Discussion
996GT2 said:
Does anyone really (honestly) notice the difference?
Yes, very much so where my last car (997S.1) was concerned. The engine note and power delivery were noticeably different on different fuels. If I put a tank of BP-97 in after running Shell V-Power for a while, you could actually feel the ECU gradually backing the timing off over the first quarter of the tank. Similarly, you could feel the performance (and particularly throttle response) improving again once there was Shell-99 back in the tank.That there can be substantial differences in an engine's power output, due solely to different fuels, was clearly demonstrated by a series of tests done by Thorney Motorsport a year or few ago. The used a E46 BMW CSL for the tests and found a 40BHP difference (yes, forty) between 'cooking' 95-RON and the best 99-RON fuels. 320BHP on 95 vs. 360BHP on 99 is one hell of a cheap way to buy horsepower!! From memory, BP-97 sat right in the middle where you'd expect.
The test results were still on their web site last time I looked.
Ian
kVA said:
Does Tesco 99 still exist?
It is called something else at our local Tesco now... Anyone know if it is still 99 octane, because it didn't say that anywhere on the pump that I used?
as far as I know it is 99; prefer Shell myself, seems to be some discussion on other forums about what goes into the Tesco petrolIt is called something else at our local Tesco now... Anyone know if it is still 99 octane, because it didn't say that anywhere on the pump that I used?
thegoose said:
V Power is not the same as V Max as I understand it. AFAIK these are the different types of Shell:
Optimax - 98 - UK premium grade no longer available (superceded by V Power)
V Power - 99 - current UK premium grade
V Max - 100 - Swiss (+ ?) premium grade
Quite right marcus I seemingly got my fuel mixed up with drag strip hooning ;-)Optimax - 98 - UK premium grade no longer available (superceded by V Power)
V Power - 99 - current UK premium grade
V Max - 100 - Swiss (+ ?) premium grade
kVA said:
Does Tesco 99 still exist?
It is called something else at our local Tesco now... Anyone know if it is still 99 octane, because it didn't say that anywhere on the pump that I used?
Some Tesco stations only do 97 whereas others do the 99, and both call it Super Unleaded. I heard the other day that the 99 stuff is 5% Bio-ethanol but no idea about the reality or what the 97 stuff is like.It is called something else at our local Tesco now... Anyone know if it is still 99 octane, because it didn't say that anywhere on the pump that I used?
997GT3 said:
Not sure why you choose any Tesco petrol, 99 or not, over Shell fuels. V-Power 100% of the time both in my GT3 and GTI Edition 30!
One of the worst 'oim considerably richer than yow' post for ages... 
However, some of us live 1/4 tank round trip away from the nearest Shell garage, but just a couple of miles from Tesco - the only other seller of 99 octane fuel in the UK that I'm aware of? Also, the Thorney Motorsport research seems to indicate that it isn't bad stuff at all and usually a couple of pence per litre cheaper than V-Power.
If your engine (mainly timing) is set up for high octane and you use a low octane fuel you will get pre-detonation (pinking) which will cause damage. If your engine management uses a knock detector you can use high or low octane fuels with a loss of performance from the low octane. If your engine management does not use a knock detector and is set up for 95 RON and you use 98 or 99 you will get no increase in performance, but the petrol companies claim that these fuels have better cleaning properties so there could be some benefits there!
HTH
HTH
Poledriver said:
If your engine (mainly timing) is set up for high octane and you use a low octane fuel you will get pre-detonation (pinking) which will cause damage. If your engine management uses a knock detector you can use high or low octane fuels with a loss of performance from the low octane. If your engine management does not use a knock detector and is set up for 95 RON and you use 98 or 99 you will get no increase in performance, but the petrol companies claim that these fuels have better cleaning properties so there could be some benefits there!
HTH
Bit of a knobby post for the Porsche forum where all models from 1984 onwards have had knock sensing IIRC, you are only going to confuse/worry owners when really it won't do any harm whatever unleaded you put in your '84 onwards Pork, it just won'y give you maximum available grunt....HTH
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