[wiggis]

Riddle me this, Batman .... !

My GP feels quicker in the mid-range (2,500 to 4,500 rpm) when running regular Shell 95 RON fuel than it does running Shell V-Power. Last time I filled up, that's all the garage had, and to my surprise, the car felt quicker within a few miles.

Why? And is there some way to unlock the extra power V-Power should be giving me? Do I need to disconnect the battery for 10 minutes to reset the adaptations in the ECU / is there a sensor I should be checking? Hoping an expert here will know the answer.

Thanks

[PmP]

Too many variables to give a definte answer on this.

Does your garage sell enough V-power for it to be as fresh as the 95 ron they sell?

How low on fuel was the car before you topped up? As a number of owners swear that when they fill up their car seems to be quicker. Not due to the ecu, but more likely due to the added pressure of fuel in the tank.

[wiggis]

Quote: Originally Posted by PmP (original)

Too many variables to give a definte answer on this.

Does your garage sell enough V-power for it to be as fresh as the 95 ron they sell?

How low on fuel was the car before you topped up? As a number of owners swear that when they fill up their car seems to be quicker. Not due to the ecu, but more likely due to the added pressure of fuel in the tank.

It was down to 30 miles left showing on the computer. I don't normally run it that low between refills, however, I took it low to get to my favourite Shell garage, in order to get the V-Power fuel rather than stop at the nearest garage for fuel. Sadly, when I got there, they had sold out, hence getting regular unleaded.

They sell loads of V-Power. Every Sunday, the place is full of performance cars all topping up with the good stuff - so I would have to believe it is just as fresh as the regular fuel. I used to go to the same garage when I had my M5, and it was smoother and quicker with the V-Power.

A real mystery at the moment why my GP likes the cheap stuff .........

[MINI-Morgan]

Try Tesco 99 when its back in stock instead of Shell! Always worth a go.....

Mine seems slower on Super Expensive Optimax too but I just figured it was just because it doesnt burn as well or as hot as Tesco 99.

[Ant FR]

I prefer Tescos 99 and so does my wallett, but last few times i have popped into fill up they have been ouit of super. It does perform better due tot he better burn etc.

[roland2003]

Tesco 99.... its the best

[Nath316]

any higher RON fuel will burn hotter and faster thus in a sense cleaning out your system of any debris and burnt on stuff meaning it will breathe in and out more easily

so when you drop a RON so to speak it is burning better, this will not last for ever as carbon deposits and build ups will occur again

[MINI-Morgan]

The bio ethanol probably helps too and with much less chance of pinking more ignition advance can be used.....

[wiggis]

Quote: Originally Posted by Nath316 (original)

any higher RON fuel will burn hotter and faster thus in a sense cleaning out your system of any debris and burnt on stuff meaning it will breathe in and out more easily

Actually, I thought the opposite was true, and that a higher RON fuel burns for longer in the combustion chamber, while they also contained more cleaning additivies to clean up the engine ?

Technical Article #3

It should be noted that having petrol with a higher than required octane rating for your engine does not necessarily mean that you will "blow it up". Higher octane fuels burn more progressively, rather than explosively. A high octane fuel can be compressed more without detonating, ignited earlier to reach full burn intensity at "top-of-stroke", burn progressively and push the piston steadily throughout the whole power stroke. A low octane fuel goes "BANG" once the spark is introduced. So, to increase the power output of an engine by increasing compression ratio, advancing the ignition to allow longer, steadier burn of the fuel, you need an appropriately behaving fuel, i.e. one with a higher octane rating. If you run a higher octane fuel in an older, less "tuned" engine, you probably just end up losing some of the unburned fuel to the exhaust system. The higher octane fuel is more calorific (has a higher energy content) and if it is all burned then it could increase operating temperatures and place extra load on the engine in that way. But higher octane does not mean more explosive, in fact it means quite the opposite.

[MINI-Morgan]

Interesting read from Greenenergy the makers of Tesco 99 :

What is bioethanol and how much is allowed?
--------------------------------------------------------------------------------

Bioethanol is both a high octane oxygenate and a renewable component with lower CO2 emissions, and is added to all Greenergy petrols in blends of up to 5%. The bulk of Greenergy bioethanol comes from sugar cane from Brazil, but in 2007 up to a third will come from British sugar beet.

