premium fuels

Forgive me if this is completely wrong, I always presumed that the higher octane fuel the more reactive it is? So developing larger amounts of power with the same amount of fuel.... provided that the air/fuel mixture is set up correctly.

[northwind]

Nope, unfortunately not... The calorific value of the fuels is about the same. But higher octane means the fuel's less likely to suffer premature detonation under compression, so you can make it work harder, ie run high boost in a turbo, or high ignition advance, or high compression. But the extra power is from the engine setup not the fuel, the fuel just makes it possible to tune for more power.

It's not quite that simple, because the premiums aren't just high octane, they tend to have other stuff, additives and the like in there too, so some testing with standard bikes and cars does show fractional power or economy increases (and decreases!). Always less than the price difference though!

I tend to put super in mine for trackdays, I sometimes think I can feel a difference in throttle response... Which may or may not be in my head, but placebo improvements are every bit as good as real ones in my book, it's about feeling good not being good

I think it's confusing to refer to them as "premiums", since the cheapest stuff is called Premium Unleaded

I've never used it (Super Unleaded, or equivalent) unless the machine would benefit. The SV doesn't afaik. It would probably make more difference to use different (better?) brands of basic "premium" stuff. I swear I get more miles to the tank when I use my local Esso garage than I do with supermarket stuff.

top gear did a test on it didnt they, conclusion was its worth putting super in your subaru or mitsy evo but not in your ford focus lx.

[the_lone_wolf]

Originally Posted by kwak zzr

top gear did a test on it didnt they, conclusion was its worth putting super in your subaru or mitsy evo but not in your ford focus lx.

in the manual from my dad's BMW 330 it recommends using a minimum octane rated fuel - most higher power cars recommend running on higher octane fuel, life the BMW K1200 engine, if the engine management system notices knocking it retards the ignition, you won't destroy the engine by using standard fuel if the car is smart enough to change the timing, but you won't be getting max performance either

my new toy is a race bike, in the manual it recommends using min 98 octane, thankfully the tank is only 7 litres so i won't notice the hole in my wallet...

haha great, I've been wasting my money for years! However I only recently noticed on my Rex that it recommends high octane fuel, although it doesn't have a turbo or supercharger. I would use it if it weren't 1.20 a litre!

Yes, if running a turbo motor.

[yorkie_chris]

Not exactly. Any engine with a knock sensor will benefit.

Carbed engines can be affected by the grade of fuel due to very slight density differences.

I find V-power and the equivalents offered by other fuel companies DO make a differance to my restricted curvy aswell; I have noticed improved throttle response and a smoother engine on the more expensive fuels.

I used it all winter to keep the problems of carb icing at bay, and switching back to cheaper unleaded now its warmer has shown that the expensive stuff DOES make a differance - to my restricted bike, at least. I will be interested to see if there is any significant (noticable) differance in bike performance when using differant fuels when the bike is back to full power.

I'll conduct a test during july, and post the results.

Matt

Yes if running a high compression motor.