boot it to hear what u installed so gas will decrease. I have my g in kms when it was stock I was making about 400km a tank and the computer would read about 400 450km at full tank now with intake exhaust hfc on full tank it reads 500 550km. If I don't boot it I can make 500km now. This is highway driving and intake increased the milage the most exhaust jus complemented the intake for even better results.

 

I was about 17-19 mpg. on mostly city traffic before I installed my Injen SRI's

Now I get about 15 mpg. with them on.

I have Tanabe exhausts as well but no changes I noticed.

 

Great thread!

 

i m really interested as to why your gas mileage droped after getting the intake installed. I felt like after i got my stillen g3s my mileage droped from 18 to 15 as well.

 

I added the Gen 3 yet My Tanabe Medallion Cat back on mine... Gas Millage seems better about 40-50 miles per tank...

One factor that I didnt see here which I do myself is a Lead foot Syndrome which at times I know we all do!

Having a Camero, Audi, Höñdæ lol want to express their love for our cars lol its another factor... I want to get a Tune and Dyno my G Right to factor that in...

Search function has taught me more on our cars but to asking if this fits or that?

So Millage plays in many ways but too our tunes...

All the Mods ive made will say its made it more snappy on the line but freeway thats where you really see the millage difference with the mods vs tje stop go stop go

 

In theory as we all know, the more efficient the engine the more power and MPG you receive. Now an exhaust, no matter what should help. Now as for an intake, I would think JWT system along with those silicone tubes would make the most efficient system. It should be a good compromise between temp. And distance traveled.

From what I've read all these stillen and cold air intakes don't do anything, more so they ruin your MPG.

Of course I base this on absolutely nothing, just a hypothesis.

Anyone ever port and polished their intake manifold? Wonder if that would help.

 

So i think (and could be wrong) but the cold air intake makes the air going into the engine colder and more dense. therefore the MAF senses this and has to add more fuel to compensate. You achieve more air and more fuel which is your 2-5 hp gain but your gas mileage goes down.

I would also guess that by adding an aftermarket exhaust back in the mix it allows for better flow to get the back pressure out that the cold air intake creates (more air and fuel) and thus gives you back your gas mileage.

 

I always thought it exhaust and intakes would alter the efficiency somewhat, but I'd never intakes to remove 25% haha.

 

well damn, that sucks. i think i'll just improve the air filter on the stock system. lol commuting sucks as it is with 19mpg.

 

W/ a tune you should see better MPG. I saw 23MPG w/ my tune and i had the injen CAI, F.I. HFC and exhaust and the light weight pulley. Next mod is going to be the CF Drive shaft and hope to see better MPG w/ that one since it will be lighter then stock

 

Cool study. Thanks for sharing

 

I put the R2C intakes on mine recently- I've seen a bit of a bump in mpg on freeway driving