5% bioethanol is permissable in all road and motorsport fuels in line with BS EN 228 and BS 7800 and MSA rules.

We have found bioethanol to be an excellent performance petrol component with positive effects beyond its obvious octane / oxygen benefits. For example, we have found that addition of up to 5% bioethanol substantially improves engine power on a turbo engine with a restrictor beyond that expected from octane alone. This is due to its high latent heat of vaporisation relative to normal petrol, which cools the charge exhaust gas temperature. This is the equivalent of having a bigger intercooler or a large cylinder capacity and adds power and performance.

[Fabio]

Quote: Originally Posted by MINI-Morgan (original)

Interesting read from Greenenergy the makers of Tesco 99 :

What is bioethanol and how much is allowed?
--------------------------------------------------------------------------------

Bioethanol is both a high octane oxygenate and a renewable component with lower CO2 emissions, and is added to all Greenergy petrols in blends of up to 5%. The bulk of Greenergy bioethanol comes from sugar cane from Brazil, but in 2007 up to a third will come from British sugar beet.

5% bioethanol is permissable in all road and motorsport fuels in line with BS EN 228 and BS 7800 and MSA rules.

We have found bioethanol to be an excellent performance petrol component with positive effects beyond its obvious octane / oxygen benefits. For example, we have found that addition of up to 5% bioethanol substantially improves engine power on a turbo engine with a restrictor beyond that expected from octane alone. This is due to its high latent heat of vaporisation relative to normal petrol, which cools the charge exhaust gas temperature. This is the equivalent of having a bigger intercooler or a large cylinder capacity and adds power and performance.

very intersting
i just got bio ethanol added fuel today, hopefully i'll see a difference compared to the 95ron

[PmP]

5% Bio ethanol, eh.

Formula Student Project at Uni looking at running a yamaha YZFR6 600cc engine on E85 bio ethanol fuel, 85% ethanol 15% petrol mixture. Pending being able to get equivalent preformance using this fuel which will produce less carbon emissions.

Would be interesting if it can be achieved, a bio fuel car capable of 0-60 in 2.8 seconds.

[MINI-Morgan]

Equivalent? I would be expecting far better performance like the limited edition exige that must be run on bio fuel which is far more powerful then all the rest.

[PmP]

Quote: Originally Posted by MINI-Morgan (original)

Equivalent? I would be expecting far better performance like the limited edition exige that must be run on bio fuel which is far more powerful then all the rest.

It is possible dont get me wrong.

But its not just a matter of change the fuel and do a wee tweak here, and a wee tweak there, lots of variables involved.

Bear in mind one Uni student spending a couple of afternoons a week over say 16 weeks in an engine test cell and what lotus have access to is slightly different. And budgets are slightly different.

[wiggis]

Quote: Originally Posted by roland2003 (original)

Tesco 99.... its the best

After filling up with this stuff this evening (down to 40 miles to empty this time), can I just say Wow !

No way am I going back to Shell V-Power, Tesco 99 rules ! The difference is staggering.

Thanks for the advice guys.

[MINI-Morgan]

Congrats Enjoy your new performance and maybe take part here : http://www.mini2.com/forum/engine-dr...ear-times.html

[TonyFoy]

I've always run Shell V Power up to a couple of weeks ago as the garage is nearest. I had to go to Chelmsford a couple of weeks ago and had to use Tesco 99 to fill tank almost from empty. Didn't notice much performance difference but driving back the OBC registered range of 425 after a couple of miles on the A12. I know range tends to increase of main routes but previous to this I can't recall range every being over 320 from full and I do motorway drives of 200 miles + often.

Tesco not the nearest but fuel economy is massively improved over V Power. Have gone from 26 to 31 mpg according to OBC over the last 3 weeks. I know the weather is a bit colder but can't make that much difference can it?

[Dr Obnxs]

Octane is knock resistance. You get power by increasing timing. So if you don't have any timing retard, you don't need any more octane. But, it's also usually the case that higher octane gas has less energy density. The best is just enough octane to prevent timing retardation, and no more.

Now, ethanol is an octane increaser, but it's also got 2/3rds (about) of the energy density of gasoline, so to make more power on ethanol, or E85 or whatever, you really need to tune for it.

Hope this helps.

Matt