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Old 30th June 2007, 12:40   #61
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I recently had a bad experience after I suddenly switched to a full tank of normal petrol after low fuel level light came on (I have been using only Speed, which was not available at that bunk). There was no problem initially as I drove from Pune to Mumbai without AC, but after crossing Expressway I switched on the AC and within 30 minutes the car started jerking and stalling when I pressed the accelerator. Had to drive at less than 60 kmph to Sion.

I have no idea what caused this problem. Among various possibilities, the sudden switchover to normal petrol and then driving at high speed (120-140 kmph) on the Expressway is one that I am keeping in mind. Probably advisable to switch over gradually (i.e., start with 1/2 tank Speed, 1/2 tank normal petrol, etc.).

After I got the car serviced (including AC service) and then switched back to Speed, there is no problem now, except that the AC tends to cool too much and gets overheated if I keep the blower setting in 2 or 3 in afternoon heat. When AC gets overheated, it goes on-off frequently when the car runs; it comes on, then probably some sensor cuts it off due to overheating, and the car jerks a lot. I don't know if this was the cause of the original problem.

Premium fuels should be used when recommended by the car manufacturer. Higher octane fuel is denser by about 2% and at least that much increase in mileage can be expected in a modern engine. Plus there is less chance of adulteration.

Last edited by rks : 30th June 2007 at 12:42.
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Old 30th June 2007, 12:57   #62
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Yes what I mean is also when we face problem its because of bad fuel than octane type we use.

When I contacted Shell people via their website I received email reply from them.

They said Shell Normal Petrol comes with 91 octane and their Premium Petrol with same 91 octane Petrol with additives, so I understood their Normal Petrol 91 octance without any additives, but we can't trust this fully, how they achieve that octane when all other normal petrol comes with 87octane.

They told me FE will be same for Normal and Premium Petrol, with Premium we can notice better performance. When I used both type of Petrol with my Swift, Innova with 3-4 tank full I can see Premium gives better performance, less noice, better pickup and .5kmpl extra FE compared with Shell Normal.

Also I noticed performance of Shell Normal petrol is better than other normal Petrols (BP, HP) I tried. I used maximum 6 petrol bunks all over Karnataka after finding out well known bunks based on my and my friend's experience. Interestingly all are BP Bunks and one Shell bunk Mysore road left side while coming to bangalore.

Regards,

Ravi.
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Old 30th June 2007, 13:18   #63
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Guys,

Is T-BHP loosing it's credibility for technical expertise?

This thread is on it's 5th page and still no great deal of technical analysis...

I am sure, you and me can read manuals or talk to service guys, but that's hardly the point.

I came to T-BHP with the hope to learn technology.
When it comes to premium fuels, T-BHP community (including me) seems to know nothing.

We have moderators, seniors, so-called car-enthusiastic guys here on T-BHP who talk so much about their expensive cars, modified air-intake/Free Flow Exhaust, performance boxes, 1-100 figues, etc...I just wonder how they do all this if they know nothing about the fuels!!!

Guys,
Please help by sharing the real difference between SPEED/POWER etc versus regular fuel and it's impact on our passenger car engines.

Else,
wear you moderator hats and just close the thread. The title and the topic is so important to everyone that we all are tempted to visit this thread everytime there is an update, just to find out that there is no "substance" in the new post.
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Old 30th June 2007, 14:35   #64
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Quote:
Originally Posted by anandpadhye View Post
Guys,
Please help by sharing the real difference between SPEED/POWER etc versus regular fuel and it's impact on our passenger car engines.
Here is a professional engineer's opinion:

Fuel saving - a professional engineer's view

This is a vast field with hundreds of fuel additives in the market with hundreds of different claims. Most of these additives are proprietary, i.e., you will not get the kind of precise technical information that you are looking for because these are trade secrets. Even the professional engineer who wrote the above article can only give you his own guesses as to the impact of premium fuels, but what he says makes sense to me.

Let me quote excerpts from the above website (which I usually do for the benefit of readers in case the website becomes defunct later):

Quote:
Certain engines - especially turbos - are "knock limited", that is to say, the ignition cannot be advanced to the optimum point because the fuel/air mixture explodes spontaneously causing engine damage. The higher octane rating allows more ignition advance and hence more torque. Providing the engine ECU has a knock sensor, it will automatically add this extra ignition advance whenever V-Power is used.


If your car manual quotes a recommended octane and says something along the lines of "lower octane fuel may be used but with reduced performance" you can be pretty sure it has a knock sensor. If your car manual specifically recommends use of 98 RON fuel, but you normally use 95 RON, then a premium fuel such as V-Power should give a noticeable performance boost. One common misunderstanding is that using a higher than intended octane fuel is actually bad for performance and economy, because it "is too hard to burn" or "burns too slowly". In fact this is wrong; unless the ignition system is extemely marginal, using high-octane fuel in an engine designed for low octane should not cause any problems.


