Author Topic: Clearing 50 mpg (Read 8292 times)

burn_your_money · « **on:** July 03, 2006, 09:22:05 am »

I just got my 84 NA diesel rabbit on the road last week and took it on a trip from north bay to toronto and back. I took my girlfriend so we had a fair amount of luggage. I added some fuel conditioner stuff to the car before I left and I ended up averaging 47 MPG. How can I get this over 50? I know that less wieght will help, but most of my trips will be with someone or lots of parts anyways.
I just replaced the fuel filter (added ATF), oil/filter change. I have a 4 speed 4A tranny. I can't find any info on the ratios for it so I'm not sure if a 5 speed would actually be benieficial or not.
My average speed for the trip was 110km/h and I had no problems climbing the big hills north of toronto (I didn't need to downshift and I actually passed a fair amount of cars going up the hill)
My fuelling screw is turned down and the car does not smoke unless I'm in third at 90km/h.
I got the car up to 130km/h and it was willing to go faster but I can't afford a ticket so I slowed back down.
So what can I tinker with to get some more mpgs?

nkb · « **Reply #1 on:** July 03, 2006, 11:30:18 am »

maybe your brakes are dragging a bit? you should also have your injectors checked for leaking. i have a 1.9td and i drive 140kmh on the highway and i still get 56mpg

jtanguay · « **Reply #2 on:** July 03, 2006, 11:34:34 am »

Quote from: nkb

maybe your brakes are dragging a bit? you should also have your injectors checked for leaking. i have a 1.9td and i drive 140kmh on the highway and i still get 56mpg

56 mpg going 140 km/h with the 1.9? ummm... where can I get one like yours? :shock:

nkb · « **Reply #3 on:** July 03, 2006, 11:48:44 am »

oops 52mpg, 70L, 1300 and some km all highway, montreal to truro nonstop and i hardly went under 130..

zagarus · « **Reply #4 on:** July 03, 2006, 12:18:51 pm »

going from kamloops to vancouver, means crossing the cascade mountains, i managed 48.5 mpg mostly going 120km/h. lots of hills and such. I just figured that the less boost i make the better my mpg will be.

burn_your_money · « **Reply #5 on:** July 03, 2006, 12:56:00 pm »

So I can definitly do better then. Would rebuilt injectors and resetting the timing help? Is there a "best MPG" setting for the pump timing or is it hit and miss or factory spec?
What about a 4:2:1 exhaust manifold or free flowing exhaust?

nkb · « **Reply #6 on:** July 03, 2006, 02:35:04 pm »

i would get those injectors and the timing checked out, my uncle has a 91 golf with a rebuilt 1.6 n/a and he gets like between 65-70mpg on the highway

houseofdiesel · « **Reply #7 on:** July 05, 2006, 01:35:34 pm »

Get the injectors done first, then set injection timing to 1.00 or even 1.10mm, remove the muffler and run a free flow resonator only, that should net you 60mpg or better. I was getting 1400kms on my 87 Jetta diesel this way at 100km/h loaded heavily.Think steady state cruising...

houseofdiesel · « **Reply #8 on:** July 05, 2006, 01:35:53 pm »

Also on that old beast adjust the vavles!

burn_your_money · « **Reply #9 on:** July 05, 2006, 01:46:31 pm »

Thanks for the pointers, I'll give them all a try

avocado_tom · « **Reply #10 on:** July 07, 2006, 04:50:55 pm »

Quote from: zagarus

going from kamloops to vancouver, means crossing the cascade mountains, i managed 48.5 mpg mostly going 120km/h. lots of hills and such. I just figured that the less boost i make the better my mpg will be.

What sorts of rpms are we talking about at 120 and 140 km/h?

I'm curious what you guys are cruising at and how that effects the efficiency.

Cheers,
Tom

zagarus · « **Reply #11 on:** July 07, 2006, 05:14:35 pm »

at 120km/h its ~3000rpm

Cheesetoast · « **Reply #12 on:** July 08, 2006, 11:43:48 pm »

question, i have my fuel turned up, no smoke at cruising in 5th. Boost is runnign 20psi, when i'm crusing its about 10psi-15psi depending on how high above 100kmph i am. Will i get better milage if i run less boost?

zagarus · « **Reply #13 on:** July 09, 2006, 12:47:23 am »

^ thats what im thinking is the case, one time coming back from vancouiver i was doing 150-170km/h the entire time (shhhhh) and well i got 34 mpg that time, and basically running 9psi the entire time.

But the other week when i went easy, 110-120km/h and keeping an eye on the boost gauge and trying not to create much boost i got 48.5 mpg. so thats what im stickin with right now, plus im sure the rpm's have something to do with it.

RAMMSTEIN · « **Reply #14 on:** July 09, 2006, 09:42:17 am »

My best so far is 64 mpg and worst in the low 50's.

The car is not aligned and I will get my cruise control later today.

House of diesel, 1400km with a 87 Jetta...you impress me.

I told the guys on another forum that I'll see 1500 km with one tank before the end of this summer, I believe it's realistic.

The car is a 1992 jetta with a rebuilt 1985 1.6D.

I've got to go fill up today, so we'll see how I manage this time (1111 km and just off the quarter tank).

Author Topic: Clearing 50 mpg (Read 8292 times)

avocado_tom