Super Unleaded Petrol.

[VicW]

I have used Tesco Momentum 99 octane fuel for some time until recently.
I used Tesco fuel because we do our main shop at our local Tesco's and get loyalty points plus and until recently they had special offers on their fuel.
Tesco Momentum has received good reviews but there is a general distrust of the quality of supermarket fuel in general and in the past some has received a bad press.
Now that the Tesco special offers on fuel have ceased I decided to stop spending the extra 4p a litre that super fuel costs and go back to using cooking petrol which,in my case, is almost exclusively BP which a local garage is selling at 100.9p/litre.
To finally get to the point, I find that returning to normal fuel has made no difference to my fuel consumption or performance so why the hell did I use super fuel at all ?

Do any other forum members use super unleaded exclusively and do you think it makes any difference of any sort ?
I do not include those who put the occasional half a tank in.

Vic.

[culzean]

I have tried all sorts of 97 and 99 octane including Tesco momentum and it does make a difference to performance and also consumption (like for like commuting journeys to give apples compared with apples results).

recently filled my wifes Jazz GE 1.4 Si with Tesco 99 and noticed it pulled better below 2K, even pulling away in second gear quite easily without pinking (have been disappointed before with its tardiness at lower revs).

My Civic 1.8 goes like Sh+t off the proverbial shovel with higher octane, went to Harlech castle recently with 4 adults on board and boot full of luggage and was well impressed with the way it steamed up the very steep hill (with tight bends) to the castle without any drama,  and in a higher gear than i thought it would.

I do go back to 95 on occasions just to make sure I am not dreaming.

https://www.youtube.com/watch?v=oZIIhP3usuA&feature=youtu.be
watch it right to the end for comparisons of mileage using each fuel

[csp]

I used to use Premium Fuel in an Alfa 156 over 12 years ago there seemed to be a difference in performance but not that significant, I did not notice any difference in fuel consumption. I do not remember trying Premium Fuel in any of my 3 Jazz vehicles and have not really noticed any difference in performance or fuel consumption between Supermarket or Branded, or between Unleaded and Super Unleaded.

Driving conditions and driving style seem to have the biggest effects on fuel consumption.

[guest1372]

Certainly for regular Jazz driving 99ron won't make any difference, but any extra additives may be beneficial although not explored below.

Petrol such as Tesco Momentum 99 is not '4% more potent' than 95ron (and consider diesel is around 20ron) like higher % alcohol would be; it will have a broadly similar hydrocarbon content across all grades. The octane rating is not an indicator of the energy content of the fuel, but a 'resistance to knock'.  The extra rating means it can withstand a greater rise in temperature/pressure before uncontrolled self ignition, therefore it can be compressed to a higher ratio and you can get a bigger bang while avoiding premature ignition i.e. knock.  We should never notice knock these days as it is closely monitored and the timing constantly advanced/retarded to keep it just at bay.   

Higher octane fuel gives a performance advantage in engines designed specifically to run on it (e.g. Golf GTI +5hp), engines intended for standard fuel will never be able to realize it's potential.

Higher compression ratios generate greater thermal efficiencies from a 4-stroke engine and derive more energy for a given hydrocarbon content, that's why blowing in more air with a turbo at the beginning of the cycle gives a higher compression ratio and a greater fuel/air mixture and bang.  The new generation of Honda 3 cylinder turbo engines are designed to get the most "activation energy" from each squirt of fuel by optimising the compression generated on each stroke to the maximum that the fuel mixture can sustain, the turbo is not for top end performance reasons.

Fuel seems to have a great placebo / marketing effect on its users, probably due to names such as "Shell V-Power Nitro+"

The trouble with habitual use of higher grades is when you diligently top-off the hire car to two clicks with it, before realising what a mug you are.

"Vauxhall spokesman Simon Hucknall says you’d be "wasting your money" by putting high octane performance fuel into most of its standard range of cars."

If I had an AMG C63 I'd fill it with 99ron, the Jazz gets 95.

As a technology demonstrator for Mobil*, we used to run a dual fuel LPG/petrol family car in the 70s controlled by a toggle switch on the dash, and the higher octane LPG (110ron) eliminated 'knock' which was a common issue back then, but not any better for standard driving due to a lower energy content.

