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914World.com _ 914World Garage _ Going for 40 MPG
Posted by: majkos Apr 20 2010, 02:57 PM
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? 
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 
Kinda of "tighen" up the motor to the car.
Worth the trouble?
Let me hear it people!
Posted by: TROJANMAN Apr 20 2010, 03:04 PM
I one tanked it from Castle Rock to Albuquerque one year. I think about 37 mpg in the Copper 2.0
Posted by: Root_Werks Apr 20 2010, 03:21 PM
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.
Posted by: Eric_Shea Apr 20 2010, 03:26 PM
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.)
Posted by: Root_Werks Apr 20 2010, 03:32 PM
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. 
Posted by: Dave_Darling Apr 20 2010, 03:33 PM
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
Posted by: TonyAKAVW Apr 20 2010, 04:14 PM
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
Posted by: smontanaro Apr 20 2010, 04:19 PM
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.)
Posted by: underthetire Apr 20 2010, 04:22 PM
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.
Posted by: number6 Apr 20 2010, 04:50 PM
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=&showtopic=30900&view=findpost&p=401255
Posted by: majkos Apr 20 2010, 04:56 PM
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 
I tell everyone to take a drive in the twisties as soon as possible,
cause I did!
4 hr trip in three 
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.
Posted by: Sleepin Apr 20 2010, 05:08 PM
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.
Posted by: majkos Apr 20 2010, 05:12 PM
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.
914 restarts?
Posted by: JTarver Apr 20 2010, 05:14 PM
Go downhill. Alot. Throw that baby into coast mode.
Find the right hill, and the sky's the limit. lol
Joe
Posted by: effutuo101 Apr 20 2010, 05:16 PM
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.
Posted by: underthetire Apr 20 2010, 05:16 PM
I haven't had to fill up in a week. Jack stands get great fuel economy.
Posted by: Gint Apr 20 2010, 05:31 PM
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.
Posted by: Porcharu Apr 20 2010, 05:38 PM
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.
Posted by: KELTY360 Apr 20 2010, 05:40 PM
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.
![yellowsleep[1].gif](style_emoticons/default/yellowsleep[1].gif)
How did you stay awake?
Posted by: effutuo101 Apr 20 2010, 05:59 PM
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.
Posted by: smontanaro Apr 20 2010, 06:28 PM
http://www.hypermiling.com/. 
Posted by: swl Apr 20 2010, 08:24 PM
Watched a myth busters last night where they proved significant milage improvement from texturing the body surface like a golf ball. Not for the CW's
Convert to diesel - good for about 25-30% milage increase.
Posted by: Dave_Darling Apr 20 2010, 09:18 PM
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.
To be blunt, you've been told wrong. The Hondas that get better mileage have taller gears. The CRX HF, in particular, has exceedingly tall gears. That's one of the things that helps it get good mileage. And a number of people have switched to taller gears in several different types of cars, and all have gotten better economy.
--DD
Posted by: campbellcj Apr 20 2010, 09:20 PM
I haven't measured it scientifically, but I think I get about 10mpg...LOL
Posted by: Teknon Apr 20 2010, 09:37 PM
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.
914 restarts?
Kevin you are a pisser
Posted by: Porcharu Apr 20 2010, 09:41 PM
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.
I did that drive but the other way around from Abbotsford BC to Colorado Springs being chased by a storm in November with near bald tires on my old truck. Got new ones in the Springs. Damn long drive by yourself.
Posted by: Brando Apr 21 2010, 01:08 AM
I was able to get 34-38mpg consistently in my well-tuned 1.8.
Okay, it wasn't well tuned. Just tuned.
205/65/15 tires. Good fuel. Clean filters. Clean injectors. Good spark (MSD). Good induction and exhaust. Keep it at 3000-3200 rpms for long distance drives.
40mpg is not unattainable. You could re-gear 5th so that you cruise at 2600rpm in 5th doing 75. There may be cooling issues but... You would get good MPG.
