Building the ultimate Gas Mileage Car

[stitches]

Okay, so most people tune for power, but I want to tune for gas mileage. I drive a 1988 CRX HF with D15B6, so I know I have a great starting platform for my goal, but I was wondering if anyone could help give me tips on getting the most possible gas mileage.

Thanks everyone, for helping me with my strange goal. (Hopefully this is in the right section.)


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[Chaos325]

I read somewhere about a d16y7 with a dpfi intake manifold in an ef sedan. It made like 35-38ish mpg

[superdewey58]

put up a sail when the wind is behind you
lol


my suggestions would be good non restrictive intake, exhaust, along with clean and ported intake mani and head. the texture of the surface metal contributes a lot to the airflow and the electrons in the o2, providing better combustion and better gas mileage

[sohcnovtec]

Don't drive like a jackass! You'll save 33% on fuel cost and consumption.

[stitches]

I read that CRX HF's can get something like over 50mpg, but I'm pretty sure that's interstate. I'd try to compare my current gas mileage to the 35, but right now my gas gauge is broken. I'm trying to get a new one as we speak. Also... I'm a total noob... I'm assuming dpfi stands for dual point fuel injection, and i know mines has a pgm-fi (programmed fuel injection?) but i'm not sure if it's dpfi or something else.


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[ddd4114]

Don't drive like a jackass! You'll save 33% on fuel cost and consumption.

haha, so that's why my mileage sucks!

[stitches]

I understood about half of what you said dewey, but I'm a total noob.

In my head, this translated to I need to get a new intake, I'm not sure what you meant by exhaust.. (maybe a whole new exhaust system..?) not sure what intake manifold is... but i hear it a lot, and I'm saving up for new headers as we speak.

God please excuse my noobiness. I'm really trying to learn.


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[ddd4114]

I'm not sure what you meant by exhaust.. (maybe a whole new exhaust system..?)
from the catalytic converter and back, called a cat-back exhaust. You can also replace the cat, but it's not really worth it, in my opinion.

not sure what intake manifold is...
http://www.angelfire.com/emo/roku21/CXintake.jpg

I'm saving up for new headers as we speak.
I recommend only getting one, since you have an inline 4...unless you want to start a collection in your garage, that is...

[stitches]

I didn't mean i was going to buy more than one set... err just refered to them as headers cuz they are in fours. Thanks for the exhaust explanation, and well.. the intake manifold picture is bandwitdthed.

I'ma google it now.

Any other suggestions, besides adding a sail?


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[UHFE CRX]

Stitches, you are right - nice platform to start from.

First things first -> drop weight. Weight (mass) are your enemy from an acceleration/deceleration (gas/brake) point of view. If you are willing to go as far as removing the spare tire, rear interior, passenger seat (JK) you can seriously cut some weight. Along those lines - don't fill up the tank (if you can help it). It adds mass. These things get great milage so don't worry about hitting the 1/4 mark ; )

The next step for efficiency would be a good tune up of the engine you have (non $$$$ answer), or for a higher $ answer swap engines/computers to a 3-stage VTEC D15B the 2-stage D15B VTEC-E. These engines were not distributed in the USA, but they can be acquired here.

Good Luck,
Brian

[MadMan]

gas milage is easy, even easyer with a 1st generation crx. I had a 86 DX that would get 42-48mpg (carbed motor)


Thinks that will free up MPG are alot of things that can relate to performance.


Basics are....

Reduce Mass
Reduce Drag
Increase Engine Effeciency
Driving the correct way

Mass= Weight of car, total weight. If you can lighten your car... it will be more efficient. Making the engine lighter is even more helpful because it doubles as total weight and engine effeciency, Such as a Light weight flywheel add on.

Reduce Drag= All the wind and traction via tires slows you down. If your car does not have a front lip, adding one will not only give you a lower more sporty look in the front, but it will also add into a more aero dynamic shape of the crx. Wheels and tires..... one of the most critical objects. On a CRX aiming for MPG, absolutly nothing bigger than a 13'' wheel is needed. VX wheels are perfect for this application do to light weight and right size. Tires come next... the wider tire you get the more drag you will have, I used P175-80R13's on the front and rear....but I could have gone with P155/165's on the rear. Notice, having less wide of tires reduces braking distance alot, and will increase the chance of losing control during the rain and slick conditions if your not a cautious driver ( I never had a problem). Windows are another thing, It's summer time and its hot outside.... I found that 2 windows down vs a/c+windows up gave more MPG (windows down did). If you can bear the heat and only roll 1 window down its even better. The best situation is at night, using the blower motor w/ NO a/c for ventilation and having the windows up.

