Supermarket fuel vs high grade fuel cla45 AMG

GAD Tuning North

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A bit of an informative post and hopefully one that I intend on giving us a better understanding of the age old question...
does higher octane fuel really make a difference or is it a placebo affect?

We had a Mercedes CLA 45 AMG in today for stage 1 tuning, a couple drove 3 hours to get to us.
unfortunately the night before they only had supermarket fuel available.
With AMG cars as an owner of a few and tuner of many, AMG states to only use 98ron fuel.

so on a dyno especially with the 45AMG's they pull timing, don't combust as intended and run excessive heat in the heads.

as a tuner I could have easily just shown bad stock numbers, put some octane booster in and shown massive gains and higher deltas stock vs tuned, BUT we at GAD like to do things the correct way, make sure the car is happy, healthy and remove one variable, fuel!!

This makes a true picture of the performance of our software which stands on its own merits.
as shown on the pictures, we carried out a few runs on supermarket fuel, the car made less than stock, very rough spikey telemetry as the cars timing and combustion was all over.

so we carried out a fair few stock runs, put some octane booster in, just enough to be running roughly 98ron.
ran the car for a while between power runs and the results are:
run 2 - car made 248bhp & 398nm @ wheels
run 4 - car made 317bhp & 418nm @ wheels
that's an increase of +69bhp & +20nm@ wheels!!!
this was just from a small amount of octane boost, equating to 98 ron!!!

once we knew the car was healthy and making the stated manufacturers claimed power output, we tuned the vehicle.
results were:
run 8 - car made 351bhp & 547nm
gains over stock (98 ron) +34bhp +129nm @ wheels!!!

some super impressive figures and on models like this, with correct equiptment and test conditions we have demonstrated a massive difference in supermarket fuel vs higher octane fuel.

unfortunately as I was doing all this I didn't get time to take pictures of the car.
 

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rorywquin

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I think the question arises when the car is not specified for 98 and people think that using 98 (or octane booster) will boost performance.

That would be a very informative test on your dyno.
 
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GAD Tuning North

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I think the question arises when the car is not specified for 98 and people think that using 98 (or octane booster) will boost performance.

That would be a very informative test on your dyno.



I think you are right, this test / experiment was at the extremes of supermarket fuel vs high grade fuel purely from how well calabrated and hightly tuned this engine is from AMG who have clearly set this engine up on premium fuel.

It would be interesting to see a lesser "normal car" and see if the differences are similar, i am doubtful.

Saying that we had a Jaguar F type 3.0 supercharged in the other day which made a little less that standard power but the plots on the dyno were so volatile that I knew straight away it was supermarket fuel.

Asked the customer and sure thing it was sainsburys fuel.

Ended up around stock figures, he is in again next week when he has some good fuel in so ill post the results once tuned



(See plots attached)
 
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LostKiwi

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You also weren't comparing apples with apples. It's not so much Supermarket Vs premium but 95 vs 98 that was tested.
What would have been more relevant is testing (for example) Tesco Momentum Vs Shell V-Power.
From my own backside Dyno in my Smart Roadster running 1.5bar the Tesco runs better than V-Power and both are better than BP. It would be interesting to see if this observations are borne out by real Dyno testing.
Testing 95 vs 98 in a car that requires 98 is fairly pointless in my view - it's pretty obvious that retarding ignition will seriously impact performance.
 
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You also weren't comparing apples with apples. It's not so much Supermarket Vs premium but 95 vs 98 that was tested.
What would have been more relevant is testing (for example) Tesco Momentum Vs Shell V-Power.
From my own backside Dyno in my Smart Roadster running 1.5bar the Tesco runs better than V-Power and both are better than BP. It would be interesting to see if this observations are borne out by real Dyno testing.
Testing 95 vs 98 in a car that requires 98 is fairly pointless in my view - it's pretty obvious that retarding ignition will seriously impact performance.
You also weren't comparing apples with apples. It's not so much Supermarket Vs premium but 95 vs 98 that was tested.
What would have been more relevant is testing (for example) Tesco Momentum Vs Shell V-Power.
From my own backside Dyno in my Smart Roadster running 1.5bar the Tesco runs better than V-Power and both are better than BP. It would be interesting to see if this observations are borne out by real Dyno testing.
Testing 95 vs 98 in a car that requires 98 is fairly pointless in my view - it's pretty obvious that retarding ignition will seriously impact performance.



I totally agree but this customer came to us from 3 hours away so we couldnt tell him to go away run 2 tanks of good fuel and come back.

My intentions are not to turn this in to an experiment, just sharing information whilst the customer came in for a tune.

Just from the curcumstances on the day, it was an interesting find to see from running the car on poor fuel, then boosting the octane to 98 ron the difference which was huge, sticking to the 1ml booster to 1 ltr fuel it made bang on stock fugures.

I only added the octane boost to actually get it to factory figures then to tune and calabrate with the fuel as a known fixed variable.

And yes it is clear to me also that it would pull timing and make less power on 95 ron, thats a given but i didnt expect a difference of 69WHP!!

Certainly did not have this car in to experiment on fuels, just sharing my findings as it may be interesting or helpful.

And I totally agree as i have this debate of tescos 99 being better than v power but would love to have a proper experiment under real test conditions to see the difference.
 
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rorywquin

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...................................
From my own backside Dyno in my Smart Roadster running 1.5bar the Tesco runs better than V-Power and both are better than BP. It would be interesting to see if this observations are borne out by real Dyno testing.
Testing 95 vs 98 in a car that requires 98 is fairly pointless in my view - it's pretty obvious that retarding ignition will seriously impact performance.

