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Discussion Starter · #1 ·
With $5 fuel looming in our near future, my focus has shifted from more HP to MPG.

I am in a 99 DX Hatch with a stock D16 and a slush box. At 154K I recently had a head gasket blow so I had the head decked and valve train re-worked. I have new E3 plugs, distributor cap and rotor. Filters are clean and tire pressures are at spec. The best mileage I can seem to eek out of it with my in town daily commute is 24 - 26 MPG keeping my foot out of it. It isn't fast but it is dependable and runs well.

So, short of replacing the slushbox for manual, which I'm not willing to do, what can I do to amp up the MPG ? Would a header and cold air intake to get it breathing better help with MPG ? Would changing the injectors and fuel pump to ones that require less fuel help ? Just want to get it running as cheap as I can for the dreaded daily commute.

Thanks for your reply.....
 

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my civic or my gsx
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purple haze all in my brain, don't know if im goin up or down, im acting funny but i dont know whyyy, squeze mee while i kiss the sky
?????????????????????????? someone is trying to up their postcount. lmfao!!!

on the flip side, to OP, yeah you could throw a header and intake on there to help it breathe a little better and even get a slight gain out of it as well, but really should just get a chip and tune to try and help it out more. that may be better for you since you dont wanna trans swap.
 

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rebuilding injects helps, but yours arnt really all that old. if your gonna get a cold air, get a full cold air intake kit, a header and a 2 1/4 inch exhaust will help. cat delete will help, you can get a tune for mileage, accelerating slowly, do an oil change with synthetic oil and put a high quality synthetic atf in your tranny, idk why your getting such low numbers in your car for mpg's when i step on the gas in my car i can still get atleast a minimum of 32mpgs

?????????????????????????? someone is trying to up their postcount. lmfao!!!

on the flip side, to OP, yeah you could throw a header and intake on there to help it breathe a little better and even get a slight gain out of it as well, but really should just get a chip and tune to try and help it out more. that may be better for you since you dont wanna trans swap.
lyrics to the song lol hahaha, i like that song its good lol jimi hendrix ftw
 

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How long do you think it will take for your potential fuel savings to recover your initial investment? Fuel economy builds just don't make sense to me. If you want to do it to prove you can, that's one thing, but spending money to save money seems silly to me.

A CAI and header would most likely decrease fuel economy. Hotter air is better for fuel economy because it allows the fuel to evaporate more completely, requires more manifold pressure to make the same power (same basic idea as EGR), and the mixture will burn a little faster and need less timing. The only time your fuel economy will drop is when you have to deal with knocking. A performance header would presumably reduce internal EGR and therefore reduce gas mileage.

A lot of it is how you drive. If I go on a long trip and cruise at 65 mph for a whole tank, I'll get 44 mpg. If I go on lots of short trips and drive like a jackass, I'll get 17 mpg. I'm not exaggerating.
 

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Man who you piss off tht put u in red lol ima keep reppin you till u get back green
lolll, asked for some opinions and got reamed on for using a particular tranny fluid. asked a question about fenders, and told some guy all i asked for was the answer adn you started giving me all this attitude about it and usless irelevent info (didnt say that) lol. haha thanks man lol thats funny.

How long do you think it will take for your potential fuel savings to recover your initial investment? Fuel economy builds just don't make sense to me. If you want to do it to prove you can, that's one thing, but spending money to save money seems silly to me.

A CAI and header would most likely decrease fuel economy. Hotter air is better for fuel economy because it allows the fuel to evaporate more completely, requires more manifold pressure to make the same power (same basic idea as EGR), and the mixture will burn a little faster and need less timing. The only time your fuel economy will drop is when you have to deal with knocking. A performance header would presumably reduce internal EGR and therefore reduce gas mileage.

A lot of it is how you drive. If I go on a long trip and cruise at 65 mph for a whole tank, I'll get 44 mpg. If I go on lots of short trips and drive like a jackass, I'll get 17 mpg. I'm not exaggerating.
really? 44 cruising highway and 17 in city bein a jackass ?? lowest mines gone is between 30-32 in the city with my foot on the gas, and 42 in city keeping my foot out, i havnt even gone highway driving at 55mph yet
 

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I run a little lean at cruise, so it will have a mileage benefit.

Either way, there is a huge fuel economy difference between driving like a jackass and driving with economy in mind. My Mustang gets 28 mpg on the highway and 7 mpg during track days.... that's a factor of four.
 

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EG8
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Man who you piss off tht put u in red lol ima keep reppin you till u get back green
You haven't seen a bunch of his threads...

:3dbiggrin:

he'll be red a long time :)
Lol

Why are you trying to pull a page out of transzex's book?

He wouldn't reply with random shit for no reason btw.


Honestly, the Cheapest mod you can do, is modify how you drive really. Do you spend a ton of time in traffic or something? Were you always getting that mileage?
 

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formerly allnaturalrex
1989 honda crx si
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i agree with everyone ask me how i know . i totally changed my driving habits at the start of the year and even my rx300 gained 2 mpg on the street. was averaging 15.5mpg now im at 17.6 mpg as long as i time those green lights and gradually speed up etc... do some searching and get to reading.
 

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Chipped ecu lean cruise to 15.5 to 16:1 add 3-5 deg timing.
 

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\/Your Mom Was Here\/
Vibe GT
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Drive the speed limit everywhere and dont accelerate fast at all. Ease into the throttle at all times. Air pressure in tires at least 35lbs. If sitting in traffic for long periods of time shut car off.
 

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Love the Civic
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Yeah man I started shifting at a lower rpm, around 3500 rpm. I used to shift at 4500-5000. I have noticed I went from ave 28mpg to 33mpg, no tune no gas change just shifting correctly for my driving route to work.
 

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Small T3 turbo, gate it at 4 PSI, drive it without getting into boost, keep the gauge a zero when pulling a hill. Run 345cc Prelude injectors, 12:1 FMU, retard timing as far as the dizzy will go, get 8.5:1 pistons. Lighten the fool out of your car, and 5 speed manual needed. Synthetic oil, non directional tires, pumped up to 38 PSI. The less rolling resistance the better. You can go as far as having alignment and take out any toe and thrust angle, making sure the tires do not create any scrub. As long as you keep your foot out of it, the turbo will help you get better gas mileage. I know it sounds lame but it works. The best I got straight freeway driving tank of gas. 42 MPG. Always slowly accelerate. And having a turbo on the car can be fun at times.

Good luck on your adventure.
 

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\/Your Mom Was Here\/
Vibe GT
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I got 42mpg out of my del slow with a completely stock d15b7 and 5spd (15in wheels with directional tires). Never got worse then 30 beating the holy hell out of it either. I get 26 mpg out of my 91 pickup truck. I can get better mileage then your car while towing your car lol.
 
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