How does high octane fuel improve performance?

GTO · 10th December 2009, 10:40

Nitrous, IIRC, Speed 93 was offered by BP in 2003. Since, it has been replaced by Speed 97.

physicspsyche · 16th December 2009, 15:10

High octane fuel cannot improve performance. It just used in sports car which operate at very high temprature hence the theory of performance improvement. Normal fuel can flame the sports cars thats why they fill high octane.

Swapnil21 · 15th February 2010, 21:16

according to what i read, the normal fuel that we get is 88 octane whereas speed is 93 octane.
Bharat Petroleum Corporation Limited- Motive Power Fuels- Petrol or Motor Spirit

what i understand is that higher the octane number, better the combustion, hence better acceleration and load taking capability of the engine but not a lot of difference in the top end performance.

KSM-Vtec · 15th February 2010, 21:42

Quote:

Originally Posted by Swapnil21

according to what i read, the normal fuel that we get is 88 octane whereas speed is 93 octane.
Bharat Petroleum Corporation Limited- Motive Power Fuels- Petrol or Motor Spirit

what i understand is that higher the octane number, better the combustion, hence better acceleration and load taking capability of the engine but not a lot of difference in the top end performance.

from what i know its 91oct in metros and 88/89 in other places.

Shan2nu · 15th February 2010, 21:44

I was using IOC 91 for 7 years in the VTEC. Have been filling normal fuel since Sept 2009 and haven't seen any drop in FE or performance. Dont even feel like going back to higher octane now.

So i dont think most Indian cars even need high octane fuel unless the cylinder compression ratio/pressure is increased by a large margin over stock.

Shan2nu

ImmortalZ · 15th February 2010, 22:01

Quote:

Originally Posted by physicspsyche

High octane fuel cannot improve performance. It just used in sports car which operate at very high temprature hence the theory of performance improvement. Normal fuel can flame the sports cars thats why they fill high octane.

Right and wrong.

With high octane fuels, you can have higher compression ratios which translates to more power. An engine designed for high octane will knock if run with normal fuel.

devrajman · 16th February 2010, 10:21

Quote:

Originally Posted by ImmortalZ

Right and wrong.

With high octane fuels, you can have higher compression ratios which translates to more power. An engine designed for high octane will knock if run with normal fuel.

Or vice-versa of it, If your engine knocks use high octane fuel!

vivprasad · 8th March 2010, 09:21

I went through the entire thread, and am still not sure about what fuel I should use.

I have the new SX4 with a VVT engine that is Euro IV. The compression ratio is 9.7:1 as given in the manual. The fuel recommended is "88 RON or higher" in the manual.

I have been regularly using IOC Xtra Premium. Should I continue or switch to Regular petrol.

Thanks

ImmortalZ · 8th March 2010, 11:34

There is not a shred of evidence that suggests that these "premium" fuels have higher octane. What they do have are additives. Some engines like them, some don't. Your wallet doesn't for sure.

I've fueled my Civic with regular petrol only. The one full tank I did with Speed showed me no difference at all.

GTO · 8th March 2010, 19:41

Vivprasad, unless your weekend hobby is to burn cash, you will do well in switching back to regular petrol

vivprasad · 9th March 2010, 12:40

Quote:

Originally Posted by GTO

Vivprasad, unless your weekend hobby is to burn cash, you will do well in switching back to regular petrol

Thanks GTO, but its not switching back to regular, it will be switching to regular, as I was topping up with Xtra Premium from the start. It seems I have already pursued my hobby on too many weekends...........and must stop

Thanks ImmortalZ

adisag · 20th April 2010, 08:26

My Hyundai i10 Kappa on Speed 97 gives 21 Kmpl

Sunday, I tanked up my blushing red beauty with Speed 97 - She gulped down 29.9 Litres of the stuff, with the tripmeter reading 437 Km (Since the last full tank of IOC xtra premium). Translated, the average was 14.61 Km/L. This number has been fairly consistent across the last 4-5 months, winters pushed the mileage as high as 15.3 Km/L - That's been my best so far, and the onset of summers and 4 or 5 rush hour drives with full ac dropped her down to 390 Litres before I needed to refuel (was to disgusted and flustered to actually check the exact mileage I got of that tank - but I reckon it was about 13) - The worst till date.