Posted by: Porcharu Apr 21 2010, 01:44 AM
My 84' Civic with a mild cam and simple header got 54MPG on the freeway at 70MPH. This was with a CARB and that silly extra valve thing that Honda used to do. After I swapped the 130HP Integra engine and trans (lower final drive) my mileage dropped to the mid 40's but never less than 30 even when beating the living crap out it (like running at full tilt to see just how fast it would go - M on the speedo, think to the left side of the odo!)
Posted by: Mark Henry Apr 21 2010, 04:27 AM
I find trying to make a high mileage car out of a sports car just sad.
Buy a Honda.
Posted by: Dominic Apr 21 2010, 05:06 AM
Programmable EFI
Posted by: johannes Apr 21 2010, 05:35 AM
Skinny tires will help. Go for the original 155 or 165 x 15
High pressure will also help
The slower you drive, the best milage you will get. Going 60 instead of 65 will help.
No cooling issue because your engine will not generate a lot of power. 15 hp are enough for 60 mph.
I owned a 1964 Citroen 2CV. It was rated for 18 HP and could reach 60 mph with a bad aerodynamic shape.
Posted by: Root_Werks Apr 21 2010, 08:41 AM
Remember as a general rule:
Torque = Acceleration
HP = Top speed
Lazy, higher torque engines with taller gear get better mpg than high strung short geared cars do.
I know, there are about a million exceptions to this.
I had a 4.5 V8 Fiero that always touched 30mpg averaged with a good tall geared 5spd.
I've also had a 77' 911S all stock that got low 20's for mpg at best driven normally. So much of it has to do with fuel delivery. CIS doesn't compare to EFI systems.
My current 914-4 2.0 with carbs probably gets upper teens. 
And I baby it. Worthless.
So if you want that 40mpg 914, get any stock FI 914-4, make sure it's tuned 100%. Good alingment, tires (no 205's either) and drive it easy. I bet you'd get darn close in any stock 914-4 FI to 40mpg. Even if you never made it, you'd get close.
Posted by: underthetire Apr 21 2010, 08:47 AM
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.
To be blunt, you've been told wrong. The Hondas that get better mileage have taller gears. The CRX HF, in particular, has exceedingly tall gears. That's one of the things that helps it get good mileage. And a number of people have switched to taller gears in several different types of cars, and all have gotten better economy.
--DD
Our little CRX ran about 2.5K at 65 MPH, so I wouldn't call that real tall gears. I mean, if you've got to keep your foot in it to keep going, your putting more air through the motor, causing the ECU to add fuel to compensate. Doesn't make sense to me. The HF CRX was like 1.3 liters, thats why they got good mileage.
Posted by: Joe Sharp Apr 21 2010, 09:08 AM
Coming back from the Route 66 in 07 Linda used 6 gallons to go 295 miles. She was running 205-50's and stayed above 70 most of the way. She was running twin Solex's with a D-Jet cam. 49.16 MPG
Thomas ran twin 34 Webers and was getting 44 all the time.
If you want to get good mileage cheap look into putting the 34's on your D-Jet and you will smile at the Pump. You will suffer from the lack of head-jerking preformence that you lost from the conversion of the 1700cc's. I have to admit that I did notice a loss of power but the MPG is there if someone wants to do it.
Just from my experience I would do an L-Jet and put it in an early car with the tallest tires I could find. Put in all new wheel bearings and clean and grease the C/V's.
I THINK 60 MPG is waiting for one of Us.
Posted by: Root_Werks Apr 21 2010, 09:13 AM
I've always wanted to build a 50mpg 914.
I was really on the fence about the yellow 1.8 CAMP914 has. I think that would be a great platform to start with.
