Super Unleaded
Discussion
Marf said:
Mr Bimmer said:
Tesco99 is awful petrol.
Shell V power = Win. Even Sainsburys 97 is better than the artificially enhanced Tesco effort.
Such utter guffShell V power = Win. Even Sainsburys 97 is better than the artificially enhanced Tesco effort.
BP + Shell for me now.
Does anyone use the BP Ultimate 102 on a regular basis on here? I'd be interested in hearing the advantages at paying twice the price per litre!
Chris
s31tof said:
Ever since Tesco had that huge petrol problem several years ago, I try and avoid them!
BP + Shell for me now.
Does anyone use the BP Ultimate 102 on a regular basis on here? I'd be interested in hearing the advantages at paying twice the price per litre!
Chris
Check out Mikeveal's lengthy post above - it'll answer this question. BP + Shell for me now.
Does anyone use the BP Ultimate 102 on a regular basis on here? I'd be interested in hearing the advantages at paying twice the price per litre!
Chris
s31tof said:
Ever since Tesco had that huge petrol problem several years ago, I try and avoid them!
BP + Shell for me now.
Does anyone use the BP Ultimate 102 on a regular basis on here? I'd be interested in hearing the advantages at paying twice the price per litre!
Chris
I tried BP102 a few years ago in an e46 M3 and found no difference to Shell V power99. The ecu doesn't dial in to anything much better than 98 octane.BP + Shell for me now.
Does anyone use the BP Ultimate 102 on a regular basis on here? I'd be interested in hearing the advantages at paying twice the price per litre!
Chris
The buckarooing from the Tesco99 was comical in the mornings. I kept thinking it was a dodgy batch, but every time I tried it the same thing happened.
OK, there are two things I'd like to make clear.
1/ Modern car with knock sensor(s).
Most car's have 'em these days. But they are not usually there to improve performance. They are there to stop detonation caused by you filling up with bad fuel. Cynically you might say that they are there to stop the warranty claim, caused by detonation, caused by you filling up with bad fuel.
So AFAIK, most cars will run a standard map (fuel and ignition), allowing them to use normal unleaded fuel. There will be some safety margin to allow for a high ambient temperature and low ambient pressure (high altitude), and to a degree, bad fuel.***
On top of this sits the knock sensor. If the sensor detects knock - despite the conservative map that the manufacturer has programmed, then the ignition is retarded (fires earlier to prevent detonation). See my earlier post for why this is bad for efficiency.
What normal run of the mill ECUs do not do is notice that the manufacturer's conservative map is wasting power because it's overly conservative. They will not advance the ignition beyond the manufacturer's conservative map when knock is not present. Or put another way, they will not be able to make use the extra detonation resistance of Super. If it doesn't produce knock with the standard map, then hey that's fine, no adjustment needed.
2/ Since someone has mentioned ethanol, it is not common knowledge, but fuel changes with the season. In the winter, it will have more of the lighter constituants (those evaporated to give LPG), in the summer less. This means that winter fuel is more viscuous and summer fuel is less likely to boil away. There will be a subtle change in calorific value because of this blending. It makes it bloody difficult to compare tank to tank.
If anyone's interested, my source for most of this stuff is A.G.Bell's book Forced Induction Performance Tuning. It's a very good and detailed book. And Bell is far better at explaining stuff than I am!
1/ Modern car with knock sensor(s).
Most car's have 'em these days. But they are not usually there to improve performance. They are there to stop detonation caused by you filling up with bad fuel. Cynically you might say that they are there to stop the warranty claim, caused by detonation, caused by you filling up with bad fuel.
So AFAIK, most cars will run a standard map (fuel and ignition), allowing them to use normal unleaded fuel. There will be some safety margin to allow for a high ambient temperature and low ambient pressure (high altitude), and to a degree, bad fuel.***
On top of this sits the knock sensor. If the sensor detects knock - despite the conservative map that the manufacturer has programmed, then the ignition is retarded (fires earlier to prevent detonation). See my earlier post for why this is bad for efficiency.
What normal run of the mill ECUs do not do is notice that the manufacturer's conservative map is wasting power because it's overly conservative. They will not advance the ignition beyond the manufacturer's conservative map when knock is not present. Or put another way, they will not be able to make use the extra detonation resistance of Super. If it doesn't produce knock with the standard map, then hey that's fine, no adjustment needed.
2/ Since someone has mentioned ethanol, it is not common knowledge, but fuel changes with the season. In the winter, it will have more of the lighter constituants (those evaporated to give LPG), in the summer less. This means that winter fuel is more viscuous and summer fuel is less likely to boil away. There will be a subtle change in calorific value because of this blending. It makes it bloody difficult to compare tank to tank.
If anyone's interested, my source for most of this stuff is A.G.Bell's book Forced Induction Performance Tuning. It's a very good and detailed book. And Bell is far better at explaining stuff than I am!
- * The manufacturer produces a conservative map because they have to allow for a high ambient temperature altitude and snotty fuel. When you take your car to be remapped, the map produced will usually give max power for the fuel you have in the tank, at the ambient temperature and pressure in the tuners bay. Work out for yourselves what happened to the design margin supplied by the manufacturer and why the manufacturer didn't program the ECU like this in the first place!
Edited by mikeveal on Wednesday 18th May 17:02
BIG DUNC said:
Sorry, its a Smart for four brabus.
Good, another one ! 
I put 97 in my forfour brabus, but I've tried noraml unleaded a couple of times.
I tend to get better fuel economy on super (on similar driving), it feels more responsive and it is said to use 98 minimum ...
As the engine is the same as a colt CZT (150bhp) but here tuned to 177bhp, I guess the map was done to make to most of super unleaded ...
DannyVTS said:
simoid said:
Experiment sire, I'm undergoing a V-power experiment with my 182. It's supposed to be a 400 mile per tank challenge, but I can't go a journey without flooring it at least once so it's an unrealistic challenge 
Engine does 'feel' nicer, however, and Renault recommend 98 ron.
How you getting on with this?Engine does 'feel' nicer, however, and Renault recommend 98 ron.
I've done around 140 miles in my 172 this week and have 300 left on the "remaining till empty" counter, and MPG is 40.2
I've been doing mainly shortish, B road/urban trips recently, as opposed to the motorway commute to uni so the best I've managed from a whole fillup (10.999 gallons - I know cos I ran out last week!) is 372 miles.
Are you on the super-unleaded? I don't think there are any fuel efficiency benefits for the RS Clios.
Re. Volvo V40 T4 (Petrol 2 litre turbo estate with 140,000 miles)
Instruction book says "98 recommended".
Inside petrol cap says >91 required. >95 preferred. 98 recommended.
I've been trying both 95 and 98 and don't seem to notice any difference in performance or MPG. Been using Texaco 95 and Shell Optimax.
"Another forum" says I really should be using 98 as it is "less dirty" and that by using 95 I risk damaging the engine due to carbon build-up on the injectors.
Any truth in this?
Instruction book says "98 recommended".
Inside petrol cap says >91 required. >95 preferred. 98 recommended.
I've been trying both 95 and 98 and don't seem to notice any difference in performance or MPG. Been using Texaco 95 and Shell Optimax.
"Another forum" says I really should be using 98 as it is "less dirty" and that by using 95 I risk damaging the engine due to carbon build-up on the injectors.
Any truth in this?
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