Although overall performance of the car has always been quite good, I have often felt low end torque to be slightly limiting, forcing a downshift (from 5th) at about 50 Km/hr. The occassional rolling start in second also caused a bit of stress on the engine. Driving without the AC, pickup at engine speeds below 1750 RPm was non existent, and if the AC was own, the additional load would cause the engine to stutter. At higher engine speeds performance has been brilliant, though occasional revving till the redline caused the engine to sound somewhat coarse.

I had been browsing through the Speed 97 threads on team-bhp late on saturday evening, and I guess this set the thought rolling. Was driving to work on Sunday (yes I work sundays :( ), I was crossing a BPCL pump, and stopped in some traffic behind a bus. I noticed the signboard reading Speed 97 - 61.?? Rs/-. I was running a bit low on fuel, and would have pulled into the IOC pump where i normally tank up (some 6-7 km down the road), but reading this made me think - why not give it a try.

I pulled into the petrol pump, and asked if they had Speed 97. They confirmed both availability and price, so I asked them to tank up. Meanwhile I chatted up the attendant who was all praises for this fuel, and was telling me how there was this gentleman in an OHC Vtec, who would use only Speed 97, and had even driven away without fuel a couple of times when it was in short supply; he carried on about how this guy often dropped the attendant home, and always tipped them etc. etc. Guess he was trying to angle for a tip from me too

. Anyway, my tank was full till auto cut-off, the attendant tried to fill some more fuel (trying to get the billing upto the nearest hundred) but I promptly stopped him. Paid up, checked the air in my tires and drove off.

Drove around a 100 km on sunday, and the fuel gauge had barely moved 1/8th of the way down (Normally its moved 1/4th), the driveability felt a little better, particularly the low end grunt - the car with ac on was driving as it would without ac on my normal (xtra premium) fuel - I was a bit sceptical and felt that maybe I was feeling this way because of the lighter than normal traffic, and as I was'nt in a state of terrific rush, but the supposed increase in mileage (as estimated by the reading of the fuel gauge) was to much to scoff away just like that.

Monday morning rush hour, a hot hot day and I left home late - worst of the heat and the traffic. It was about halfway to work when I realized that I had been driving in bumper to bumper stop-start traffic, with the ac on, without shifting down to first at all, I had even taken 4-5 dead starts in second gear without even realizing - Normally, the engine stutters even without ac, and I normally drive 1st-2nd gears in stop start traffic, but here I was happily driving only 2nd (no downshifts required) and I had'nt even realized it. FOr the rest of my drive, i paid close attention, and was seriously impressed by the significant improvement in low end driveability.

Returning home in the evening (10 pm or so) traffic had waned out, and I got an empty stretch of road, so decided to check the top-end with this new grade of fuel - revved her upto 5 K RPm in 3d gear, pickup seemed to have improved, and that slight rough sound that prevailed above 4500 RPm earlier was gone.

I was in awe of Speed 97. I had driven 225 km and my tank was still 70% full - I got impatient and decided I would tank up (even if it was just 10 odd litres) with SPeed 97 right away, just to put an actual figure on the kind off mileage I was getting. Tanked up an hour ago on my way to work. Here are the figures 241 Km and 11.47 Litres of the fuel (till auto cut-off and the same petrol pump) - Thats 21 Km/L - I'll even accept that he put in say an extra 500 Ml last time around before I could stop him (Read Para 1), even then its still over 20 Km/L - up from my previous best of barely 15.5 Km/L - This is just superlative, and seems to good to be true.

Economics - Assume Xtra Premium (or Speed or Power) costs 50 Rs (Its actually 50 Rs and some paisa in Delhi now) and returns 15 Km/L - this works out to be 3.33 Rs Per Km. Speed 97 costs 61 Rs and gives a mileage of say 20 Km/L - thats 3.05 Rs Per Km.

This is fantastic - I was seriously shocked by my own findings - I'm a Speed 97 addict now. Will soon update on full tank mileage and other details.

I seriously wonder why the car manufacturers state that their cars should only use such and such fuel (whatever that particular car is designed for), This would ensure that more petrol pumps stock higher grade fuels, better customer awareness (I had no idea an i10 demanded Speed 97 - Just a matter of chance), better mileage (solves my grouse of having to tank up every 450 Km as my car will now have extended range), lower pollution (? - I suppose this is a side effect of better FE and the correct grade of fuel for which the engine is designed).

