E10 Notes
Its 3 or 4 years since I first tried different octane fuel in my
current petrol 4wd , a Patrol GU 4800. At the time my conclusions
where that it was basically a non event.
This is pretty much as theory and government reports predict.
The recent fuel price increases promted me to re-check the situation
using
United's 95 octane E10 fuel which gets its increased rating by
adding 10% ethanol. This fuel is on average 4c cheaper and its octane
up by 4 points from ULP's 91.
A higher octane rating just means that a fuel is more stable, slower
to ignite and this effectivily retards the timing a little.
This change is within the range of automatic adjustment of knock sensor
equipped modern cars ECU's.
Most of the automatic adjustment takes place in first 50km of driving.
In my car I noticed that it hesitated and almost stalled on first use
but this effect was reduced by the next day.
Two principle measurement were to be made
1/ Fuel consumption over not less than 1000km.
2/ Acceleration over wide engine rev range.
Fuel Consumption
---------------
Accurate results are hard and require consistentcy in type of
driving , weather, loads and fill up process.
In this test everthing was done to maximize accuracy including
such things as filling up at the same pump with car on same angle
as shown by a permanent vehicle bubble guage which prevents a part load
effecting fill up level. As a double check I record the cars sub-
tank
fillup capacity seperately, and fill up at same time of day at similar
temperatures.
Have a long history of recording fuel use at points along the cars fuel
gauge and at every point a small deviation was noted from my long term
average. For the first time in ever the car recorded less than 800km
at the empty mark.
795km compared to average 825km amounted to a drop of 3.5%
Acceleration
------------
While it's fun to say the car has "200kw" this doesn't mean much.
What's important is how the car performs thru its typical rev range under load.
Accurate results are in a way harder to achieve here than fuel use as it
requires multiple accurately timed runs and you need to be able to
set up a process in which this is achieveable without looking like a hoon!
I use a straight flat section of road which can be driven on my way to work
each day. This means I can get 2 or 3 clean runs in a week as some times are
spoilt by traffic etc.
3rd gear for me is useable from 25kmh to 110km, generally allowing
valid results from 40-90kmh as first and last few km's are lost by backing
off to avoid speeding and to allow getting a clean start.
Data is recorded by using a GPS.
Mine a garmin 3, can be set to record
location at 1 second intervals which usually allows about 20 recording points.
The GPS points can be displayed as a revealing plot directly in OZI-explorer
(shareware version).
Note - Ozi is a guide only, as its method of display is inherently lumpy
as it normalizes decimal data to the nearset 1 second interval.
Use of GPS eliminates many potential errors as it gives exact distance
speed and timing intervals.
To make use of multiple runs, the data collected is cut and pasted via
text editor into excel and various runs can be overlaid on each other.
To achieve best results the data is normalized to 40kmh.
(a run's speeds may be shifted up or down to nearset 1 second reading).
RESULT - The result of several runs overlaid on previous history
shows no discernable difference in power and acceleration with E10.
The car has two selectable engine maps, and neither showed a difference.
CONCLUSIONS
-------------
A small but discernable fuel use drop, that roughly matched its lesser cost
combined with no measurable power difference means to me that E10 is basically
a non event and offers no advantages or disadvantages.
Robin Miller