In terms of fuel economy, being able to advance the spark at full load certainly gives better economy, since the engine is making more efficient use of the energy in the fuel. It also potentially allows use of a higher gear in certain situations (due to the increased torque), which is in itself more economical. Finally, many engines run very rich at full load in order to cool down the exhaust gas, and if the ignition is retarded due to knock, even more additional fuel is needed. So under high load conditions, higher octane is definitely good for economy.


However, knock isn't an issue at part load, where the engine spends most of its time. In terms of overall "real world" fuel economy benefit due to increased octane rating, the effect is likely to be small unless you drive much of the time at high load - either because you have an "enthusiastic" driving style, or because you have a relatively large, heavy car with a relatively small but powerful (typically turbocharged) engine. (The latter is becoming increasingly important with the move to downsizing.)


An additional advantage is that, due to their different composition, "premium" fuels are typically two or three percent more dense than "normal" fuel, which means that each litre contains two or three percent more mass of fuel, and hence two or three percent more energy. All other things being equal, that automatically translates into a two or three percent improvement in fuel consumption (miles/gallon or litres/100 km).


Finally, "premium" fuels usually contain more effective detergent additives to keep the engine internals (injectors, valves, combustion chamber, etc) clean. In general I am sceptical of the need for anything other than a good quality "ordinary" fuel to perform this service, but if I did want additional cleaning I would more inclined to run my car on a "premium" fuel for a month or so than to spend the same money on an aftermarket cleaning product. [...]



Personally, my view is this:
  • if your manual specifically recommends use of high octane fuel, and particularly if you have a small turbo engine in a large vehicle, "premium" petrol should be used whenever possible
  • if your manual recommends "ordinary" fuel but your engine has knock sensors, use of "premium" petrol on occasion may be worthwhile
  • otherwise, it is hard to justify unless you particularly feel your engine needs additional cleaning (though in the US, I would be very tempted to stick to "Top Tier" gasoline to be on the safe side)
My own driving style on the highways is "enthusiastic" and I do accelerate hard. Perhaps that is why Speed or similar premium fuels would be preferable in my case.

Last edited by rks : 30th June 2007 at 14:39.
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Old 30th June 2007, 15:32   #65
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Quote:
Originally Posted by anandpadhye View Post
Guys,

Is T-BHP loosing it's credibility for technical expertise?

This thread is on it's 5th page and still no great deal of technical analysis...

I am sure, you and me can read manuals or talk to service guys, but that's hardly the point.

I came to T-BHP with the hope to learn technology.
When it comes to premium fuels, T-BHP community (including me) seems to know nothing.

We have moderators, seniors, so-called car-enthusiastic guys here on T-BHP who talk so much about their expensive cars, modified air-intake/Free Flow Exhaust, performance boxes, 1-100 figues, etc...I just wonder how they do all this if they know nothing about the fuels!!!

Guys,
Please help by sharing the real difference between SPEED/POWER etc versus regular fuel and it's impact on our passenger car engines.

Else,
wear you moderator hats and just close the thread. The title and the topic is so important to everyone that we all are tempted to visit this thread everytime there is an update, just to find out that there is no "substance" in the new post.
Not much can be done by T-bhp members as what is added and why it is added are all not revealed by oil psu s. Nobody in this forum can help in understanding the real difference between them. Because some have faced problems from particular fuels. Some claims better mileage from speed, some from x tra premium etc. None of these claims are scientifically proven. We all know onething that we are cheated again and again by the oil psu s.

So the only thing we bhpians can do is to get these information through RTI Act. And for that just a person should take initiative.
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Old 1st July 2007, 00:34   #66
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Friends,
On fuels It doesn't harm the engine I can bet. I can also argue that the fuels having high octane numbers would not help much compare to Normal fuels in India due to engine to engine variations are too high.
Let us talk about engine specification for a while: If you see engine of 90 BHP in a vehicle, based on the normal distribution and process capability engines will be made from 82 BHP to 97 BHP on an average. You might have got a engine with 82 BHP even though its specified 90 in leaf let. Its like you running your vehicle wiht Xtra premium is equal to another customer running his engine 97 BHP (assuming that you got the lower spec engine and he got upper spec engine - According to companies both engine will pass QC ! ) !! What they all do in fuels of normal and extra octane is to improve the chain reaction by adding additives which are within the fuel specification range. It would never harm !
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Old 1st July 2007, 19:20   #67
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Hi all,

Every eingine is designed with certain parameters which works in tandem with each other and accordingly car manufacturer prefer to use certain Octane rated fuels which works well within the design criteria of car at all rpm.....