Posted by: realred914 Apr 21 2010, 10:05 AM
my old 1.7 914 would do about 35 mpg driven HARD round trip to yosemite (about 500 miles) lots of hills and windy roads, really had my foot into it, (really hit 100 mph and caught air on a hill) this with 195 50 tires (stock gears) so my rpms were a bit high. this was an ealry car (lighter doors)
i assume if I had high pressure tires that were skinny i would have done better, also would have done better if I had actually tired to go slow
this was the early high comnpression 1.7 with stock FI system. good old real 92 octane gas (now days expect 10-15% lower milaegae on the "new" oxygenated gas shit that the nazi smog folks force on us. I noticed the drop in MPG in all my cars when they switched to the shit gas. just as they said it would do, 10-15% reduction in mpg. dam the californianazi government
keep in mind, depending on the attitude of the jack boot thugs that run your state, your milage may differ with their "new ' gas. (plus it cost more!!!)
Posted by: kwales Apr 21 2010, 10:11 AM
You want a high mileage car?
Saw a 80-115 MPG Mustang once at an American Society of Mechanical Engineers meeting. It was built by one of the Ford GT engineers that built cars for the 1960's Lemans races. He went into exactly what he did in front of a pack of initially critical engineers, and how he allowed several packs of reporters to beat the crap out of his car for several days to verify his results. Basically, he handed them the keys on Friday and said "Bring it back on Monday". They verified the mileage.
How did he do it?
First thing- replace the V-8 motor with a small displacement 4 banger turbo diesel that had high torque at low revs . That's a max torque at about 1200 rpm and never run it above 1800 RPM. It was rev limited to 1800 rpm.
For today, new engines are available and maybe you should look at Kubota garden tractor engines. I think there is a 2-3 cylinder diesel engine that meets the high mileage requirements and it would sip even less fuel than a 4 cylinder. Not much on acceleration but high mileage.
Go with the proper gearbox gearing to have the max engine torque at 1200 RPM to coincide with 60 MPH.
Use special high pressure tires.
No muffler to impede back pressure.( ie use straight pipes ) Why? With a max of 1800 rpm, it's a little faster than idling and the engine it doesn't make much noise.
A little bit of aero ( plex headlight covers) and that was it.
A high mileage gutlless wonder that never exceeded 1800 rpm.
Wit the normal teener engine, you should never put your foot down on the accelerator or your mileage goes to heck. Put in a rev limiter that kicks in at peak torque. This will cause your top speed to go down becasue you can't exceed peak torque, but hey, your stated goal is simple- high mileage which means not fast.
And I agree with Mark. Why turn a great handling sports car into a low revving gutlless wonder? Wouldn't a garden tractor engined Yugo work about as well or maybe better?
Posted by: Root_Werks Apr 21 2010, 10:18 AM
"First thing- replace the V-8 motor with a small displacement 4 banger turbo diesel that had high torque at low revs . That's a max torque at about 1200 rpm and never run it above 1800 RPM. It was rev limited to 1800 rpm."
There you go, torque = acceleration coupled with tall gears and low revs, you've got the formula for high mpg. That's exactly why my old POS V8 Fiero was quicker and got better MPG than any CIS 911 I've ever had. Just the way of things.
I agree, while it would be cool to have a 914 that got 40-50mpg, what would that do to the "fun factor" of the car? If I can drive a 914 like I want and still get 30's mpg, I'd be happy.
Posted by: zymurgist Apr 21 2010, 10:19 AM
I find trying to make a high mileage car out of a sports car just sad.
Buy a Honda.
You can have both.
Posted by: kwales Apr 21 2010, 10:25 AM
Yup, and gutless at normal teener RPM's too
That's just sad....
Posted by: Porcharu Apr 21 2010, 10:52 AM
"First thing- replace the V-8 motor with a small displacement 4 banger turbo diesel that had high torque at low revs . That's a max torque at about 1200 rpm and never run it above 1800 RPM. It was rev limited to 1800 rpm."
There you go, torque = acceleration coupled with tall gears and low revs, you've got the formula for high mpg. That's exactly why my old POS V8 Fiero was quicker and got better MPG than any CIS 911 I've ever had. Just the way of things.
I agree, while it would be cool to have a 914 that got 40-50mpg, what would that do to the "fun factor" of the car? If I can drive a 914 like I want and still get 30's mpg, I'd be happy.
