Premium Fuel in a V12V
Discussion
I've always been one to use Shell V-Power in any high performance car I've owned. Upon purchasing my V12V I was told by the dealer that 95RON was perfectly fine and premium unnecessary. Nonetheless (following tradition), I've been using V-Power in the V12V since it says 98+ inside the cap.
I was interested in the opinion of other V12V owners, perhaps ones that have used both regular and premium and can comment on any real world differences. I doubt I will change to regular but I'm intrigued to know.
I was interested in the opinion of other V12V owners, perhaps ones that have used both regular and premium and can comment on any real world differences. I doubt I will change to regular but I'm intrigued to know.
Whilst these cars are well out of my league, I always use vpower in anything performance orientated even if I know there is no performance benefit as in my VX220.
Much like I won't use supermarket oil, I won't use supermarket fuel - wether I've just fallen for a marketing swindle I don't know, but it makes me feel better! The placebo effect is worth a few quid a tank
Much like I won't use supermarket oil, I won't use supermarket fuel - wether I've just fallen for a marketing swindle I don't know, but it makes me feel better! The placebo effect is worth a few quid a tank
Yup complete waste of money in a V12V engine as no knock sensors to adjust the timing and so cannot take advantage. Read the fixed threads above - I think it was covered in the BR thread from a posting by BamfordMike.
The Vanquish and V12VS engines have a later version of the V12 and do have a knock sensor and so are worthwhile putting in super unleaded / v-power.
The Vanquish and V12VS engines have a later version of the V12 and do have a knock sensor and so are worthwhile putting in super unleaded / v-power.
Having read some independant tests on V Power it does have other benefits apart from the higher RON rating with the main one being cleaning properties.
I am sure it was Evo who stripped 2 engines and inspected them and then ran them on V Power for a few thousand miles, when re inspected the internals had been cleaned by the additives in the fuel.
I am sure it was Evo who stripped 2 engines and inspected them and then ran them on V Power for a few thousand miles, when re inspected the internals had been cleaned by the additives in the fuel.
controlz said:
If premium fuel is waste, why does it say 98RON+ under the filler cap when unleaded is 95RON
As a clean engine should be more efficient then presumably because of the cleaning properties only.My old 5 litre Griff used to pink if I ran it on 95 RON and I don't think the V8 in that had knock sensors so maybe its to reduce the risk of that on your V12.
Quote from page 4 of the BR thread at the top of the page:
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.
Onto the V8
The V8 does have knock control (thanks to great hardware from Jag and a fantastic cal job from someone on this forum..)
The base mapping was conducted on 97 Octane, meaning 380BHP for 4.3L and 420BHP for 4.7L is achieved using 97 Octane. If 95 Octane is used then the quoted performance levels will not be achieved. Using the same standard above; 372.5 BHP for 4.3L and 412.5 BHP for 4.7L will be returned. Furthermore, if 91 Octane fuel was used then the knock control system would re-adjust spark so that no damage to the engine would occur, causing the loss of over 10 BHP (yes, this number doesn't follow the same rule stated above re performance loss / retardation of spark, as it is not a linear relationship over the entire fuel octane range).
This is one reason the AM power upgrade option works quite well. As discussed previously on this thread, the kit consists of valves in the airbox which open (outside noise drive-by regulations) to return lower induction system losses, worth approx. 10 BHP. Together with, and ONLY when 100 octane fuel is used, the remainder of the 10 BHP comes from advanced spark, re-adapted to the higher Octane fuel. However, you pays your money you takes your choice... The kit is £2k and to get the final 10BHP you need to fill with 100 Octane (if you can find it), meaning a very expensive fuel fill to get that last little bit of performance. So the debate would be... is there a better performance upgrade option for the outlay of around £2k..??!!
Hope this answers your questions..
Mike.Note that this was written before the latest Vanquish / V12VS version of the V12 engine was developed with a knock sensor, so relates only to the versions in the V12V/DBS/DB9 and earlier.
BamfordMike said:
alex2 said:
Thanks for your various interesting technical contributions Mike.
Out of interest and given your experience with engine development at Aston Martin, is there any performance advantage to be gained from using higher octane fuel in the recent V8 and V12 engines?
Good question, I understand this is a topic which is often discussed.Out of interest and given your experience with engine development at Aston Martin, is there any performance advantage to be gained from using higher octane fuel in the recent V8 and V12 engines?
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.
Onto the V8
The V8 does have knock control (thanks to great hardware from Jag and a fantastic cal job from someone on this forum..)
