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What fuel do you prefer in your roc?

  • Unleaded (95 RON)

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  • Super Unleaded (97 RON+)

    Votes: 6 66.7%
  • Diesel!!

    Votes: 2 22.2%
  • I dont care as long as it goes!!

    Votes: 1 11.1%
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Discussion Starter · #1 ·
Which fuel do you run your cars on? Does anyone go with the higher octane fuel (99RON) like vpower or bp ulimate(102)? If so, is it really better performance and efficiency or just 10% on your petrol bill.
 

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The book says it should be run on super unleaded i think? FSI engines are designed to run on the expensive stuff.
 

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I use shell v power. Just feel happier putting the stuff in. I've never used the normal stuff to make a comparison. If I couldnt get to a filling station which sold a premium fuel, I would put in a bit of the normal stuff. But I would never, never, never, never use supermaket fuel.
 

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As far as i can remember, there is no specific instruction to fill up on anything more than 95RON ( i looked when i got mine and couldnt see anything, cant be certain though ), i had a mk5 GTI and it had clear instructuons to use nothing less than 98 RON or the engine would suffer as a result ( i ignored this, and after 3 years the engine was getting rough ).

To be on the safe side i use V power, petrol prices are ok at the moment so i can live with the cost.
 

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HI
Just put 99oc tescos best in the roc today no change!
put vpower in the 120d would transform the car seems to work better on the big D
 

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I was led to believe that 95RON would be fine for the 2.0 tsi, although using higer RON will improve performance as the anti-knock sensors will contunually try to advance the ignition and the higher RON will allow this but it can take best part of a tank to be fully realised so just going for a 1 tank trial is not sufficient.
 

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30060744 said:
why not supermarket fuel
Because although the petrol is the same rating etc, supermarket fuels don't have the additive package that you get at Shell etc etc. Although you may see a Shell/Texaco tanker filling the tanks, what they wont do is put in the additive package afterwards. No question about it, supermarket fuel is not the same quality as the big boys.............
 

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i read somewhere you can put both normal unleaded or super unleaded in. i think it was 5th gear that did a test on whether there is actually any difference in performance between super and normal and there is, you get about 6bhp more using the super stuff. yea it was def 5th gear.
 

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business manager said:
Apparently the vehicle will only FSI if it has low sulpher fuel (which is usually super), so better fuel should make it run better around town (sub 50mph)
Great thread - it does amaze me that manufacturs don't put information like this out there as every owner of every car would like to know this wouldnt they? Some cars it helps and some it's just a plain waste of money.

Cheers, Tim
 

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business manager on Mon Mar 30, 2009 6:01 pm

Apparently the vehicle will only FSI if it has low sulpher fuel
What do you mean by this, FSI is an acronym not a verb, either the FSI functions or it doesn't.
 

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FSI stands for Fuel Stratified Injection which is the system your engine uses. Basically (according to my training) it pumps the fuel into the piston at the last minute reducing the amount of air present meaning that you get a larger spark and burn less fuel. This only operates under 50mph because over 50mph it gets too hot. For some reason (will need someone technical for this next bit) it needs low sulpher fuel to operate properly. This is why VW recommends better fuel for FSI based engines, which of course all TSI engines come from.

I hope someone more technical than me will come on here a ratify this as this is straight out of a 3yr old training session.
 

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OK, are you ready for this, note the sentence in the middle which states the technology reduces the potential to 'knock' which is the same as saying the same output can be gained with lower RON fuel.

The desired "stratified charge effect" is obtained in this way: the cloud of air containing sufficient fuel to form an ignitable mixture is kept to a confined volume and surrounds the spark plug at the moment of ignition. Since the fuel is delivered at a shallow angle by the injector, the cloud of fuel makes scarcely any contact with the piston crown: a so-called "air-guided" process.

After combustion, a layer of insulating air remains between the ignited mixture and the cylinder wall. This cuts the amount of heat lost to the engine block and increases the engine's operating efficiency.

