High Octane fuel - the facts and the fiction.

[obi_waynne]

So does high octane fuel give more power? Does it make your car more economical? Will it work well in all engines?

Read the new article for more details.

http://www.torquecars.com/articles/fuel-octane-ratings.php

Does it say what you thought all along? Do you use high octane fuel?

 

[fingers]

I have to say that the only car that I have ever known to run any better on the roads for day to day driving is my old Rover, that runs like a bag of nails on 95 RON stuff. But that does have a red sticker in the rear window from the factory saying not to put anything lower than 97RON or 5 star fuel (who remembers that?) in it.

 

[obi_waynne]

I remember 4 star leaded!

 

[fingers]

I think leaded fuel came in 2, 3, 4, and 5 star grades.

2 star - 87 octane
3 star - 93 octane
4 star - 97 octane
5 star - 101 octane

I can remember my mum pulling into a petrol station when I was a kid and seeing these on pump.

 

[obi_waynne]

Which fuel do you use in your car then?

 

[TCJBOLDIE]

98 RON in the Starion. It would easily crack the 400 HP ATW at the existing 19 psi boost on the E85 fuel but that would require app 30% more injector flow and a retune.

 

[SLEEPER]

For tuned engines high octane fuel is better and in some cases a must unless the car has been mapped for a lower octane


i use 99 momentum and the stagea has been mapped for it.

on the caldina the ecu is supposed to recognise if the engine doesnt have the correct fuel and changes the settings

 

[HDi fun]

High octane does not mean high calorific value. Tesco Momentum 99 is one of the poorest fuels available in that respect.

 

[RobBentley]

There's numerous factors to take into account here, as to if its worth it. Firstly does the car have knock detection, secondly is the ECU setup in such a way it has the ability to advance the timing beyond what's going to be achievable on 95 octane fuel. Thirdly octane isn't everything. As HDI says the calorific value of the fuel can also be taken into account. This is an interesting one though because what works best will be very engine dependant. Where cylinder temperatures are very high a fuel which burns cooler can be beneficial with regards to knock prevention.

I keep thinking about doing some proper testing of the different fuels, and the actual effect on power and timing - but its just finding the time to do it.

 

[HDi fun]

High octane fuel doesnt necessarily burn cooler. It justr resists ignition better than lwoer octane fuel.

 

[RobBentley]

I wasn't refering to the octane... I was refering to the calorific value in relation to what you said about Momentum 99

 

[HDi fun]

I wasn't refering to the octane... I was refering to the calorific value in relation to what you said about Momentum 99

Yes - I reread your post.
There are many factors that influence uncontrolled igntion. Fuel/air mixing is a biggie. Ultimately it's combustion chamber temperature. Diesels operate on higher [temperature] the better principle.

 

[RobBentley]

Yes - I reread your post.
There are many factors that influence uncontrolled igntion. Fuel/air mixing is a biggie. Ultimately it's combustion chamber temperature. Diesels operate on higher [temperature] the better principle.

Glad we're on the same page now . As I said there are so many variables with petrol it would be good fun to test a load of fuels - it's just time consuming!

 

[HDi fun]

I'm up for a rporting project !!! Mssrs Esso and Shell can supply you & I with fuel to play with. Anyone else interested in joining?? :-D

 

[obi_waynne]

I'll join as well and I think we'd need at least a year to conduct proper tests!

 

[HDi fun]

I certainly need 30,000 plus miles to form a valid opinion. Anything less would be unfair and therefore unreasonable for others to base their opinions upon. The more the merrier