CMSMJ1 wrote:

alexibrow wrote:

I notice no difference at all in power / economy no matter what type of fuel I use. Provided the bike is running properly all modern petrols burn really really cleanly, and considering the VFR's 20 years old now I really think these modern fuels are wasted on the engine.

The octane rating is different though, and that's where the extra power comes from. :D

Extra power comes from extra air into the motor. The higher octane allows you to run higher compression rations which is a way of getting more air into it.

Higher octane fuel on it's own at the same compression as std is not likely to blow your socks off and I would guess it does onthing for power from the bang.

If it does lower internal friction, or does cause a more complete burn then yes...but the octane rating on it's own does nowt but let you squeeze more in if you want to..

rock on..the mental effect of the higher octane are more difficult to measure

Indeed.

A lot of it is psychological. The point I was trying to make about the 'added detergents' is that the VFR is a clean burning engine anyways, It's not as if using unleaded will make your engine dirty.

I have an NC24 engine here in pieces that has 57000km on the clock and internally it is spotless and that was always run on standard unleaded.

Unless you have some kind of electronic ignition with various knock sensors to adjust ignition timing etc performance gains will be minimumal if noticable at all.

I can't remember if it was topgear or 5th gear or a similar kind of show that did as identical test as possible using unleaded / super unleaded and didn't notice any difference.

UK Fuel is all good quality, and it says minimum RON 95 for Regular Unleaded, maybe higher. I could understand if your car / bike was built for it.

Each to their own though!

Ah found it...

just to everyone who took part in this post......just watched fifth gear and they did a test on optimax, bp ultimate and supermarket fuel on three cars:- a 81bhp clio, a 172bhp golf gti and a subaru impreza with 235bhp. They connected each up to a power/tourqe machine a did six runs for power increase only, each time resetting the ecu. Here are the results;

Clio- supermarket 81
BPU 81
Optimax 81

Golf-supermarket 172
BPU 174
Optimax 177

Impreza-supermarket 235
BPU 247
Optimax 249

As you can see, optimax is a winner but they did a tourqe test on the subaru to decide a clearer winner, optimax was well ahead of ultimate. (cant remember the exact figures) Thing is, looking at this your car needs to be powerful in the first place, as they pointed out if your car is geared to be economical a difference is non-existent. After 2 years of umming and arring wether optimax was better for my 1.6 90bhp xsara, its back to good old standard for me (although still steering clear of 'supermarket' petrol) the next time i fill up.

The fact is that any car with a decent ECU is likely gonna noticably benefit from using higher octane (slower burning) fuel, whereby the ECU can achieve much greater control of the (pre)ignition process resulting in more power and torque, as proven by the fifth-gear dyno tests....

what is it you don't want to believe about the results, that ECUs have moved on a bit in the last 20 years?

The test does have it's flaws / critcisms but unless it's closer than anything I could do. Basically you need an ECU and an engine that is capable of utilizing the higher octance for it to be any improvement.

nah..you need a turbo charger...which can use the additonal anti knock properties of higher octance to allow itself to run higher boost..more air...more power

good find nesophist

Is the golf a turbo too? just a lightweight one?

I stand corrected re octane rating! :D

alexibrow wrote:I stand corrected re octane rating! :D

Like a man in special shoes..lol

The mental effect works though...and going faster and making loud combustion noises is all in the head

That test is a little unfair as the Imprezza's timing will have been set up for high octane fuel in the factory and its ECU is designed to pull timing when a lower octane fuel is used. The Clio will be set up for a lower octane fuel hence no improvement when the higher octane fuel is used.
Soooo, save your 60p a tank its all in your mind.

Unless you live up Mt. Everest then it will make a difference....

Nooo it won't. That would require a change in air/fuel mixture.

using a higher octane doesn't always increase ur power output but wat it does do is help lower the stress on parts of the engine.
where i live we are 1400m above sea level & we have 93 octane & back in the day we had 87 octane up here i think. higher altitude less octane. but if u use a low octane at sea level u run the risk of knocking.
all that the higher octane will help wit is putting less stress on parts in the engine, or so that is what i have heard.

To be honest I have found that since I stopped using the higher octane fuel my nc30 runs much more smoothly, especially at idle. As when I was using the high octane fuel it was a bugger to start and keep running, now my bike will start and run without the choke, whether it's cold or not.