How do some people get so high gas milage?

[lonchair]

I've known since I got my car that my gas milage has never been as high as several people have claimed to get (27-30mpg). What do you peple do to get such high milage and what is your average speed?

On a 300 mile trip this past Saturday, I averaged 70 mph and got 22.5 mpg. I have not jacked with my fuel system at all. Stock injectors, stock cam, stock fuel pump, new fuel filter. All I've done is install a 5.0L throttle body, but my milage was pretty much the same when I had the stock SVO trottle body.

[SVOeric]

humm -- keep foot out of boost, and drive downhill a lot


My last trip to bama -- on the way down I ran between 72, and 75 -- got right at 30 mpg

maybe going south helps

[SVOMARK]

Mileage

I think you'll find the guys getting 26-30 mpg have 84's with differnet gearing. The 85-86 will get 22-25 mpg.

[Ken Potter]

Drafting helps...

If you can find a big rig going fast enough ( running empty ) that doesn't mind you hanging out in his wash / draft it can be very helpful on gas mileage. I try to do this no matter what I'm driving as my 94 F-150 has the aerodynamics of a brick. I've also added "Prolong" ( not to be confused with Viagra Ha Ha! ) in the crankcase on all my vehicles and it seems to help alittle. I have really given up even checking my mileage anymore much less looking as gas prices as it's too depressing. Also the 2R has the infamous wandering gas needle... I just reset the trip odometer every time I fill up and start looking for a station around 220 miles or so in the SVO.

[GAboySVO]

Lon,

Pat_in_LA has installed a bleeder in the vacuum line to the FPR. He indicated that at around 3000 rpm and up the ECU commands the A/F ratio to go rich. The bleeder effectively reduces the fuel pressure causing a leaner condition at highway speeds. You might want to contact him for details.

Please note: Do not do this if you thrash the thottle a lot.

[Kendal Coker]

I bought a new svo in 84 and have never gotten over 23, I also have a turbo gt that I changed the rear end out and put 3.08 thinking I would get better. I get mostly 20 with it. Guess you get the picture with my turbo fords. later

[svobud]

Lon - I was getting 26mpg with the 85 prior to the LA3 swap - now I'm down to 22mpg.

Biggest factors - everything is top tune, back the fuel pressure down, stay out of the boost, and keep it under 3k rpms.

[lonchair]

Every thing is in good tune. New plugs, wires, cap and rotor, all with under 2k miles. Also fresh all synthetic oil change and all tires with proper pressure.

If one of the keys is to stay under 3k, then I'll never get better milage. My car turns 3k at 70mph in 5th. On the open road, I just can't bring myself to do less than 70mph.

But 22mpg at 70mph isn't bad concidering my daily driver truck gets somewhere around 15 at 70mph with the cruise control on.

[Pat_in_L.A.]

For long trips, try a set of 245/50R16 rear tires. The speedo will be off by 3-4 MPH to the low side but at highway speeds you'll be just under the rich mode that the ECU sees at ~3060 RPM. To add the fuel economy savings, just multiply your current calculations by 1.04 to 1.05.

Regarding the FPR bleeder, I have it and use it on my 84 that has gotten 30 MPG. I DO NOT recommend it to anyone who is modding their car for performance! This is a fuel economy trick only. Thank goodness for the detonation sensor.

[kennycoulter]

sorry to kinda hijack, but 245/50r16? are you sure they fit? i got some used from a rich guy(about half life)(used to work in a tire shop) they are goodyear eagle gs-c's i wasnt sure if the side wall would pinch in too much. these wheels are 16x8? or 7? the tires just look too wide for the wheels. but im really hoping youll tell me they fit.

[Pat_in_L.A.]

mine fit. no rub.

[johnbasler]

In a pure highway situation, I could coax 29 or so out of my '84 with the 3.45 gears. 2 years ago I got about 27 out of the ghetto 85 on the way to Alabama.

However, mixed or city driving really would drop it to 20-22 in either car.

Several years ago, Huber was able to get 38 MPG on the highway out of his '79 Mustang when it was still a daily driver after it was first converted to EFI. It had 5.13 gears, but a trick overdrive ratio in the T5 for max fuel economy.

[SVOeric]

I do believe that the big valve head, and roller cam help my car on milage -- I can tell a big difference when I run over about 72-3 MPH tho.

[Bruce]

My car got 22 on the trip back from CA. (ALOT of 85 mph with the air on) Now that I have it in WI I get 22 all the time! I always drive it hard though! But what else are these cars made for? For the amount of fun I get out of it I would like to think getting 22 is a bargan!

Bruce

[turbizzy]

I was wondering the same thing about gas mileage as asked on the first post. My needle also likes to float around when im near empty. Ive never let it run out of gas completely but i want to one day with a spare gas can so that i can really see my mileage from full to empty.

So far ive gotten 16 mpg as my best mostly on the highway w/ light city driving. I usually just go off of my trip odometer like Ken Potter does exactly to 220. I do like to... BOOST occasionally just on the on ramps tho, yeah right, maybe this doesn't help.

Someone should try not boosting at all through an entire tank of gas and post mileage.