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Discussion Starter #1
My dealer advised me to use 87 Octane petrol only and also not to add any additives whatsoever. Here in India we have what is called "Premium Petrol" which is 91 Octane petrol with additives. The USP claimed is that it is meant for "today's high compression engines". There is also a claim of improved mileage.
The Elantra booklet talks of "Unleaded petrol of 87 octane or higher". I am quite confused. :blink:

I need help and advice from experienced Elantra owners.
 

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We run our Elantra on 97 RON all the time with no problems. You may get a slight mileage improvement with higher octane but it probabaly wouldn't be worth the extra cost.

The additives will help the engine run cleaner with less carbon build-up so spark plugs may last longer.
 

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Dear friend I'm going to tell you my experience.
Here in URUGUAY we have a 87 Octane Petrol (But it is only use in very old cars).
Then we have a 95 octanes and a Premium of 97 octanes.
All Petron is unleaded.
I know de elantra's user manual says we can use 87, but I have always used
95 and I think it is the best Octanage .
Or al least is what I had experienced.

Best regards

Selenico77



Originally posted by kajitkumar@Oct 10 2004, 12:00 AM
My dealer advised me to use 87 Octane petrol only and also not to add any additives whatsoever. Here in India we have what is called "Premium Petrol" which is 91 Octane petrol with additives. The USP claimed is that it is meant for "today's high compression engines". There is also a claim of improved mileage.
The Elantra booklet talks of "Unleaded petrol of 87 octane or higher". I am quite confused.  :blink:

I need help and advice from experienced Elantra owners.
[snapback]1630[/snapback]​
 

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I drive a '97 GLS and use 87 unleaded. Highway MPG is 34-36 at 75 MPH. A couple of years ago I tried using only 91 premimum and got the same milage and had a lot less money in my pocket. I change the spark plugs every 25k miles which is twice a year. I now have 165,500 miles on my car and it shows no sign of stopping. I also run Mobile1 10w-30 for older engines and Mobile1 transmission fluid and axle/differential lube. With the Mobile1 oil I can go 7,000 miles before any signs of dirty oil. Use a K&N air filter and you will notice an increase in performance too!
 

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Discussion Starter #7
Originally posted by MIKE91559@Oct 15 2004, 07:15 PM
I drive a '97 GLS and use 87 unleaded. Highway MPG is 34-36 at 75 MPH. A couple of years ago I tried using only 91 premimum and got the same milage and had a lot less money in my pocket. I change the spark plugs every 25k miles which is twice a year. I now have 165,500 miles on my car and it shows no sign of stopping. I also run Mobile1 10w-30 for older engines and Mobile1 transmission fluid and axle/differential lube. With the Mobile1 oil I can go 7,000 miles before any signs of dirty oil. Use a K&N air filter and you will notice an increase in performance too!
[snapback]1759[/snapback]​

Thanks Mike for all that info. I'll stick to 87 unleaded as advised by you and also save some money in the bargain! :rolleyes:
 

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Originally posted by kajitkumar@Oct 10 2004, 04:00 PM
My dealer advised me to use 87 Octane petrol only and also not to add any additives whatsoever. Here in India we have what is called "Premium Petrol" which is 91 Octane petrol with additives. The USP claimed is that it is meant for "today's high compression engines". There is also a claim of improved mileage.
The Elantra booklet talks of "Unleaded petrol of 87 octane or higher". I am quite confused.  :blink:

I need help and advice from experienced Elantra owners.
[snapback]1630[/snapback]​



I am drivng a 1995 Elantra and, yes, the manual says "Unleaded petrol of 87 octane or higher". That means you use anything higher than 87. I have been using 92Oct (the lowest u can find in Singapore) for years without any problem. Why use higher octane and waste money when you don't get any significant increase in power in higher octane. Stick with 87oct if it's available in India. Cheers!
 

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There's a common misconception about higher octane ratings giving more power. Octane has nothing to do with power but instead serves to delay the explosion (detonation) of the fuel-air mixture. In a high-performance car (my turbo Volvo S70) the engine compression (pressure in the cylinder) is far greater than in my 1998 Hyundai Elantra. If I used regular 87 octane my Volvo suffers because the detonation occurs too early to develop full power so the engine underperforms. Or the engine sensors detect the premature detonation and delay the spark from the plug, which then fires when the cylinder is no longer in the optimal position. In my Elantra, with its 1.8 L low-pressure engine, the compression is far less so I don't need the delay in detonation (from the higher octane) for optimum performance. There's absolutely no advantage to using higher octane gas in a Hyundai Elantra unless you enjoy throwing away your money. In fact, using slower-burning high octane gas might even decrease engine performance when used in an engine designed for regular octane fuel. Hope this helps.

