Discussion
CatalystV12V said:
Thanks for the confirmation. Was trying to find the thread but search engine is down again.
The info is on the Bamford Rose thread. To quote for posterity:BamfordMike said:
The V12 engine has no adaptive knock control / spark control hardware (sensors) or software (ECU program).
This means there is no mechanism to advance the spark angle if high (97 or greater) Octane fuel is used, or retard the spark if low (<95) Octane is used.
Higher the Octane rating number means the detonation limit is reduced, reduced detonation means that the spark can be re-advanced to gain additional power. The lower the Octane rating means detonation is increased and if the spark is not retarded, severe damage is likely (holed or cracked piston or failed sparkplug leading to damage from debris).
The basic mapping on all current V12's was conducted by the factory on 95 Octane. As there is no hardware or software present to re-advance the spark angle if higher Octane fuel is used, means there would be no performance benefit to be had, whatsoever, if high Octane fuel was used. Conversely, in markets (such as the States) where low fuel grades are available, if, say, 91 Octane was filled and the engine was held at high speed and load for prolonged periods, severe damage might occur. For this reason there are not many manufactures today that release engines to the market without knock control.
To give you an idea of the value of knock control, an industry standard charts an extra 1.5 degrees spark per additional octane rating. The same standard releases approx. 2.5 bhp per 1 degree spark. Meaning that when knock control technology is present, running 97 Supergreen will return an additional 7.5 BHP over 95 Octane performance.
So, until the day knock control is available on V12, save your money and fill with 95 Octane as there is no benefit whatsoever to be had from the higher octane fuel.
This means there is no mechanism to advance the spark angle if high (97 or greater) Octane fuel is used, or retard the spark if low (<95) Octane is used.
Higher the Octane rating number means the detonation limit is reduced, reduced detonation means that the spark can be re-advanced to gain additional power. The lower the Octane rating means detonation is increased and if the spark is not retarded, severe damage is likely (holed or cracked piston or failed sparkplug leading to damage from debris).
The basic mapping on all current V12's was conducted by the factory on 95 Octane. As there is no hardware or software present to re-advance the spark angle if higher Octane fuel is used, means there would be no performance benefit to be had, whatsoever, if high Octane fuel was used. Conversely, in markets (such as the States) where low fuel grades are available, if, say, 91 Octane was filled and the engine was held at high speed and load for prolonged periods, severe damage might occur. For this reason there are not many manufactures today that release engines to the market without knock control.
To give you an idea of the value of knock control, an industry standard charts an extra 1.5 degrees spark per additional octane rating. The same standard releases approx. 2.5 bhp per 1 degree spark. Meaning that when knock control technology is present, running 97 Supergreen will return an additional 7.5 BHP over 95 Octane performance.
So, until the day knock control is available on V12, save your money and fill with 95 Octane as there is no benefit whatsoever to be had from the higher octane fuel.
bizar......in the V8V I always tried to tank 98 (or even 100-102 when in Germany) and, however not (very) noticeable in performance, on averag I drove 50-60 kms more on a full tank (in similar driving conditions of course!), but I understand correctly that with the V12 engine it does not make any sense?
ok, will drive a few tanks with 98-102 and a few with 95 and see if the mileage differs significantly or not, but I am surprised that the V12 has no knocking sensor, I hought every modern engine has this....???
ok, will drive a few tanks with 98-102 and a few with 95 and see if the mileage differs significantly or not, but I am surprised that the V12 has no knocking sensor, I hought every modern engine has this....???
the question then is, can knock sensors be retro fitted and made to work with the existing ecu
or would you need a new ecu and the cost would then make the small potential power increase a bit pointless
regardless, such is the affection I have for my car, I can't quite bring myself to fill it with 95 ron yet.
some kind souls took pity on me in another thread that touched on this issue and reassured me that 97+ ron fuel is actually better, purer fuel anyway.
or would you need a new ecu and the cost would then make the small potential power increase a bit pointless
regardless, such is the affection I have for my car, I can't quite bring myself to fill it with 95 ron yet.
some kind souls took pity on me in another thread that touched on this issue and reassured me that 97+ ron fuel is actually better, purer fuel anyway.
The Pits said:
the question then is, can knock sensors be retro fitted and made to work with the existing ecu
or would you need a new ecu and the cost would then make the small potential power increase a bit pointless
regardless, such is the affection I have for my car, I can't quite bring myself to fill it with 95 ron yet.
some kind souls took pity on me in another thread that touched on this issue and reassured me that 97+ ron fuel is actually better, purer fuel anyway.
Upgrading would be insane (costly) I think, but indeed, I have the same psycholgical hurdle to fill with 95, after years of 98-102........but ok, happy that my Audi still "loves" this premium stuff (also increase in mileage of roughly 40-50 km on 60 liter tank) or would you need a new ecu and the cost would then make the small potential power increase a bit pointless
regardless, such is the affection I have for my car, I can't quite bring myself to fill it with 95 ron yet.
some kind souls took pity on me in another thread that touched on this issue and reassured me that 97+ ron fuel is actually better, purer fuel anyway.
As I wrote on the other thread, the only benefit is a better quality fuel with additives.
Anecdotally people often get better mileage on a tank, hard to see how this works though...
I still put Super in my DB9, 2-3 quid a tank doesn't kill me and keeps everything nice and clean in there.
Anecdotally people often get better mileage on a tank, hard to see how this works though...
I still put Super in my DB9, 2-3 quid a tank doesn't kill me and keeps everything nice and clean in there.
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