Yes, the original tire size was 205/75/R15, as the door sticker states. If
you use the original tire, you will get better acceleration, and better
"indicated" fuel mileage, but lower actual fuel mileage. If you use the
larger tires, you will get longer tire life, better actual fuel mileage, and
slightly poorer acceleration. I have run both sizes on the 4 '81-82's I
have owned, and have decided that next time I "retire", I will go back to
the original size, although I certainly won't do it until I wear out the
215/75/R15 Michelins that are on it now - which will probably take as long
as I am able to drive.
According to the dash readout, I am getting about 28 MPG at a steady
(indicated) 55 MPH on a flat,level road with no headwind or tail wind. If I
were running the original tire size, this would read about 10% higher due to
the odometer correction, plus some additional correction because I would be
going through air resistance about 10% slower, so I'd estimate the readout
would be 32 MPG or so.
According to careful measurements on our most common trip, which just
happens to be almost exactly 500 miles (Temecula California to Lake Tahoe
California) I get about 25 MPG average on the trip. I drive between 75 and
80 on the trip about 2/3 of the way, the rest is mountain driving on windy
roads, so I probably average about 60.
This number is the result of dividing the known actual mileage by the total
gas consumed, determined by a brim full fill-up before and after each trip.
Note that this 1000 mile round trip involves about 30% driving in very high
altitudes (8000-9000 feet) and some very long hills (11 mile, 6% grades in
two places). We make this trip once or twice per year, and have every year
since I have owned the current '81 (since 1987), and the results are quite
consistent.
For around town use, I average about 18 MPG (ours is not a very congested
town, by eastern standards!)
For those who question the wisdom of taking these cars on trips, I can
report that we have driven these cars all this time without ever having to
call the man with the hook to get us home (although a failing fuel pump made
me worry a bit on a trip to Boise one time in 1989, but we did make it under
our own power!).
Dick Benjamin
----- Original Message -----
From: "William" <mopar@xxxxxxxxxxxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Wednesday, May 01, 2002 10:47 PM
Subject: IML: 83 EFi spark plugs, MPG update...
> Hi everyone,
> I finally managed to track down the "correct" spark plugs for the '83.
> Thank you to all who helped (and even offered to pick some up for me and
> ship them!) on that one. I ended up with Autolite 985's. The 945
supersedes
> to the 985 for some reason. It made a noticeable difference over the
> RN14YC's that the previous owner had installed.
> The car runs very well, except for a small hesitation at WOT from a
stop
> (mostly while warming up) and a very minor hot start issue (doesn't always
> fire up on the first try). I will iron these issues out eventually. Now
that
> I am putting some miles on the car, what type of fuel economy should I be
> expecting? I know this is a loaded question with myriad variables, but I
> would love to hear what some other EFI owners are getting. I tried
searching
> the IML archives, but didn't find much on MPG numbers. I have to check my
> odometer to see that it is accurate before I get too excited. The car is
> currently shod with 215/75/15 tires, and it seems to me that they are
> supposed to be 205/75/15?
> William
> 83 EFI
> Edmonton, Canada
>
>
>
>
Back to the Home of the Forward Look Network