Here's to hoping a fuel revolution is going to happen across the country !!

Skindleberg · 20th April 2010, 15:25

I think there is a difference. We at home always put speed 91 in our swift and the result is stark. There was a time after a year of using speed 91 my mom decided to pop regular petrol in the car and a month later when I came back from college the moment I drove it (and the moment meaning before I shifted into second gear) I knew something was wrong and the power was gone. and I asked mom if she'd put regular stuff and she said yes and I checked up the fuel consumption, it had gone up. (I did get everyone at home to start writing the mileage at the back of the receipt and throw it in the glove compartment specifically to keep track of fuel consumption, much before this incident so I had a month of regular stuff to compare to earlier consumptions) She said gas had gotten expensive and she felt it was a waste of money but when I explained that fuel consumption had also gone up and we were actually getting less kms per rupee with regular stuff she agreed to roll back to speed 91 and within 2 tankups the car was driving better and again consumption dropped. So I have practically tested out that speed 91 helps.
Now why it helps? I'm guessing it reduces knocks and we all know modern ecus take feedback from the knock sensors and advance or retard spark to keep away knocks. So with speed gas incipient knocks are less and the spark is advanced giving more power in each stroke so one uses less accelerator to get the desired movment of the car.
Again in a car like the swift, everyone would agree that the low end torque is so pathetic that when you get off a light it's very easy to stall so we end up giving it more gas and clutch to get a fast getaway. If spark is retarded you'll have to give yet more gas.

In city I'll get about 12-13 with ac and on highways It's gone upto 19kmpl!!!! I know but it has....

rk_sans · 17th May 2010, 12:43

Quote:

Originally Posted by adisag

.
This is fantastic - I was seriously shocked by my own findings - I'm a Speed 97 addict now. Will soon update on full tank mileage and other details.

@adisag,
Any update on the full tank to tank mileage details. I tried Speed for last couple of weeks and i could feel the improvement in the engine response but yet to test the mileage.

adisag · 18th May 2010, 07:22

@rk-sans - I got 548Km/29.8Litres = 18.6 Kmpl from the first full tank on 97(Got a service done during this tank-so may not be all that accurate) and then 573Km/28.7Litres= 20 Kmpl on the second. Unfortunately I had to tank up on IOC Premium on my last fill as Speed 97 was'nt available :( definite drop in driveability and the mileage seems to be hovering back around the 15Kmpl mark.

10th December 2009, 10:40	#106
GTO Team-BHP Support Join Date: Feb 2004 Location: Bombay Posts: 70,530 Thanked: 300,725 Times View My Garage	Nitrous, IIRC, Speed 93 was offered by BP in 2003. Since, it has been replaced by Speed 97.
	() Thanks

16th December 2009, 15:10	#107
physicspsyche BHPian Join Date: Oct 2008 Location: New Delhi Posts: 42 Thanked: 0 Times	High octane fuel cannot improve performance. It just used in sports car which operate at very high temprature hence the theory of performance improvement. Normal fuel can flame the sports cars thats why they fill high octane.
	() Thanks

15th February 2010, 21:16	#108
Swapnil21 Newbie Join Date: Apr 2006 Location: Mumbai Posts: 10 Thanked: 0 Times	according to what i read, the normal fuel that we get is 88 octane whereas speed is 93 octane. Bharat Petroleum Corporation Limited- Motive Power Fuels- Petrol or Motor Spirit what i understand is that higher the octane number, better the combustion, hence better acceleration and load taking capability of the engine but not a lot of difference in the top end performance.
	() Thanks

15th February 2010, 21:44	#110
Shan2nu Senior - BHPian Join Date: Feb 2004 Location: Hubli - Karnata Posts: 5,533 Thanked: 125 Times View My Garage	I was using IOC 91 for 7 years in the VTEC. Have been filling normal fuel since Sept 2009 and haven't seen any drop in FE or performance. Dont even feel like going back to higher octane now. So i dont think most Indian cars even need high octane fuel unless the cylinder compression ratio/pressure is increased by a large margin over stock. Shan2nu
	() Thanks