Sounds like my truck. 8000 pounds empty, with 3-5 people and a bed full of crap it consistently gets 23-24 MPG on trips to our house in the mountains. Big lazy diesel that never sees over 2000 RPM. The same truck with the gas V8 gets half that if your lucky.
I bet a VW TDI swap (maybe the 3 cylinder one) would easily get 50 MPG - and be fun to drive (same HP much more Torque.)
Posted by: Root_Werks Apr 21 2010, 11:11 AM
Didn't the later Vanagon's have a 2.5 diesel? That'd be a cool swap.
Posted by: underthetire Apr 21 2010, 11:13 AM
I think a VERY small diesel hybrid would be very cool. I figure if you can get 50MPG on a prius with a gas hybrid, a 914 diesel hybrid should get 100MPG.
Posted by: kwales Apr 21 2010, 12:51 PM
And very, very, very, gutless...
To do this right, it's idle to max torque in 300 RPM,
And a whole extra 600 RPM beyond that so you can pass....
Wooo whoooo...... 
VW van diesels were the stock VW Rabbit gasoline block with a diesel head. All the durability of a block designed for gas engine forces, with the extra shock loading from diesel pinging. None are rumored to survive.
Posted by: orange914 Apr 21 2010, 04:36 PM
The HF CRX was like 1.3 liters, thats why they got good mileage.
honda (80's anyway) ... small displacement + lightweight = M.P.G.
Posted by: Root_Werks Apr 21 2010, 04:40 PM
Hybrids these days chant about 45-50mpg figures. Big deal, my folks bought one of those Geo thingies in the early 90's. It got 45mpg with 5 people crammed in it while driving in town. They took it on a weekend trip shortly after getting it and I can remember my Dad getting all excited when they came back. Almost broke the 60mpg mark with all the freeway driving they did.
Slow, small and ugly sure. But they bought it just for commuting. Didn't care what it looked like.
Posted by: realred914 Apr 21 2010, 04:52 PM
funny how big and fat "small cars" these days are, compare the early civic to the latest. the mpg is horrible, back int eh 1970's/80's we all thought mpg would go up to double or triple of 30 mpg, instead it has not, cars are bigger with more power crap in them, yet the mpg is about the same or worse
the new hybrids gets near 50 mpg. my old 1958 VW bug got about 35 mpg, so I am not impressed with all this wizbang tech giving a less than 50% boost in mpg.
the old Triumph Spitfires with Overdrive would get 40+mpg
50 years and no real progress in mpg of the average car. oh well, the arabs love it.
Posted by: effutuo101 Apr 21 2010, 05:26 PM
I remember when oil companies like oh, ELF were major shareholders in the car companies...
Posted by: Porcharu Apr 21 2010, 05:48 PM
And very, very, very, gutless...
To do this right, it's idle to max torque in 300 RPM,
And a whole extra 600 RPM beyond that so you can pass....
Wooo whoooo......
VW van diesels were the stock VW Rabbit gasoline block with a diesel head. All the durability of a block designed for gas engine forces, with the extra shock loading from diesel pinging. None are rumored to survive.
Sorry I call BS - they are dimensionally the same but the blocks are stouter, the cranks are different and the rods are much bigger. Some VW peeps are up to 200HP with the turbo 1.6 @ 6000RPM. I have no idea how they do it. Those engines last a long time if maintained.
Posted by: Porcharu Apr 21 2010, 05:53 PM
Didn't the later Vanagon's have a 2.5 diesel? That'd be a cool swap.
The euros had a delivery van that had a 2.5 TDI. 140HP with a safe for for big loads tune. If I can find one it is going into my Volvo (I have the special bellhousing for the diesels - Volvo used a 6cyl version of the VW diesel so the bolt pattern is the same.)
Posted by: realred914 Apr 21 2010, 05:54 PM
And very, very, very, gutless...
To do this right, it's idle to max torque in 300 RPM,
And a whole extra 600 RPM beyond that so you can pass....
Wooo whoooo......
