| [ car ] in KIDS 글 쓴 이(By): hongsang (NSX) 날 짜 (Date): 1995년02월14일(화) 08시00분57초 KST 제 목(Title): The final verdict: DOHC vs. SOHC Dear Mr. SBS: You have raised a good question a few days ago. Although I knew DOHC is better than SOHC, I did not know ther reason why. After poking several people around here, I think I now have a explanation that seems quite reasonable and convincing. The following words are from a guy who had worked at Saturn for a few yrs. According to him, there's nothing inherent about having 2 camshafts that lets an engine make more power. Most engines with multiple camshafts end up making more power for 2 reasons. 1) By placing one camshaft towards each side of the cylinder head, it's easier to put the spark plug in the center of the cylinder. This makes an engine more resistant to detonation, allowing higher compression ratios. 2) With 2 camshafts, most manufacturers use direct acting linkages, where the camshaft rides directly on top of the valve stem (with some type of adustable lifter in between). When using one cam shaft, a more complicated linkage is required. The extra rockers and other pieces add mass to the system, which makes the valves "float" (ie. lift off the spring seats) at lower speed. This places a lower limit on engine speed. However, these aren't hard and fast rules. For instance, the Honda Civic engine is a 16 V, SOHC which spins pretty fast. Finally,this Saturn guy concluded that using one or two camshafts is really a matter of design choice. I hope this has been helpful. NSX... |