Improving MPG

Regan Wareham
5

Asked by Regan Jul 13, 2008 at 08:50 PM about the 2008 Honda Civic Coupe Si

Question type: Car Customization

If I have an AEM cool air intake and a Catback exhaust, will that improve my car's MPG. If so, by how much?

17 Answers

Ryan Wagner
5

No, this will not improve your mileage. It will improve your cars performance, but not the mileage. Performance parts improve power, not mileage. If you plan on any serious upgrades, plan on sacrificing mileage for power.

Fred McClelland
1,755

haha are your serious? you bought an si and you want to improve the mileage? you should be modifying it and not worrying about the mileage its a damn si

2 out of 2 people think this is helpful.
Fred McClelland
1,755

you should of bought the civic hybrid if you were going to worrying about mileage

James Lykins
50

lol... i think hes looking for an excuse so his mommy and daddy will pay for mods

2 out of 2 people think this is helpful.
Matt Jacot
15

Yes, modifying your car does increase gas mileage, because it allows the engine to flow a lot better than a restricted exhaust and air box. The engine doesn't have to work as hard. It's not going to be a noticeable difference around town, but on the highway you can add a mpg or two. As long as you keep your foot out of the gas you will increase your gas mileage.

Chikezie Birchwood
75

at most just a little the both the mods help but its hardly going to be noticeable.

Jason Yu
10

actually it will improve your mileage... especially if you don't reflash your ECU. However, you will *really* improve your mileage if you drive more smoothly (less hard accelerates and then hard brakes; shifting into neutral when coasting to a red light). Also if you're short shifting (like below 3000rpm) you'll save mileage as well. I have an Si sedan... get around 31mpg just going to work and stuff... (even with dipping into VTEC about 2-3 times a day).

1 out of 1 people think this is helpful.
Phillip O'Brien
5

put in an electric fan purty much tru dual exaust not glass packs

Ryan Maillet
5

Swap the motor into a 94 civic hatch, you will probably get around 40MPG and still run 12's in the 1/4 mile.

James Lykins
50

hella BAD information in this thread... go to honda-tech.com and search for answers yourself...

1 out of 1 people think this is helpful.
James Lykins
50

yep, pretty much *thumbsup*

Chris Yager
65

first off any mods that are not HKS approved will void your waranty to that section you modded. did you buy an extended warany? Is this a track car or a red light warior?( which i do not endorse) is this a six speed stick you already have a fast car! stick with factory approved mods for you may need your warenty unless you have unlimited bankroll

Chris Yager
65

car is stock in si with electric fan

Chris Yager
65

thats crazy dude!!! how about a crx swap if your that nuts

Rob Dabb
0

www.mileagewillvary.com..... Check it out. I get 33 with my 2008 SI on the highway. Your car will compensate for the extra air it is taking in, as well as the exhaust flow, and add fuel which will actually decrease gas mileage.

Adam Morgan
3,935

good idea in theory, but I think you fail to understand what the additional fuel results in... Thats the same as saying... if you step on the peddle more it will use more gas... Well yes, of course that is obvious, but it also results in more force(torque)/speed. The idea of better mileage is to reduce the amount of work the engine has to do to pull air in. The principle is easy to understand.... Grab two straws with the same internal diameter. Breath in through a 5 inch straight one and then through a 6 inch curved one... Which one did you waste more energy trying to breath with? The curved one right? Same principle as a 4-stroke engine on it's intake stroke. This just makes it easier to breath... The problem with most CAI is the fact that they are open element and tend to pull hot air into the engine... This defeats the entire purpose since hot air is less dense.

William Cooke
30

the air intake is actually working against you if you want to increase gas mileage you should probably change your oil more often and try not to be so heavy on the gas. by puting in a high performance air intake and exhaust you will make more air go through the engine and the engine will have to work harder to pump the fuel through the car. in effect you will have to have oil changes more often and you will lower your gas mileage. Aem is a good brand though but you are just using it for the wrong purpose!!!!!!

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