A fuel question.

D

Duggy72

Registered User
Joined
Dec 16, 2012
Messages
83
Reaction score
14
Points
8
Location
NULL
Hello all,

I have read many threads regarding the benefits of using super unleaded so I'm not asking that question again.

When refuelling yesterday I noticed on my S4 fuel flap it said std petrol 91 ron or super unleaded 95 ron.

In the UK I believe that Shell fuelsave unleaded is 95 ron. Does this mean that the car thinks its on super unleaded? I believe that using super 97 ron or greater will only see greater power and economy gains but if the car thinks 95 ron is super then it will be achieving it's factory quoted power outputs with 95.

I'm not sure what ron the other main suppliers quote for their std fuel but I have read that Shell is 95.

Thanks.
 
The engine does not know what the octane is as such. Getting increased efficiency from fuel burn (be it as increased power or increased economy) is primarily a matter of ignition timing. As I understand it the S4 ECU has timing set for 95 RON. The ECU will act on knock sensors to allow the timing to ****** for lower octane fuel, but not to advance for higher octane. This must have been a decision at Audi during development.
With an ECU remap I believe that this process can be adjusted to allow timing advance for higher octane fuel, and that's why you'll see different power curves for different fuel (APR as an example).

So unless I'm wrong, you will see no benefit from using super 97 RON, 98 RON or higher in your S4 with the OEM ECU.
 
  • Like
Reactions: Chop., Duggy72, Bristle Hound and 1 other person
Standard unleaded is 95, VPower I believe is 99 (as is Tesco Momentum 99). Other "super" unleaded varies. Some are 97. You are correct the fuel flap states 91 min, 95 recommended. This is typically less than the 2.0T cars which are designed to be at their optimum using super unleaded.

In terms of how it works, the car should make the quoted figures on 95. The engine will adjust to different fuel grades so best to pick one and stick with it. If you're getting the car remapped it will need super by default.

On my standard S4 I found no fuel economy or power difference using super. Details here My S4 thread

My old B7 2.0T FSI fuel flap and manual clearly show these are designed from factory for super. The dealers don't make that clear to the punters as they don't like splashing out for super. So in effect many people are inadvertently de-tuning their cars.

IMG 20140604 1434372221
IMG 20140604 1431521881
 
  • Like
Reactions: swimboy, Duggy72 and Bristle Hound
Dippy said:
The engine does not know what the octane is as such. Getting increased efficiency from fuel burn (be it as increased power or increased economy) is primarily a matter of ignition timing. As I understand it the S4 ECU has timing set for 95 RON. The ECU will act on knock sensors to allow the timing to ****** for lower octane fuel, but not to advance for higher octane. This must have been a decision at Audi during development.
With an ECU remap I believe that this process can be adjusted to allow timing advance for higher octane fuel, and that's why you'll see different power curves for different fuel (APR as an example).

So unless I'm wrong, you will see no benefit from using super 97 RON, 98 RON or higher in your S4 with the OEM ECU.
Click to expand...
scotty76 said:
Standard unleaded is 95, VPower I believe is 99 (as is Tesco Momentum 99). Other "super" unleaded varies. Some are 97. You are correct the fuel flap states 91 min, 95 recommended. This is typically less than the 2.0T cars which are designed to be at their optimum using super unleaded.

In terms of how it works, the car should make the quoted figures on 95. The engine will adjust to different fuel grades so best to pick one and stick with it. If you're getting the car remapped it will need super by default.

On my standard S4 I found no fuel economy or power difference using super. Details here My S4 thread

My old B7 2.0T FSI fuel flap and manual clearly show these are designed from factory for super. The dealers don't make that clear to the punters as they don't like splashing out for super. So in effect many people are inadvertently de-tuning their cars.

View attachment 61717 View attachment 61718
Click to expand...
Sold on 95 RON for my S4 then :)
 
  • Like
Reactions: Duggy72 and scotty76
Thanks guys. I was surprised to notice that on the filler flap. Tbh I hadn't bothered to look.

It is strange that a 2.0 has 98 as super and the S4 has 95.

If no one has seen any benefits to using super on a std car that means more money for beer lol.

:)
 
  • Like
Reactions: Bristle Hound and scotty76
Scotty I just read your thread. Very informative. Thanks for the link.
 
  • Like
Reactions: scotty76
Duggy72 said:
Scotty I just read your thread. Very informative. Thanks for the link.
Click to expand...
You are welcome. If there's anything else you'd like to know just ask by replying to that thread or one of the many other threads or start a new one. :) Plenty of S4 owners on here now.
 
  • Like
Reactions: Chop. and Duggy72
Interesting the RS4 differs. Thought it was usually forced induction which needs the higher grade which is why the S4 seems an oddity.
 
Same here. 95 RON recommended. 91 RON 2nd choice in S4s. RS4s, 98 RON with 95 if necessary.
 
scotty76 said:
Interesting the RS4 differs. Thought it was usually forced induction which needs the higher grade which is why the S4 seems an oddity.
Click to expand...
Perhaps it's all to do with keeping the S4 firmly in it's intended slot in the B8 range.
 
  • Like
Reactions: scotty76
As we know the 3.0 TFSI is quite a capable engine and can easily be tuned to around 480PS. The stock B8s were around 350PS even though they were supposed to make 333PS and that's why Audi reduced the redline in the B8.5 to keep the power down. They needed to ensure there was a significant enough power gap between the S and RS. Maybe the decision to tune to 95RON instead of 98RON was part of this, but I think the reason is simpler: Audi are trying to sell S cars to the general public and not just enthusiasts. My guess is that there are a lot of S car buyers who would be annoyed that their car 'needs' super, especially if its a company car and their policy is 95RON only.
 
