I saw a press release from Honda UK a year ago which said that although all models could run on 95, 98 was recommended, and the labelling was amended to this effect.

I think the impression given on the earlier models was that it was 98 RON or not at all. MY02 onwards now make it clear that while 98 is recommended, 95 will do under emergency conditions.

 

Funny then, that whenever I've test driven an S, or when I picked my last one up that it was run on 95RON.

When will the dealers ever learn

 

Optimax is 98 RON....

Here's an email from Shell..........read from the bottom up....

Shell Optimax is a completely new unleaded petrol that is suitable for all cars that run on unleaded petrol.
The octane rating of Shell Optimax is 98 which means it is the highest octane fuel currently available in the UK.
It is not just the octane rating that differentiates Shell Optimax from other fuels. Shell Optimax is a unique highly refined new formulation which burns more cleanly to give you smooth power delivery. It is able to do this because:
* as the petrol with the highest octane rating in the UK it enables advanced modern design engines to work more efficiently thereby delivering more power
*it has the ability to remove performance sapping deposits left by other fuels from the airways of the engine
*it is free of the heavy constituents of petrol that leave dirty residue in you engine.
The combination of these effects means that the fuel and air flow smoothly and quickly to the engine, burning more effectively to give you increased performance and a quicker response.
All our service stations including those selling Optimax can be found on the following website;
www.shellstation.biz
If you require any further information then please do not hesitate to contact our Customer Service Centre on our free phone number 0800 731 8888.

Retail Customer Relations
Shell U.K. Oil Products Limited
Rowlandsway House, Rowlandsway, Manchester M22 5SB, United Kingdom

Tel: +44 161 947 5523 Fax: +44 161 499 8088
Email:
Internet: http://www.shell.com/uk

-----Original Message-----

Sent: 17 August 2003 18:25
To: Customer Services,
Subject: Fw: New fuel type



Dear Customer Services,

Thanks for the info, what is the current RON rating for Optimax ?
What are the other factors influencing performance other than Octane rating?

Thank you


> ----- Original Message -----
> From:
> Sent: Friday, August 15, 2003 8:19 AM
> Subject: RE: New fuel type
>
>
> Thank you for your recent e-mail.
> Shell has a Global programme of developing unique fuels tailored to meet
> local customer needs on a market by market basis. Shell has already
> successfully launched differentiated fuels like V-Power in over 30
countries around the world. We have, however, gone out of our way to tailor each
fuel specifically for the requirements of the consumers, their cars and local
> legislation in each country. V-Power is not the same as Optimax, it is
> solely a performance based initiative (the increased performance is not
> necessarily octane derived), whereas Optimax is both a performance and
> protection based initiative, and in general it is a higher octane fuel.
> Shell Optimax is a completely new unleaded petrol giving Optimum
performance
> and maximum protection. There are currently no plans to introduce V-Power
> to the UK.
> I very much regret that I do not have any other information on the V-Power
> which is sold in other countries.
> Kind regards,
>
> Customer Service Professional
> Shell U.K. Oil Products Limited
> Rowlandsway House, Rowlandsway, Manchester M22 5SB, United Kingdom
>
> Tel: +44 (0)161 947 5875 Fax: +44 (0)161 499 8088 Other Tel: +44 (0)800
731
> 8888
> Email:
> Internet: http://www.shell.com/uk
>
>
> -----Original Message-----
> From: Sent: 14 August 2003 18:47
> Customer Services, Customer C SUKOP-UOCS/89
> Subject: Re: New fuel type
>
>
> Dear Customer Services,
>
> I've heard Shell is dropping Optimax in favour of a 100 RON fuel called V
> Power.
> Can you advise if this is true?
>
> Regards

 

well, the Q8 opposite my house has 'real' 98 ron.

 

Great email Steb, I really thought that V-Power was the same as Optimax, so good call

Also reassuring to know that Optimax is 98RON, but I am confused to why this is not stated on the pumps

 

[QUOTE]Originally posted by wedgemorgan
[B]I saw a press release from Honda UK a year ago which said that although all models could run on 95, 98 was recommended, and the labelling was amended to this effect.

I think the impression given on the earlier models was that it was 98 RON or not at all.

 

Almost correct
The octane rating of a fuel is derived from it's ability to reduce knock. To test the octane rating fuel is put in a specially designed single cylinder engine that can alter the compression until knock occurs. This is then compared to two reference fuels (n-heptane - zero octane - and iso-octane - 100 octane) that are blended and when the knock characteristics are the same the fuel is given that rating.

When you run an engine there is a base map in the ecu that derives initial settings for the engine (VVT angle, Ignition timing, fueling ratio's etc.) at the moment of engine start-up the engine uses this as it's immediate setting (these will be well clear of any point where knock would ever occur). Once it's turning over it can collect data and begin accessing various other maps within the ECU to try and boost power, cool the exhaust, save fuel etc.

To try and improve the power of the engine the ECU will begin to advance the ignition timing until the knock sensor "hears" (it is listening for a specific vibration frequency in the engine) the engine knocking and that knocking crosses a threshold limit. At this point the ECU retards the timing again and the two maps then begin to argue where the ignition timing should be.

The higher the octane (RON) rating the later the engine can ignite the mixture and hence power increases. With lower octane rating's knocking occurs earlier therefore the timing has to be retarded and you will get power loss and loss of fuel economy.

Using Lower octane rating fuel will not damage your engine. However higher octane fuels tend to be purer and in some countries the contaminants (such as sulpher) are high enough to cause damage if used for extended periods (say 30,000 miles plus). These countries tend to be the eastern/southern european ones (and america actually) France, Germany and England have to have sulphur content of petrol less than 50ppm by law (whatever the octane rating) whereas in Poland, Hungary and the states they are allowed 500pm and due to working practices (of using the same tankers for petrol and diesel) often tend to have sulphur contents of 1000ppm or greater.

In conclusion there is no problem with using 95ron in UK as long as you can live with the performance loss

 

So... is it the fact that the higher RON gives a slower burn which allows the ignition timing to be closer to TDC?

 

[QUOTE]Originally posted by fluffyninja
[B]
When you run an engine there is a base map in the ecu that derives initial settings for the engine (VVT angle, Ignition timing, fueling ratio's etc.) at the moment of engine start-up the engine uses this as it's immediate setting (these will be well clear of any point where knock would ever occur). Once it's turning over it can collect data and begin accessing various other maps within the ECU to try and boost power, cool the exhaust, save fuel etc.

To try and improve the power of the engine the ECU will begin to advance the ignition timing until the knock sensor "hears" (it is listening for a specific vibration frequency in the engine) the engine knocking and that knocking crosses a threshold limit. At this point the ECU retards the timing again and the two maps then begin to argue where the ignition timing should be.

 

Not entirely.

Kind of difficult to explain without sketching pictures but knocking/pinking is detonation of the fuel where as what you want in an engine is the fastest possible burn. When the spark plug ignites the fuel mixture it generates a flame front that burns across the combustion chamber. Behind that flame front it begins to compress the unburnt mixture. If that level of compression is two high then the unburnt mixture detonates (giving the familiar rattle). The octane rating helps to allow the mixture to burn without detonating