checking the fuel consumption (80)

G

Guest

Guest
Hi Guys
I have been moaning about the apparent hugh rise in my fuel consumption over the last while. I now have decided to check a theory which others have put forward and see what is what.
I used to get 6 miles per litre all the time over years and over the last while I have been getting 4 miles per litre or so it would seem , which is a hugh drop of about 33%.
Not so long ago I changed the stock wheels and tyres ( 265x 70x 15) to ( 285x 75 x16) and we all know the bigger the wheel the less it needs to go around to complete the same distance as the smaller one.
So bearing that in mind, can I trust my speedo anymore I dont knoe and others say I cant.
Can I trust the readings on the mileage counter, I dont know and others say no.
Since having a body lift and bigger wheels maybe the drag is stronger on the cruiser both from the road and the wind, which has also been suggested.
I have no intentions of having a body lowering done or skinny wheels put on just to save fuel but I am very curious.
I have put the old stock wheels back on and will run the Cruiser for a tank full and then I will know. I think
I have to say that it ( the cruiser ) looks really crap with the body lift and those small wheels on now.
But ill just have to take the funny looks people are going to give me for a while.
The other thing it could be is the injectors need servicing, but I dont want to do that if its not needed now do I
I will also do a set mileage route with the smaller ones on and then repeat it with the bigger ones on and see what the difference is.
I have no way of comparing the speed because I dont have a GPS for now.
So we will see and ill let you know the results
John C
92HDJ 80 1HDT Ireland
 
G

Guest

Guest
Hi John
By changing to your new tyre size your speedo will be reading about 11%
slow. Also your mileometer will be reading 11% low so if it says 100
miles you have actially done 111 miles. Increase your apparent mileage
driven by 11% before you work out your MPL figure.
Pete
John Byrne wrote:
 
G

Guest

Guest
John,
Check out http://www.miata.net/garage/tirecalc.html
The tyre calculator will tell you the differences on your
speedo/odometer between the two tyre sizes.
Whilst the speed/distance difference will only be around 3-4% don't
forget that the bigger tyres will be slightly heavier.
The larger tyres will result in less revs at motorways speeds and
therefore a saving, you will however require more juice to maintain the
same amount of acceleration around town.
Having said all that I would be interested to know how things go with
trial.
--
Regards,
Julian Voelcker
Mobile: 07971 540362
Cirencester, United Kingdom
1994 HDJ80, 2.5" OME Lift
 
G

Guest

Guest
John,
Check out http://www.miata.net/garage/tirecalc.html
The tyre calculator will tell you the differences on your
speedo/odometer between the two tyre sizes.
Whilst the speed/distance difference will only be around 3-4% don't
forget that the bigger tyres will be slightly heavier.
The larger tyres will result in less revs at motorways speeds and
therefore a saving, you will however require more juice to maintain the
same amount of acceleration around town.
Having said all that I would be interested to know how things go with
trial.
--
Regards,
Julian Voelcker
Mobile: 07971 540362
Cirencester, United Kingdom
1994 HDJ80, 2.5" OME Lift
 
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G

Guest

Guest
I too have 285x 75 x16 , 2 inch lift & ARB racks and I have checked my
speedo with the GPS and its now spot on with the speedo in the truck
were as before with stock 265x 70x 15 its must have been showing more
on the the speedo. I know this sounds strange but they are both showing
exactly the same speed now ?. I know I am getting less per tank due to
the large ARB roof racks and 2 inch lift but I have fitted the "
vaporate" to the injectors as well as a "Fitch fuel catalyst", 7mm
spark plug leads and the Bosh Super 4 plugs which as helped with my fuel
economy. It gave me an increase of about 50 -90km in total on both
tanks (145 liters). I now get around 700 -750 km depending on driving
conditions. I drive a 1993 80series 1FZFE petrol with front ARB winch
bull bar, rear Kamar bar and tire carrier as well as a snorkel and K&N
air filter.I also have my timing set at 5deg BTDC rather than the stock
3 deg which gives more power and runs better on 95 octane fuel.
I have just ordered the "Fuel Saver 5000" to help save petrol as well
.Will see if it works won't I :)
Here are links for the Vaporate, Fitch catalyst & Fuel Saver 5000 fyi
http://www.vaporate.com/main.php
http://www.fitchfuelcatalyst.com/products/auto/inline_instruct.html
http://www.agsint.com/atoms-fs.htm
BTW I'm not a rep or have any links to these product I was desperate to
find anything to help with my economy as I don't want to have to sell my
truck due to rising fuel costs :)
Marek Wojak
Sydney,Aust
93 80 series 1FZFE
John Byrne wrote:
> Hi Guys
> I have been moaning about the apparent hugh rise in my fuel
> consumption over the last while. I now have decided to check a theory
> which others have put forward and see what is what.
> I used to get 6 miles per litre all the time over years and over the
> last while I have been getting 4 miles per litre or so it would seem ,
> which is a hugh drop of about 33%.
> Not so long ago I changed the stock wheels and tyres ( 265x 70x 15) to
> ( 285x 75 x16) and we all know the bigger the wheel the less it needs
> to go around to complete the same distance as the smaller one.
>
> So bearing that in mind, can I trust my speedo anymore I dont knoe and
> others say I cant.
> Can I trust the readings on the mileage counter, I dont know and
> others say no.
> Since having a body lift and bigger wheels maybe the drag is stronger
> on the cruiser both from the road and the wind, which has also been
> suggested.
> I have no intentions of having a body lowering done or skinny wheels
> put on just to save fuel but I am very curious.
> I have put the old stock wheels back on and will run the Cruiser for
> a tank full and then I will know. I think
> I have to say that it ( the cruiser ) looks really crap with the body
> lift and those small wheels on now.
> But ill just have to take the funny looks people are going to give me
> for a while.
> The other thing it could be is the injectors need servicing, but I
> dont want to do that if its not needed now do I
> I will also do a set mileage route with the smaller ones on and then
> repeat it with the bigger ones on and see what the difference is.
> I have no way of comparing the speed because I dont have a GPS for now.
> So we will see and ill let you know the results
> John C
> 92HDJ 80 1HDT Ireland
>
>
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