15 replies to this topic

[MiniGrin]

I have just watch an episode of fifth gear where they have tested different octane fuels (95 and 97) to see which is best and concluded that in the golf GTI it is marginally quicker. And I know that with some performance cars such as TVR they recommend higher octane fuels.
But what about the Classic Mini, is it worth the extra cost for higher octane petrol? Have you tried it and did you see a difference? 

[IainStallard]

I find that when I run BP ultimate, then my spi runs better and returns better mpg, but when I run v power, its not so good as its much higher octane and the standard ECU can't cope

Higher octane fuel works to a point, but too high and the standard ECU can't cope

On carb cars, the higher octane allows you to run more advance on the timing and can increase power

EDIT: Adding more to the subject of BP Ultimate, when driving at 30mph and then suddenly use full throttle, the car still pulls, whereas with any other fuel, it bogs down and struggles. So I definitely notice the difference

Edited by IainStallard, 12 September 2013 - 11:18 PM.

[Alex_B]

Provided the car is set up to make the most of the higher octane then yes it allows the engine to run with slightly more power, but don't expect it to just make it a rocket ship when you fill the tank with 97

[jaydee]

Its simply depending on the CR whether you need it or not, and you need some fine tuning to get it work properly.

Less than 10.5:1 and you will be fine with 95.

[IainStallard]

On my TVR I swear by V Power and have and will only run it on that as that's what the car has been set up to run on. Runs like a rocket though

Esso Super Unleaded = 98 octane
BP Ultimate = 97 Octane
Shell V Power Nitro = 99/100 octane
Tesco Momentum = 99/100 octane

BP Ultimate being 97 might explain why my mini runs better on that rather than V Power

[MiniGrin]

My dad also swears by tesco momentum and shells vpower for his TVR. 
My mini tho is a 1275 Cooper Sport MPI and is reletivly standard, mods are: K&N air box, Maniflow manifold with cat with a fletcher back box. I have never tried a higher octane but was thinking of giving it a go, do you reckon Id see any improvements?

Edited by MiniGrin, 12 September 2013 - 11:35 PM.

[RedRallyMini]

It's actually better to use high octane fuels, it burns at a much lower temperature than low octane fuels so your valves and valve seats will last longer, people who have a classic car with an engine that normally uses leaded fuels will use high octane fuels if they don't have any lead substitute (the lead in the fuel acts as a coolant)  +  the car performes better.

 

I personally always use super 98.

Edited by RedRallyMini, 12 September 2013 - 11:49 PM.

[majourlittle]

Higher octane ratings are a rating of how resistant a fuel is to auto igniting when under pressure. As you CR goes up, the pressure exerted on the fuel is energy and this energy can cause the fuel to ignite before it should and causes detonation. 

http://en.wikipedia....i/Octane_rating

Going higher than needed is only a waste of money.  

 

What the fuel is made out of is what gives you power. The octane rating and the BTU rating do not correlate. With modern fuels, many components are stripped for different reasons. In some places, to maintain a lower vapor pressure of standard gasoline ETBE is added as an octane booster, while lower vapor liquids are removed like butane, which is a octane and BTU booster. The result is lower BTU fuel that has the same octane rating and is more stable at higher temperatures. This is better to the market, but is not better for your car. 

 

Also, adding components like MTBE, ETBE and Ethanol to fuels changes the stoichiometric ratio of the fuel and reduces power. by in most cases creating a rich condition. To me locally, E10 is common in our fuel which is a 10% ethanol and 90% gasoline. Where Petrol is a 14.7:1 stoic, ethanol is 9:1 resulting in a 14:1 ratio. Generally EFI cars come from the factory on the rich side anyway for safety, by going to a blend fuel, your overall power goes down because you car shoots farther away from stoichiometric.

 

 

In short, find a fuel brand that you like and stick with it, but don't select it based on octane rating alone.

[Dolly 89]

Higher octane fuel definitely makes a difference, when I was racing motocross a few years ago, I used to run 40% av gas and 60 % pump 99octane fuel, when I didn't have any av gas for the last meeting of the year once I just ran pump gas, I couldn't get a good start all day, the bike was just nowhere near as responsive, I would usually be very good off the start all the time but that day it was hopeless, I wouldn't say it makes much difference top end but acceleration it definitely does, all the cars I have had that have the little trip computer have always done more mpg with the higher octane fuel in, it was actually worth the extra cost because of the extra mileage I would get

[Hrimfaxi]

Like IanStallard's, my SPI doesn't seem to like Shell V-Power, I put about about half a tank from pretty low, so not much mixing going on.  Just does not like it, even on a motorway blast.

Esso super unleaded is my standard go to fuel.  

[MiniGrin]

Well I gave it a go, put just over half a tank in of Texaco "high octane unleaded" which is a 97 into my vertualy empty tank and went out a blast round the peak district. I found it revved a bit easier and quicker over 3500 rpm, also seemed to pick up a little quicker and not bog down when under 2000 rpm in 3rd and 4th. Some of this could have been placebo (in my mind) but its not too much more expensive and is suppose to get you more mpg and any possible pozative effect on the engine is a bonus. 

Edited by MiniGrin, 14 September 2013 - 11:41 PM.

[A-Cell]

I reckon the reason to use the higher octane fuels available in the UK in a classic is the reduced amount if any of added ethanol, which prematurely ruins some of the fuel system components.

[Tahiti Joe]

I reckon the reason to use the higher octane fuels available in the UK in a classic is the reduced amount if any of added ethanol, which prematurely ruins some of the fuel system components.

 

This is increasingly important. Regular 95 ron fuels are having more and more ethanol adding into the fuel, it's good for emissions and fuel cost and storage and all that, but its really not good for classic Mini engines. Some manufacturers only approve there cars that are made post-2000 for use on high ethanol fuel. V-Power, momentum and the like dont have the high ethanol levels so that helps. Due to the higher octane, they run cooler, can allow you to run more ignition advance for a wee more power, and they also tend to have a better detergent base in them, helping keep the intake/combustion/exhaust components cleaner.

 

I use V-Power pretty religiously, so much so they even sent me a V-Power card!

[Spud_133]

I always use vpower wherever possible, I don't know the increase in responsiveness it provides as I've always run it, but my 1293 has a higher than standard CR so I originally used it to keep the car run cooler. I do have an expirence of once when I was racing my lightning rod in Ireland, we didn't know the garage so got regular as they didn't have ultimate, and the head gasket went. So it must do something

[Cooperman]

You can only gain power by increasing the C.R. and altering the advanced curve at which point you need a petrol which will allow more advance without 'pinking'. Then the better power potential of the high C.R. can be utilised.

In a standard engine with, say, 9.5:1 CR no benefits will be noticed.