How does high octane fuel improve performance?

[RX135]

Originally Posted by amitabh_kaushal

Recently overdrive tested all petrol for bikes & said HP power is the best in performance & mielage in terms of money spent.

Speed or Power are not high octane petrols (Speed 93 IS), but petrol with additives. They help you in keeping fuel injectors/valves clean. There is no harm using it. And no, they are not supposed to cleaner or purer than regular unleaded, contrary to what some people say.

[Kaizer Sozay]

I Personally feel that Power from HP does give slightly better performance than Speed from BP. But these are my views and no supporting technical facts to back it up.

[imjimmy]

I guess for all Euro II cars 87 Octane should be ok.

the contentious issue is about using higher octane fuel for Euro III cars.

The general opinion here seeems to be that Engines with a higher compression ratio benefit from the higher Octane.

So a Euro III Getz with a 10:1 compression shd benefit more from a 91 Oct Fuel as compared to a Euro III Baleno with a 9:1 compression ratio.

Hopefully someone can put more light on this.

[amitabh_kaushal]

Originally Posted by imjimmy

I guess for all Euro II cars 87 Octane should be ok.

the contentious issue is about using higher octane fuel for Euro III cars.

The general opinion here seeems to be that Engines with a higher compression ratio benefit from the higher Octane.

So a Euro III Getz with a 10:1 compression shd benefit more from a 91 Oct Fuel as compared to a Euro III Baleno with a 9:1 compression ratio.

Hopefully someone can put more light on this.

That means in indigo its no-use to use higher octane petrol as its compression ratio is 9:0:1. The only thing is to get smooth ride i can go for higher octane level. So once in a month i will go for it.

[pranil]

Originally Posted by imjimmy

I guess for all Euro II cars 87 Octane should be ok.

the contentious issue is about using higher octane fuel for Euro III cars.

The general opinion here seeems to be that Engines with a higher compression ratio benefit from the higher Octane.

So a Euro III Getz with a 10:1 compression shd benefit more from a 91 Oct Fuel as compared to a Euro III Baleno with a 9:1 compression ratio.

Hopefully someone can put more light on this.

GETZ manual reccomends Octane 87 and Up as regular fuel along with optional additives for better economy and longer engine life.


I personally found little diffrence in getz but the car is only one week old. My Santro on the oother hand improves in the bootm end torque on the higher octane( This is 1999 Santro - One of the few old origanal Epsilon engines) No idea of compression ratio though

[turbo_c]

Originally Posted by raajks

Question --- What is the right Octance rating for an Esteem?
I use Speed. Would like to know your opnion on this.

Experience --
Milage ---
I have driven the Esteem with the normal fuel available at BPCL
I did notice that a 10 L fuel getting exhausted in 1 1/2 weeks time.
When I used Speed the same amount of fuel came for 2 weeks

This has been a regular run, where I take the car to work and back. No additional runs. Nothing

Performance --
With Speed, I noticed a good power surge on the low end torque (Meaning car running on the lower 2 gears)
High end Torque, I could nt notice much of a difference between the two fuel types

My experience with my MPFI Esteem:

1. Plain Regular 87 Octane: Lots of knocking at RPM below 1500, poor acceleration, poor average (12Kmpl highway, 10Kmpl city)

2. Regular 87 Octance + System G: Some knocking below 1500 RPM, slightly improved average (13Kmpl highway, 10Kmpl city)

3. Speed / Power: Moderate knocking below 1500 RPM, lots of knocking while accelerating in 4th and 5th at almost all RPMS! (This was a big surprise to me too!). 13Kmpl highway, 10Kmpl city.

4. Xtrapremium: No knocking right down from 1000 RPM! Slight knocking below 1000 RPM, but this is really asking for it... Great average... as high as 17Kmpl on the highway once, but normally 15Kmpl highway, 12Kmpl city. Best acceleration too... no knocking = lots of torque!

