MB ability to detect SuperFuel

[harvin1975]

Fuel Types - PetrolPrices.com

Quote from above:
"... a few vehicles, such as the new BMW K1200R motorbike, can sense knock and adjust their engine tuning to take advantage of higher grade fuels. Another user commented that the 2004 BMW 330 also does this, according to the driver’s handbook it makes 231 BHP on 98 octane and 221 BHP on 95. This ability is apparently widespread amongst German performance cars using Bosch / Siemens electronic engine controls."

Do recent MB cars have the ability to adjust engine tuning depending on fuel type? I would understand AMG may run better on these superfuels, but wondering if anyone is aware of this ability in all recent MBs?

 

[Bellow]

"... a few vehicles, such as the new BMW K1200R motorbike, can sense knock and adjust their engine tuning to take advantage of higher grade fuels.

20th century technology. VW had it on their Polo in the 1990s.

 

[F1BHP]

Yes they all do. It will take one or two tanks of fuel to fully adjust. How much increase depends on each engine and what kind of tune it has from the factory.

 

[harvin1975]

Crikey - why do I not know this!

 

[Bellow]

Yes they all do. It will take one or two tanks of fuel to fully adjust.

For sure?
My understanding is that if no knock is detected with the timing set for an upper octane fuel then the timing remains as it is. If knock is detected (due to lower octane fuel) then the timing is retarded until knock ceases then advanced incrementally and if knock is again detected the process repeats.
That is how it was for the Polo running Bosch Digifant 25 years ago. Does it really take two tankfulls a quarter of a century later to achieve the same result?

 

[Rory]

I thought it was a pretty instantaneous thing too.

I can remember Cavaliers around the late 80's having a selector for high or low octane fuel. They were a lot flatter on low octane.

 

[Dryce]

Crikey - why do I not know this!

Beware - it's not that simple - and the general assumption 'one or two tanks to adapt' is just a perfect scenario for internet mythology.

If you go for a high performance variant - eg. an AMG engine - then the engine itself will be setup to run at higher compression ratios (though just looking at the specifications isn't straightforward because of issues such as supercharging and turbocharging).

The engine management system will be setup to assume higher RON fuel eg. RON 99 and then adapt to lower RON values - but always try to adapt the ignition timing to higher RON numbers.

Now with a more mundane variant then the advantages of higher RON fuel may well be minimised by the different engine configuration - with a lower compression ratio. And the engine management system may be setup to assume a lower RON value such as 95 and then adapt only to lower RON numbers.

The problem is you don't know for sure. The owner manuals of higher performance cars may be explicit in suggesting higher RON fuels - but manuals for more mundane cars may only go as far as specifying that RON95 is normally used.

My guess (yes guess) is that the one or two tanks thing is a crock. Why? If I was programming up an engine management system I'd probably reset it to try the ignition setup for higher RON at least every time the car was started. Probably start on RON 95 and then bump things a little in steps as the car warmed up -and back off and go no further as soon as the sensors started letting me know there was an issue.

 

[st13phil]

Does it really take two tankfulls a quarter of a century later to achieve the same result?

I doubt it, but it will take a couple of tankfulls to raise the octane of the "mixed" fuel to the highest fuel octane (depending upon how much was left in the tank when you refueled, of course).

 

[whitenemesis]

From WIS -


"The anti-knock control is active from engine start. If knocking was
detected at a cylinder, the ignition angle of this cylinder is retarded
from the next ignition. If knocking continues to occur, the ignition
angle (depending on engine speed) continues to be retarded in
stages until maximum retardation is achieved.

If knocking-free combustion exists, the retardation is reduced in
stages after a few ignitions (depending on engine speed) until the
normal performance map value is achieved or knocking once again occurs.

If the anti-knock control specifies retardation of the ignition angle
for a lengthy period then the engine control system reduces the
engine power output to protect the engine.

A default setting for the RON correction can be preprogrammed
using the STAR DIAGNOSIS."

 

[MancMike]

I definitely notice a difference in torque and general sprightliness from the engine when going from 95 to 99 RON.

Generally when I'm on fumes with 95 (needle doesn't even lift up off it's stop when starting car, and then a few more miles), when I add some 99, it takes a mile or two, which must be both a combination of some time for it to work through the fuel filter and up the fuel lines and the engine then adjusting for it.

 

[TheFoX]

I know that Shell have their V-Power range, but does a car benefit from a higher grade diesel, or is this just a gimmick?

Would filling my tank with a higher grade diesel benefit my 3 litre V6 diesel, or is this just wasting my money?

 

[Stratman]

Is the power increase due to there being inherently more energy in 99 octane compared to 95, or is it more the 99 allowing the engine to take maximum advantage of a higher compression ratio?

