Discussion
George H said:
I think 97 RON develops more power with the V8. Doesn't affect the V12 at all as no knock sensor, I always use BP ultimate or Shell V-power in all my cars though.
Yup, benefits seen in the children's V8, not in the man's V12 - unless you have it remapped of course and timing changed to use 97/98. Then it makes a difference 
However, at this time of year with the traction available, how often are you really using maximum power in the car? Stick in sonme nice V-Power every few tanks to get the detergent benefits and switch to 97/98 in the summer when that extra bit of horsepower is useable.
yeti said:
Yup, benefits seen in the children's V8, not in the man's V12 - unless you have it remapped of course and timing changed to use 97/98. Then it makes a difference
However, at this time of year with the traction available, how often are you really using maximum power in the car? Stick in sonme nice V-Power every few tanks to get the detergent benefits and switch to 97/98 in the summer when that extra bit of horsepower is useable.
I think 470bhp is plenty for me, won't be remapping any time soon However, at this time of year with the traction available, how often are you really using maximum power in the car? Stick in sonme nice V-Power every few tanks to get the detergent benefits and switch to 97/98 in the summer when that extra bit of horsepower is useable.
I just use 97 RON all the time, for the sake of a few quid more per tank, I'll just stick with it. It's recommended on the Polo so I have to use it for that. I noticed a massive difference between Texaco's 97 RON fuel and BP Ultimate/Shell V power though, the latter 2 are of a better standard imo, and the only 2 I use now.
Yup, I have run all my cars on V-power for many years but upon reading the Bamford Rose article about 6mths ago I stopped putting V-power in the V12V and switched to 95 Oct Shell Fuel Save unleaded. There was no change in performance at all, but I swear I am actually getting a tiny bit MORE mpg now.
Mako V12V said:
I'm genuinely surprised at this 
So what happens to the extra RON?
The higher the Research Octane Number (RON), the more ignition advance angle the engine can withstand before detonating (metallic knocking sound that worst case destroys an engine). At peak power 1 degree spark equates to roughly 3 BHP. Roughly 1 increment in octane rating means it is possible to run 1.5 degrees extra ignition advance (95 to 97 = 2 octane rating x 1.5 x 3 = 9BHP).So what happens to the extra RON?
What happens to the RON and the potential BHP increase when 97 is filled into current V12 - it is entriely wasted because the engine isn't fitted with a knock sensor which costs a few quid. But as Lewis mentioned earlier, these premium fuels also come with good detergents, so it is not a completely wasted spend - but almost..!
Edited by BamfordMike on Monday 12th December 22:21
BamfordMike said:
Mako V12V said:
I'm genuinely surprised at this
So what happens to the extra RON?
The higher the Research Octane Number (RON), the more ignition advance angle the engine can withstand before detonating (metallic knocking sound that worst case destroys an engine). At peak power 1 degree spark equates to roughly 3 BHP. Roughly 1 increment in octane rating means it is possible to run 1.5 degrees extra ignition advance (95 to 97 = 2 octane rating x 1.5 x 3 = 9BHP).So what happens to the extra RON?
What happens to the RON and the potential BHP increase when 97 is filled into current V12 - it is entriely wasted because the engine isn't fitted with a knock sensor which costs a few quid. But as Lewis mentioned earlier, these premium fuels also come with good detergents, so it is not a completely wasted spend - but almost..!
Edited by BamfordMike on Monday 12th December 22:21
Mako V12V said:
Thanks for the detailed response. But does the inside of the fuel flap not recommend 98 Ron?
The reason the engine does not deliver additional performance for high octane fuel is that there is no knock control system or other device to measure the octane rating of fuel used. As important is the inverse. If low octane fuel is used (say 91RON), using the fixed ignition which was set for 95 RON would likely destroy the engine because of excessive detonation. So to avoid this situation the instruction is to fill with as high a grade fuel possible in markets where low octane fuel is present.
The absence of knock control causes many headaches and the only way to overcome them is to back off on performance output to return a safe plodding engine. Only problem for V12 is this can't be done as the performance Vs rivals is low to start with.
Catch 22... So the engine is optimised somewhere in the middle of the fuel spectrum, the advice is to fill with high grade fuel in the hope nobody will fill with low grade fuel.
Retro fit knock sensing - epic..! To the point the better bang for buck would be performance gains from mechanical improvements (imo).
I believe the aftermarket tuning companies that advertise ecu remapping do just that (optimise for 98) - to return a performance gain they erode safety margins applied by OEM. They can do this because in reality they know an owner in UK can't fill with low octane fuel, whereas in US it is a reality . And some report that the engine producing more torque for less pedal returns improved efficiency
I believe the aftermarket tuning companies that advertise ecu remapping do just that (optimise for 98) - to return a performance gain they erode safety margins applied by OEM. They can do this because in reality they know an owner in UK can't fill with low octane fuel, whereas in US it is a reality . And some report that the engine producing more torque for less pedal returns improved efficiency
and both have the knock sensor.Gassing Station | Aston Martin | Top of Page | What's New | My Stuff