Petrol and Ignition Advance

[Engineer]

I know that the 1200GS only requires 95 octane petrol - however if I put in 98 octane fuel will the engine management system advance the ignition any further?

I suppose what I'm asking is : Does the engine management system advance the ignition to the point of 'knock' being detected and then back off slightly regardless of the fuel rating?


This should cause a debate!! )

 

[Greg Masters]

Does the engine management system advance the ignition to the point of 'knock' being detected and then back off slightly regardless of the fuel rating?

Likely to be 'Yes', but only up to a certain point. There is a value with all ICE engines where further advancing the ignition produces no more power.

Greg

 

[Deleted account 211025001]

I've often thought this must be the reason people feel an improvement in power when using Optimax etc

Andres

 

[cookie]

I've often thought this must be the reason people feel an improvement in power when using Optimax etc

Andres

i wonder why they report improvements on 1150s which have no knock sensor & no means of advancing the timing due to higher octane fuel

 

[Deleted account 211025001]

i wonder why they report improvements on 1150s which have no knock sensor & no means of advancing the timing due to higher octane fuel

Doh! Hadn't thought of that..................

I'll get me coat

Andres

 

[Alex]

i wonder why they report improvements on 1150s which have no knock sensor & no means of advancing the timing due to higher octane fuel

Late dual spark 1150s have knock sensors, so some of the ones who reported improvement may have a point

The question however is the following. Does a manufacturer who sells a bike to be run with 95 unleaded give it the option to advance its timing enough so as to use the improved performance the 98 unleaded offers? Or does he simply give the option to retard the timing so as not to damage the engine should a lower quality fuel be used, keeping the optimum condition for 95 fuel??

Do you think manufacturers would risk the increased pollution and engine temperatures caused by the engine producing more power or the higher development and product costs(so as to develop engine mapping to suit a wider range of conditions) just for these few people who wish to see improvement when running higher quality fuel than the one specified??

I think it's unlikely, although i wish it was true...

 

[Deleted account 211025001]

Thanks Alex, I've hung my coat back up

I wonder if, it's not a case of the timing adjusting to suit higer than 95 RON petrol - as you say, this would seem unlikely - but more to do with the fact that petrol quality may vary and the petrol we buy is maybe more like 92/3/4 RON?
This could cause the engine management system to retard the timing in some instances.

Put in Optimax etc. and as far as the engine is concerend it has full on, proper 95 RON petrol and is able to run at optimum ignition timing and this is the improved 'feel' that alot of people experiance with such fuels?

Just my two pence worth, ready to put my coat back on.........

Andres

 

[cookie]

Late dual spark 1150s have knock sensors, so some of the ones who reported improvement may have a point

The question however is the following. Does a manufacturer who sells a bike to be run with 95 unleaded give it the option to advance its timing enough so as to use the improved performance the 98 unleaded offers? Or does he simply give the option to retard the timing so as not to damage the engine should a lower quality fuel be used, keeping the optimum condition for 95 fuel??

Do you think manufacturers would risk the increased pollution and engine temperatures caused by the engine producing more power or the higher development and product costs(so as to develop engine mapping to suit a wider range of conditions) just for these few people who wish to see improvement when running higher quality fuel than the one specified??

I think it's unlikely, although i wish it was true...

interesting that late bikes have knock sensors, i didn't know that.

i believe timing advance to to improve performance with higher octane fuels is standard on audi TTs & impreza turbos at least.

 

[Greg Masters]

interesting that late bikes have knock sensors, i didn't know that.

I don't think that BMW know that either!

Here's what they say about the 1200GS:

... and this is the equivalent for the last R1150GSA:

Greg

 

[Alex]

The latest 1150GSAs as used by Ewan McGregor and Charlie Boorman have twin spark engines with knock sensors and can use lower octane fuel. Maybe the web page you display hasn't been updated recently.
All pre 2003 1150s are single spark.

 

[Alex]

Interesting. The international section of the BMW website is exactly the one you have shown us above. The Greek section of the BMW website says it has the twin sparks and knock sensors. Also my Greek market 1150GSA has twin sparks. Maybe it was a market specific option?