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Read the WELCOME ALL BMWFANATICS post.
Advantage of 95 ULP at altitude
- Thread starter msm
- Start date
Legacy
///Member
I'm definitely not a guru but on a 1999 E46 328i you get worst consumption and there is no increase in power or torque that you can feel, I have tried it several times with about 20l of 95 and then 20l of 93 and it seems to be exactly the same petrol, even the 540i feels exactly the same with either 93 or 95 and with 93 consumption is about 15l/100km and with 95 about 18l/100km but maybe that is just due to the myths that 95 makes the car "faster" so you drive it more with the pedal to the floor.
P1000
///Member
Nope. Octane requirements gets derated as you go up in altitude.
That said, getting an exact number is not as easy, as it seems to be engine-dependent, and our fuel in SA is not exactly the octane they say it is. But if you go and do the calculations, your car is far in the safe-zone on our 93 on the reef, since the BMEP gets reduced by around 14.5% in PTA/JHB.
If you really want to know if you gain anything by using 95, you need to see the spark adjustment values of the ECU. I'm unsure if you can do so in INPA/DIS, but it would be interesting.
The reason that turbo cars need higher octane up here is because their manifold air pressure is less affected by altitude - and consequently BMEP, since it is electronically regulated.
That said, getting an exact number is not as easy, as it seems to be engine-dependent, and our fuel in SA is not exactly the octane they say it is. But if you go and do the calculations, your car is far in the safe-zone on our 93 on the reef, since the BMEP gets reduced by around 14.5% in PTA/JHB.
If you really want to know if you gain anything by using 95, you need to see the spark adjustment values of the ECU. I'm unsure if you can do so in INPA/DIS, but it would be interesting.
The reason that turbo cars need higher octane up here is because their manifold air pressure is less affected by altitude - and consequently BMEP, since it is electronically regulated.
Chucky
Active member
Im no expert either but i do have experience on this and had a word from the "inside"
My experience, drove my car till almost empty on 93 pump fuel and then proceeded to fill up with 95 pump fuel, and heres what i found
1. performance - no diffs same as on 93
2. consumption - no diffs same as on 93
it was all the same, then I spoke to a friend of mine that works for one of the biggest petroleum companies 'in the world'(Said in a Jeremy Clarkson voice )
and she confirmed that using 95 on a normally aspirated car in JHB makes no difference at all, and it is suited more for turbo applications, and i asked her what does she put in her car she said 93 Octane she drives a e90 320i.
My experience, drove my car till almost empty on 93 pump fuel and then proceeded to fill up with 95 pump fuel, and heres what i found
1. performance - no diffs same as on 93
2. consumption - no diffs same as on 93
it was all the same, then I spoke to a friend of mine that works for one of the biggest petroleum companies 'in the world'(Said in a Jeremy Clarkson voice )
and she confirmed that using 95 on a normally aspirated car in JHB makes no difference at all, and it is suited more for turbo applications, and i asked her what does she put in her car she said 93 Octane she drives a e90 320i.
the tuners should know if it makes a difference...
Skwinty
New member
See this link for the NAAMSA database for model specific fuel recommendations.
http://www.naamsa.co.za/unleaded/databases/index.php
http://www.naamsa.co.za/unleaded/databases/index.php
looks like most bmws are recommended to use 95 at the reef... mine is not... i think it is because mine is very detuned...
Fordkoppie
///Member
P1000 said:
What you say is 100%, but most NA petrol BMW engines are fairly high compression motors.
Higher octane does sweet blue bugger all for performance, but if the knock sensors detect any detonation, it will retard the ignition timing and therefore you lose power as you already know.
Increased octane just aids in preventing pinking since spontaneous combustion gets suppressed more.
I surely won’t put in anything except the highest octane I can get for the M3, because I can really feel how it retards the timing (after hearing a short burst of pinking) with lesser grade fuels. I have tried this numerous times, since I have to go up a very steep and long hill when I just start driving (from cold) at work. Trying to keep the RPMs low since the motor is still cold, and with the high load, this “surging†is very pronounced as it starts pinking; retarding timing; then upping the timing again; pinking; retarding…. etc.
