Going for 40 MPG, Let me hear your 2 Cents worth Options

[majkos]

Title says it all..
What I'm working with,
'71 1.7 F.I. Yellow 914
Recently yank dual carbed 1.7,(smokes)Oh really? (IMG:style_emoticons/default/confused24.gif)

anyhow I've installed another good used motor, with complete F.I.
Pertronix ignition and Stainless Steel Heat Ex's.
Bursch exhaust.
Sorry, no K & N, staying with Oil Bath Air cleaner
The guy has to drive thru a couple miles of dirt road.

Any other tricks to help with getting the 40 MPG goals?
I said he'll have to stay with those skinny tires though.
Am I correct?

I've over 30yrs of "Practice" on 914.
One thing struck me, I found some SOLID alum. motor mount.
I know it helps with shifting but (IMG:style_emoticons/default/idea.gif)
Kinda of "tighen" up the motor to the car.
Worth the trouble?

Let me hear it people!

[TROJANMAN]

I one tanked it from Castle Rock to Albuquerque one year. I think about 37 mpg in the Copper 2.0

[Root_Werks]

40mpg isn't out of reach on a good strong 1.7 or 1.8 for freeway traveling.

I'd think it'd have to be FI and tuned 100%.

I've had a couple of stock 1.7's that always seemed to pull mid 30's even after calculating how far off VDO speedo's always seem to be.

[Eric_Shea]

I think about 37 mpg in the Copper 2.0

Dave (DraperJoJo) got 37 in his 2.0 coming back from RRC. 40 should be doable in a 1.7 but, I'm thinking you'll need all the help you can get (tailwind, downhill, etc.)

[Root_Werks]

I did a "best mpg" 74' super beetle a few years back. Being carb'd it had it's limits, but I learned alot from it:

Disc brakes have less drag than drum (Not a 914 issue I know)

Tire size has a lot to do with it. For a mpg 914, I would go with 185/65/15's pumped to almost 40psig.

Fuel delivery, no carbs, keep it stock FI with good clean working components

Strong spark and plugs, like the old DTC's, loose the points etc

Healthy engine, 60lbs comp isn't going to help you in your quest for mpg

Good alingment, this added 2.2mpg to my Bug.

I almost bought the yellow 1.8 CAMP914 has for sale just to do a mpg 914. But everyone knows yellow is just too fast. (IMG:style_emoticons/default/smile.gif)

[Dave_Darling]

High pressure in the tires. Like the "MAX PRESSURE" rating on the tire sidewall.
Low speeds. Rolling resistance goes up linearly with the speed, aero drag generally with the square of the speed.
Tall gearing. You want the RPMs to be as low as you can live with. (NOTE: This can be a problem in air-cooled cars, where the RPM determines the fan speed!) It is better to be at 1/2 throttle in a very tall gear than just off-idle in a lower gear.

So pump the tires up to 40+ PSI, and run the car at the lowest speed you can stand in 5th gear. Keep a close eye on the head temps, and if they get hotter than you like either downshift or speed up. (The latter by downshifting then speeding up then upshifting, of course.) And avoid slowing down and stopping if at all possible! If you're driving in the city, this means "timing" the lights so you hit as many of them green as you can.

In a more modern water-cooled car, you can shut the engine off and coast, but I think that opens up the door to the possibility of significant problems in an air-cooled car.

--DD

[TonyAKAVW]

Aerodynamics:
Diffusor tabs on the trailing edge of the roof.
Front air dam to keep air out from under the car
Remove rear valence or put a sheet of somethnig under the rear of the car (careful with cooling)
Remove the mirrors and use a single small F1 stlye rearview mirror
Remove the antenna
Put skirts over the rear wheels
Chrome dome wheels

Weight reduction
Replace bumpers, hoods with glass or carbon fiber
Remove sound deadening materials
Go with early style doors
Plexiglass rear window
Strip the interior as much as comfortable


More advanced:
Replace motor with small displacement Subaru and custom EFI tuned for low fuel consumption.

With all of that you could get 60 mpg I bet.

I have heard of a stock 1.7 (carbed) 914 getting 49 mpg on a long highway trip, driven very carefully.


-Tony

[smontanaro]

Tall gearing. You want the RPMs to be as low as you can live with. (NOTE: This can be a problem in air-cooled cars, where the RPM determines the fan speed!) It is better to be at 1/2 throttle in a very tall gear than just off-idle in a lower gear.

Would a thermostatically controlled electric fan work? In theory, it would only run fast enough to keep the cylinder heads (or oil) in the correct range. I've never heard of that used on air-cooled cars before but I'm pretty sure that's how most/all late model water pumpers work. (Of course the heat transfer properties of water are better than air. That might have something to do with it.)

