Premium fuels tested, results suggest no improment over 'normal' fuels

[staffsMike]

"loose marble in my engine" noise.

That's a nice way of putting it.. Such an unattractive sound for a car to make

I've been forced to run my car on 95 RON fuel before due to sheer desperation (fuel light on for a good 75 miles lol)..it was fine on the motorway etc.. but at idle it was very lumpy and accelerated very differently. It's not as bad as a misfire but it wasn't sounding healthy at all.

[Vimeous]

What we need Mr Zak Saah is a Hexus list of cars with cylinder knock-sensors (clearleh innit)!

Honda Civic 1.8VTi - No idea
Toyota Celica 2.0 GT 16v - No idea but doubt it

Hmm... maybe not lol

Whenever I get a works pool car I use 'super' fuels as I know how hard they get worked and any extra TLC posh fuels might give them (not matter how theoretical) has to be worth a try!
In my own cars it's simply a case of available finance and mileage. Our local Shell happens to be slightly cheaper than Tesco so I get my fix from them.
Does it make a difference? I've done so few miles in my own car recently it's always been on 'super' so I've forgotten what other fuels are like! That said I do think it makes the engine seem ever-so-slightly smoother. Mileage gains of 30 miles or so would be irrelevant to me anyway as that will be for normal driving meaning for me it'd probably be only 5-10 miles anyway!

[GoNz0]

my car likes super unleaded, better mpg (proven by the obc) nice throttle responce.

the one time i couldnt get super and filled with normal it ran crap until i got super back in the tank.

the engine managment adapts to the better fuel and remaps the timing to suit.

[chriswood_7]

IMO unless you have a turbocharged engine, its not worth the extra expense. If you do (like me) then its not gonna harm you when you put normal fuel in BUT you wont get the extra performance and response that higher octane fuel gives you.

Either way, if you read your cars manual and find out what fuel it should be run on if you want piece of mind. Mine states 95 and 98 RON, hence why I use both depending on how skint I am. If however you have a Evo or Subaru and it STATES 98 RON minimum, then you will end up damaging your engine if you put 95RON in.

Hope this helps,

[kalniel]

What we need Mr Zak Saah is a Hexus list of cars with cylinder knock-sensors (clearleh innit)!

Surely any car with an electronically controlled ignition is going to have a knock sensor? (ie, nearly all).

[Lowe]

Yes, but most basic cars will only retard the ignition. Not that many will advance it and make the most of the fuel.

[joshwa]

Short term tests show no immediate benefit - but if the petrols contain more cleaning agents, then presumably your car's engine and internals will benefit from being clean, and less clogged with carbon deposits etc.

Surely Which should be performing long term tests to see what happens... disappointing article. Fifth Gear covered this a while ago with similar results.

[kalniel]

Yes, but most basic cars will only retard the ignition. Not that many will advance it and make the most of the fuel.

*confused*

If a car is knocking, how does retarding the ignition help? By then the fuel has already banged. I would have thought the two solutions to knocking are to advance the ignition, or retard the fuel injection?

Agreed about the test length though - it should be longer. But I can see that they could address the immediate power/mpg claims.

[Vimeous]

The answer is simple.

Buy a Koneigsegg!
Whatever you throw at it seems to like ('cept the nasty black stuff ofc).
I reckon it'll run on low-lead prune juice and still produce a handy 900hp

[schmunk]

The answer is simple.

Buy a Koneigsegg!
Whatever you throw at it seems to like ('cept the nasty black stuff ofc).
I reckon it'll run on low-lead prune juice and still produce a handy 900hp

Aye, if you fit the optional tow-bar and hopper-trailer, it'll run on anthracite...

[mycarsavw]

The answer is simple.

Buy a Koneigsegg!
Whatever you throw at it seems to like ('cept the nasty black stuff ofc).
I reckon it'll run on low-lead prune juice and still produce a handy 900hp

It didn't like the Stig being thrown at it

[kalniel]

It didn't like the Stig being thrown at it

I don't know, it seemed to leap with joy..

[badass]

OK, lets sort some tech stuff now:

As Lowe says, the higher the octane rating (RON) the more potential bang is avalable IF the engine allows the compression to go high enough prior to the spark plug firing.

Just to clarify here (I'm not disagreeing with you) The calorific value (i.e. the amount of potential energy in the fuel) is completely seperate from the RON. the RON is simply a measure of how quickly the fuel can burn. Higher octane = slower burn and less likely to explode. When fuel is ignited in a normal petrol engine, it doesn't explode, it burns very quickly.
This isn't exactily what happens but I'm not going to go into any more detail as those that would be interested probably know what happens, and those that aren't won't read it anyway.

Pinking is when the fuel detonates itself, under the sheer pressure of the piston's compression, before the spark plug gets a chance to do it.

Not quite true. Pinking can be caused by compression ignition, but it is also caused by the ignition being too far advanced and peak cylinder pressure being hit whilst the piston is still on its way up or not far enough on its way down.

When an engine is at higher revs, weirdly, it is normally better and less susceptible to pinking....pinking happens at lower revs, under heavy loads (going up hills and pulling away) and that's because the pistons are travelling much slower and therefore the compression gets a long, slow chance to bang the fuel prior to any input from the spark plug. At higher revs, it's so bloody fast, that the difference between the compression starting it off and the spark plug going at it, is miniscule.

Thats also not quite right. Ask any turbocharged car owner what happens when they wither run too much boost or not enough fuel top end and they'll tell you about the skeleton knocking one out in a biscuit tin sound of their engine shortly followed by holes in the pistons and other undesirable things. It tends to be called detonation instead but its the same thing essentially.

Don't forget....diesels pink by their very nature. It's OW the diesel fuuel is set off to go bang,.,,,aint no spark plug....just compression. The noise of a diesel IS pinking. It's the "loose marble in my engine" noise.

Diesels do NOT pink/detonate. A Pinking diesel lasts less time than a pinking petrol. They do use compression ignition but still burn nice and smoothly.

[Butuz]

As far as i am concerned the article is a crock of poop. Its like comparing a focus 1.4 and a gt40 both at 20mpg and 3 corners and 10 miles around the streets of london - theyre both going to be pretty much as slow as eachother when their stuck in a traffic jam! Put them both on a lap of silverstone however and you will then see a measurable difference.

You could put rocket fuel into a focus 1.6 and 1.4 and it still would be slow as a snail.

I've tested Optimax vs Supermarket fuel in serveral high performance cars from 250 - 400bhp and i have consistently had 30-50 miles per tank more on Optimax.

Butuz