Driving around in my automobile, The 3.2 giving me about 32 mpg. Flipped HB Options

[worn]

I been driving my 914 this summer. Closing in on 5 Kim so far this year. When I go, I get the highest octane that I can find; 91 or 92 with no EtOH where I live, trending towards more ethanol as we get west. So, I have been old guy writing down the numbers and have consistently hit 31 -32 mpg. This decreases if I leave my gas cap off just before a drive with the RRC 2024 folks.
The interstates let you drive at around 80 mph, and that adds up to a light throttle 3,000 rpm with my gears. The car must be pretty good with airflow.

[mepstein]

Light weight really helps.

[technicalninja]

If you're hitting those numbers via gallons/miles calculations and that is the AVERAGE you're kicking ass on the economy numbers.

I believe you are beating the 4-cylinder factory numbers by 20% with nearly three times the power...

That's high enough mileage that I would want to see the AFR numbers.

I'd be worried about being too lean.

Still really good mileage numbers!

[Front yard mechanic]

Isn’t that a Chuck Berry tune

[930cabman]

I been driving my 914 this summer. Closing in on 5 Kim so far this year. When I go, I get the highest octane that I can find; 91 or 92 with no EtOH where I live, trending towards more ethanol as we get west. So, I have been old guy writing down the numbers and have consistently hit 31 -32 mpg. This decreases if I leave my gas cap off just before a drive with the RRC 2024 folks.
The interstates let you drive at around 80 mph, and that adds up to a light throttle 3,000 rpm with my gears. The car must be pretty good with airflow.

The way life should be

[worn]

I been driving my 914 this summer. Closing in on 5 Kim so far this year. When I go, I get the highest octane that I can find; 91 or 92 with no EtOH where I live, trending towards more ethanol as we get west. So, I have been old guy writing down the numbers and have consistently hit 31 -32 mpg. This decreases if I leave my gas cap off just before a drive with the RRC 2024 folks.
The interstates let you drive at around 80 mph, and that adds up to a light throttle 3,000 rpm with my gears. The car must be pretty good with airflow.

The way life should be

I am a very law abiding driver in general, and the fifty five limit saved both gallons and lives. With all of that said, I saw almost no speeding on the interstates with the high speed limits. Maybe with so many miles to cover in this amazing country sometimes people just watch things go by and wait out the distances. As for that, I am grateful for my 914 to ride in.

[brant]

I been driving my 914 this summer. Closing in on 5 Kim so far this year. When I go, I get the highest octane that I can find; 91 or 92 with no EtOH where I live, trending towards more ethanol as we get west. So, I have been old guy writing down the numbers and have consistently hit 31 -32 mpg. This decreases if I leave my gas cap off just before a drive with the RRC 2024 folks.
The interstates let you drive at around 80 mph, and that adds up to a light throttle 3,000 rpm with my gears. The car must be pretty good with airflow.

I get around 32 with a stock djet. But at 4k on the highway… close to 90 with 16 inch wheels


And keep a paper log book of gas stops like a normal person should…. (IMG:style_emoticons/default/biggrin.gif)

[emerygt350]

My 2056 gets about 20 in town, maybe 27 on a really good day on the highway. Anything over 60 starts to pull at that number. I have come to grips with that. It's still better than the 12 mpg I get with the mustang in town and 14 mpg I get with the explorer in town. Highway on those is 22 and 24 respectively.

Do I drive like grandma? Hell no. If you aren't playing in the 3k to 6k rpm range why are you driving a 914? If my mustang had a manual I can't even imagine how bad my mpg would be in that car.

Oh, and I used to get far better mileage before the cht and afr gauge. I like my heads, I don't want to buy new ones.

Truth be told I can't even get good mpg in the mini. I just can't drive that way. The volt, another story entirely.

[scallyk9]

I envy you. I have a 74 914 with an '87 Carrera 3.2L engine with Motronic FI and 916 Transaxle with Guard LSD. And I'm only averaging 22 MPG over the last 4000 miles including lots of time on Interstates. This was not unusual for the Carrera it came out of but I should be doing better.

[emerygt350]

I envy you. I have a 74 914 with an '87 Carrera 3.2L engine with Motronic FI and 916 Transaxle with Guard LSD. And I'm only averaging 22 MPG over the last 4000 miles including lots of time on Interstates. This was not unusual for the Carrera it came out of but I should be doing better.

Not if you are having fun....