In stratified charge operation, incidentally, we achieve lambda values of up to 4.0 related to the combustion chamber as a whole. This is essential if fuel consumption is to be reduced at low and medium engine speeds.

At full load, the fuel in injected synchronously with the air intake phase. This fills the combustion chamber homogeneously. Here again, this produces a definite reduction in fuel consumption together with higher power-output and torque figures than would be possible indirect fuel injection. This was demonstrated on the race-winning Le Mans engine, which runs permanently in the homogeneous mixture mode.

This has the advantages of reducing the tendency to knock as a result of direct fuel injection into the combustion chamber and the resulting internal cooling effect. In addition, the engine is capable of operating at a higher compression ratio.

The first of these new-generation engines is a two-litre four-cylinder unit. The engine block and the main dimensions are identical with the 96 kW (130 bhp) engine already familiar from the A4 and A6. It has a common rail injection system and a single-piston injection pump. Unlike Audi engines with fuel injection into the intake port, the cylinder head has four instead of five valves per cylinder. This is essential in order to provide space for the injector in the combustion chamber.

A two-stage intake pipe is used, with two length settings for use at higher and lower engine speeds. A continuous adjuster on the inlet camshaft varies the inlet valve opening times as required.

On the exhaust side of the engine we can see one of the fundamental elements needed for efficient exhaust emission control, the exhaust gas recirculation system. This operates more efficiently than previous systems, and diverts up to 30 percent of the exhaust gas back to the engine's combustion chambers. Two catalytic converters are provided for exhaust emission control: an underbonnet multi-stage three-way converter, and a NOx storage-type converter under the floor pan.

The NOx storage converter has been specially designed to suit the needs of a direct injection engine, and has a NOx sensor installed at the discharge end. It is a well-known fact that the conventional three-way catalytic converter is unable to break down oxides of nitrogen sufficiently in the engine's lean-burn phase; for this, the composition of the exhaust gas must be stoichiometric.

The higher levels of oxides of nitrogen that remain therefore have to be reduced to harmless nitrogen gas. This task is performed efficiently in the storage-type catalytic converter, which has a barium coating with which the oxides of nitrogen combine.

The storage-type converter is controlled by a mapped operating characteristic and by temperature. When the converter is saturated, the engine's mixture is enriched for a short time. This raises the temperature of the exhaust gas, so that the barium molecules in the converter release the oxides of nitrogen, which are then converted into nitrogen. The frequency of this enrichment depends of course on the engine's operating conditions, but normally averages only a few seconds in each minute of operation.

The maximum power output of this two-litre, four-cylinder engine is 150 bhp at 6000 rpm. Its peak torque of 200 Newton-metres is available between 3500 and 4000 rpm. Compared with an engine with the same output and indirect injection, a fuel saving of up to 15 percent is thus possible.
 

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LOL fair plays to you le savage. Hands up I'm totally out of my depth, by my own admission I'm not technical and rely on the professionals for this stuff. I can't say if this is true or not but sounds quite convincing. As I can't tell you why it needs to be low sulpher in the first place all I can do is regurgitate what I hear in my sales training which is technology for people who know nothing.

Like me
 

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LOL, am I really that convincing... thank god for google :D

Actually I do know a bit, well at least I used to, and I might have overstated myself before in saying that "the same as saying the same output can be gained with lower RON fuel" as this is not true and what I actually meant was that using a lower RON fuel can accommodated by the engine but will result in lower power output. It may be debatable that using a lower RON (less refined) fuel will lead to increased deposits and build up in the fuel system leading to quicker deterioration of the entire system, but this would take quite some time and could be mitigated by using good quality 95 RON.
 

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Actually that ties in to what I was saying. You can run it on nasty stuff but you won't get the increased power/fuel benefit which leads us to the same place.

Maybe I knew what I was talking about after all, just didn't know it. :shock:
 
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