The M3 has a compression ratio of 11.5:1
P1000
///Member
Fordkoppie said:
That is a bit strange, but yes 11.5 is a high compression ratio for a manifold injected motor. I wanted to mention that it might start affecting high CR cars like M3's and M5's, but did not want to cause confusion. That said, it seems that you are only experiencing the problem when cold?
Oh, and as a sidenote, Audi's 2.8l V6 runs a CR of 12.5:1 (but that is a tale for a different day since it is direct injection.)
Fordkoppie
///Member
For interest sake - The upcoming Mazda SKYACTIV (can they call it anything more retarded?) NA petrol engines operate at a CR of 14:1 also with direct injection that enhances latent heat dissipation amongst others.
Like you said - "that is a tale for a different day". Sorry MSM for derailing your thread.
Like you said - "that is a tale for a different day". Sorry MSM for derailing your thread.
Ephraimramodike
New member
Okay guys....
Thank you all for your inputs and advise.... but I'm still with MSM about the advantages of using 95 or 93...
Since we know that there's no diff in performance... Does your engine last longer if using 95 for a N/A engine? Or would there be any mechanical problems in the lifespan of the engine?
If not... then clearly there's point in spending extra cents per litre for 95 if you have a N/A engine... right?:thinking:
Thank you all for your inputs and advise.... but I'm still with MSM about the advantages of using 95 or 93...
Since we know that there's no diff in performance... Does your engine last longer if using 95 for a N/A engine? Or would there be any mechanical problems in the lifespan of the engine?
If not... then clearly there's point in spending extra cents per litre for 95 if you have a N/A engine... right?:thinking:
If you get on the web and read deep into the subject, RON is nothing more than resistance to detonation.
A big misconception here is RON Vs energy density. Guys think 110 octane will have more energy in it than 93, when in fact as octane goes up energy content in the fuel goes down, only it's burn rate slows helping high compression engines that have a problem with a lower octane.
If your ECU is not pulling (retarding) the timing on 93 then anything higher is going to do bugger all and the car may even run worse if you go too high.
On the other hand if you have a modified NA engine running a 13:1 or 14:1 compression you would have to use a higher octane to prevent problems and actually get all the power out of the mods.
To your unmodified (Compression wise) car using 95 will just be a waste of money. it's not cleaner or anything, it's just a higher RON that's all. It's more expensive because it's harder to make.
A big misconception here is RON Vs energy density. Guys think 110 octane will have more energy in it than 93, when in fact as octane goes up energy content in the fuel goes down, only it's burn rate slows helping high compression engines that have a problem with a lower octane.
If your ECU is not pulling (retarding) the timing on 93 then anything higher is going to do bugger all and the car may even run worse if you go too high.
On the other hand if you have a modified NA engine running a 13:1 or 14:1 compression you would have to use a higher octane to prevent problems and actually get all the power out of the mods.
To your unmodified (Compression wise) car using 95 will just be a waste of money. it's not cleaner or anything, it's just a higher RON that's all. It's more expensive because it's harder to make.
Skwinty
New member
For each model, the data will indicate, separately for coastal and for inland operation, which grade is recommended (by the manufacturer for optimal operation) and with which other grades the vehicle is compatible (i.e. on which it will operate satisfactorily and without engine damage, but not necessarily with optimal power, performance and efficiency on certain vehicles). The motorist has the option to use any grade which is shown as being either recommended for, or compatible with, the vehicle. Motorists should remember that their driving habits may have an influence on which octane grade they find best suited to their particular needs.
If I was to live on the reef, I would use the recommended petrol. :fencelook:
If I was to live on the reef, I would use the recommended petrol. :fencelook:
Ephraimramodike
New member
Okay... I'm beginning to understand now. :thumbs:
P1000
///Member
Ephraimramodike said:
Your post does not make much sense. But 95 vs 93 makes no difference in engine life/wear/power/anything if you have a normal non-M non-turbo car.
So there is absolutely no merit in wasting your money on 95, unless you have a turbo, or experience the timing being pulled.
In fact, there is also not any price difference between 95 and 93 apart from the artificial "demand management levy" introduced to discourage people from using 95 when they do not need it.
Skwinty said:
That makes sense, since your car has a forced-induction engine...