[underthetire]

High pressure in the tires. Like the "MAX PRESSURE" rating on the tire sidewall.
Low speeds. Rolling resistance goes up linearly with the speed, aero drag generally with the square of the speed.
Tall gearing. You want the RPMs to be as low as you can live with. (NOTE: This can be a problem in air-cooled cars, where the RPM determines the fan speed!) It is better to be at 1/2 throttle in a very tall gear than just off-idle in a lower gear.

So pump the tires up to 40+ PSI, and run the car at the lowest speed you can stand in 5th gear. Keep a close eye on the head temps, and if they get hotter than you like either downshift or speed up. (The latter by downshifting then speeding up then upshifting, of course.) And avoid slowing down and stopping if at all possible! If you're driving in the city, this means "timing" the lights so you hit as many of them green as you can.

In a more modern water-cooled car, you can shut the engine off and coast, but I think that opens up the door to the possibility of significant problems in an air-cooled car.

--DD

I've been told exactly opposite. You want the engine to be at cruise speed about 40-60% of your max horsepower RPM. Thats why those little fuel efficient Hondas and such run a fairly high RPM on the freeway.

[number6]

I recall seeing a Raby 50mpg 2.0 advertised (or perhaps under development?). Is anyone here running that motor?

Update:

A quick google search turned up:

http://www.aircooledtechnology.com/r_d_sds_efi.htm

From the last paragraph of above page:

"'Super 2 liter plus' 2016cc RAT R&D engine that’s working toward a 50MPG fuel efficiency while making 110+ HP with a flat torque curve"

That's a motor I would love for a daily driver!

Found another discussion:

http://www.914club.com/bbs2/index.php?s=&a...st&p=401255

[majkos]

Great tips guys!

I knew there's a few more ideas.

My very first trip in my first 914, (bought in '85)
Made a trip from Denver, to ASPEN!
Work related (IMG:style_emoticons/default/aktion035.gif)
I tell everyone to take a drive in the twisties as soon as possible,
cause I did!
4 hr trip in three (IMG:style_emoticons/default/driving.gif)
and after getting home, on same tank!
I figured around 40 +!
All this during ski season.
Think the COLD air helps?


When I change tires for handling (wide)
there went the mileage.

[Sleepin]

you can shut the engine off and coast, but I think that opens up the door to the possibility of significant problems in an air-cooled car.

--DD

Yup....the 914 only restarts 60% of the time. (IMG:style_emoticons/default/lol-2.gif)

[majkos]

you can shut the engine off and coast, but I think that opens up the door to the possibility of significant problems in an air-cooled car.

--DD

Yup....the 914 only restarts 60% of the time. (IMG:style_emoticons/default/lol-2.gif)

914 restarts? (IMG:style_emoticons/default/headbang.gif)

[JTarver]

Go downhill. Alot. Throw that baby into coast mode.
Find the right hill, and the sky's the limit. lol
Joe

[effutuo101]

Hiya Kevin,
I averaged 32 mpg in the silver car from Denver to Seattle. Average speed about 68 mph dial it in, inflate the tires and go for it.
In driving my wifes jeep I found that I could squeek out a couple of more miles per gallon by shifting to netrual and coasting down hills, up off ramps, to a stoplight. No reving the motor unless necessary, and long un intrupted highway driving. 60 mph may be slow when the speed limit is 75, but that extra 15 mph cost a lot of fuel. and the puppies may have to deal with the windows up during free way driving.

[underthetire]

I haven't had to fill up in a week. Jack stands get great fuel economy.

[Gint]

Got 44 mpg from NorCal to Denver in a 1.7 and I was haulin ass every chance I got. It's easily do-able.

[Porcharu]

Think the COLD air helps?

Cold air is BAD for MPG - kills the vaporization. The mileage nuts put manual choke cables on the heated air coming from the exhaust manifold that is usually only on only during cold starts. Claims of several MPG are claimed. Skinny tires are good. On my 8000 pound truck going from 235/85's back to 265/75's (same brand and type, same diameter) cost me a about 1 - 1-1/2 mpg 24 down to 23 or a bit less.

[KELTY360]

Hiya Kevin,
I averaged 32 mpg in the silver car from Denver to Seattle. Average speed about 68 mph dial it in, inflate the tires and go for it.
In driving my wifes jeep I found that I could squeek out a couple of more miles per gallon by shifting to netrual and coasting down hills, up off ramps, to a stoplight. No reving the motor unless necessary, and long un intrupted highway driving. 60 mph may be slow when the speed limit is 75, but that extra 15 mph cost a lot of fuel. and the puppies may have to deal with the windows up during free way driving.

(IMG:style_emoticons/default/yellowsleep[1].gif)

How did you stay awake?

[effutuo101]

Ah, the crisp morning air and a bunch of 914's racing through the Rockies on thier way to RCC. Then just wedge the foot and headed for home. I started about 4am and had to stop at 11pm due to weather in Idaho. Then back up at 6 and home. Way to much Mt. Dew.