8th March 2010, 09:21	#113
vivprasad BHPian Join Date: Oct 2009 Location: Lucknow Posts: 154 Thanked: 114 Times	I went through the entire thread, and am still not sure about what fuel I should use. I have the new SX4 with a VVT engine that is Euro IV. The compression ratio is 9.7:1 as given in the manual. The fuel recommended is "88 RON or higher" in the manual. I have been regularly using IOC Xtra Premium. Should I continue or switch to Regular petrol. Thanks
	() Thanks

8th March 2010, 11:34	#114
ImmortalZ Senior - BHPian Join Date: Jan 2008 Location: Trivandrum Posts: 2,179 Thanked: 488 Times View My Garage	There is not a shred of evidence that suggests that these "premium" fuels have higher octane. What they do have are additives. Some engines like them, some don't. Your wallet doesn't for sure. I've fueled my Civic with regular petrol only. The one full tank I did with Speed showed me no difference at all.
	() Thanks

8th March 2010, 19:41	#115
GTO Team-BHP Support Join Date: Feb 2004 Location: Bombay Posts: 70,530 Thanked: 300,725 Times View My Garage	Vivprasad, unless your weekend hobby is to burn cash, you will do well in switching back to regular petrol
	() Thanks

20th April 2010, 08:26	#117
adisag BHPian Join Date: Feb 2010 Location: Gurgaon Posts: 143 Thanked: 60 Times	Difference in Mileage by using Speed 97 My Hyundai i10 Kappa on Speed 97 gives 21 Kmpl Sunday, I tanked up my blushing red beauty with Speed 97 - She gulped down 29.9 Litres of the stuff, with the tripmeter reading 437 Km (Since the last full tank of IOC xtra premium). Translated, the average was 14.61 Km/L. This number has been fairly consistent across the last 4-5 months, winters pushed the mileage as high as 15.3 Km/L - That's been my best so far, and the onset of summers and 4 or 5 rush hour drives with full ac dropped her down to 390 Litres before I needed to refuel (was to disgusted and flustered to actually check the exact mileage I got of that tank - but I reckon it was about 13) - The worst till date. Although overall performance of the car has always been quite good, I have often felt low end torque to be slightly limiting, forcing a downshift (from 5th) at about 50 Km/hr. The occassional rolling start in second also caused a bit of stress on the engine. Driving without the AC, pickup at engine speeds below 1750 RPm was non existent, and if the AC was own, the additional load would cause the engine to stutter. At higher engine speeds performance has been brilliant, though occasional revving till the redline caused the engine to sound somewhat coarse. I had been browsing through the Speed 97 threads on team-bhp late on saturday evening, and I guess this set the thought rolling. Was driving to work on Sunday (yes I work sundays :( ), I was crossing a BPCL pump, and stopped in some traffic behind a bus. I noticed the signboard reading Speed 97 - 61.?? Rs/-. I was running a bit low on fuel, and would have pulled into the IOC pump where i normally tank up (some 6-7 km down the road), but reading this made me think - why not give it a try. I pulled into the petrol pump, and asked if they had Speed 97. They confirmed both availability and price, so I asked them to tank up. Meanwhile I chatted up the attendant who was all praises for this fuel, and was telling me how there was this gentleman in an OHC Vtec, who would use only Speed 97, and had even driven away without fuel a couple of times when it was in short supply; he carried on about how this guy often dropped the attendant home, and always tipped them etc. etc. Guess he was trying to angle for a tip from me too . Anyway, my tank was full till auto cut-off, the attendant tried to fill some more fuel (trying to get the billing upto the nearest hundred) but I promptly stopped him. Paid up, checked the air in my tires and drove off. Drove around a 100 km on sunday, and the fuel gauge had barely moved 1/8th of the way down (Normally its moved 1/4th), the driveability felt a little better, particularly the low end grunt - the car with ac on was driving as it would without ac on my normal (xtra premium) fuel - I was a bit sceptical and felt that maybe I was feeling this way because of the lighter than normal traffic, and as I was'nt in a state of terrific rush, but the supposed increase in mileage (as estimated by the reading of the fuel gauge) was to much to scoff away just like that. Monday morning rush hour, a hot hot day and I left home late - worst of the heat and the traffic. It was about halfway to work when I realized that I had been driving in bumper to bumper stop-start traffic, with the ac on, without shifting down to first at all, I had even taken 4-5 dead starts in second gear without even realizing - Normally, the engine stutters even without ac, and I normally drive 1st-2nd gears in stop start traffic, but here I was happily driving only 2nd (no downshifts required) and I had'nt even realized it. FOr the rest of my drive, i paid close attention, and was seriously impressed by the significant improvement in low end driveability. Returning home in the evening (10 pm or so) traffic had waned out, and I got an empty stretch of road, so decided to check the top-end with this new grade of fuel - revved her upto 5 K RPm in 3d gear, pickup seemed to have improved, and that slight rough sound that prevailed above 4500 RPm earlier was gone. I was in awe of Speed 97. I had driven 225 km and my tank was still 70% full - I got impatient and decided I would tank up (even if it was just 10 odd litres) with SPeed 97 right away, just to put an actual figure on the kind off mileage I was getting. Tanked up an hour ago on my way to work. Here are the figures 241 Km and 11.47 Litres of the fuel (till auto cut-off and the same petrol pump) - Thats 21 Km/L - I'll even accept that he put in say an extra 500 Ml last time around before I could stop him (Read Para 1), even then its still over 20 Km/L - up from my previous best of barely 15.5 Km/L - This is just superlative, and seems to good to be true. Economics - Assume Xtra Premium (or Speed or Power) costs 50 Rs (Its actually 50 Rs and some paisa in Delhi now) and returns 15 Km/L - this works out to be 3.33 Rs Per Km. Speed 97 costs 61 Rs and gives a mileage of say 20 Km/L - thats 3.05 Rs Per Km. This is fantastic - I was seriously shocked by my own findings - I'm a Speed 97 addict now. Will soon update on full tank mileage and other details. I seriously wonder why the car manufacturers state that their cars should only use such and such fuel (whatever that particular car is designed for), This would ensure that more petrol pumps stock higher grade fuels, better customer awareness (I had no idea an i10 demanded Speed 97 - Just a matter of chance), better mileage (solves my grouse of having to tank up every 450 Km as my car will now have extended range), lower pollution (? - I suppose this is a side effect of better FE and the correct grade of fuel for which the engine is designed). Here's to hoping a fuel revolution is going to happen across the country !! Last edited by Jaggu : 20th April 2010 at 10:05. Reason: Please use Search and continue in any of the existing thread, Thanks
	() Thanks

