Fuel Milage

[NoDOHC]

My record mileage stock ('86 6-port N/a) was 31.2 mpg. This was driving through Ohio Westbound on a 95 degree day at 85 mph (that is how fast the traffic was going). At 85, I was turning about 3200 rpm (which backs up Ted's theory).

We should have a sticky on here somewhere for mileage tips:
Don't lug below 1,500 rpm.
Don't rev past 3,800 rpm (as Ted said, try to leave a little margin here).
Do not move the throttle any more than necessary.
Try to keep speed above 60 mph.
Advance timing 10 degrees or so.
Remove power steering belt for long trips.
Keep new spark plugs.

This should get you into the mid 20's consistently. My '91 with power steering connected Automatic trans, etc, will give 28 mpg highway (more like 21 city).

[My5ABaby]

Originally Posted by NoDOHC

We should have a sticky on here somewhere for mileage tips:
Don't lug below 1,500 rpm.
Don't rev past 3,800 rpm (as Ted said, try to leave a little margin here).
Do not move the throttle any more than necessary.
Try to keep speed above 60 mph.
Advance timing 10 degrees or so.
Remove power steering belt for long trips.
Keep new spark plugs.
Buy a Geo Metro

Fixed.

[tweiss3]

Lmao, I can deal with the shitty milage, that's not too much of an issue (other than the 100+ bucks in fuel a week) but this thread was more or less determining if my milage was about normal.

I honestly believe consistantly tracking or checking your fuel milage is one of the best ways to find out early if something is going wrong with your drivetrain.

[RETed]

I agree.
This is why I track all my cars mileage just to get a hint something is wrong.
The way I do it, which makes it easiest for me, is to just run 10 gallons per fill-up.
Calculating MPG is easy!

My '87 Turbo does a consistent 12.5mpg now.
This is basically all city driving, as work is only 4 miles away for me.
When I jump on freeway, it'll hit 20mpg pretty easily.
Ported 13BT, hybrid turbo, Haltech E8, Crane Cams HI-6 on leadings

My best record has been a Sacramento, CA to Las Vegas, NV run...
400 miles between fill-up's
~13 gallons per fill-up, due to smaller S4 gas tank (16.6 gallon max)
That nails exactly 30mpg.
All freeway / highway, keep tach under 3,800RPM, average speed around 80mph
Car back then was running reprogrammed ECU, small hybrid turbo, Crane Cams HI-6 on leadings, same ported 13BT motor.


-Ted

[Ender]

When I was still a car n00b (14yo) my Mazda 323 dropped suddenly from ~28mpg to about 14 and had no power (like it had any to begin with). A couple days later the damn timing belt broke trying to start the car, the tensioner pulley had seized! Now if my RX-7's mileage drops it probably means the stupid wastegate is broken open again

[sv51macross]

Originally Posted by Pete_89T2

Another factor to consider with mileage, besides the mix of highway/city driving is the length of each of your trips (i.e., run time). If a large percentage of your trips were made doing short runs (city or hwy driving), where you spent most of your time getting up to operating temps, it will drag your average mileage down.

Hmm...I'm averaging 11-12mpg with Lucy. No O2, possibly bad thermo, and rusty BAV/IAC. Mostly trips back and forth to class. The college is 10 mins away and it's almost all 'city'. I keep RPM between 2 and 3 thousand. Nowdays I just let her idle a couple minutes to warm the oil and go.

Guess I know why my mileage is so bad.

[Ender]

The lack of an Oxygen sensor is probably KILLING your mileage. The ECU can't know if it's running rich or lean, so it will default to running very rich just in case. Install one and report back with how much it improved.

[tweiss3]

Ive worked on driving habits and am up to 16.2 without any change of areas driving. Also im not taking it easier, just being more aware of gear choice and cruising rpms.

[Jims5543]

Hmmm...

13B-REW swapped.

475 RWHP.

1300/870 injectors.

Motec M4 tuned for cruising keeping the AF ration in the 14.1 range at 80 MPH.

MPG - 21 on the highway
- 17 around town
- 10 when I am not being nice and trying to get arrested
- 5 on the track

[Ender]

Drove from Iowa to Kansas and back this weekend. Cruised about 82mph 90% of the way there and got 19mpg. Majority of the way back I was driving ~73mph and got 23mpg. Both ways, naturally, had at least a few quick sprints.