"Normal" Unleaded vs "Premium" Unleaded

[yorkie_chris]

Originally Posted by jonny.boyd

I would imagine that with a higher octane level it would burn / explode with a larger bang therefore perhaps reducing the amount of unburnt fuel in the engine? (just a scientific guess....)

Scientific? Where?

Go and understand the definition of the octane rating system before partaking in discussions about it

The standard SV is designed to run on standard fuel so it's a complete waste of money to put anything more expensive in.

I sometimes use higher octane fuel in my MX5 Turbo in the summer when it's hot to stop the engine knocking. I think the only difference is that higher octane fuel is harder to ignite so is more knock resistant.

An SV engine is only good for about 250,000 on standard fuel, so perhaps use premium










If you're a frickin MOON COURIER!

[jonny.boyd]

I have no scientific knowledge, was just guessing, found this though:

"Octane reduces gasoline's tendency to auto-ignite, protecting the engine against detonation or pre-ignition. Manufacturers will recommend the minimum amount of octane necessary to protect the engine against damage. High compression engines tend to need more octane, because they are more susceptible to detonation."
(http://www.active.com/lifestylevehic...ium_Price_.htm)

AND

Interestingly the TV programme "Fifth Gear" tested these two fuels against normal unleaded with three different cars:

Renault Clio - and found that the premium fuels made no difference to the power output of 81bhp
VW Golf GTI - Found that Ultimate increased power output from the standard 172bhp to 174bhp and Optimax increased output to 177bhp.
Subaru Impreza WRX STI - found that power increased from standard 235bhp to 248bhp with Ultimate and 249bhp with Optimax.
(http://savefuelsavemoney.co.uk/carfuelsave3.htm)

Originally Posted by jonny.boyd

I have no scientific knowledge, was just guessing, found this though:

"Octane reduces gasoline's tendency to auto-ignite, protecting the engine against detonation or pre-ignition. Manufacturers will recommend the minimum amount of octane necessary to protect the engine against damage. High compression engines tend to need more octane, because they are more susceptible to detonation."
(http://www.active.com/lifestylevehic...ium_Price_.htm)

AND

Interestingly the TV programme "Fifth Gear" tested these two fuels against normal unleaded with three different cars:

Renault Clio - and found that the premium fuels made no difference to the power output of 81bhp
VW Golf GTI - Found that Ultimate increased power output from the standard 172bhp to 174bhp and Optimax increased output to 177bhp.
Subaru Impreza WRX STI - found that power increased from standard 235bhp to 248bhp with Ultimate and 249bhp with Optimax.
(http://savefuelsavemoney.co.uk/carfuelsave3.htm)

Preigniting is normally because of huge pressure. You won't find a naturally aspirated street car that will even approach that kind of compression ratio.
...
...hence the cars in that list that work are all turbos! Here they can adjust for the higher octane fuel accordingly.

Edit: that's a **** explanation. But I'm tired.

[phi-dan]

Originally Posted by Owners Manual

Your motorcycle requires regular
unleaded gasoline with a minimum
pump octane rating of 87

so the standard is more than enough.

[yorkie_chris]

Originally Posted by jonny.boyd

I have no scientific knowledge, was just guessing, found this though:

I guessed

Those cars all have a knock sensor so can take advantage of the higher octane rating.

I've been using Shell Vpower for ages and ages. I find that it provides slightly better low down pick-up when on a tiny whiff of throttle; less snatchy than normal unleaded.

But tis too expensive now, so will be using 95 ron again. There is no significant gain to be had from using super unleaded fuels, at least many tests show no improvment when full throttle is used. I've not seen any tests though that show if super unleaded fuels give any advantage at part throttle...i'd expenct not, but it would be nice to see data showing what it does / dosn't do

Originally Posted by yorkie_chris

Care to back that claim up with some logic and/or evidence?

no because i dont have any but i would pesume that it could make some difforence

Originally Posted by barwel1992

no because i dont have any but i would pesume that it could make some difforence

The extra 3p/litre probably covers the advertising