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W8 Fuel Octane Rating

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markw8 View Drop Down
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  Quote markw8 Quote  Post ReplyReply Direct Link To This Post Topic: W8 Fuel Octane Rating
    Posted: 11-May-2010 at 17:57
My european spec W8 states 98 octane fuel, but will run on 95 octane with a slight loss of power (no thanks!). I notice also that in the U.S. they have 91 octane and the W8's power output is rated at 270 bhp. There are several petrol suppliers in the U.K. & Europe that now have higher octane fuel:

BP ultimate 97 or 102
Tesco 99
Shell V-Power 99

Some of these fuels are available with higher octane in Germany for example. The penalty you pay cost wise is around 5p per litre more than 95 octane.

Has anyone tried these higher octane fuels and noticed a difference?

W8 owner Northampton, U.K.
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  Quote XeRo Quote  Post ReplyReply Direct Link To This Post Posted: 11-May-2010 at 23:05
Higher octane doesn't mean more power. High octance simply mean there is less of a chance to get knock (detonation, bad :( ). The increase in power comes from the ability to advance the timing resulting in more power. You won't see a gain from 91/95 to 100+ unless it's setup from the factory to utilize the octance knock prevention or you have a custom tune and have tuned it to run on 100 octance.

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  Quote RobG Quote  Post ReplyReply Direct Link To This Post Posted: 12-May-2010 at 03:11
Not sure if it helps, but the US has a different rating system to Europe as regards octane ratings. I got this from wikipedia (so may be completely inaccurate :)

Generally, octane ratings are higher in Europe than they are in North America and most other parts of the world. This is especially true when comparing the lowest available octane level in each country. In many parts of Europe, 95 RON (90-91 AKI) is the minimum available standard, with 97/98 RON being higher specification (being called Super Unleaded). The higher rating seen in Europe is an artifact of a different underlying measuring procedure. In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in Canada, the United States and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in Canada and the US, would be 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90–91 US AKI=(R+M)/2, and deliver 98, 99 or 100 (RON) (93-94 AKI) labeled as Super Unleaded - thus regular petrol sold in much of Europe corresponds to premium sold in the United States.

Since i got it, i've tried to only fuel it with shell's vpower. I have on occasion had to put other super in (usually tesco) but it's felt slightly sluggish, and the miles per tank has dropped a bit.
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  Quote yesimalex Quote  Post ReplyReply Direct Link To This Post Posted: 12-May-2010 at 13:46
I use sheetz ultimate .... sheetz are f*n awesome
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  Quote markw8 Quote  Post ReplyReply Direct Link To This Post Posted: 12-May-2010 at 15:15
Not heard of them as they are a family run business in the U.S.

http://en.wikipedia.org/wiki/Sheetz

I guess that the W8's engine management system is "mapped" for the fuel available in the country where it's destined for. Also the mapping must allow for a range of fuels. The knock sensors will automatically back off the timing if the fuel quality is poor/under spec.



Edited by SirRangeALot - 12-May-2010 at 20:22
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  Quote yesimalex Quote  Post ReplyReply Direct Link To This Post Posted: 12-May-2010 at 18:21
All of this is controlled by the ecu and is adaptive to whatever gas your using. As far as best gas or what additives are better...

"EPA requires the use of additives to control the formation of engine and fuel supply system deposits in all U.S. gasoline. An interim program has been in place since 1995 which requires the use of detergents to control intake valve deposits (IVD) and port fuel injector deposits (PFID) in gasoline engines, but did not include rigorous performance standards for the additives. The requirements of the interim program have recently been replaced by those of the detergent certification program which requires specific vehicle-based performance testing, using industry-standard test procedures, to demonstrate the effective control of IVD and PFID." -epa.gov granted thats US folks but.


I think the people who see better performance are really only seeing consistency. The ecu changes the air fuel mix in accordance to what it's sensors tell it. If you constantly use the same gas you will see consistent results. Lots of thing in life worth fretting about.. gas is not one of these things.
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  Quote RobG Quote  Post ReplyReply Direct Link To This Post Posted: 13-May-2010 at 03:22
Just curious, what does it cost to fill the tank over there? On average its costing me 85 gbp just now (would be around 125 dollars)
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  Quote squish Quote  Post ReplyReply Direct Link To This Post Posted: 13-May-2010 at 06:34
A fill-up of BP or QT Premium costs me ~$65 USD
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  Quote yesimalex Quote  Post ReplyReply Direct Link To This Post Posted: 13-May-2010 at 09:49
about 55 usd for premium (last week). You guys (over the pond) pay way heftier taxes for gas. I mean a 1.8 is considered pretty large for a commuter car there. Your driving a 4.0
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  Quote Majorn Quote  Post ReplyReply Direct Link To This Post Posted: 13-May-2010 at 10:14
I wouldn´t do anything other then drive if we had your gas prices, a complete fil-up over here costs about $150
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