Why do people buy high octane petrol?

[TW]Fox;20863563 said:
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.
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I remember watching a 5th gear episode once where they had 3 cars and 3 different types of fuels.

Clio (1.2 I believe)
Golf GTi
Subaru Impreza WRX STi

In the clio, no difference in all readings. In the Golf GTi, I think the power went up by 2hp using the higher octane fuel as opposed to 95 RON (worth it?). The big difference was made in the Subaru, which I have been stating all along, that if you have a high performance car, then high octane fuel is acceptable.

I can't find any MPG figures unfortunately.

So IMHO, I don't think it a necessity to fill up a standard hot hatch with V Power, when there isn't a noticeable improvement in performance, if by filling up with V Power that is your main goal of course. If you are filling up purely for bragging/coolness rights, then I can't argue with these folks!

If performance is what your after, getting rid of the car mats will probably make your hot hatch faster than filling up with V Power. Will also be cheaper too ;)
 
rossk26 said:
I remember watching a 5th gear episode once where they had 3 cars and 3 different types of fuels.

Clio (1.2 I believe)
Golf GTi
Subaru Impreza WRX STi

In the clio, no difference in all readings. In the Golf GTi, I think the power went up by 2hp using the higher octane fuel as opposed to 95 RON (worth it?). The big difference was made in the Subaru, which I have been stating all along, that if you have a high performance car, then high octane fuel is acceptable.
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But those results mirror what we have been saying! You won't find a recommendation to use anything more than 95 RON fuel in the owners manual of a 1.2 Clio. You will in the Golf and Subaru, and both cars demonstrated higher power as a result of using a higher RON fuel. If the book says use it, its because the manufacturer has designed an engine/MAP combination which delivers the quoted power/economy figures on higher RON fuel. If it doesn't say use it, its because they have not. It's really that simple.

You need to drop this high performance CAR thing because its not the CAR that dictates fuel requirements its the ENGINE.

You'd probably consider a Golf R32 high performance - anyone would. Yet the same engine is found in some really very slow cars as well. It's fuel requirement doesnt change..
 
[TW]Fox;20863759 said:
But those results mirror what we have been saying! You won't find a recommendation to use anything more than 95 RON fuel in the owners manual of a 1.2 Clio. You will in the Golf and Subaru, and both cars demonstrated higher power as a result of using a higher RON fuel. If the book says use it, its because the manufacturer has designed an engine/MAP combination which delivers the quoted power/economy figures on higher RON fuel. If it doesn't say use it, its because they have not. It's really that simple.

You need to drop this high performance CAR thing because its not the CAR that dictates fuel requirements its the ENGINE.

You'd probably consider a Golf R32 high performance - anyone would. Yet the same engine is found in some really very slow cars as well. It's fuel requirement doesnt change..
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*doesn't

(sorry I had to)

So a gain of 2-3hp is worth paying the extra? I'm not even sure on a normal day to day drive you would even use the extra performance it's giving you. Unless you drive everywhere like the stig.

There's no requirement for an R32 to have V Power. Invalid argument, you could stick the 1.4TSI engine in a Caterham shell, giving it unreal amount's of performance. Doesn't mean I think it still needs V Power.
 
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rossk26 said:
So a gain of 2-3hp is worth paying the extra? I'm not even sure on a normal day to day drive you would even use the extra performance it's giving you. Unless you drive everywhere like the stig.
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Its up to you if its worth the extra. Only you can decide. What we are saying is that to get the manufacturers quoted figures, you should use the manufacturers recommended fuel grade. You'll notice a similar difference with fuel economy as well.

There's no requirement for an R32 to have V Power. Invalid argument
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That example was pointing out why you can't just say 'high performance car' when you are talking about engines. It's just an example of an engine found in a high performance car *and* a low performance car.
 
I feel like im talking to my self.

99.9% of the time if you advance the ignition a car will create more power, advancing ignition can and will cause knock, you can advance the ignition further without knock using higher octane fuel.

ALL modern cars have this ability from the factory. The amount of extra power generated is totally down to the design of the engine though. The reason FI cars see such an increase is due to the way the ecu pulls timing to stop knock WOT.
 
rossk26 said:
*doesn't

(sorry I had to)

So a gain of 2-3hp is worth paying the extra? I'm not even sure on a normal day to day drive you would even use the extra performance it's giving you. Unless you drive everywhere like the stig.

There's no requirement for an R32 to have V Power. Invalid argument, you could stick the 1.4TSI engine in a Caterham shell, giving it unreal amount's of performance. Doesn't mean I think it still needs V Power.
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*amounts

You also seem to enjoy using two spaces after full stops, you only need one.
 
Just to back what Fox is saying about the engine and not the car my XFR, which I believe comes under the High Performance banner :) , only needs 95RON as thats what the manufacture has built the engine to use. I might get more economy or performance from it with 97-99 RON fuel but the fact it makes north of 500 BHP with "just" Shell unleaded doesn't to me seem to warrant the extra for the higher octane fuel.
 
rossk26 said:
I couldn't measure if the higher octane fuel is giving me more MPG though. I could have a trial. Fill 3 tanks with V Power and use my RoadTrip app to see the results compared to my previous fill ups using normal fuel.

This won't be accurate though.
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You won't just see the difference over that short amount of time. It's more about the consistency of higher octane fuel that is going to yield better results.
 
rossk26 said:
I also have another story regarding Sainsbury's fuel. But I shall save this one for your inevitable reply to this post :)
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In North Midlands area all fuel is supplied by Shell Stanlow refinery, I believe the only exception is the Tesco 99 as that contains 5% biofuel additive.

I do recall a couple of years ago some Sainsbury's fuel was imported on a boat tanker, and the tank had not been cleaned prior causing contamination and damage of catalitic converters, this was London / South area however.

I live in Crewe and have used either Sainsburys 97 RON and Tesco 99 RON for many years with without issues. Ran a Integra Type R the last 4 years. I have used v power but in Crewe price is not justified over Tesco 99.

Here is another Thorney Motorsport rolling road comparison done in 2006 between Tesco 99, then Shell Optimax, BP 97 and normal 95.

http://www.thorneymotorsport.co.uk/content/site/downloads/press-release-full-290806.pdf
 
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