Question:
90 # 93 # 97 # What is the difference of gasoline?

Answer:
the so-called No. 90, 93, 97 unleaded petrol means that they contain 90%, respectively, 93 %, 97% of the anti-knock ability of the “iso-octane,” that contains 10%, respectively, 7%, 3% of the anti-knock ability of poor n-heptane. So octane level of gasoline engines has become the ability to combat knock level indicators. Should use 97 petrol engines, so if 90 # gasoline, of course, prone to knock.

the engine compression ratio and knock

the most current vehicles to use the so-called four-stroke engine, which is a piston inside the cylinder reciprocating motion in order to “intake, compression, broke out the exhaust of the” four stroke, inhalation of petrol and air mixture, and then compress it, and then blasting it spark plug point gain momentum, gains momentum again after the gas after the discharge point of explosion.

First, we have to understand that the four-stroke engine with the fuel is not necessarily gasoline, compressed natural gas, liquefied petroleum gas, or even alcohol, can be used as a motor fuel. Gasoline will be the main reason for fuel because it is relatively easy to obtain, easier storage, a relatively low price.

is because the engine can use a variety of fuels, so in the beginning of engine development, engineers have made many attempts, in addition to trying different designs, the engine did not have the same performance, but also try to use different fuels will be different results. The results showed that when other conditions are unchanged, so long as the engine’s compression ratio raised even higher, it will be even greater horsepower output. However, the compression ratio increase is not unlimited, and when the compression ratio raised too high, the engine knock occurs. The so-called knock is the result of compressed oil or gas mixture, not in the ignition before the spark plug on the compression stroke because they are caused by the movement of gas molecules heat generated by light, forming the so-called spontaneous combustion, and then once again ignited spark plug oil or compressed gas mixture, resulting in two groups of high explosive fireball in the combustion chamber violent collisions, and thus produce a knock on the door in general, “Cameroon, Cameroon, Cameroon” sound. After careful study, engineers discovered that they knock and fuel choices, and if the election for the fuel, so even though we increase the engine compression ratio, it will not happen knock.
aware of the relationship between the detonation and fuel, the engineers began to refinery generated, can be used as motor fuel each brought a variety of tests and experiments and found that the worst effects of the anti-knock “is G alkyl “, so the engineers put the strongest earthquake index of 100 to the iso-octane, while the worst-heptane gave it a seismic index of 0. Thus, from the beginning of the high and low octane gasoline engines has become high and low ability to knock against the indicators. So what is octane

do? It was engineers in the laboratory, using an adjustable compression ratio single cylinder engine to do tests measured data. In the experiment, along with a gradual increase in compression ratio, test the fuel never knock, combustion and smooth the situation began to gradually adjust to the knock. When one began to emerge when the detonation, and went over to the iso-octane and n-heptane mixture situation, if there is knock the status of timing, coinciding with the 97 copies of iso-octane and 3 copies of the test status of n-heptane exactly the same as then the test fuel octane number is 97. So, when we say 90, 93, 97 unleaded petrol, when in fact it is just an octane number of the ratio.

correct choice of petrol label

Many owners mistakenly believe that the label is the oil gas purity and quality standards for gasoline vehicles, the higher the better use of labels, such thinking is wrong. Label simply means that the level of gasoline octane number of the size, should be based on the engine compression ratio of different to choose a different label of gasoline. Compression ratio in the 8.5-9.5 should generally be between the mid-range cars to use 93 gasoline; compression ratio greater than 9.5 should use the 97 gasoline cars. The compression ratio of the current China-made cars are generally more than 9, it is best to use 93 or 97 gasoline.

high compression ratio engines if the use of low-grade gasoline will lead to a sudden rise in temperature of the cylinder, gasoline combustion is incomplete, a strong vibration machine, so that power output decreased mechanical damage. Low compression ratio engines insist on using high-grade oil, there will be “ignition delay” phenomenon, that is down to his head it is less than self-ignition point, the same phenomenon will appear incomplete combustion, the engine is also no good.