[Geezer914]

My 2056 gets around 24-25 mph at 3400-3500 rpm. AFR is around 13.2-13.4. Check your plugs to make sure you are not running lean.

[930cabman]

My 2056 gets close to 35 mpg cruising at 75 - 80 mph. Twin Webers (IMG:style_emoticons/default/piratenanner.gif)

Flat terrain and a constant throttle opening help

[technicalninja]

My 2056 gets around 24-25 mph at 3400-3500 rpm. AFR is around 32-34. Check your plugs to make sure you are not running lean.

Your AFR numbers are different than mine.

Air/Fuel ratio is usually based on air by weight/fuel by weight and stoic is 14.7/1

Often folks leave off the one.

14.7 is "perfect" combustion with exactly the right amount of oxygen to fuel for complete combustion of the fuel with "hopefully" the least amount of CO and HC being produced.

12.5 is rich, normally a max power mixture.

10.0 is PIG rich

16 is getting lean, some cars will do OK running 16. This is the beginning of "lean burn" IMO. You only want to see as high as 16 in cruise at speed.

18 is dangerously lean. A few max effort fuel economy vehicles run this high.
You need computer controlled hyper fast FI with multiple knock sensors to make this work.
Run an old school T4 with carbs at these numbers and you will MELT stuff...


What does 32-34 refer too?

The mileage numbers that members have been posting are interesting.
Even seriously modified cars can achieve decent numbers if driven in a "highly responsible" manner.

And that is NOT how I'd drive those cars. (IMG:style_emoticons/default/devil.gif)

[emerygt350]

I try to keep my cruise AFR between 13 and 14, but closer to 13. I think my air dam and such doesn't do any favors for mileage. That 6 might be hardly working moving a 914, however I would still want to know my head temps and AFR, and my engine won't cost 20k to rebuild.

[rick 918-S]

HB gears in the 901 in the Alien. /i don't track mileage but it has to be good since I was able to tune the CIS.

[mlindner]

Worn, I just did the Waumandee Hill climb/time trial last weekend. 2.3 miles with 400 ft elevation. Very fast, want to go next year. Mark

[Literati914]

On the subject of AFR and mileage - I remember watching a video on YT, where the driver of an old school 911 (while basically being interviewed by the channel's host), running thru the twisties of some northern California mountain roads - would manually change the A/F ratio on the fly via a knob he had installed between the seats!!

I think he may have been running carbs but can't exactly remember. I thought that was kind of a slick solution and may try to mimic it at some point. Anyone heard of this before? Know how that could be done?

[emerygt350]

I set that up on my car. Very easy with d-jet. All you need to do is modify the resistance detected at the cht. I used a Bluetooth switch. Didn't keep it because it didn't affect head temps as much as I was hoping.

[brant]

On the subject of AFR and mileage - I remember watching a video on YT, where the driver of an old school 911 (while basically being interviewed by the channel's host), running thru the twisties of some northern California mountain roads - would manually change the A/F ratio on the fly via a knob he had installed between the seats!!

I think he may have been running carbs but can't exactly remember. I thought that was kind of a slick solution and may try to mimic it at some point. Anyone heard of this before? Know how that could be done?

Can’t change AFR on the fly with carbs
As it would require a jet change on the carbs


Easy with djet
Possible with modern injection

[Geezer914]

My 2056 gets around 24-25 mph at 3400-3500 rpm. AFR is around 32-34. Check your plugs to make sure you are not running lean.

Your AFR numbers are different than mine.

Air/Fuel ratio is usually based on air by weight/fuel by weight and stoic is 14.7/1

Often folks leave off the one.

14.7 is "perfect" combustion with exactly the right amount of oxygen to fuel for complete combustion of the fuel with "hopefully" the least amount of CO and HC being produced.

12.5 is rich, normally a max power mixture.

10.0 is PIG rich

16 is getting lean, some cars will do OK running 16. This is the beginning of "lean burn" IMO. You only want to see as high as 16 in cruise at speed.

32-34 it is supposed to be 13.2-13.4 AFR.

18 is dangerously lean. A few max effort fuel economy vehicles run this high.
You need computer controlled hyper fast FI with multiple knock sensors to make this work.
Run an old school T4 with carbs at these numbers and you will MELT stuff...


What does 32-34 refer too?

The mileage numbers that members have been posting are interesting.
Even seriously modified cars can achieve decent numbers if driven in a "highly responsible" manner.

And that is NOT how I'd drive those cars. (IMG:style_emoticons/default/devil.gif)