95ron on Motorway journeys

[Number86]

Erm, what do you think is happening inside your engine?

It's simple chemistry - the spark causes the petrol/air mixture to explode, the force of which drives the pistons. 99 RON fuel produces more explosive force per unit volume of petrol. Therefore, you require less volume of 99 RON fuel to provide the same driving force to the pistons compared to 95 RON.

LC, LCR both adapt the fuel/air mixture depending on the grade of fuel and intake volume of air + some other parameters. When cruising at a constant speed, your car will consume less 99RON fuel than 95, resulting in improved MPG.

But it doesn't produce more explosive force. That's not the point of higher octane fuel. Hence my last comment.

 

[Willie]

Well, i drove 240 Miles at 75 ish the whole way (saturday morning 6am - 9am no traffic) and managed to achieve 32.4MPG, i was basically looking at the read out the whole way, adapting my driving for the best figures. I used 30 litres, and then filled the car back to the brim.
Did a days work (yawn, Blackburn Vs Newcastle)
I had a party to get home to, so it's far to say i wasn't driving slowly, in busy traffic (speeding up and slowing down) and i made 28MPG (34.6 Litres)

Oh i was using 95Ron to achieve these figures (first time i've used it in a year of buying the car), don't really know what my point is, just thought i'd throw this up. I have no idea how people are getting 30MPG + over 1000 + miles of varied driving, makes me quite proud of my 26 over the last 3000.

30+MPG makes me think that people haven't noticed that there are two stages for the consumption, Combined, trip/live
I've seen 33MPG over a very short distance and driving like miss daisy
Which is not how my car is supposed to be driven

 

[Gnollins]

But it doesn't produce more explosive force. That's not the point of higher octane fuel. Hence my last comment.

I was going for maximum simplification.

Higher octane fuels may or may not contain more energy than their lower octane equivalents, but their main purpose is that they prevent knocking by being more resistant to compression ignition, and thus the compression ratio in the cylinder chamber can be safely increased, resulting in an increase in engine power output.

 

[Gnollins]

30+MPG makes me think that people haven't noticed that there are two stages for the consumption, Combined, trip/live
I've seen 33MPG over a very short distance and driving like miss daisy
Which is not how my car is supposed to be driven

I'm aware of the live/average readouts.

Also, I get lower MPG over short distances, typically 20-25MPG on any journey less than 10 miles, but that's probably due to the engine being cold.

 

[Wackojacko]

30+MPG makes me think that people haven't noticed that there are two stages for the consumption, Combined, trip/live
I've seen 33MPG over a very short distance and driving like miss daisy
Which is not how my car is supposed to be driven

I am very aware of how my trip computer works thankyou

There is one constant MPG readout.... and then two "trip" averages, one which resets after nearly every trip (oh go on then correct me) and another which only resets when the users chooses too, or it max's out at something like 6000 miles.

 

[Number86]

I was going for maximum simplification.

Higher octane fuels may or may not contain more energy than their lower octane equivalents, but their main purpose is that they prevent knocking by being more resistant to compression ignition, and thus the compression ratio in the cylinder chamber can be safely increased, resulting in an increase in engine power output.

I know.

But

http://www.strawbsweb.co.uk/related/jford/jf_bt.jpg

 

[Willie]

Come on boys was just trying to bash your heads together to sort this out
AND finally you agree about something

 

[Leigh15]

Anyway.......

Aren't you supposed to only run the LCR on Super unleaded though and only use standard 95 RON unleaded in an emergency?

 

[Gnollins]

Basically, if your run your LCR on 95 RON you won't be maximising its potential, however it won't harm the engine as the knock sensor will adapt to prevent any pre-ignition.

 

[Jay20VT]

i always use 97 ron plus and do in fact get better miles to the full tank than the cheaper shite

 

[bcstudent]

Higher octane fuels may or may not contain more energy than their lower octane equivalents, but their main purpose is that they prevent knocking by being more resistant to compression ignition, and thus the compression ratio in the cylinder chamber can be safely increased, resulting in an increase in engine power output.

Yes, but the point of using higher octane fuels in the majority of cars on here does not relate to the safe increase of compression ratio, more the safe increase of boost.

...but you already knew that, I'm sure.

 

[Gnollins]

Yes, but the point of using higher octane fuels in the majority of cars on here does not relate to the safe increase of compression ratio, more the safe increase of boost.

...but you already knew that, I'm sure.

Of course.

 

[fozzybear]

at the end of the day as the hand book says recomend use 98 ron fuel for best performance of engine but can use 95 ron but performance will be mildly affected ...........i would think this also goes for mpg being mildly affected too

 

[speedinsaxo]

My R has had nothing but V-power from the day I collected her. Done 33,000 miles now in just over 2 years.

I have Kept every petrol receipt - I might work out my mpg over this period. Then again I might not because I would probably cry at the cost of owning the car...

But 50 mile + journeys for me now = between 35 and 40mpg on the tripm computer and the drive to work is 7 miles and anywhere inbetween 25 - 35mpg depending on how I drive...

Would never use anything other than v-power even for the lot of motorway driving that I do.

 

[Leigh15]

I have Kept every petrol receipt

That's a LOT of receipts!

 

[push110]

At least you lot have the choice of using higher quality fuels, don't get anything other than 95ron at the pumps up here

 

[traumapat]

iirc you need a couple of tankfulls of a different fuel for the ecu to adapt properly anyway...

stick to the good stuff. like for like it`ll get you futher and with v power it`ll clean the engine too.

 

[wackyracer]

I travel from southampton to gosport every day which means about 2 thirds motor way and the rest a/b roads. I also do half of it in the rush hour ( creep along!) and half outside of rush hour ( much faster!) i have been getting about 120miles to £20 of normal fuel and 130 on the super stuff.