For more info on the subject check out:

http://www.straightdope.com/columns/041008.html
 

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Thanks Ed for providing that link, very interesting to read.

However it was not mentioned about the fact that higher compression engines will require as higher rating fuel as you can provide them from the pump, for engine safety reasons.

On a cool day, as long as your fuel meets the standard minimum requirement of the manufacture, then you will be in the safety zone.

However, on a warm day, the air can hold alot more moisture. Meaning, per intake stroke, you are actually pulling in less oxygen than your engine would like.
As moisture can bond with oxygen, you end up with a very poor combustable mixture.

The performance of a fuel relies on it's ability to bond with oxygen atoms. This ability determines it's octane rating, so the better a fuel can bond with the oygen atoms for combustion purposes, the better the burn will be due to the fact that it will reduce the chances of pinging.

With the Elantra having quite a high compression ratio of 10:1, it's efficiency relies totally on the fuel quality which you as the owner provides it.
If you choose to provide it cheap and a more unstable fuel(unstable being the unability to bond with oxygen atoms), then you are assured a poorer burn.

Which brings us back to the hot days. As oxygen can bond to moisture particles, i.e humidity, then you are actually attempting to bond not only a small amount of oxygen to your fuel particles, but you are attempting to burn moisture aswell.
So if you are using a fuel that will not accept oxygen as readily as premium, then your behind the 8 ball to begin with.

Which brings us to Parafins and Iso-parafins.
But that is another story in it's own! :)
 

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Hi all,
first of all, in Canada the octane is rated in AKI (Anti Knock Index), which is MON + RON devidet by 2 = AKI.
According to the enginers at HMC (at my last visit to Ulsan), the HP-rating is acheived using 92 octane RON (ecxept LC)

Ok, here I go again, I try to keep it low-tech.
Combustion process:
The air-fuel mixture burning duration (at mixture of 14.7 parts of air to 1part of fuel) is +- 3.5ms (depending on combustion chamber design). The mixture is ignited +- 1/3rd of the time at BTC (Before the piston is at Top dead Centre), and continues as the piston descends after TDC (Top Dead Centre).
As the plug ignites a tiny flame, and the flame expands (like a stone into the pond creates ripples), it creates heat, and want to expand. BUT, the piston is still going up towards TDC, and compressing the expanding mixture further. This in turn will heat the mixture further, which will speed the burning and heating process.
Pre-ignition:
If the mixture is ignited too soon, the mixture will get hot enough to overheat a particle (piece of carbon or machining edge etc.) in the combustion chamber (or piston top). This hot spot will act as a plug, and at the next compression stroke, will ignite the mixture just before the plug does. Now you have 2 flame fronts, and as they collide, you hear the PINKING. This pre/self ignition creates a sound frequency of 5550zh, which the knock sensor is tuned in to. Should this occur, the sensor signals the ECM, and it will retard the plug ignition of that cylinder. This will prevent a flame collision, and hence, no pinking.
Ignition process:
All today Hyundai’s have a high compression engine of 10:1 ratio, meaning, that the piston compresses its sweep-volume into a 1/10th big a volume (combustion chamber).
With 87octane fuel, the ignition time is very much retarded. At 91octane fuel, the timing is more advanced. The advanced timing creates a higher combustion temperature, and with it more power on the down stroke of the piston.
The higher octane is more resistant to pre/self ignition, and therefore will not self ignite on the next compression stroke.
There are other factors to consider. In the wintertime, where the ambient temp is in the freezing range, the cold intake air (no pre-heated air with fuel injected engines) alone causes lower combustion temp and is more “unfriendly” to ignition. A lower octane fuel will help compensate for it.
In summer, there is a different scenario. The warm intake air will add to the pre/self ignition possibility, and the result with low octane fuel is, a more than necessary retarded ignition time.
Thanks to the electronic technology, doe to the presence of the KNOCK-SENSOR, one can get away with 87 in the summer. This on the other hand will not give you the capable performance or the fuel economy.
With the help of the knock sensor, the ECM will advance the ignition time to the maximum possible, and always close to the pre/self ignition threshold.

The owner’s manual states “MINIMUM of 87 octane fuel is recommended”. Hyundai finally realises this mistake, and as from 2002 states “MINIMUM of 87 octane fuel OR HIGHER is recommended”.

I hope I was clear enough.
 

