[fry]

Originally Posted by reignofchaos

I have a 1.6L ecoboost in my Volvo. It was 180HP from factory and I remapped it to 200HP via the manufacturer sanctioned Polestar map.

I have tried speed 97 (there is only one pump in bangalore) once and to be honest didn't notice that big a difference over the normal 91 octane Shell VPower. Good quality 91 octane should be fine. Don't bother with octane boosters.

Just to say that my EcoBoost is loving the sonax octane boost along with power petrol.

91 RON is power BTW I though it was 93.
Sad state.
These modern petrol pump engines love higher octanes.
Cheers!

[Jeroen]

Engines are designed for a specific octane number. Running your engine with a higher octane number then recommended will have, in essence, no effect. Running it on a lower number then recommended can cause problems as your engine could suffer from pinging/knocking and even get damaged.

Modern engine management systems have anti knock sensors. So to some extend they will be able to adjust the ignition towards the octane rating.

The single most important factor that determines which octane rating to use is an engines compression ratio. That is fixed and thus the best recommended octane rating is fixed. You can remap your ECU to your hearts content but that doesn't Change the compression ratio.

Modern fuel refinery techniques have come a long way. But still on some cheaper fuels higher octane Rated fuels could be considered poorer quality then low octane rated. Ie the caloric value of high octane fuel could be less then on a low octane fuel. The higher compression makes up for it eventually. But if you use high octane fuel in a low compression engine, you could end up with even less power.

I often read about people claiming that their cars run much better on high octane fuel. I have an explanation for that, but it's not very scientific.

Jeroen

[SnS_12]

Originally Posted by kbk_75

Lastly, in India where fuel adulteration is so rampant, I have been informed by someone with contacts in the petroleum ministry that the "least adulterated" fuel of all the various petrol companies is Bharat Petroleum, the makers of Speed and Speed 97 fuel, so some people may be willing to pay a premium just to get less adulterated fuel.

I have been told the same thing. If you fill from a Bharat Petroleum pump then you car or bike would provide a better mileage as well as the fuel quality is better. So now, I make it a point to fill from BP pumps, whenever possible.

[Jeroen]

Originally Posted by SnS_12

I have been told the same thing. If you fill from a Bharat Petroleum pump then you car or bike would provide a better mileage as well as the fuel quality is better. So now, I make it a point to fill from BP pumps, whenever possible.

True, regardless of octane number adulteration can have a big effect of fuel efficiency and performance, obviously.

Technically speaking high octane fuel used to be produced by taking a low octane fuel and then adulterating it with anti knock additives. From a marketing point of view that wasn't particularly sexy, so they came up with fancy product names and charged more. Often claiming very doubtful performance improvements.

These days it is a little bit more cleverer Maybe somebody with a solid background in chemical engineering can explain in some more detail the exact difference between low and high octane. (BTW the octane number as such doesn't say anything on the actual iso-octane in your fuel. It is ratio comparison to a standardised/normalized fuel/engine performance if my memory serves me correct)

Would love to hear from somebody with real (chemical) insights into the curious wold of octane ratings and numbers!

Jeroen

[Monaro]

Just topped up my CLA 200 with Speed 97 @ ₹78. The recommended fuel is 95RON, so i suppose this suffices.

Driven around 15kms with it, no significant difference felt yet. The engine sound seems to have gone up a little, but i guess its just me paying too much attention to the anticipated 'change' :P

[Sahil]

Originally Posted by Monaro

Just topped up my CLA 200 with Speed 97 @ ₹78. The recommended fuel is 95RON, so i suppose this suffices.

Driven around 15kms with it, no significant difference felt yet. The engine sound seems to have gone up a little, but i guess its just me paying too much attention to the anticipated 'change' :P

Ironically, I just booked a CLA 200 and was wondering if using 97 octane in it will make a difference. My RS5 has sipped nothing but 97 octane since the day I bought it. However, I am not sure if the CLA 200's 2L engine requires such a potent and expensive fuel.

15kms is too short a run to make a judgement. You will need to go atleast 2 tankfuls to really come up with some observations. Do keep me posted on this and also please calculate your FE to see if there is an improvement. There is a chance that you get better FE which will equate the additional cost you paid for the fuel to some extent.

Have you had an trouble with you engine on regular petrol that made you want to switch to 97 octane this time?

[sweetvar26]

Originally Posted by Monaro

Just topped up my CLA 200 with Speed 97 @ ₹78. The recommended fuel is 95RON, so i suppose this suffices.

Driven around 15kms with it, no significant difference felt yet. The engine sound seems to have gone up a little, but i guess its just me paying too much attention to the anticipated 'change' :P

Correct me if I'm wrong but isn't that regular speed @78? I thought Speed 97 is around the Rs.100 price bracket.

