95 RON

[pazz]

For the first time since owning the ED30 I've been forced to put 95 RON in her. It wasnt an easy decision believe me  

Partly as an experiment but mostly due to the fact that I just couldnt bring myself to pay 109p a litre for VPower. Especially when diesel was only 103p.

The car is not re-maped so I cant see it being any cause for conern.

But I'd be interested to know if anyone sticks by 95 RON and uses it reguarly? Are there any drawbacks other than the expected lower power figures?

FTW!!!

[Top Cat]

I thought it worked out cheaper to put in the higher RON as you get better mileage from it.   

[Janner_Sy]

i know my car runs like sh*t on 95ron fuel. the higher the octane is cleaner and better for the engine. plus better mpg on mine by 2-3mpg

[john_o]

in emergencies then yeah its fine ...
but in a std ed30 it makes the car feel 'flat'
i guess if you drove everywhere 'slowly' then the economics might work out but then we dont buy GTI's to go slowly....

[pazz]

in emergencies then yeah its fine ...

See I dont agree with this on a standard map. 95 RON will admitedly produce more knock but will be solved by chucking more fuel in to adjust.

I had guessed that the MPG may suffer, but thought I'd give £15 worth a try to guage the difference of using a lower grade of petrol.

I use my ED30 to get to work and back everyday, so I dont always drive it like I've stolen it.

[Tarmac_Terrorist]

I always use V Power in mine but i've been trying to get a grasp of how these detergents in fuel actually help (aside of keeping injectors clean).
Obviously, higher octane fuel will allow the timing to advance and run better. There is an article in Auto Express this week on buying a used GTI mkv and they very briefly mention cylinder head issues on some arising from using 95 ron fuel??? Unfortunately it doesn't elaborate.
The only cylinder head issues I can imagine is the coking of the valves which can affect some direct injection engines (FSI)  (oil mist spraying on the valves i think). The thing is, if the fuel is directly injected, exactly what do the detergents clean anyway?

I'm personally a bit confused as to how 95 ron fuel could harm anything. Perhaps someone could advise in simple terms (I'm no mechanic but have basic engine understanding).   

[bacillus]

Using that lower octane fuel will also mean that your car will emit more enviromentally unfriendly NOx...

btw using the lower octane fuel will cause the ecu to pull timing and run less efficiently vs 98/99 RON fuel hence the lower mpg.

[pazz]

I'm personally a bit confused as to how 95 ron fuel could harm anything. Perhaps someone could advise in simple terms (I'm no mechanic but have basic engine understanding).   

You generally obtain lower combustion charge temps by using higher grades of petrol. This results in less "knocking" and is more prominent in engine's running high compression ratio's.

See here for a fantastic definition of knocking: http://www.britannica.com/EBchecked/topic/320471/knocking

[Hurdy]

I can't see the point in spending £XXK on a sports hatch and then saddling it with a lower octane fuel that won't clean the engine as well as 98 octane, nor will it give you a better mpg, nor is it the recommended fuel for the ED30.......and all for the sake of saving 8p a litre

[Oli]

You'll be wanting to put budget tyres on it next!!!

Don't do it, the engine was designed for the higher octane, and the FSI engines need it, for lubrication and cleaning purposes

[Tarmac_Terrorist]

You'll be wanting to put budget tyres on it next!!!

Don't do it, the engine was designed for the higher octane, and the FSI engines need it, for lubrication and cleaning purposes

Oli, how does the higher octane fuel lubricate / what does it lubricate / clean - especially with direct injection?

[DaveB@Vagbremtechnic]

The cleansing properties of fuel have nothing to do with the Octane rating, Shell Fuel may have cleansing properties that Esso doesnt have and vice versa, the octane rating demonstrates the calorific value of the fuel and its detonative behaviour. In the old days of 4* it used to be tetra ethyl that used to be used to bump up the octane value, Old aircraft engines used to use 110 octane for more power.

I'm not sure what they use now  - any metallic compounds will reduce knocking obviously not lead anymore.

Anybody who has decatted should technically be able to use 100 octane aviation fuel  - anybody willing to try it   

[iainalpine]

95 RON - this cant withstand high compression pressure. you will find at the end of the compression stroke the pressure is at its highest point, this when using 95 RON will allow the remainder of the air/fuel mixture to detonate/knock.

99 RON - this can withstand higher internal pressures and temp's.

I remember back in the days of running the impreza with the GEM's engine management ECU, i could switch between 95 and 99 RON, but when dropping back down the car felt so much slower. The gems ECU allowed the use of a flick switch to switch which changed the timing setting pulling the timing back quite a few degree's.

Advanced Knock controll found on MKV's allow the ECU to controll timing very well, but when pushing on with 95RON you will find a lot of correction.

Bottom line..............................stick with 99 RON

Just my 2 pence

Iain

[tony_danza]

The cleansing properties of fuel have nothing to do with the Octane rating, Shell Fuel may have cleansing properties that Esso doesnt have and vice versa, the octane rating demonstrates the calorific value of the fuel and its detonative behaviour. In the old days of 4* it used to be tetra ethyl that used to be used to bump up the octane value, Old aircraft engines used to use 110 octane for more power.

I'm not sure what they use now  - any metallic compounds will reduce knocking obviously not lead anymore.

Anybody who has decatted should technically be able to use 100 octane aviation fuel  - anybody willing to try it   

I was running mine on 100 at the 'Ring - it was an animal on it!!

[Janner_Sy]

i use shell v power racing 100. and it makes the car run sweet