VW van diesels were the stock VW Rabbit gasoline block with a diesel head. All the durability of a block designed for gas engine forces, with the extra shock loading from diesel pinging. None are rumored to survive.
Sorry I call BS - they are dimensionally the same but the blocks are stouter, the cranks are different and the rods are much bigger. Some VW peeps are up to 200HP with the turbo 1.6 @ 6000RPM. I have no idea how they do it. Those engines last a long time if maintained.
Yeah my thought too, didn't the rabbit come optioned with a purpose built deisel?? and that was the basis for the vanagon diesel.
my dad test drove a vanagon deisel back in 1986 he bought the gas one. with only about 55 hp it was less HP to lbs ratio than his old 63 microbus.
Now when the rabbit deisel came out, during the gas crunch when I was a kid, it was known to be very reliable. unlike some American deisels cars that actually were nothing more than gas engines modified to run deisel, they had short life spans, and were a joke. Thats what I recall, detroit offered a lot of gas engines convereted to deisel and it was a disaster. VW had a great reputation for its diesel rabbits
Posted by: BiG bOgGs Apr 21 2010, 06:18 PM
I am enjoying finally getting my 914 on the road, but I too am interested in getting more MPG's out of her. My other toy is a 88.5 Suzuki Samurai that I transplanted a VW 1.6L turbo diesel into. Even though it is a junkyard dog pulled from an 85 Jetta, it is on the low end of acceptable compression, and Samurais have all of the aerodynamics of a brick, I get 29 MPG while driving mostly in the 45-50 mph range.
Really makes me interested in what one of those 1.6L TDi engines would do for a 914.
Posted by: charliew Apr 21 2010, 06:49 PM
My youngest son had a 98 integra type r when he went to a&m in 99. It was geared about 4:44 with a 5 spd. We had put a 4-2-1 header on it and a cold air intake. It sounded like a early z28 at about 6k-8k. He drove it 80 and that was 4k, it got 35-38 all day long with the ac on. That was a great little college car. We made a mistake and he traded it on his 05 sti after he graduated, it only had 60k on it. Then he started hot rodding the sti and he bought a suzuki sidekick 1.6 with auto and ac and 4wd for a commuter. It got 28 at 75 with the ac on, he wanted a 5 spd but the auto one was priced right. He drove it three years and got back what he paid for it. We got it wholesale in oklahoma on the net. I worked on it two weeks after we got it home doing the belt and plugs and checking the valve lash and etc. He did have to put tires on it while he had it. My opinion only is that a air cooled motor will always need a richer ratio to run cool enough to be safe than a water pumper.
Posted by: kwales Apr 21 2010, 07:31 PM
All I can say is: having lived through the Rabbit era, the original Rabbit diesels used the same engine block as the gasoline engine ( aka - a cost cutting measure), but bolted a higher compression head on them. Same rod bearings as a gas engine, but with knock loads applied to the same bearing surface area. It was a topic of discussion one night in my Graduate level college class ("Combustion Engines") complete with math analysis. The classmate that that brought up the topic had owned one, hads lost an engine, and insisted it was a POS. The math showed why using a different block with wider bearings is a good thing for diesels to survive the higher loads from knock.
Another friend lost an engine too. So, two of my friends owned them, both lost an engine, and both thought they were a POS. Not to mention the other "fun" problems they were notorious for. So, BS to yer BS, I got pissed Engineer friends to argue design flaws with you, and the professor that did the analysis was reasonably competent. He did the landing gear on the Apollo lunar lander.
Posted by: spankmeister7 Apr 21 2010, 08:53 PM
All I can say is: having lived through the Rabbit era, the original Rabbit diesels used the same engine block as the gasoline engine ( aka - a cost cutting measure), but bolted a higher compression head on them. Same rod bearings as a gas engine, but with knock loads applied to the same bearing surface area. It was a topic of discussion one night in my Graduate level college class ("Combustion Engines") complete with math analysis. The classmate that that brought up the topic had owned one, hads lost an engine, and insisted it was a POS. The math showed why using a different block with wider bearings is a good thing for diesels to survive the higher loads from knock.