*Father = chartered automotive engineer in ExxonMobil Special Products division.  ExxonMobil (Esso) produce Tesco fuels.
--
TG  (oiled by Mobil 1 since first change)

[edam]

I use Tesco Momentum  most of the time and find that I get better MPG and also the engine revs lower for a given speed ( don't start the CVT subject again).
If I'm just driving in town then I use standard petrol but for longer journeys, when I start fishing again, then I will use the Momentum

[culzean]

Certainly for regular Jazz driving 99ron won't make any difference, but any extra additives may be beneficial although not explored below.

Petrol such as Tesco Momentum 99 is not '4% more potent' than 95ron (and consider diesel is around 20ron) like higher % alcohol would be;

--
TG  (oiled by Mobil 1 since first change)

http://www.edmunds.com/fuel-economy/e85-vs-gasoline-comparison-test.html

Every test i have ever read on 'E' fuels (ethanol) gets (considerably) lower MPG than even lowest grade of gasoline (petrol) without ethanol added.  Ethanol is a con trick to save the planet by burning down rainforest to plant sugar cane or maize to make into alcohol, far better to leave the rainforest alone or plant food on the land.  Ethanol has higher octane than pure gasoline but has 33% less energy - so engines designed to run on high ethanol blend fuels can have a high CR but then cannot run on normal gasoline grades because of pre-ignition (auto-ignition) problems,  and MPG is lower anyway,  the environmental cost of ethanol production is huge and it is heavily subsidised by taxpayers,  so not at all cheap either.

I also notice you use Mobil 1 oil,  which is an overkill for a humble Jazz engine and 'lower octane' oils that will do the job splendidly at considerably lower cost are readily available.

Why do cars have 'anti-knock' sensors on their engines ? they allow the engines to run at higher CR on lower grades of fuel and will constantly retard and advance engine ignition timing to reduce knocking (where the mixture ignites too early and piston is compressing a mixture that is already burning, which is actually trying to push the rising piston back down ie reverse the flywheels direction),  they do this without any of the drivers input or awareness.  This means that the warning in the Honda handbook to use minimum 95 RON is the least they can get the engine to run on without damaging knocking even with all their trickery and advanced engine management technology.  Unfortunately when the knock sensors are triggered they retard the ignition to fire the spark later in the compression stroke,  this results in lower peak cylinder pressure as the fuel is still not fully burnt as the piston starts to go down,  with fuel that is more resistant to knocking the ignition will be advanced to fire earlier in the stroke and allow the fuel more time to fully burn resulting in higher cylinder pressure.  Higher octane fuels actually have less energy content than lower octane ones, this is because they have more additives (which don't have energy) designed to stop them burning prematurely - it is only modern engines with clever combustion chamber designs and automatically variable ignition timing that allow engines to run better by making full use of the fuels characteristics.

The Jazz has a 10.8:1 CR which is higher than some sports cars which apparently 'require' higher octane fuel.  This means the Jazz (and other Honda engines) is well able to make use of higher octane. Direct injection petrol engines can have a higher compression ratio because the fuel is atomised and injected directly into combustion chamber at the same time as the spark (so up until that point piston is only compressing plain air) - but DI petrol engines have higher NOx emissions than manifold injected engines,  so bad news for peoples health.

My sports motorbike engine actually runs worse on higher octane fuels because it doesn't have knock sensors or an ECU and ignition timing is fixed for 95 RON to prevent pinking,   higher octanes burn differently with less energy and I can feel the difference.

[Garyman]

I've only used Shell VPower since I had my Civic Type R.

As for any additional benefits like better mpg or responsiveness, I don't know as I hadn't tried any other fuel

[guest4312]

I use Shell V power nitro diesel in Volvo xc90-definite difference in responsiveness and overall fuel efficiency-the Jazz less so with the petrol Vpower but still noticeable(use every other fill).

[Pine]

Never noticed any improvement in performance or MPG when using Tesco Momentum in my jazz but in my 3 cylinder Fiesta Turbo  it ticks over smoother and pulls a lot better uphills.

[madasafish]

I use Shell or Sainsbury 95 octane . When I use Shell V Power, there is NO difference in mpg/power etc. I use Fuelly to keep track of mpg.

[guest5669]

All placebo effects these different petrols 

[applicationcen]

The higher Research Octain Number (RON) petrols have extra detergents and other chemicals that reduce friction and ensure the ignition point (Pressure and Temperature) is stable.