I have not tried Speed 93 or anthing with a higher octane rating than Xtrapremium. I tank up on the Mumbai - Pune Expressway and actually let my car run on fumes to reach the only pump selling Xtrapremium!

My vote for the MPFI Esteem: Xtrapremium when you can get it, otherwise Regular 87 Octane + System G.

I may be wrong though... maybe my car is setup with an advanced / retarded ignition timing that gives a good performance with a slightly higher octane fuel, but makes it incompatible with the lesser stuff.

My dad's carburetted '96 Esteem runs pretty well with the regular 87 octance and performs best with "Power"... nothing special happens with the more expensive higher octane fuels.

- T u r b o C -

[Gurkha]

Most of today's cars like Honda City, Accord, Corolla, Palio, Optra have knock sensors, which is nothing but a sophisticated and insulated high quality microphone attached to the engine block. What it does is monitor for engine knock and then tells the ECU to retard timing, leading to loss of power, using high octane fuel is one good way of assurance that knock won't occur, specially on hot day with a/c running and vehicle heavily loaded going uphill. One of the reasons for better mileage with high octane fuel is due to the engine running at its full efficiency rating and thereby developing its rated power. This means that the driver doesn't have to hold the throttle for longer duration to get to his/her desired power.

Same thing with additive added higher cetane diesels like Turbo Jet etc. Not only do they keep injectors and combustion chamber clean, the high cetane ensures better burn preventing power robbing knock, specially in turbo diesels.

One thing I would like to point out, if your vehicle suddenly develops knock using your regular brand of fuel, then using higher octane/cetane is stop gap measure, you have other problems looming like incorrect timing, bad plugs, clogged inkectors and most likely culprit, carbon build up inside the combustion chamber.

[imjimmy]

My experience with my MPFI Esteem:

1. Plain Regular 87 Octane: Lots of knocking at RPM below 1500, poor acceleration, poor average (12Kmpl highway, 10Kmpl city)

2. Regular 87 Octance + System G: Some knocking below 1500 RPM, slightly improved average (13Kmpl highway, 10Kmpl city)

3. Speed / Power: Moderate knocking below 1500 RPM, lots of knocking while accelerating in 4th and 5th at almost all RPMS! (This was a big surprise to me too!). 13Kmpl highway, 10Kmpl city.

4. Xtrapremium: No knocking right down from 1000 RPM! Slight knocking below 1000 RPM, but this is really asking for it... Great average... as high as 17Kmpl on the highway once, but normally 15Kmpl highway, 12Kmpl city. Best acceleration too... no knocking = lots of torque!

I have not tried Speed 93 or anthing with a higher octane rating than Xtrapremium. I tank up on the Mumbai - Pune Expressway and actually let my car run on fumes to reach the only pump selling Xtrapremium!

My vote for the MPFI Esteem: Xtrapremium when you can get it, otherwise Regular 87 Octane + System G.

I may be wrong though... maybe my car is setup with an advanced / retarded ignition timing that gives a good performance with a slightly higher octane fuel, but makes it incompatible with the lesser stuff.

My dad's carburetted '96 Esteem runs pretty well with the regular 87 octance and performs best with "Power"... nothing special happens with the more expensive higher octane fuels.

- T u r b o C -

Hey thanks!

That's a very good analysis.

I hope you are talking about XtraPremium 91 Octane fuel from Indian oil?

I have topped up my tank for both the Baleno and the swift with this XtraPremium fuel. It's about 1.5 Rs costlier per litre to normal 87 Oct.

Let's see the effect on FE and driveability..

( i do notice the Baleno to be a tad..quicker at low rpm's but that cud be a illusion!)..

BTW pardon me for the ignorance..but what do you mean by System G - are these the Iftex additives.

[raja_ys]

i have purchased wagon r lxi e3 model last month, first service done at 1100 kms. the owner manual and service engineer recommends unleaded plain petrol, and says that higher fuels are not required since the vehicle is an mpfi oneand also that engine life will be damaged. is it true, will higher fuel really show diff in performance and wht fuel is recommended?