Another friend lost an engine too. So, two of my friends owned them, both lost an engine, and both thought they were a POS. Not to mention the other "fun" problems they were notorious for. So, BS to yer BS, I got pissed Engineer friends to argue design flaws with you, and the professor that did the analysis was reasonably competent. He did the landing gear on the Apollo lunar lander.
My Diesel Rabbit kicks ass! When I bought it, I pulled the 4-speed gearbox and replaced it with a 5-speed, which was an option. I looked around and found that VW sold a half-dozen variants of the transmission with various gear ratios. I went with the one with the tallest 5th gear. I average 50mpg. It's not stylish, but it puts me in the good graces of the local Diesel crowd. I fill up every .. month. Those diesel motors started off with the lousy 1.5 motor, but it improved every year. The best ones are from 1983-1985, especially if you're lucky enough to find an EcoDiesel model.
Besides, what's the worst that can happen? Changing the head gasket could take you, I don't know, ALL MORNING to change out thanks to the uncluttered, simple layout.
Posted by: johannes Apr 22 2010, 06:31 AM
I got theese figures from a french magazine called "Autojournal". The figures come from three different issues from 1970 to 1973.
The test was always made at the same place: Montlhery speed track.
Mpg are mesured at constant speed in fifth gear, so they are the best you can reach.
The tests are made with regular cars with regular tires at regular pressure (the 1.7 had 155 tires).
Targa top in on, windows closed, headlights are turned off and there is only the driver on board.
These figures are for european cars wthith slightly higher compression and may be a little better than the US cars...
As you can see, you better drive slowly if you want to achieve 40 mpg, but it is doable with a regular 1.7 914.
Posted by: Bleyseng Apr 22 2010, 06:56 AM
I got theese figures from a french magazine called "Autojournal". The figures come from three different issues from 1970 to 1973.
The test was always made at the same place: Montlhery speed track.
Mpg are mesured at constant speed in fifth gear, so they are the best you can reach.
The tests are made with regular cars with regular tires at regular pressure (the 1.7 had 155 tires).
Targa top in on, windows closed, headlights are turned off and there is only the driver on board.
These figures are for european cars wthith slightly higher compression and may be a little better than the US cars...
As you can see, you better drive slowly if you want to achieve 40 mpg, but it is doable with a regular 1.7 914.
That is a interesting chart and yes, my 2056 gets 30mpg going 75mph on long trips!
I had a new 84 Rabbit diesel and it got a easy 50mpg when new on trips! Totally gutless like a 30hp 57 bug.....I never had a engine problem and sold it when it had 75,000 miles for a POS Colt Vista 4 wheel drive that the tranny blew up at 25,000miles....
Posted by: BarberDave Apr 22 2010, 07:27 AM
My orginal 1.7 not in particularly good condition. Tuned well, stock size tires,(
any bigger throws off the trip odometer ,& speedometer ) . I could make the
trip from Toledo to Tweeks Fur Fest on 1 tank of gas . It was just ofer 400
miles with a little remaining . This i credit to the punny 34 itc's i had a it then.
Damn thing would run 90 mph all day long, ( but It took a half hr. to reach that
) . I still think a well tuned F.I. is the over all best for performace and mileage
you can do a lot to increase mpg but at a big price in driveablty . I feel the
reason I have this car is to drive the curvies with wild abandon.
Dave 
Posted by: pbanders Apr 22 2010, 08:14 AM
I didn't read the whole thread, sorry if I'm repeating anything. If I were going for max highway MPG from a 1.7 w/D-Jet, here's what I'd do:
1. Drive with the roof on, windows up, no passenger-side mirror. Use interior ventilation.
2. Change to narrow, stock sized-tires. Inflate to spec pressure for the 914. If you want, experiement with higher pressures up to the max recommended pressure, be aware this could negatively affect handling
3. As the chart from the French magazine showed, lower speeds equal higher mileage. Avoid driving 5 - 10 mph over the speed limit.