Increase Engine efficency= Intake and exhaust done right can add MPG. On a HF I would use 2'' exhaust piping (having a uncloged catlytic converter), and a normal style CAI with the filter next to the battery. Underdrive pulleys and lightweight flywheel will also benifit you. Changing to a aftermarket header will have you losing a few pounds and freeing up the exhaust airflow. A new O2 sensor is a very good thing to have, also a lowered idle. Instead of 750.. turn it down to 600. having good spark plugs properly gaped is also something to look for, I personally prefer OEM NGK. Dont waste money on octane boosters...or anything in a bottle that promises mpg. Having a clean intake manifold free of carbon build up and seafoaming the injectors (I prefer having them professionally cleaned). And ofcorse changing your oil/filter every 3-5k miles helps, I noticed no diffrence in MPG when I switched to synthetic but they "Claim" a increase. Nobody does this either but letting your engine idle for about a minute will prevent coolish air from slowing down the warming process in the morning, your engine gets maximum MPG at normal temp, by the time it has idled for about a minute its getting warm.

Driving= the slower you can possibly drive the more mpg you can get. I drove my 86 like a bat out of hell and got 30-35. Drive it shifting at 2k-2.2k rpms and cruising at 55mph got 42-48 (depending on the time.......night time I got 48 w/ windows up)

[stitches]

The key is tasteful here, so I'm thinking I'm gonna have to keep the spare tire etc, but I'm looking to cut a tad of weight here and there. I figure my seats are already pretty much torn to shreds, so after working on the engine a bit, I might buy a set of lighter seats. I'm trying to keep it stock, and go for performance at the same time, and well... they kinda interfere with each other. ^_^

Thanks for all the tips so far, and yes, I have read the thread on getting better gas mileage, I was just wondering if there were any more tuning related tips.


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[MadMan]

I kept spare tire and jack to change a flat. your seats are torn up, but they are HF seats... its hard to find anything lighter than those that will be comfortable. Seat covers FTW. Even with my 86 dx in full MPG form.. I could out run any dual point sohc out there...and still get more MPG than them.

tuning can get you better mpg, but a simpler easyer way is what I stated above. Basic modifications. I had 15'' scion steelies on my crx...swaped for vx wheels and gained about 6-8mpg instantly. swaped my P195-60R14's on my 86 corolla for some P175-70R13's and gained 7-8mpg.

[romaredcx]

really you gained that much from lighter wheels? I was thinking of putting vx wheels on my ek in place of my blades, now I will def do it, if they fit.

[Willie S.]

Change your fuel filter, especially on an older vehicle. Will defiently see a difference. Have your injectors cleaned and balanced. Around $100 for 4 from RC. Will end up paying for themselves.

[Willie S.]

really you gained that much from lighter wheels? I was thinking of putting vx wheels on my ek in place of my blades, now I will def do it, if they fit.

I'm pretty sure 13's wont clear on an ek without spacers, which will also require extended studs.

[torturedsol]

haha, so that's why my mileage sucks!

Werd ROFLAMO! I may as well weld my gas pedal to the floor.

As for the quesiton at hand, d16z1 VTEC-E head with its respective manifolds. Pea shooter exhaust and a stock intake

[vtecencrx]

Are You Wanting To Keep Your Hf Tranny, And How Much Performance Do You Want Vs Gas Mileage?

[vtecencrx]

If I Was Too Have The Ultimate Gas Mileage + Performance Without Being Too Complicated,
1st Install A Dx, Or Si Head
2nd Install A Si Intake & Throttle Body, With The Hf Injectors
3rd Install A Header With A Cat And B-pipe From A Si
4th Install A Si Ecu
5th Ram Air Intake
6th Keep You Hf Tranny

Just My 2 Cents, Since I Have Started Off In A Similar Setup Before
I Have Seen Around 45 Mpg Before, With Some Good Power

[xotic_crx]

I drive a 90 CRX Si with the A6 and am capable of getting an avg. of 40 mpg over a whole tank of gas. I've got a full exhuast(header, high flow cat, etc.), CAI, and some good plug wires and plugs. Now, to attain this, I shift at about 2K-2500 rpms and drive quite conservatively. Now the key to this is that you don't speed and drive 55 and don't get on the interstate (at least with the Si trans, if you have the HF trans i'd probably run 70 everywhere). I'm sure if i had the HF trans and some lighter rims i'd pick up some more mpg, and maybe a full multristrike ignition system.

[lsturbohatch10]

If I Was Too Have The Ultimate Gas Mileage + Performance Without Being Too Complicated
2nd Install A Si Intake & Throttle Body, With The Hf Injectors

isnt an hf dpfi??? i could be wrong

[transzex]

your wrong :)

[lsturbohatch10]

lol.

[romaredcx]

my vtec-e head will be on in 2 weeks, as well as my 13s :p