[Sahil]

Originally Posted by sweetvar26

Correct me if I'm wrong but isn't that regular speed @78? I thought Speed 97 is around the Rs.100 price bracket.

Used to be but prices have come down over the past year or so

[sweetvar26]

Originally Posted by Sahil

Used to be but prices have come down over the past year or so

Oh damn. Sucks I can't get access to 97 anywhere close to where I live. I've only been filling my car with regular speed.

[Fstlndrive]

Originally Posted by Sahil

Ironically, I just booked a CLA 200 and was wondering if using 97 octane in it will make a difference. My RS5 has sipped nothing but 97 octane since the day I bought it. However, I am not sure if the CLA 200's 2L engine requires such a potent and expensive fuel.

My 320i manual states that the recommended fuel is 95 RON, but minimum requirement is 91 RON. The dealer said 91 RON is enough and I should not have problems. For the last tank, I filled with 91 RON, I read this thread and am confused whether to use 91 RON petrol or 97 RON petrol. Although the engine is detuned, does 91 RON will affect the engine in the long run?

[M AUTO]

Originally Posted by Fstlndrive

My 320i manual states that the recommended fuel is 95 RON, but minimum requirement is 91 RON. The dealer said 91 RON is enough and I should not have problems. For the last tank, I filled with 91 RON, I read this thread and am confused whether to use 91 RON petrol or 97 RON petrol. Although the engine is detuned, does 91 RON will affect the engine in the long run?

If the manual says 97 then car is tuned for it, how ever you can use 91 also but decrease in power which can't be seen in every day commuting. But if you mix both 91and 97 then firing will be affected, so does the engine

[anandpadhye]

Originally Posted by Monaro

Just topped up my CLA 200 with Speed 97 @ ₹78. The recommended fuel is 95RON, so i suppose this suffices.

Driven around 15kms with it, no significant difference felt yet. The engine sound seems to have gone up a little, but i guess its just me paying too much attention to the anticipated 'change' :P

Same here. I filled Speed 97 in my 1.8TSi - 1st time ever (car has done 45000km - all on regular petrol so far). Have driven only ~30km so far on 97, so too early to judge but I also feel it's become slightly louder. Also, ~5L of regular petrol was in the tank when I filled 97, so I may try one more tank full of 97 before I switch back to regular :-) Will update in a month.

[Fstlndrive]

Last tank I filled with speed 97 petrol (recommended fuel - RON 95). I have driven 200 kms after filling. At high speeds, I did not see any improvement in the mileage over RON 91. But at bumper-bumper traffic, I felt an increase in the mileage (approx. 1 kmpl). But, it needs to be checked over long periods of time and fills with speed 97 petrol.

[Fstlndrive]

BMW 320i: Suggested fuel 95 RON. Minimum 91 RON.

First tank filling gave me 7.3 kmpl with 91 RON. (Dealer told me that 91 RON is enough).
After going through this thread, I decided to use speed 97 for my second tank.

Second tank refilling gave me 10.3 kmpl with speed 97.

The increase could be because of the following reasons:

1. Engine is still in break-in period. Now the odo shows 930 kms. (need to redo the calculations after few fillings above odo 2000 km reading).
2. Whole first tank was done only in city driving (370 kms) and the second tank was done 160 kms on highway driving with some kms on sport mode (out of 462 kms).
3. Speed 97 might have helped to improve the fuel efficiency.

Approximate calculations I did for the cost:
7.3 kmpl: 50.68 litres, 370 kms (1st fill) - Rs. 3221 (Rs. 63.55 per lit)
10.3 kmpl: for the same kms (370) (2nd fill): 35.9 liters, - Rs. 2918 (Rs. 81.24 per lit)
Savings : Rs. 303.

Since the fuel efficiency increased based on the above data and approximate calculations, I decided to stick with speed 97 for rest of the fillings for my car.

[Monaro]

Originally Posted by Sahil

Ironically, I just booked a CLA 200 and was wondering if using 97 octane in it will make a difference. My RS5 has sipped nothing but 97 octane since the day I bought it. However, I am not sure if the CLA 200's 2L engine requires such a potent and expensive fuel.

15kms is too short a run to make a judgement. You will need to go atleast 2 tankfuls to really come up with some observations. Do keep me posted on this and also please calculate your FE to see if there is an improvement. There is a chance that you get better FE which will equate the additional cost you paid for the fuel to some extent.

Have you had an trouble with you engine on regular petrol that made you want to switch to 97 octane this time?

Been 3 tankfuls with Speed 97 so far, and I think I feel the ride being smoother and acceleration better (placebo maybe? )

But with rising costs, I think i'll go back to 91 for now and in case i feel any decrease in performance, think about it later!