4. Engine in perfect mechanical condition (incl. valve adjustment). Timing and dwell spot-on, plugs perfect.
5. Verify injector spray patterns are perfect, fuel pressure at 2 atm.
6. Fuel and air filters clean
7. Use the procedures on my page to set the part-load adjustment of the MPS to the leanest tolerable mixture. In a cooler climate you will be able to get away with lower CO. Start at 2.5% and work downward. I've had good results with 2.0% in cooler weather, and the car even ran decently at 1.5%. Invest in a CHT meter and oil temperature gauge to make sure your engine temperatures aren't too hot.
Posted by: Drums66 Apr 22 2010, 12:51 PM
I find trying to make a high mileage car out of a sports car just sad.
Buy a Honda.
Yes.......what a bloody sacrifice?.....gas milage over raw unchained
*POWER*
Posted by: Root_Werks Apr 22 2010, 01:47 PM
I think most also don't factor in cost of this high mpg figure.
A 40-ish mpg 914-4 isn't going to break the bank by any stretch.
A 45mpg Prius will set you back what, $45-50k?
Umm, gonna never see a return on that fuel savings vs another new car for $25k that would get 35mpg and be twice as fun let alone a decent little 914 for $5-8k.
Posted by: zymurgist Apr 22 2010, 01:50 PM
Umm, gonna never see a return on that fuel savings vs another new car for $25k that would get 35mpg and be twice as fun let alone a decent little 914 for $5-8k.
although the VW TDI contingent might not agree.
Posted by: DblDog Apr 22 2010, 05:02 PM
Way back when...
I drove my 72, 1.7, which was about 2 or so years at the time, from Portland O, to the SF Bay area, a distance of about 640± miles. Tuned regularly, all stock, lowered slightly, 165 x 15 tires, top on, driving in the 60 to 65 mph range...many miles of straight line driving, weather was generally cool. Left about 7 am, got in about 8 pm, I-5 wasn't quite complete then...the mileage: 41.5± mpg. I was amazed...beside the mileage, I drove straight through...with one or two p stops.
As road trips go it was not as much fun as the drive up...many more stops!
Posted by: Al Meredith Apr 22 2010, 06:54 PM
Back in the 70's there were several articles in "Hot VWs and Dunebuggies" on high mileage Type 1s. I still have some of these. The one I still want to build is a 2 cylinder. Very easy to do using the rear two jugs. Some airplane engines I'v seen use two on the same side. They bolt a plate over the other side. Cooling no issue as they are "slipstream" cooled. The other thing I remember from those high mileage engines is that you want a lot of rotating weight, IE heavy flywheel and front pully. I'll build a 2 cylinder one of these days.
Posted by: Dave_Darling Apr 22 2010, 11:09 PM
Our little CRX ran about 2.5K at 65 MPH, so I wouldn't call that real tall gears.
My 2nd-gen Si runs 3000 RPM at 60 MPH. Short gearing. (0.771 5th, 4.25 final drive)
The 2nd-gen HF runs about 2000 RPM at 60 MPH. Much taller gearing. (0.695 5th, 2.95 final drive)
...An as I said, it is one of the reasons. The 2nd-gen HF had a 1.5L engine, but only made about 60 HP. The 1.5L "DX" (or standard model) made about 90 HP. The Si only had 100cc more displacement, and made 108 HP. Much worse mileage; EPA rating of about 30 on the freeway as opposed to 50 for the HF.
One reason that we don't see high MPG simple cars any more is because nobody will buy them. They fold up like accordions in a wreck, they don't carry much stuff or many people, they don't have 67 cupholders, there are no airbags, no ABS, no air conditioning, they accelerated from 0 to 60 MPH in about a month... They made compromises that were acceptable in the 60s, or 70s, or 80s, but that nobody is willing to make these days.
Don't blame today's cars for not being yesterday's cars.
--DD
Posted by: Rick_Eberle Apr 22 2010, 11:25 PM
I got 42mpg driving from L.A. to Las Vegas in my 1.7 once.