Now normal compression in car is from 8.5 to 9.5 or more and fuel must be able to work within this range.....Octane Rating denotes Resistance to Self Ignition so high octane rated fuel will not ignite under certain compression.....now to utilise this property of fuel ignition is advanced till we get knock...knock represents self ignition under extreme temperature when compressed.....so essentially using high octane need slightly more compression ratio and increased ignition without which engine doesnt utilise this Peculier property of fuel.....

Now inorder to distinguish normal fuel from premium one certain additives are added which works depending upon its property.....normally increasing octane rating slightly is the main purpose apart from some cleaning ability of engine parts.....now there are so many methods to increase octane rating hence we get so many additives added in normal fuels which not neccesarily work well every time....this makes fuel so different from our point of view even though they are of same octane rating.....this difference is bound to get reflected in performance of different vehicles hence we get different result.....

We are observing more compression in newer cars hence more octane rated fuel is becoming common....
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Old 1st July 2007, 19:40   #68
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hi rks even i had faced the same problem with my fiesta but the change was from speed to reliance one,the same thing had happened earlier also so had everything checked during that time but nothing at fault but the problem occured again so no idea whats happening
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Old 2nd July 2007, 12:38   #69
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Hi all,

Thanks.

Now we are talking...

1)
Compression ratio:
NHC (iDSI) has a ratio of 10.5.

I think this is very high (high enough to benefit from high octane fuel).
Any thoughts?

2)
ECU control and monitoring:
ECU controls the air-fuel mixture. NHC website says the ECU monitors fuel quality (not sure how...).
So, why many of us think high octane fuels will not improve things?

Also, any idea on how ECU determins fuel quality in real time? What sensors? What's the time response?

If ECU monitors fuel quality in real-time, why do we have popular opinion here on T-BHP that ECU has to be reset if you want to benefit from the new fuel?

Friends,
Please shed some light on how (and how) well this technology works.

And yes, I agree, the impact of fuel quality may be different for every engine and we can not generalise.

hence, please discus specific engines one by one and then we can consolidate the observations/truth.

Let's start with NHC i-DSI...unless others have a preference.

Thanks.
Hoping to give and take the highest quality data at of Team-BHP > Under the hood > Technical Stuff section...
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Old 5th July 2007, 21:33   #70
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The most funny situation in India is that the GOVT makes manufacturers to make E3 cars and still except for few cities the rest all have E2 Fuel !!!
You use Additive fuel or Normal , always dont swap as much as possible. This will damage fuel system parts.
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Old 21st July 2007, 22:01   #71
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I have one more observation I think HC emissions are probably more in premium compared to regular. My pollution check certificates show 3400 with regular and 4600 while I used premium. I will get back to confirm the numbers. Any opinions or comments ?
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Old 21st July 2007, 22:21   #72
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I used to fill IOC premium in my adventure. But its performance was nothing to say about as against normal petrol. I tried speed 91 and power but all was same. But i got a chance to fill reliance petrol , the difference was not like 5% gain but certainly there was difference which was absent in other brands. The engine become less noisy and did give me mileage like 15+ and 16+ consecutively.

But reliance pumps are to my knowledge is not in tvpm dist. That s my biggest worry.
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Old 21st July 2007, 22:30   #73
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I've heard somewhere that normal IOC petrol is 91 Octane too. The Extra Premium Brand just has some additive added to this 91 OCtane fuel. If this is true there is not much point in going in for the premium version for every refill. MAybe a tankfull everymonth would do t clean things up (if at all it works!!) Can anyone confirm the Octane of normal IOC petrol?
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Old 21st July 2007, 22:57   #74
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Quote:
Originally Posted by gemithomas View Post
I've heard somewhere that normal IOC petrol is 91 Octane too. The Extra Premium Brand just has some additive added to this 91 OCtane fuel. If this is true there is not much point in going in for the premium version for every refill. MAybe a tankfull everymonth would do t clean things up (if at all it works!!) Can anyone confirm the Octane of normal IOC petrol?
Ive heard that the normal regular petrol is 89 Octane. Can confirm tomorrow after I ask one of my friends who owns a pump.
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Old 23rd July 2007, 00:43   #75
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The answer to IOC fuels:

Indian Oil Corporation :: Products_Gasoline

BSII fuels come in RED / ORANGE colour. Red is 93 octane, orange is 88 octane

BSIII fuel only has an ORANGE coloured fuel - thats 91 octane

XTRA PREMIUM is regular BSIII Fuel (i.e. 91 octane) plus multifunctional additives. Xtrapremium also contains a component called "friction buster", you can read more about it here: Friction Buster

I got a palio 1.6 stile sport and have been using only power - now have switched to xtrapremium (still can't share results since i haven't refueled as yet) but i'm going to switch over to regular IOC fuel.

Hope this helps and puts an end to the debate (as far as IOC is concerned).
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