20th April 2010, 15:25	#118
Skindleberg Newbie Join Date: Jan 2007 Location: Delhi Posts: 4 Thanked: 0 Times	I think there is a difference. We at home always put speed 91 in our swift and the result is stark. There was a time after a year of using speed 91 my mom decided to pop regular petrol in the car and a month later when I came back from college the moment I drove it (and the moment meaning before I shifted into second gear) I knew something was wrong and the power was gone. and I asked mom if she'd put regular stuff and she said yes and I checked up the fuel consumption, it had gone up. (I did get everyone at home to start writing the mileage at the back of the receipt and throw it in the glove compartment specifically to keep track of fuel consumption, much before this incident so I had a month of regular stuff to compare to earlier consumptions) She said gas had gotten expensive and she felt it was a waste of money but when I explained that fuel consumption had also gone up and we were actually getting less kms per rupee with regular stuff she agreed to roll back to speed 91 and within 2 tankups the car was driving better and again consumption dropped. So I have practically tested out that speed 91 helps. Now why it helps? I'm guessing it reduces knocks and we all know modern ecus take feedback from the knock sensors and advance or retard spark to keep away knocks. So with speed gas incipient knocks are less and the spark is advanced giving more power in each stroke so one uses less accelerator to get the desired movment of the car. Again in a car like the swift, everyone would agree that the low end torque is so pathetic that when you get off a light it's very easy to stall so we end up giving it more gas and clutch to get a fast getaway. If spark is retarded you'll have to give yet more gas. In city I'll get about 12-13 with ac and on highways It's gone upto 19kmpl!!!! I know but it has....
	() Thanks

18th May 2010, 07:22	#120
adisag BHPian Join Date: Feb 2010 Location: Gurgaon Posts: 143 Thanked: 60 Times	@rk-sans - I got 548Km/29.8Litres = 18.6 Kmpl from the first full tank on 97(Got a service done during this tank-so may not be all that accurate) and then 573Km/28.7Litres= 20 Kmpl on the second. Unfortunately I had to tank up on IOC Premium on my last fill as Speed 97 was'nt available :( definite drop in driveability and the mileage seems to be hovering back around the 15Kmpl mark.
	() Thanks