95 Ron Fuel

[driftin jo]

I have always used V-power or tesco 99 fuel unless I could not get any then and only then would I put 95 Ron petrol in my s2.
One of these time however was last week and I did not notice when booting it the usual lack of power that I get with lower octane petrol .
My conclusion was that maybe as it was sub zero temps night and day that this had meant that the ecu had not had to retard the ignition as there was no knock at all detected .
Anyway after thinking this I decided to keep putting 95 Ron in the S2 and see how it was .
I have been running it on 95 Ron now for nearly 2 weeks and it flies just as good as ever, so until the weather warms up or I notice the usual drop in performance I'm going to save some money.
Also I'm getting I few mpg higher wile cursing and think that this is as the lower octane is getting the bang going quicker and making better power , this makes me think that the timing is not advanced enough wile cruising in very cold weather on 99 Ron fuel .
Maybe if this can be checked and verified by a few people then a tweak in the map for very low temps for cruising could save us all some money .
For ref my car is home fried ABY avant.
Has anyone else tried this and if not maybe you might see if it is the same for you

[rob martin]

i doesn't matter what i put in my rs2, normally always shell v-power, it still only does 200-250 miles per tank! if i take it easy or give the beans everywhere, it's just the same.

[S2central.net]

You do get more ignition advance in cold air but with n-stream you get reduced boost in cold air - same behaviour as factory chips. On v-stream you get same boost regardless of air temp.

The extra advance explains better fuel efficiency in these cold temps.

[4WheelDrifter]

On a long winter motorway trip I tested a few different fuels in my MRC'd 3B. At a constant 70mph I managed 30mpg on Shell V-Power, 27mpg on BP Ultimate, and 23mpg on a supermarket 95 RON. Other than the test I always use V-Power where possible.
I always got more boost in the winter. It's the same in my MRC'd A3, ~1.3 bar in the summer, ~1.5 bar in the winter.

[20Vcqdriver]

You do get more ignition advance in cold air but with n-stream you get reduced boost in cold air - same behaviour as factory chips. On v-stream you get same boost regardless of air temp.

The extra advance explains better fuel efficiency in these cold temps.

So which version did you fit in mine? Certainly ran far better in colder weather and on really hot days felt slow by comparison!! 99 Tesco appears to alway run the best in mine though I notice V-power is also now 99 octane..

[johne]

I've done 140,000 miles in my standard ABY, the vast majority of it on regular 95 ron petrol. For the last 20,000 miles I've been Homefried.

What I've found is that unless it's really warm - and we're talking hot summer here - you can't tell that it's 95 over 99 ron. Nor is the mpg significantly different between them but Homefries is worth an extra 3 mpg on 95 ron.

John

[Rocco]

and what about if for track days we use for example a octane booster like NOS has for sale??

street formula = +3 octanes for more or less 60litres of fuel

racing formula = +7 octanes for 60 litres of fuel too

it is Real or complete unbeliable?? because here in SPain the best fuel for sale it is only with 98 Ron octane and i´ve heard that in Germany for example the 104octane it´s available in some fuel stations

really it is a good one for a trackdays??