The base mapping was conducted on 97 Octane, meaning 380BHP for 4.3L and 420BHP for 4.7L is achieved using 97 Octane. If 95 Octane is used then the quoted performance levels will not be achieved. Using the same standard above; 372.5 BHP for 4.3L and 412.5 BHP for 4.7L will be returned. Furthermore, if 91 Octane fuel was used then the knock control system would re-adjust spark so that no damage to the engine would occur, causing the loss of over 10 BHP (yes, this number doesn't follow the same rule stated above re performance loss / retardation of spark, as it is not a linear relationship over the entire fuel octane range).
This is one reason the AM power upgrade option works quite well. As discussed previously on this thread, the kit consists of valves in the airbox which open (outside noise drive-by regulations) to return lower induction system losses, worth approx. 10 BHP. Together with, and ONLY when 100 octane fuel is used, the remainder of the 10 BHP comes from advanced spark, re-adapted to the higher Octane fuel. However, you pays your money you takes your choice... The kit is £2k and to get the final 10BHP you need to fill with 100 Octane (if you can find it), meaning a very expensive fuel fill to get that last little bit of performance. So the debate would be... is there a better performance upgrade option for the outlay of around £2k..??!!
Hope this answers your questions..
Mike.
The premium fuels are more beneficial than just allowing a more aggressive timing curve,
They run a cleaner engine and this alone improves engine performance , or to be more accurate, maintains engine performance on new engines and cleans and improves already fouled, older engines.
You can always take advantage of the additional octane rating by remapping the car to suit the higher spec of the fuel.
Shell V-Power is not generally considered the best option though as there are numerous reports of engine poor running when using it across all marques in the performance car ranges. I use BP ultimate personally when available and have the car mapped to suit although I experience no issues at all using normal 95 RON either.
It may make even lower spec fuel a bit dicey but I dont think I have ever seen any lower here in the UK or Western Europe anyway.
They run a cleaner engine and this alone improves engine performance , or to be more accurate, maintains engine performance on new engines and cleans and improves already fouled, older engines.
You can always take advantage of the additional octane rating by remapping the car to suit the higher spec of the fuel.
Shell V-Power is not generally considered the best option though as there are numerous reports of engine poor running when using it across all marques in the performance car ranges. I use BP ultimate personally when available and have the car mapped to suit although I experience no issues at all using normal 95 RON either.
It may make even lower spec fuel a bit dicey but I dont think I have ever seen any lower here in the UK or Western Europe anyway.
@F1NDW: Because the (new) Vanquish has the newest V12 engine WITH knock sensors (like the new V12VS), so higher octan will help (a little bit). Has no use however on V12V/DB9/DBS without ECU remap.
Indeed Shell V-Power is not the best option. Over here (NL) it is even considered the worst premium fuel, and BP Ultimate or Aral 102 the best. AS example: did an engine and performance test with my daily driver - RS5 - and V-Power showed much more "injection corrections" at higher revs then with BP Ultimate, which resulten in a measured 10-15 BHP difference on the power bench!
8Tech said:
You can always take advantage of the additional octane rating by remapping the car to suit the higher spec of the fuel.
Shell V-Power is not generally considered the best option though as there are numerous reports of engine poor running when using it across all marques in the performance car ranges. I use BP ultimate personally when available and have the car mapped to suit although I experience no issues at all using normal 95 RON either.
Any ideas about a good ECU remap for the V12 WIHTOUT knock sensors?Shell V-Power is not generally considered the best option though as there are numerous reports of engine poor running when using it across all marques in the performance car ranges. I use BP ultimate personally when available and have the car mapped to suit although I experience no issues at all using normal 95 RON either.
Indeed Shell V-Power is not the best option. Over here (NL) it is even considered the worst premium fuel, and BP Ultimate or Aral 102 the best. AS example: did an engine and performance test with my daily driver - RS5 - and V-Power showed much more "injection corrections" at higher revs then with BP Ultimate, which resulten in a measured 10-15 BHP difference on the power bench!
Edited by AWV12 on Sunday 14th September 17:02
F1 NDW said:
The manual recommends 98ron for best performance. I wonder why that is, after all its not as if Victor Gauntlet(RIP) still has a vested interest?
AWV12 this shot is from the manual from my car, the original V12 Vanquish not the new one with anti knock!You made an assumption didn't you? The wrong one! But I should have given all the info so fair play.
Also the Octane number, like the Cetane number in diesel relates to the speed of the flame front through
the mixture. The higher the number the slower it travels. Therefore the higher the number it should burn for longer.
It should actually give a bit more power.
Edited by F1 NDW on Sunday 14th September 17:40
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