Detergents and reduced friction will make an engine last longer. Ignition point stability is essential in all engines as pre-ignition causes knocking which damages engines. Knocking is violent kick back against the direction of stroke. The higher content of air to fuel  reduces hydrocarbon emissions and generates more usable power - but requires much higher compression (pressure) in the cylinder.

So it is factual that the higher the ron of petrol used then an engine will last longer. Similarly higher compression ratios can be achieved without damage.

But here is the rub -

The difference between 95 and 99 RON is for all practical purposes is negligible. It is a price point marketing statement and if any one says different, like the petrol forecourt retail sales giants, they are deluding you on purpose because it bags them more of your cash.

You would have to do a lot of finely balanced comparison to notice the difference in mileage and acceleration based on engine friction alone. Why, because the calorific energy content of the fuel has very little to do with the RON. For instance higher octane fuel does not add more hydrocarbon content or oxygen, so the engine cannot develop more power. The manufacturer decides that.

Research Octain Numbers are measured under very precise lab conditions, using engines that run at 600rpm with variable compression ratios (variable CR). BUT that has nothing to do with how a Jazz engine works. Jazz engines have variable valve and ignition timing and huge variation in rpm. Essentially the cylinder size and stroke depth do not vary so have a stable CR. You might well argue that RONS are no good basis to indicate how much power you will get for any give engine.

So along side RONS, you actually have other measurements such as MONS, AKI, RdONS - RdONS are more along the lines of real world measurements.

However the 105 RON, which has been phased out, is necessary in cars like the Suberu and Mitsubishi Turbos. Hence they don't sell them in the UK any more.

So it is true the higher the RON fuels facilitate access to extra power in specialist engines and aid longevity. BUT it is the engine manufacture that dominates the the real output.

[guest5669]

The higher Research Octain Number (RON) petrols have extra detergents and other chemicals that reduce friction and ensure the ignition point (Pressure and Temperature) is stable.

Detergents and reduced friction will make an engine last longer. Ignition point stability is essential in all engines as pre-ignition causes knocking which damages engines. Knocking is violent kick back against the direction of stroke. The higher content of air to fuel  reduces hydrocarbon emissions and generates more usable power - but requires much higher compression (pressure) in the cylinder.

So it is factual that the higher the ron of petrol used then an engine will last longer. Similarly higher compression ratios can be achieved without damage.

But here is the rub -

The difference between 95 and 99 RON is for all practical purposes is negligible. It is a price point marketing statement and if any one says different, like the petrol forecourt retail sales giants, they are deluding you on purpose because it bags them more of your cash.

You would have to do a lot of finely balanced comparison to notice the difference in mileage and acceleration based on engine friction alone. Why, because the calorific energy content of the fuel has very little to do with the RON. For instance higher octane fuel does not add more hydrocarbon content or oxygen, so the engine cannot develop more power. The manufacturer decides that.

Research Octain Numbers are measured under very precise lab conditions, using engines that run at 600rpm with variable compression ratios (variable CR). BUT that has nothing to do with how a Jazz engine works. Jazz engines have variable valve and ignition timing and huge variation in rpm. Essentially the cylinder size and stroke depth do not vary so have a stable CR. You might well argue that RONS are no good basis to indicate how much power you will get for any give engine.

So along side RONS, you actually have other measurements such as MONS, AKI, RdONS - RdONS are more along the lines of real world measurements.

However the 105 RON, which has been phased out, is necessary in cars like the Suberu and Mitsubishi Turbos. Hence they don't sell them in the UK any more.

So it is true the higher the RON fuels facilitate access to extra power in specialist engines and aid longevity. BUT it is the engine manufacture that dominates the the real output.

Are you a scientists by any chance? 

[applicationcen]

Why - coz I am barking mad?

[Theophilus]

Has anyone else noticed the exorbitant differential in price charged for super unleaded petrol of late? I belong to the "no noticeable difference" in mpg or driving characteristics school of thought, but on my last visit to fill up noticed that price of "normal" Shell was 103.9 p/l, and the Nitro+ 118.9 p/l - the last time I had registered the difference it was only 6 p/l.
It seems that as fuel prices have fallen, the companies are trying to maximise profits!