 

[BIRMA]

Two of the very early tests that showed how superior V-Power or Optimax as it was years ago were discredited when it was found out the engine/dyno place was sponsored by Shell.
One thing I concluded from the tests was that this fuel has excellent cleaning properties. V-Power diesel is 10p a litre dearer than Morissons boggo diesel so I only use V-Power every fourth fill purely for its cleaning properties. I buy my vans brand new and run them for 10 years or about 180K miles then throw them away more or less.
I run my SL63 on V-Power and my motorbikes.

 

[190]

Is the power increase due to there being inherently more energy in 99 octane compared to 95, or is it more the 99 allowing the engine to take maximum advantage of a higher compression ratio?

I don't think the specific energy of the fuel is much different if any different to 95 RON. It varies anyway summer to winter and on ethanol content.

Any power increase can only arise if the engine cannot optimize it's ignition timing on 95 RON i.e. it runs a compression ratio higher than 95 RON can support.

To be honest I have some difficulty believing that a driver can detect a difference in power output of a few % and that's all it can be something less than 5%. Yes it's easy to detect the difference between an engine running properly and not running properly but a few % more horsepower doesn't do much for performance given speed is proportional to getting on for the cube of the power.

 

[Bellow]

Is the power increase due to there being inherently more energy in 99 octane compared to 95, or is it more the 99 allowing the engine to take maximum advantage of a higher compression ratio?

The latter - higher compression. Or more boost if boost is variable - as it is with turbocharged motors.

 

[del320]

20th century technology. VW had it on their Polo in the 1990s.

All I know is my '78 SAAB 99 Turbo required 5 Star and the one and only time I took it to France, it became very ill!

By comparison, my '84 SAAB 900S Turbo did the European Grand Tour and would drink anything above paraffin without complaint.

I think SAAB were one of the earliest manufacturers to use this technology. Of course, performance was affected by the rubbish put into the tank, but no harm was done.

 

[Bellow]

All I know is my '78 SAAB 99 Turbo required 5 Star and the one and only time I took it to France, it became very ill!

By comparison, my '84 SAAB 900S Turbo did the European Grand Tour and would drink anything above paraffin without complaint.

I think SAAB were one of the earliest manufacturers to use this technology. Of course, performance was affected by the rubbish put into the tank, but no harm was done.

Possibly - or more likely I suspect in the early 80s they reduced the boost level to contain knock (SAAB's turbocharging expertise came via Scania so boost control would have been a strategy well known to them). They were early with electronics though. By the early 90s their cars had more computing power on board than did early Apollo space rockets.

Paradoxically, some of the most powerful NA aspirated engines of the past would happily run on fuel with an octane rating no higher than paraffin's. The race engines from Honda, Yamaha, etc of the 60s with very small cylinders and revving highly would consume RON 65 without complaint.

edit PS: Didn't SAAB have APC? Automatic Pressure (ie boost) Control?

 

[moonloops]

All I know is my '78 SAAB 99 Turbo required 5 Star and the one and only time I took it to France, it became very ill!

By comparison, my '84 SAAB 900S Turbo did the European Grand Tour and would drink anything above paraffin without complaint.

I think SAAB were one of the earliest manufacturers to use this technology. Of course, performance was affected by the rubbish put into the tank, but no harm was done.

Correct, my "modern" SAAB 95 Aero adapts rapidly between 95 and 98/99/100 RON fuel, on the good stuff the boost gauge goes into the danger-zone (sorry not a top gun reference)

 

[Gene]

I definitely notice a difference in torque and general sprightliness from the engine when going from 95 to 99 RON.

Generally when I'm on fumes with 95 (needle doesn't even lift up off it's stop when starting car, and then a few more miles), when I add some 99, it takes a mile or two, which must be both a combination of some time for it to work through the fuel filter and up the fuel lines and the engine then adjusting for it.

Very interesting. I notice you have the W204 280.
I had the same 280 3.0 ltr engine before I got my GLA 250.

I noticed the same change in performance between 95 and V-Power including
Better Mpg on V-power.

However, I don't experience any difference in performance in the GLA 2.0 turbo when I switch fuels grades.

 

[MancMike]

Glad you noticed the same. Double confirmation I'm not imagining it.

A college with a C180 (the 1.6 turbo) doesn't notice a shred of difference too, so maybe the extra ron gets a bit more potential out of a NA engine than a charged one.

I get better MPG on VPower if I drive the same, but for the extra money I tend to enjoy the bit of extra oomph so tend to get less! I did achieve my best ever mpg figure of 39mpg indicated on the motorway using VPower though.