Fuel Issues
Posted: Wed Apr 26, 2006 4:17 pm
Since a couple of members have asked I open a new thread about fuel, here it goes with a few pointers from my limited knowledge. I would guess that the fuel in Dhaka, providing it has not been adulterated, would be rated at 93-95 ron, which is not that bad. For those who do not know what this means – “RON” stands for random octane number. This value is actually an indication of the “anti-knock” properties of the fuel concerned. In the UK you get several qualities at the pumps – 95, 97 and in recent years Optimax was introduced which is about 99 ron. (In the USA you get about 91 ron in many states and other states have about 97 ron (they say 87 ron and 93 ron, because they use a different method of calculating this). In Japan they have been selling 100 ron for many years now.
If you are not familiar with the term “engine knock”, this basically refers to the situation where the fuel in the engine cylinder catches fire BEFORE the spark plug fires, that is, before it was supposed to catch fire. This usually occurs in turbocharged and very high performance cars where this extra performance extracted from the engine has the side-effect of producing a lot more heat within the cylinder, so, if you use lower RON quality than was meant for this particular engine, then you will most probably experience “engine knock”, also referred to as “ping” and “detonation”. Also, in a regular car, if you use fuel that has been adulterated with a lot of kerosene (which has a low ron/octane rating) you can still experience “knocking”. So, the higher the RON of the fuel the more temperature it can sustain before catching fire.
The Japan domestic models of high performance cars are tuned to run on 100 ron octane, because it is readily available there and on a higher ron rated fuel you can run more aggressive ignition timing which gives more horsepower. That is, the ignition can be timed very late into the upward movement of the piston - referred to as “ignition advance” – which allows a bigger explosion in the cylinder leading to more power. But, in regular cars the ignition is timed sooner so as to minimise risk of “knock” and increase reliability and longevity of the engine. In a turbocharged car, the more the boost pressure, the higher the temperatures in the cylinder. So, there are 2 ways to increase the engine power here – ignition advance AND increasing turbo boost. But, for maximum horsepower you need very high octane fuel. The potential difference between regular fuel and 120 ron race fuel can be staggering. A turbocharged car making 300 bhp on 95 ron fuel could make over 400 bhp on race fuel by running more advance and boost ! In this case, the car should be tuned to the quality of the fuel, and degree of ignition advance and amount of turbo boost are limited by the ron rating of the fuel.
The problem with engine knock is that it is very damaging to cylinder parts. If your engine is experiencing knock, the premature fire in the cylinder could be a single flame or even multiple irregular flames before the spark could fire. When detonation occurs just as the piston is moving upward the sudden fire (detonation) will force the piston down with immense force which, if it happens continually, will cause a “knocking” sound from which you get the word “knock”. This detonation of fuel will burn holes into the piston base thereby damaging the engine.
Now, you may ask the question, will I get more power out of my regular car by using higher ron fuel – the answer is NO. If your car was tuned to run on 95 ron, you won’t get any advantage running higher ron fuel and if that costs you more, you are wasting your money.
If you are not familiar with the term “engine knock”, this basically refers to the situation where the fuel in the engine cylinder catches fire BEFORE the spark plug fires, that is, before it was supposed to catch fire. This usually occurs in turbocharged and very high performance cars where this extra performance extracted from the engine has the side-effect of producing a lot more heat within the cylinder, so, if you use lower RON quality than was meant for this particular engine, then you will most probably experience “engine knock”, also referred to as “ping” and “detonation”. Also, in a regular car, if you use fuel that has been adulterated with a lot of kerosene (which has a low ron/octane rating) you can still experience “knocking”. So, the higher the RON of the fuel the more temperature it can sustain before catching fire.
The Japan domestic models of high performance cars are tuned to run on 100 ron octane, because it is readily available there and on a higher ron rated fuel you can run more aggressive ignition timing which gives more horsepower. That is, the ignition can be timed very late into the upward movement of the piston - referred to as “ignition advance” – which allows a bigger explosion in the cylinder leading to more power. But, in regular cars the ignition is timed sooner so as to minimise risk of “knock” and increase reliability and longevity of the engine. In a turbocharged car, the more the boost pressure, the higher the temperatures in the cylinder. So, there are 2 ways to increase the engine power here – ignition advance AND increasing turbo boost. But, for maximum horsepower you need very high octane fuel. The potential difference between regular fuel and 120 ron race fuel can be staggering. A turbocharged car making 300 bhp on 95 ron fuel could make over 400 bhp on race fuel by running more advance and boost ! In this case, the car should be tuned to the quality of the fuel, and degree of ignition advance and amount of turbo boost are limited by the ron rating of the fuel.
The problem with engine knock is that it is very damaging to cylinder parts. If your engine is experiencing knock, the premature fire in the cylinder could be a single flame or even multiple irregular flames before the spark could fire. When detonation occurs just as the piston is moving upward the sudden fire (detonation) will force the piston down with immense force which, if it happens continually, will cause a “knocking” sound from which you get the word “knock”. This detonation of fuel will burn holes into the piston base thereby damaging the engine.
Now, you may ask the question, will I get more power out of my regular car by using higher ron fuel – the answer is NO. If your car was tuned to run on 95 ron, you won’t get any advantage running higher ron fuel and if that costs you more, you are wasting your money.