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Discussion Starter #13
Thanks Duke. I have now started using 93 octane premium and I can make out a marked improvement in performance. 93 incidentally is the highest octane rating available in India. Thanks for your inputs. Technical no doubt, but made sense.
Ajit :D

Originally posted by duke@Nov 1 2004, 11:21 PM
Hi all,
first of all, in Canada the octane is rated in AKI (Anti Knock Index), which is MON + RON devidet by 2 = AKI.
According to the enginers at HMC (at my last visit to Ulsan), the HP-rating is acheived using 92 octane RON (ecxept LC)

Ok, here I go again, I try to keep it low-tech.
Combustion process:
The air-fuel mixture burning duration (at mixture of 14.7 parts of air to 1part of fuel) is +- 3.5ms (depending on combustion chamber design). The mixture is ignited +- 1/3rd of the time at BTC (Before the piston is at Top dead Centre), and continues as the piston descends after TDC (Top Dead Centre).
As the plug ignites a tiny flame, and the flame expands (like a stone into the pond creates ripples), it creates heat, and want to expand. BUT, the piston is still going up towards TDC, and compressing the expanding mixture further. This in turn will heat the mixture further, which will speed the burning and heating process.
Pre-ignition:
If the mixture is ignited too soon, the mixture will get hot enough to overheat a particle (piece of carbon or machining edge etc.) in the combustion chamber (or piston top). This hot spot will act as a plug, and at the next compression stroke, will ignite the mixture just before the plug does. Now you have 2 flame fronts, and as they collide, you hear the PINKING. This pre/self ignition creates a sound frequency of 5550zh, which the knock sensor is tuned in to. Should this occur, the sensor signals the ECM, and it will retard the plug ignition of that cylinder. This will prevent a flame collision, and hence, no pinking.
Ignition process:
All today Hyundai’s have a high compression engine of 10:1 ratio, meaning, that the piston compresses its sweep-volume into a 1/10th big a volume (combustion chamber).
With 87octane fuel, the ignition time is very much retarded. At 91octane fuel, the timing is more advanced. The advanced timing creates a higher combustion temperature, and with it more power on the down stroke of the piston.
The higher octane is more resistant to pre/self ignition, and therefore will not self ignite on the next compression stroke.
There are other factors to consider. In the wintertime, where the ambient temp is in the freezing range, the cold intake air (no pre-heated air with fuel injected engines) alone causes lower combustion temp and is more “unfriendly” to ignition. A lower octane fuel will help compensate for it.
In summer, there is a different scenario. The warm intake air will add to the pre/self ignition possibility, and the result with low octane fuel is, a more than necessary retarded ignition time.
Thanks to the electronic technology, doe to the presence of the KNOCK-SENSOR, one can get away with 87 in the summer. This on the other hand will not give you the capable performance or the fuel economy.
With the help of the knock sensor, the ECM will advance the ignition time to the maximum possible, and always close to the pre/self ignition threshold.

The owner’s manual states “MINIMUM of 87 octane fuel is recommended”. Hyundai finally realises this mistake, and as from 2002 states “MINIMUM of 87 octane fuel OR HIGHER is recommended”.

I hope I was clear enough.
[snapback]2232[/snapback]​
 

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Discussion Starter #14
Thanks Ed. That link was very useful. Theres a lot more clarity now.
Anyway, I have experimented with all fuel grades available in India- 87; 91 and 93. 93 gives me the best performance- acceleration, economy. Moreover, the engine is least noisy with 93. I'll stick to it I guess. :D


Originally posted by Ed H@Oct 29 2004, 08:33 PM
There's a common misconception about higher octane ratings giving more power.  Octane has nothing to do with power but instead serves to delay the explosion (detonation) of the fuel-air mixture.  In a high-performance car (my turbo Volvo S70) the engine compression (pressure in the cylinder) is far greater than in my 1998 Hyundai Elantra. If I used regular 87 octane my Volvo suffers because the detonation occurs too early to develop full power so the engine underperforms. Or the engine sensors detect the premature detonation and delay the spark from the plug, which then fires when the cylinder is no longer in the optimal position.  In my Elantra, with its 1.8 L low-pressure engine, the compression is far less so I don't need the delay in detonation (from the higher octane) for optimum performance. There's absolutely no advantage to using higher octane gas in a Hyundai Elantra unless you enjoy throwing away your money. In fact, using slower-burning high octane gas might even decrease engine performance when used in an engine designed for regular octane fuel. Hope this helps.

