Why do people buy high octane petrol?

rossk26 said:
I also have another story regarding Sainsbury's fuel.
Click to expand...

Emphasis on story. One or two stories evolving into some kind of rossk26 fuelled urban myth does not make a truth.

While I don't doubt that on occasion fuels and other products can become contaminated before reaching the consumer, I doubt this is something that is particularly widespread or limited to one particular outlet... especially given the fuel often comes from the same place anyway - I believe that BP actually supply Sainsbury's with the fuel they sell.

FWIW, I run my M5 and mostly ran my previous M5 on Sainsbury's Super Unleaded fuel and never had any issues pointed out to me at any point during servicing or maintenance work, including when the fuel filter has been replaced as part of preventative work.
 
MOOGLEYS said:
There have been quite a few dyno's done by the big name tuning company's showing 97-99 Ron fuel to give a performance gain over 95 Ron especially in tuned forced induction engines.
It makes sense if a car is mapped for a higher octane fuel that there will be an advantage in using it.
Click to expand...

Agreed, and not once have I suggested otherwise.

My point is that It's highly unnecessary in low performance cars to pay the extra for claims of more performance.

In comparison, my car is fitted with a K&N air filter. This was not a performance increase choice. It's proven to improve airflow, and it also saves money in the long run (Ford charge £40 for a new standard air filter every year). The K&N air filter will last 50k miles before it needs a service, of which the kit costs £10 I believe.
 
Westyfield2 said:
Did anyone else go to Autosport International at the NEC a couple of years ago when BP had a stand? They had a remapped Turbo Porsche on a rolling road and ran it back to back on 98 and 102. The power increase varied during the day (ambient temperature etc), but every single time it made more power on 102 than 98.


Note the keypoints rossk26, it's performance tuned engine, in a performance car, with a turbocharger, and is mapped to take advantage of the better fuel.
Click to expand...

Good find. How this contra-indicate anything I have said so far?
 
rossk26 said:
In comparison, my car is fitted with a K&N air filter. This was not a performance increase choice. It's proven to improve airflow, and it also saves money in the long run
Click to expand...


Does it save money in the long run? What kind of air metering does you car have? Assuming it's a hot wire MAF sensor just after the air box, you'll probably find that over time the oil sprayed onto the K&N will contaminate it resulting in it needing replacing at a greater cost than a periodic air filter replacement.
 
Gibbo said:
Also people need to remember, you can't just go and put £20-£30 of Vpower in your tank and expect an instant improvement.

It requires a good 2-3 tank fulls to get the gains and by which time you probably won't notice the improvements.

But it is worth extra horses but more so the benefit is a clean engine and a clean engine means better reliability. :)
Click to expand...

Only in cars that "learn" - I can hook my laptop up and see the differences immediately.
 
PeterNem said:
Does it save money in the long run? What kind of air metering does you car have? Assuming it's a hot wire MAF sensor just after the air box, you'll probably find that over time the oil sprayed onto the K&N will contaminate it resulting in it needing replacing at a greater cost than a periodic air filter replacement.
Click to expand...

In all honesty I have no idea

EDIT: K&N Panel filter for Focus ST is £42. Given that K&N recommend servicing every 50k miles. That's a ratio of 1 K&N panel filter to every 5 Ford air filters (£40). Quite a saving.
 
Last edited:
rossk26 said:
My point is that It's highly unnecessary in low performance cars to pay the extra for claims of more performance.
Click to expand...

Its nothing to do with the performance of the car, why would it be? It's all about the engine. Certain engines (Not all!) benefit from fuel with a higher RON rating. You take great pleasure in pointing out NathWraiths Seat has a 1.4 litre engine. It does, but it also has a supercharged and turbocharged engine with a very very high specific output - and its these which dictate its fuel needs not the car its fitted to.

The performance of the car in question is irrelevent because the same engine can offer vastly different levels of performance depending on the car its fitted to.

For example the Golf R32 is very much a high preformance car. The VW Pheaton with the same engine fitted to it with the same fuel requirements is dog slow.

Put simply - if the engine map is designed to take advantage of higher RON fuel, then using lower RON fuel will result in a reduction in the nominal performance values of the engine. In terms of both power output and fuel consumption.

It isnt so much that 97-99RON gives you more power and more mpg, its that 95 RON fuel gives some cars LESS power and less mpg.


It quite clearly states in my user manual that the manufacturers stated performance and economy figures for my engine are preserved only with 98 RON fuel. 95 can be used, but the car won't acheive its stated performance and economy figures.

Which makes perfect sense, really.
 
Last edited:
[TW]Fox;20863435 said:
Put simply - if the engine map is designed to take advantage of higher RON fuel, then using lower RON fuel will result in a reduction in the nominal performance values of the engine. In terms of both power output and fuel consumption.
Click to expand...

Put simply - by how much?
 
ITT: rossk26 doesn't understand the finer points of what happens when fuel goes into an engine, tries to cover it up by saying everyone that needs/uses V-Power or similar is just trying to justify their purchase.

My 4.3L V8 Mercedes engine doesn't need V-Power. My 1.8L I4 Mazda engine does.
 
rossk26 said:
Put simply - by how much?
Click to expand...

How long is a piece of string? It depends entirely on the engine in question. Some cars? Very little. Other cars? A bit more. Typically though expecations of anything more than a 1-2mpg difference or a loss of more than 5-10mph are unrealistic. It's also the case that forced induction cars seem more sensitive to it.

There are also some cars where not using super unleaded has caused significant issues - notably the earliest examples of direct injection petrol engines (Mitsubishi GDI and Audi's first gen FSI engines). However it's pretty dumb to sell mainstream cars that break when you use the wrong fuel so as you can imagine it wasn't deemed an acceptable situation.
 
[TW]Fox;20863435 said:
It quite clearly states in my user manual that the manufacturers stated performance and economy figures for my engine are preserved only with 98 RON fuel. 95 can be used, but the car won't acheive its stated performance and economy figures.

Which makes perfect sense, really.
Click to expand...

*Achieve
 
[TW]Fox;20863491 said:
I take that as you conceding my points given you couldn't find anything more than spelling to take issue with.
Click to expand...

I haven't conceded your point. Nor should you concede my point. Until there is black and white proof that higher octane fuel delivers these figures in cars which are not mapped, not high performance, not imported from countries with high octane fuels as standard.

This is a very grey area in my views, If I were to ever upgrade the performance on my car and have a tailored re-map. Then I would fill her up with V Power, to warrant paying all that money on upgrades. As I have seen evidence that the higher octane fuel is needed in these situations. But just because my user manual states I will benefit from higher octane fuel. My view is there is not a need to buy V Power fuel until there is proof of these figures, and not just a line in the user manual stating so.
 
You are the one challenging the printed claims of car manufacturers, not us. It is therefore you which must prove your point and not us.

Thats generally how things work. If you wish to challenge accepted convention, you provide evidence to support that challenge.
 
You must log in or register to reply here.
Back
Top Bottom