Chinese:90#93#97#的汽油有什么分别?

问题:
90# 93# 97#的汽油有什么分别?

回答:
所谓90号、93号、97号无铅汽油，是指它们分别含有90％、93％、97％的抗爆震能力强的“异辛烷”，也就是说分别含有10％、7％、3％的抗爆震能力差的正庚烷。于是辛烷值的高低就成了汽油发动机对抗爆震能力高低的指标。应该用97号汽油的发动机，如果用90号汽油，当然容易产生爆震。

发动机压缩比与爆震

目前汽车使用最多的是所谓的四行程发动机，它是利用活塞在气缸里往复运动，以“进气、压缩、爆发、排气”四个行程，吸入汽油与空气的混合物，然后压缩它，再用火花塞点爆它而获得动力，得到动力后，再排出点爆后的废气。

首先我们要了解的是，四行程发动机用的燃料不一定是汽油，压缩天然气、液化石油气，甚至酒精，都可用来作为发动机的燃料。汽油之所以会成为主要燃料，是因为它相对容易取得，较容易储存，相对价廉。

正因为发动机可使用多种燃料，因此，在发动机发展之初，工程师们也做过许多尝试，除了尝试发动机不同的设计会有不一样的性能之外，也尝试使用不同的燃料会得到什么不同的效果。结果发现，当其它条件不变时，只要把发动机的压缩比提得愈高，就会得到更大的马力输出。然而，压缩比却不是可以无限制提高的，当压缩比提得太高时，发动机就会出现爆震现象。所谓爆震，是经过压缩的油或气混合物，在火花塞还没点火之前，就因为被压缩行程所造成的气体分子运动产生的高热点燃，形成所谓的自燃现象，随后火花塞又再次点燃压缩油或气混合物，造成两团高爆火球在燃烧室里剧烈碰撞，因而产生如敲门一般的“喀、喀、喀”声。经过仔细研究，工程师们发现，原来爆震又和燃料的选择有关，如果选对了燃料，那么即使提高发动机压缩比，也不会发生爆震。
知道了爆震与燃料的关系后，工程师们开始把炼油厂里所产生的，可以作为发动机的各种油料逐一拿来测试和实验，结果发现，抗爆震效果最差的是“正庚烷”，因此工程师们就把最强的抗震指数100给了异辛烷，而最差的正庚烷则给了它一个0的抗震指数。于是，从此开始，辛烷值的高低就成了汽油发动机对抗爆震能力高低的指标。

那么什么是辛烷值呢？那是工程师们在实验室里，利用一部可调整压缩比的单缸发动机做试验所测得的数据。在实验中，随着压缩比的逐渐提高，测试燃料从没有爆震、燃烧顺畅的状况，逐渐调整到开始出现爆震。当爆震一开始出现的时候，就去比对异辛烷与正庚烷混合物的状况，如果出现爆震的状况时机，正好与97份异辛烷和3份正庚烷的测试状况一模一样，那么这个测试油料的辛烷值就是97。所以说，当我们说90号、93号、97号无铅汽油的时候，其实它的辛烷值只是一个对比值。

正确选择汽油标号

许多车主误认为，汽油的标号就是油品纯净度和质量的标准，车辆使用标号越高的汽油越好，这种想法是错误的。汽油标号的高低只是表示汽油辛烷值的大小，应根据发动机压缩比的不同来选择不同标号的汽油。压缩比在8.5—9.5之间的中档轿车一般应使用93号汽油；压缩比大于9.5的轿车应使用97号汽油。目前国产轿车的压缩比一般都在9以上，{zh0}使用93号或97号汽油。

高压缩比的发动机如果选用低标号汽油，会使汽缸温度剧升，汽油燃烧不xx，机器强烈震动，从而使输出功率下降，机件受损。低压缩比的发动机硬要用高标号油，就会出现“滞燃”现象，即压到了头它还不到自燃点，一样会出现燃烧不xx现象，对发动机也没什么好处。