Just once...
A head melted on the trip back. 
Posted by: Elliot Cannon Apr 22 2010, 11:25 PM
I think only one post even mentioned aerodynamics, which plays a huge roll in gas mileage. I like to run my car with roof off and windows rolled down as much as possible. With the 3.2 liter car I get 23 MPG with that configuration. With the roof on and at least the passenger side window up I get 26 MPG. A 3MPG difference just for putting on the roof and rolling up a window.
Cheers, Elliot
Posted by: Root_Werks Apr 23 2010, 10:02 AM
Back in the 70's there were several articles in "Hot VWs and Dunebuggies" on high mileage Type 1s. I still have some of these. The one I still want to build is a 2 cylinder. Very easy to do using the rear two jugs. Some airplane engines I'v seen use two on the same side. They bolt a plate over the other side. Cooling no issue as they are "slipstream" cooled. The other thing I remember from those high mileage engines is that you want a lot of rotating weight, IE heavy flywheel and front pully. I'll build a 2 cylinder one of these days.
They did another series not to long ago as well. I believe they produced a Super Beetle with 100hp that was touching 40mpg averaged out. Pretty impresive.
If I remember correctly, the best combo they got was using little dual 34's, not the EFI kit, single carb combos or dual 36's or 40's etc. I wish I still had the magazine. I probably still do somewhere.
I think the EFI tunned for mpg lost power over the 34's, but only yeilded like 1mpg better than the carbs. Tuned for the same power as the carbs, it lost 2-3mpg vs the little carbs. It was a really good series. I read through it the same time I was building my mpg super beetle. It really brought to light the significance of tire size, pressure, alignment, body CD, brake drag etc. Lowering the beetle too much didn't help, but some did and so on.
Very good series. It's probably online somewhere.
Posted by: realred914 Apr 23 2010, 10:40 AM
I got theese figures from a french magazine called "Autojournal". The figures come from three different issues from 1970 to 1973.
The test was always made at the same place: Montlhery speed track.
Mpg are mesured at constant speed in fifth gear, so they are the best you can reach.
The tests are made with regular cars with regular tires at regular pressure (the 1.7 had 155 tires).
Targa top in on, windows closed, headlights are turned off and there is only the driver on board.
These figures are for european cars wthith slightly higher compression and may be a little better than the US cars...
As you can see, you better drive slowly if you want to achieve 40 mpg, but it is doable with a regular 1.7 914.
remember to subtract about 4-6 mpg from the peak value shown onthe chart to account for todays oxygenated fuel that has about 10-15% less energy content per gallon than the typical fuel found when this report was written.
that 40 mpg quoated could be translated to low as 34 mpg with the "improved " gasoline forced on some of us.
all my cars dropped this percentage in mpg when they switched to the reformulated fuel. (plus the price per gallon went up )
Posted by: kwales Apr 24 2010, 06:03 PM
Ain't the green thought process wonderful.
You go to a lot of trouble to figure out how to to better yer mileage, and they diddle the fuel to reduce your mileage.
Posted by: swl Apr 25 2010, 06:51 AM
ain't that the truth. so many shades of green. Sustainability versus air quality versus global warming. only answer is going back to living in caves. I'm working on converting my old teener to the fred flintstone look. rust is doing most of the work for me.
Posted by: majkos Apr 25 2010, 07:01 AM
Somebody say RUST?
Posted by: majkos Apr 25 2010, 07:05 AM
This 914 wasn't getting 40 MPG!
Time to lighten her up 
Posted by: computers4kids Apr 25 2010, 08:49 AM
This thread has peaked my curiousity.
As many of you know, I have a stock 1.8 ljet with an Audi automatic. I've never checked the gas mileage. Now the tub is a 75 and currently has the anchor bumpers and is completely stock, except it does have an early 2ltr exhaust system (exhchangers, banana muffler, no cat).
Any predictions for gas mileage?
1st = 2.71
2nd = 1.50
3rd = 1.00
Rev = 2.43
Final = 3.45
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