Mileage VS Performance?

[ftm1776]

OK, so the best control of economy, i.e., mileage, is the right foot !!!

Other than that, what could be done to the 1.6 non-turbo diesel engine to improve fuel economy??

Let's assume that it is a stock engine in good running order?? Is that as good as it gets then???

What if I wanted to go full out and see what I could achieve???

Easy to do to more far out approaches???

And the big question, "Is it worth it???" whatever IT may be.

Any thoughts on this would be appreciated.

[vanbcguy]

Make sure the system is fully up to temp - these engines provide the best economy when hotter.  Cooler temperatures don't do anything useful - the internal clearances of the engine are designed for about 100C, if you run it at a lower temp then you are basically pumping useful energy produced by burning diesel out your radiator rather than putting it in to turning the wheels.

Advancing the timing will generally help with economy, to a point.  Go for the upper limits of the stock range, or maybe even a little higher.  You can basically advance the timing till the engine starts getting overly clattery and then back it off a hair.  Most vehicles have sub-optimal timing specs as more advance = higher NOx levels.

Obviously make sure your air filter is clean - dirty filters or obstructions in your air intake system make the engine have to work harder to fill itself with air, reducing economy.  Some folks have added intake ducts going to the front firewall so the engine is getting lots of cold air - this will help to a point as you can pack more colder denser air in the engine.

If your injectors are old, get them checked out.  If they aren't spraying nicely any more you will have an economy drop.  Any diesel shop that works on GMC 6.2L/6.5L engines can work on the VW NA injectors as they are exactly the same type (though they use different nozzles).

Finally if economy is your main goal, then back out the max fuel screw a little.  That's basically the "horsepower" screw for these engines, you can back it out until the performance becomes unacceptably poor.  The more you screw it inwards the faster the car will be but the more fuel you'll burn.  Basically find a spot where performance is 'good enough' if mileage is your main concern.

[Blocksmith]

Let's assume that it is a stock engine in good running order?? Is that as good as it gets then???

What if I wanted to go full out and see what I could achieve???

Easy to do to more far out approaches???

Just how full out are you willing to go? Other than making sure everything is in a properly maintained state, I would think the next real 'trick' to getting good fuel economy would be to improve airflow over the, uh, sub-optimal aerodynamics of the old chassis 

[damac]

My cars get between 42-45mpg.  The best is the 85 jetta non turbo right now but it isn't being driven as hard as the others.

My worst experience is with my truck with dirtbikes and having to hit hills on a certain trip.  It came out at like 32 and has a turbo, I was racing it to try and keep up to the speed limit.

I didn't have a good experience with turning out the fuel screw performance wise on one of my routes due to a hilly up/down mountain I was used to.  Had performance issues in 2nd gear so quit experimenting.

I guess if you knew your route and changed the fifth gear out for flat land runs at the speed limit maybe that would help?

I drive the hell out of my 79 rabbit mostly freeway 70+mph, and that is most of all for safety to keep up with traffic and so I can get to where I'm going.

When I look at the spreadsheet and considering I work on the cars myself and how cheap they are for insurance, no smog, etc. I don't have a reason to spend more $$$$ on my rigs vs. the payoff for a few more mpg?  There is no way I'm slowing down either, I tend to leave earlier/later to avoid traffic and take naps and do other stuff out of town so I am in the fast lane.  I drive my rabbit for stretches at a time at 85-90mph and it hasn't let me down yet

To me it seems its better to the tdi swap route and drive the heck out of the cars for the long haul.  Get a good project to drop in, sell the other engine and hopefully be able to drive it for 100,000+ miles

[mystery3]

What tires/wheels are you currently running? Also more specifics on your vehicle may help. Weight reduction and aero could probably yield gains for little outlay.

[Enslaved_Pickle]

Not a 1.6 na but heres my findings.

Specs- stock 1.9 aaz timed to .96mm
 ko3 turbo
Car- mk3 golf
No aero mods
Che 020 trans
195 60 14 tires on aluminum rims

Starting mileage- 47 canadian mpg

Mods,
Power steering delete- 1 or 2 mpg more
cut out lower airbox- no increase in mpg, but more power
Turbo control selenoid delete- turbo full time, max of 12 psi- 2 more mpg
Power to the lower selenoid on the pump- made a huge power difference, 2 mpg more
Fuel line check valve delete- slightly more power "very little"
2.5 inch cat back straight pipe- more power no mpg increase.

Best mpg "canadian" = 55mpg
Average is 51-54

[theman53]

The other normal things are tire pressure, alignment, and non hanging brakes. I have heard one of the best aero mods is a belly pan under the car.

[GEE-BEE]

CTN TRANS ( O2A )

3:15 FINAL

.658 FIFTH GEAR

You will need some updates to do this mod

GB

[vanbcguy]

Don't know that an NA would have the torque to push along with that .658 5th...

[GEE-BEE]

from a ff .71 to .658 ?

I wouldnt put my money into a 020 , just a upgrade

cable shift etc.

[ftm1776]

My first VW diesel, 1978 Rabbit NA, consistently got in the low to mid 50 mpg range; stop-and-go or pushing wind seemed to work out the same. I did many MPG checks and kept a written record.

Some light items have been removed from my car. I took lower back seat to increase utility...and just never put it back in. I switched to a full size spare though for backcountry safety.

The wheels are 13 inch; tires 165R x 13; usually 40 psi.

The lower engine bay cover is not in place and has been lost to history.

I drive like I'm trying to eak out the mpg, but usually do a 1500 mile check just to average things out. Last time, a few months ago: 45 mpg. My goal has been to break 50 mpg. Never did it, even when the car was new.....maybe 48-49 or so.

I just had the pump and injectors rebuilt at Diesel Fuel Injection Service in Portland, Or. This was after the last mpg check so I am wondering if their work has had any effect.

I admire people who drive the hell out their cars and really enjoy themselves !!! Just not my style.......always have been an mpg weenie !!!

[theman53]

Fwiw I always did the best mileage with the 155/80r13

[ftm1776]

Fwiw I always did the best mileage with the 155/80r13

I chuckle at my ignorance when I read terms like "Fwiw". I don't speak "text" !!!

What is "Fwiw"?

ftm1776

[vanbcguy]

FWIW = "For What It's Worth"

[RabbitJockey]

I admire people who drive the hell out their cars and really enjoy themselves !!! Just not my style.......always have been an mpg weenie !!!

if only i had the self control to drive for mpg haha.  but my daily commute is 12 miles of a 2-3 lane "freeway" that has a light every 1/4 to half mile, so it seems no matter what i do i will get poor mpg, usually 21-25mpg in my mk3 2.0.  its a frustrating drive each day to stop so much so often, but i have no other choice since that is the main road going west-east in this town... which basically handicaps the whole area.