For more info on the subject check out:

http://www.straightdope.com/columns/041008.html
[snapback]2141[/snapback]​
 

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Originally posted by duke@Nov 1 2004, 10:51 AM
Hi all,
first of all, in Canada the octane is rated in AKI (Anti Knock Index), which is MON + RON devidet by 2 = AKI.
According to the enginers at HMC (at my last visit to Ulsan), the HP-rating is acheived using 92 octane RON (ecxept LC)

Ok, here I go again, I try to keep it low-tech.
Combustion process:
The air-fuel mixture burning duration (at mixture of 14.7 parts of air to 1part of fuel) is +- 3.5ms (depending on combustion chamber design). The mixture is ignited +- 1/3rd of the time at BTC (Before the piston is at Top dead Centre), and continues as the piston descends after TDC (Top Dead Centre).
As the plug ignites a tiny flame, and the flame expands (like a stone into the pond creates ripples), it creates heat, and want to expand. BUT, the piston is still going up towards TDC, and compressing the expanding mixture further. This in turn will heat the mixture further, which will speed the burning and heating process.
Pre-ignition:
If the mixture is ignited too soon, the mixture will get hot enough to overheat a particle (piece of carbon or machining edge etc.) in the combustion chamber (or piston top). This hot spot will act as a plug, and at the next compression stroke, will ignite the mixture just before the plug does. Now you have 2 flame fronts, and as they collide, you hear the PINKING. This pre/self ignition creates a sound frequency of 5550zh, which the knock sensor is tuned in to. Should this occur, the sensor signals the ECM, and it will retard the plug ignition of that cylinder. This will prevent a flame collision, and hence, no pinking.
Ignition process:
All today Hyundai’s have a high compression engine of 10:1 ratio, meaning, that the piston compresses its sweep-volume into a 1/10th big a volume (combustion chamber).
With 87octane fuel, the ignition time is very much retarded. At 91octane fuel, the timing is more advanced. The advanced timing creates a higher combustion temperature, and with it more power on the down stroke of the piston.
The higher octane is more resistant to pre/self ignition, and therefore will not self ignite on the next compression stroke.
There are other factors to consider. In the wintertime, where the ambient temp is in the freezing range, the cold intake air (no pre-heated air with fuel injected engines) alone causes lower combustion temp and is more “unfriendly” to ignition. A lower octane fuel will help compensate for it.
In summer, there is a different scenario. The warm intake air will add to the pre/self ignition possibility, and the result with low octane fuel is, a more than necessary retarded ignition time.
Thanks to the electronic technology, doe to the presence of the KNOCK-SENSOR, one can get away with 87 in the summer. This on the other hand will not give you the capable performance or the fuel economy.
With the help of the knock sensor, the ECM will advance the ignition time to the maximum possible, and always close to the pre/self ignition threshold.

The owner’s manual states “MINIMUM of 87 octane fuel is recommended”. Hyundai finally realises this mistake, and as from 2002 states “MINIMUM of 87 octane fuel OR HIGHER is recommended”.

I hope I was clear enough.
[snapback]2232[/snapback]​


 

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Hello, I have always wondered about this. Yet so far, I have not be able to find answer related not to power, but to engine longevity. As higher octane burns slower preventing knocking it should release energy less rapidly, consequently less impacting pistons and bearings with force same as with regular gasoline. In pure physics this means longer engine bearings life. Please correct me if I am wrong, but in my books higher octane means longer engine life.
 

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Originally posted by Pavel@Dec 13 2004, 11:11 PM

[snapback]3663[/snapback]​



Ok, the octane rating for certain engines is more than just simple number crunching ( not with intent to offend anyone ) The process in which a cumbustion engine works is all the same for every vehicle ( exception of course to rotorey engines ) The process in which the components are created are quite different however. performance vehicles have a significantly higher casting PSI rating and metal purity then regular family sedans. This is due to the difference in heat, stress, and internal force which is exherted on the engine. A car made for picking up the kids from soccer doesn't need the expensive high purity metals, and the high pressure casting. they are both expensive to do and more time consuming. You might ask what it has to due with octane ratings. well high octaines burn better, hotter, and more violently. when you fill up with your 91 or 95 octane fuel you're basically adding more stress on the engine components, and a hotter environment. Performance vehicles are made to effectively burn the high octane fuels, family vans and sedans are not. You can actually be doing more harm than good. the gaskets on the pistons are usually the victim of the access heat, however there are other areas effected. But I cannot deny the better mileage ( although it's honestly not worth the extra money )
 

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I think, that I explained it well enough.
higher octane does burn at the same rate as lower octane (when under same conditions), BUT is more resistent to self-ignition (pinking or also refered to as combustion knock) created by high pressure/heat.
The higher the compression ratio, the graeter the need for higher octane. The engines of today, are capable to run on lower octane, doe to the presens of the knock sensor. The ECM will receive that signal and retard the ignition time to prevent "knocking/pinking". If the ECM failes to do so, THAT WILL DESROY THE ENGINE, by burning a hole into the piston top or deforming the piston
 

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Hi
I Live in South Africa and we have 97 leaded and 95 Unleaded octane. When I purchased my
2005 Elantra I asked the dealer what they recomended. I was told it is better to run my car on
95 unleaded octane as the 97 leaded fuel can foul and clog up the catalytic covertor. Been running on the 95 so far with no problems.
 
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