[turbo_c]

Originally Posted by imjimmy

Hey thanks!

That's a very good analysis.

I hope you are talking about XtraPremium 91 Octane fuel from Indian oil?

Yup... that's it!

Originally Posted by imjimmy

I have topped up my tank for both the Baleno and the swift with this XtraPremium fuel. It's about 1.5 Rs costlier per litre to normal 87 Oct.

Let's see the effect on FE and driveability..

( i do notice the Baleno to be a tad..quicker at low rpm's but that cud be a illusion!)..

BTW pardon me for the ignorance..but what do you mean by System G - are these the Iftex additives.

Yes, I'm taking about the Iftex petrol additive "System G" ... I used to be sceptical about these before, but it does work... reduces knocking noticably and my spark plugs stay clean for a long time too... but I use it as only an emergency measure when I can't get Xtrapremium and I have to fill the regular stuff.

- T u r b o C -

[amitabh_kaushal]

Hi Turbo C,

I tried with Xtra Premium this time. Ride so far is OK and not so smooth like speed93 but i have noticed one change. Noq my car temp gauge goes slowly to half way mark. Earlier it used jump on half way straight. Maybe its bcos my car has crossed 1300 km and engine is getting tuned. Pickup and smoothness is ok. Calculating milage now......

[speed0mania]

i stick to power definately feels better to drive there is slight but definate difference(in my zen and ikon 1.6 both) no change in milage from speed (hav tried all except 97)or power either and also speed felt just the same!! but i feel power makes the car feel a littllle bit peppier!!

i guess due to the compression ratio being low it doesnt respond to higher octane fuels but according to my knowledge any engine with a compression ratio of 10 or higher should respond to higher octane fuel !!

[devarshi84]

I dont know whether this premium fuels are really good or not but they surely give me piece of mind. I know my car is having the best drink available. I additionally also get the additives extra some 2-3 months.

[rdkarthik]

Originally Posted by turbo_c

My experience with my MPFI Esteem:

1. Plain Regular 87 Octane: Lots of knocking at RPM below 1500, poor acceleration, poor average (12Kmpl highway, 10Kmpl city)

2. Regular 87 Octance + System G: Some knocking below 1500 RPM, slightly improved average (13Kmpl highway, 10Kmpl city)

3. Speed / Power: Moderate knocking below 1500 RPM, lots of knocking while accelerating in 4th and 5th at almost all RPMS! (This was a big surprise to me too!). 13Kmpl highway, 10Kmpl city.

4. Xtrapremium: No knocking right down from 1000 RPM! Slight knocking below 1000 RPM, but this is really asking for it... Great average... as high as 17Kmpl on the highway once, but normally 15Kmpl highway, 12Kmpl city. Best acceleration too... no knocking = lots of torque!

- T u r b o C -

Thats because your inital advance is high. With a stock setup this wont happen. Usually people make the mistake of setting the timing on the mpfi just like on a carb engine. What you got to do is short two terminals (terminal E and D) of the diagnostic coupler at idle, then set a timing of 5 +/- 1 degrees of ignition advance.

Looking at the coupler (from the terminal side), sorry abt poor graphics,
--------
| * * * |
| E D * |
---------

Hope this helps !!

[amitabh_kaushal]

Originally Posted by speed0mania

i stick to power definately feels better to drive there is slight but definate difference(in my zen and ikon 1.6 both) no change in milage from speed (hav tried all except 97)or power either and also speed felt just the same!! but i feel power makes the car feel a littllle bit peppier!!

i guess due to the compression ratio being low it doesnt respond to higher octane fuels but according to my knowledge any engine with a compression ratio of 10 or higher should respond to higher octane fuel !!

Hi,

I have Indigo GSX euro-III and i felt considerable performance boost with xtra premium. Also i have got 10-11 kmpl in city driving with 50% AC on. I tried speed, power & speed 93 before xtra premium. I would say for indigo euro-III this is the best fuel dont know abt other cars. compression ratio is 9:1 as per manual.