一般來說，同等排量情況下，氣門越多，進排氣效率越好，就像一個人跑步，累得氣喘吁吁時，需要張大嘴巴呼吸。傳統的發動機多是每個氣缸一個進氣門和一個排氣門，這種二氣門配氣機構相對比較簡單，制造成本低，維修起來也相對容易。對于輸出功率要求不太高的普通發動機來說，兩氣門就能獲得較為滿意的發動機輸出功率與扭矩性能。
Generally speaking, the same displacement situations, the more the valve, inlet and exhaust efficiency, the better, like a man running, tired panting, need to open mouth breathing. More than the traditional engine is an inlet valve for each cylinder and an exhaust valve, the two valve distribution mechanism is relatively simple, low manufacturing cost, maintenance is also relatively easy. For ordinary engine output power requirement is too high, the valve can get more satisfactory engine power output and torque performance.
排量較大、功率較大的發動機要采用多氣門技術。最簡單的多氣門技術是三氣門結構，即在一進一排的二氣門結構基礎上再加上一個進氣門。世界各大汽車公司新開發的轎車大多采用四氣門結構。四氣門配氣機構中，每個氣缸各有兩個進氣門和兩個排氣門。
Displacement is larger, the power of the larger engine more valve technology must be used. The simplest valve technology is more three valve structure, namely the one into a row of two valve structure based on coupled with an inlet valve. The world's largest car company newly developed cars mostly adopted four valve structure. Four valve of valve-train, each cylinder has two inlet valve and the exhaust valve.
四氣門結構能大幅度提高發動機的吸氣、排氣效率，新款轎車大都采用四氣門技術。當然，大眾汽車多采用五氣門技術，如老款捷達王的20V發動機，寶來1.8T發動機也是五氣門。
Four valve structure can greatly improve the efficiency of the suction, exhaust of engine, the new cars are mostly adopted four valve technology. Volkswagen more, of course, take five valve technology, such as old 20 v engine, jetta baolai 1.8 T engine is five valve.
不過，達到或超過六氣門不僅使配氣結構過于復雜，還會導致發動機壽命縮短，氣門開啟的空間簾區(氣門的圓周和氣門的升程)也較小，效率下降。因此，四氣門技術目前使用最為普遍。
However, reach or exceed six valve not only makes the distribution structure is too complex, can also lead to shorten the life engine, the valve open space of the shade area (the circumference of the valve and valve lift) is small, efficiency is decreased. Therefore, four valve technology currently in use is most common.
需要指出的是，氣缸和氣門數可以作為判斷發動機優劣的標準之一，但不是唯一標準。比如，寶馬公司的直列4氣缸2.0升發動機，由于其獨特的可變氣門技術，在功率和扭矩輸出上絲毫不遜于普通的6缸機，這也是寶馬318轎車動力性廣受好評的原因。奔馳公司長期采用每個氣缸3氣門技術，也達到了很好的功率、扭矩和環保水平。此外，配備渦輪增壓技術后，寶來1.8T4缸機的功率和扭矩也能達到普通6缸機的水平。
It should be pointed out that, number of cylinders and valves can be used as one of the advantages and disadvantages of standard judgment of engine, but it is not the only standard. For instance, BMW's 2.0 -liter inline 4 cylinder engine, because of its unique variable valve technology, on the power and torque output is no worse than the ordinary 6 cylinder machine, this is why BMW 318 sedan performance critically acclaimed. Mercedes with 3 valves per cylinder technique for a long time, also reached the good power, torque and the environmental protection level. In addition, equipped with a turbo technology, baolai 1.8 T4 cylinder machine power and torque can reach common six-cylinder machine level.
