mark
usually the 200tdi is slightly more economical than the 300tdi but i
think this is purely down to turbo boost pressure on the 200 being
somewhat less than a 300tdi and if you [like i did] drop the boost
pressure on a 300tdi you get better mpg .
for a 200tdi you should see 26-32mpg registered on speedo , there is a
BUT though .
that is because mpg readings vary considerably between landy owners due
to tyre sizes used .
if you have standard 90 205x16 tyres then they are more or less the
smallest diameter that will be used , hence mpg will read higher than
another vehicle using say 7.50x16 or 235x16 tyres .
there are 2 speedo drive for the LT77 box you are using , one is for
205 tyres and other for 7.50x16 , which have different diameters .
basically between a 205 and a 7.50x16 there is 5% rolling difference ,
and again between a 7.50 and a 235/85x16 there is another 5% rolling
difference, the 235/85 being slightly taller than a 7.50x16 tyre .
i have a 2.5n/a 90 with an lt77 box and a 300tdi 90 with an r380 box
..
i have checked mine against a GPS and i find that my 300tdi reads 5%
low and my 2.5n/a reads 5% high on mpg dervide from speedo
measurements .
use a gps and take an exact 10mile drive according to speedo reading
and then stop .
check the GPS mileage reading and compare to youre speedo reading, then
you will know how far out the speedo is and make an accurate measurment
as to how much to compensate speedo measurements by in order to work
out actual miles travelled .
then all you need to do is to fill the tank to the very brim of the
filler , set oddometer to zero and drive until the next time you fill
tank to top again .
note the mileage covered and litres of diesel put into the tank at
that point ..
divide the litres of diesel used by 4.546 to get gallons .
divide the amount of miles driven by the amount of gallons of diesel
used .
then add the compensation factor of the speedo reading difference , ie
if speedo reads 5% low you add 5% to mileage . ie mileage x 1.05
i am not exactly sure on youre actual 90 tank fuel holding capacity ,
in the RAVE workshop manual it states that a 90 fuel tank useable
capacity is 54.58 litres which is 12 gallons and i think max capacity
is 60 litres airspace within tank itself .
i know a freind who has a 200tdi 90 and he drives it conservatively and
says it will do 360miles to a tank which gives a reading of 30mpg .
my own 300tdi is doing 27mpg with 0.9bar of turbo boost , it was set
at 1.2bar previously and returned 25mpg , i may drop to 0.8bar now and
just increase mpg a little more .
if you want to back off the black smoke either unscrew the grub screw
by about 1 turn thats on top of diaphragm housing [ its located under a
20mm dia blanking plug ] or unscrew the fuel metering [full load]
adjuster on the rear of the pump by 1/4 turn at a time until you notice
black smoking under load stops , you may also note the performance
drops a little , but it was only better before due to the increased
fuel input .
to get best MPG figures you need to run the lowest boost pressure you
can live with and also keep the injector pump metering backed off on
the lean side , oh and of course drive at 50-55mph .
try adding 3 litres or veg oil to youre tank fill of diesel , you will
see slightly higher mpg , not a lot but it will be a bit more , due to
higher viscosity of fuel .
if you notice , the low sulphur fuels are very thin compared to red
diesel or white diesel sold some years ago , hence you use more of the
thin stuff per mile !!!! and less mpg ..
..
low sulphur diesel is really 50% kerosene [heating oil] and 50% white
diesel and little else except perhaps a small amount of lubricant
[maybe self mixing 2 stroke oil ??] , you could make youre own if you
wanted to and lubricate it with 5-10% of SVO veg oil per 10galls .
..
..
Mark Solesbury wrote:
> Evening
>
> What do other D90 200tdi owners expect for Miles Per Tank?
>
> My 90 has just done 250 on the 1st tank after the roll. It smokes a
> little white on starting from cold, and it smoke a bit of black under
> hard acceleration - Much like my 53' Golf so i assume this is normal.
>
>
>
> --
> Mark
> 90 90 200tdi - Fixed 
> 87 RR V8 EFI - Sorn'd
>
> http://www.mozilla.com/firefox/ - Firefox Rules!
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