  • Like
Reactions: Duggy72
Tesco is a supermarket yeah? I remember drinking their cider in 2 ltr plastic bottles 30 years ago. Whose fuel do they rebrand? Is it less expensive? I ask this because we haven't gone down this pathway yet.
 
Tesco Momentum 99 for me (REVO stage 1+)
 
My mk5 GTI and 8P S3 had 98 as the recommended fuel type and it was something to do with allowing the engine to operate in the FSI mode more of the time which helped emissions etc though it did also develop more power for better fuel efficiency. I think the latest versions of the GTI / S3 2.0 TFSI engines now recommend 95 rather than 98 as well and presumably thats because the technology has advanced to the stage where then can better control the NOx thats generated as part of the FSI process and this was the reason why it couldn't run in FSI mode all the time.

Presume its the same for the 3.0TFSI in that they've just moved the technology on to allow the same result (emissions) for a lower / cheaper grade of fuel.
 
  • Like
Reactions: Duggy72
I seem to remember reading that there was a European directive that dictated that after a certain date, all new models of cars coming to the market had to run on "normal" fuel, obviously any car models coming on the market before that time but still being sold were/are not subject to that directive.

What I don't know is if supercars get hit a bit more with taxes and so can continue to get round that directive.
 
  • Like
Reactions: Duggy72
91, 95 & 98 RON fuel and all other sold at common fuel garages are what you call "normal" fuel so there is nothing out of the norm avaialbe.

Supercars are taxed and legislated in exactly the same way every other car is in both the UK and mainland Europe. I pay ovrer £495 a year in road tax because of the emissions which is the same as my mates brand new Range Rover and a friends Gallardo.
 
  • Like
Reactions: Duggy72
I think that you will find that what I refer to as "normal" fuel are what sells under the description of "UL" as opposed to "UL+".
 
Image
Out of curiosity I checked my fuel filler cap earlier and this is what's on my 2011 2.0 TFSI.
I always use Shell V-Power Nitro+ by the way...
 
  • Like
Reactions: scotty76
I thought Super, Premium were a minimum of 98 RON not 95?
Think we've started something now..
May need to get a new sticker lol...
 
Irrelevant of the name super etc. 95 is 95 etc, go by the numbers. Also, they don’t just print the minimum, mine has both but in reverse, 98 then 95 stating that 98 is the preferred fuel.
 
  • Like
Reactions: skiptowncat
My sticker shows 95 & 91. Can you actually find 91 in the UK?
 
GeoffDunk said:
Irrelevant of the name super etc. 95 is 95 etc, go by the numbers. Also, they don’t just print the minimum, mine has both but in reverse, 98 then 95 stating that 98 is the preferred fuel.
Click to expand...
Image

I decided to check the vehicles handbook as my fuel filler label only mentioned a min of 95 RON. Strangely the handbook mentions 91 as an emergency measure if there's no other fuel available too.
Doesn't really mention 98 RON & above/Super Plus however like I said I wouldn't use any thing other than Shell V-Power Nitro+
Seems to run the best (quicker and cleaner - exhausts tips stay clean) on that even if it does cost a bit more..
 
Last edited:
  • Like
Reactions: scotty76
Steroids/Super Unleaded
 
Last edited:
Interesting thread.

I honestly think there is some sort of mistake in the labelling on the B8 S4 in the UK, or Europe.
And since when have we called 95 premium? That is what the US guys call premium.

95 and 91 Ron just doesn't make sense. For a start when was the last time you saw 91 ron in Europe?

In the US they have shown gains of nearly 20hp using 94 vs 91 (we are talking Octane here) and nearly the same using 87 (which is 91 ron).

The B8 does have a knock sensor and it does ****** the timing going from 94 to 91, so why would the UK model be any different?
I just can't see them limiting you to 95 ron fuel, especially as far better detergents go into the premium fuels too.
 
I'd reckon that if you went "on tour" on "new Europe" and/or its neighbours, you might just find 91 ron petrol, as I said a lot earlier, there is a directive - or maybe just a "drive" to limit/stop the general demand of 98 ron etc petrol in established/developed Europe, so that translates into new cars "requiring" 91>95 ron petrol.
 
But why in the USA do they recommend 98 ron in the S4, but over here 95? It makes little sense.

Allowing 98 ron will allow advanced timing which not only gives better power but also better mpg, so it makes very little sense to not use what is commonly available, and I just can't see Audi limiting the map which in turn gives poorer official figures.

What other model says 95ron max?
 
I'm not saying I am right by the way, just that it makes no sense to me for Audi not to map their cars for the best fuel and the knock sensors ****** the timing as the fuel gets poorer.

They only have to show figures for the best fuel available, power and mpg, so why would they not allow 98 ron?

With the **** the VAG Group are in currently with regards to doctoring the official MPG/Emissions figures, it just doesn't make any sense for them to not bother allowing 98 ron fuels which can give a good 5-10% better MPG than 95 ron.
 
You must log in or register to reply here.

Similar threads

Marky007
Fuel filter change question
Replies
0
Views
472
Marky007
Marky007
J
A hello and a question
Replies
24
Views
1K
gary_a4_quattro
gary_a4_quattro
M90KKL
What a nightmare!! Drl question
Replies
0
Views
562
M90KKL
M90KKL
C
Question (may be a silly one)
Replies
1
Views
864
Necroscope
N
B
A question about the difference in B8s
Replies
8
Views
1K
bi_a_op
B
Top
Back