The Shell V power (99) is a higher octane than BP (98) ? I only have BPs (3) near me so always use it. I used the Shell 100 RON in Germany for a week when I was there and didn't notice much difference, perhaps I need to recalibrate my "dyno" .:)
 

John Laidlaw

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I am currently (see what I did?) comparing the old EDF with Avro to see if there are any performance boost available, more to follow....:p
 

V6Matty

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The Shell V power (99) is a higher octane than BP (98) ? I only have BPs (3) near me so always use it. I used the Shell 100 RON in Germany for a week when I was there and didn't notice much difference, perhaps I need to recalibrate my "dyno" .:)
If your car is made for a specific RON then there is very little point running anything other than said octane, your engine was designed to produce its optimal performance using a certain rated fuel, using something lower mean the ECU pulls timing to get the optimal burn from a less optimal fuel, putting in a higher rated fuel won’t make any difference either, now it won’t retard the timing and pull power but due to the different burn pattern of the higher octane fuel it still won’t run quite as well as it’s specified one. Now if you remap while using the 99/100 RON fuel you will see some further gains but as soon as you start dropping back down the effects are like going from 98 to 95
 

Tony Dyson

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Nothing new here as I have read as it's all in the OM!:geek:
 

Craiglxviii

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I am currently (see what I did?) comparing the old EDF with Avro to see if there are any performance boost available, more to follow....:p
Avro certainly had performance improvements available, upgrading the Olympus engines several times. Plus the zip fuel boron additive for the proposed supersonic Vulcan ;)
 

rorywquin

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If your car is made for a specific RON then there is very little point running anything other than said octane, your engine was designed to produce its optimal performance using a certain rated fuel, using something lower mean the ECU pulls timing to get the optimal burn from a less optimal fuel, putting in a higher rated fuel won’t make any difference either, now it won’t retard the timing and pull power but due to the different burn pattern of the higher octane fuel it still won’t run quite as well as it’s specified one. Now if you remap while using the 99/100 RON fuel you will see some further gains but as soon as you start dropping back down the effects are like going from 98 to 95

SL400 manual says to use highest available:);)..... The difference between 98 and regular is noticeable - car is less responsive - I noticed this while on regular for 2 weeks touring Ireland & as previously noted I didn't feel a difference with 100 when in Gemany for a week.
 

MinionBob

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I totally agree but this customer came to us from 3 hours away so we couldnt tell him to go away run 2 tanks of good fuel and come back.

My intentions are not to turn this in to an experiment, just sharing information whilst the customer came in for a tune.

Just from the curcumstances on the day, it was an interesting find to see from running the car on poor fuel, then boosting the octane to 98 ron the difference which was huge, sticking to the 1ml booster to 1 ltr fuel it made bang on stock fugures.

I only added the octane boost to actually get it to factory figures then to tune and calabrate with the fuel as a known fixed variable.

And yes it is clear to me also that it would pull timing and make less power on 95 ron, thats a given but i didnt expect a difference of 69WHP!!

Certainly did not have this car in to experiment on fuels, just sharing my findings as it may be interesting or helpful.

And I totally agree as i have this debate of tescos 99 being better than v power but would love to have a proper experiment under real test conditions to see the difference.

I think the point is that the title of the post, to be more reflective of the content should be something like '95 vs 98 RON'. The fact it is supermarket fuel is immaterial; supermarkets sell 98+ RON fuel too.

This minor point aside, nice investigative work.
 

John Laidlaw

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Interesting post, and thanks to GAD for doing it, I'm not sure it merited some of the criticism but at least it did encourage some interesting dialogue.
 

BillyBoy

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Be interested to see how this pans out for diesel. Since buying my 400d, I've been filling up with Shell V-Power diesel as with lockdown, I'm not using a lot, however one normality returns, and I'm back to 400 miles a week odd, I'll be thinking of Sainsbury's diesel instead as V-Power is around another £12 - £15 per tank full which adds up over the year.
 

rorywquin

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Be interested to see how this pans out for diesel. Since buying my 400d, I've been filling up with Shell V-Power diesel as with lockdown, I'm not using a lot, however one normality returns, and I'm back to 400 miles a week odd, I'll be thinking of Sainsbury's diesel instead as V-Power is around another £12 - £15 per tank full which adds up over the year.

People have views about this but the wife's diesel (used only for short runs) was running terribly on 'plain' diesel and was always regenerating the dpf. We switched to the top (BP) fuel and have not had an issue since.
 

Wearsafoxhat

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Not a proper test but an observation over 15 years.
I drove Astra 1.7 diesels for work, large company with a fleet of 70 odd in our branch. Our fuel use, along with just about every other fact and figure was scrutinised, put on a graph, on a league table and used to “ beat us” with.
I used Shell as the garage is at the top of the road. Most others used Tesco, next to the office.
With my last two cars I used Shell V power, mainly for the points and free fuel for the E55. .
I drove sensibly quick as I had always done, covered the same 30k pa and still remained firmly in the top 1/4. Was expecting trouble for using it, but all okay with the bean counters. The Astra drove really well on V power.
More miles per litre I presume with V power. Cost vs miles.

My nephew works for that company from Stuttgart and his company fuel card only allows Tesco or Texaco. No Shell for them . What do they know that we don’t. ????


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