DOHC v.s SOHC
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Whats the difference between the two engine types?
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I know that DOHC=Double OverHead Cams & SOHC=Single OverHead Cams but I dunno the significance of the 2 differences.
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generally dohc are much better than sohc performance wise, but honda's an exception. compare nissan sunny 1.6l and civic esi 1.6l--sunny is dohc engine and produce 110hp, while my esi is sohc and produce 125hp(without my mods). ppl may say that subaru 1.6ts(sohc) are underpowered, but i think that 100hp is the normal power rating without any valve timing technology for sohc(only sti got avcs and dohc engine), so subarus are good 'original' comparisons
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Toyota Starlets are SOHC but can speed like hell.....so are Mitsubishis'....DOHC can mean double punching power against the pistons instead of one punching power....imagine this.....a boxer raining punches on your face left and right....compare to someone punching your face using one hand......but this means that the former uses more energy....double number of spark plugs if i am not wrong.....
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err, not really. wasn't this post discussed awhile ago? twin cams juz means instead of having one cam (SOHC) doing both jobs of opening and closing the inlet and exhaust ports, u have one cam controlling the inlet ports and one cam to control the exhaust ports. the number of spark plugs stay the same (ie 4 cylinders uses 4 spark plugs).Originally posted by 2004Lancer:Toyota Starlets are SOHC but can speed like hell.....so are Mitsubishis'....DOHC can mean double punching power against the pistons instead of one punching power....imagine this.....a boxer raining punches on your face left and right....compare to someone punching your face using one hand......but this means that the former uses more energy....double number of spark plugs if i am not wrong.....
the advantage of this is that the overlapping/ duration/ and lift of individual inlet/ exhaust cams can be mixed and matched to produce optimal results as compared to when u have juz one cam to work with. -
Clear and concise, I'm enlightenedOriginally posted by tailslide:err, not really. wasn't this post discussed awhile ago? twin cams juz means instead of having one cam (SOHC) doing both jobs of opening and closing the inlet and exhaust ports, u have one cam controlling the inlet ports and one cam to control the exhaust ports. the number of spark plugs stay the same (ie 4 cylinders uses 4 spark plugs).
the advantage of this is that the overlapping/ duration/ and lift of individual inlet/ exhaust cams can be mixed and matched to produce optimal results as compared to when u have juz one cam to work with.
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how come qns keep resurfacing....
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aiyah...tailslide....layman term is one hand punch VS 2 hand punches la.........what i know is if i punch with 2 hands, i will get tired easily.......but more thrusting power..........maybe next time may have TOHC (Triple) and QOHC (Quadret) ........
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Sure why not. Quad cams have been out for a long time. eg Toyota 3MZ-FE, lots more.Originally posted by 2004Lancer:aiyah...tailslide....layman term is one hand punch VS 2 hand punches la.........what i know is if i punch with 2 hands, i will get tired easily.......but more thrusting power..........maybe next time may have TOHC (Triple) and QOHC (Quadret) ........ -
Lexus IS200 uses QUAD Cam.... If I am not wrong....
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Are you sure? Quad cams on a 24v car??Originally posted by ongsw:Lexus IS200 uses QUAD Cam.... If I am not wrong.... 
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hey thanks guys... know more abt it now... ENLIGHTMENT..........
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A good place to obtain visual understand as well is www.howstuffworks.comOriginally posted by zacus:hey thanks guys... know more abt it now... ENLIGHTMENT.......... -
actually, quad cams are the wrong terminology being used. whether an engine is DOHC or SOHC is purely dependant on how many cams are operating above each bank of pistons.Originally posted by brisance:Sure why not. Quad cams have been out for a long time. eg Toyota 3MZ-FE, lots more.
the quad cam term was hatched because since there are 2 cylinder banks, for eg, on V engines and boxer engines, there are effectively 4 pieces of cams altogether. however, since there are only 2 cams over each bank of cylinders, these engines should be collectively described as DOHC engines. -
By your own definition, "how many cams are operating above each bank of pistons", since there are 2 cams above 2 banks of pistons, then it should rightly be called quad cams.Originally posted by tailslide:actually, quad cams are the wrong terminology being used. whether an engine is DOHC or SOHC is purely dependant on how many cams are operating above each bank of pistons.
the quad cam term was hatched because since there are 2 cylinder banks, for eg, on V engines and boxer engines, there are effectively 4 pieces of cams altogether. however, since there are only 2 cams over each bank of cylinders, these engines should be collectively described as DOHC engines. 
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wait wait wait....so SOHC is 1 cam over 1 single bank of piston and DOHC is 2 cams over 1 single bank of pistons right?
and QUAD cam is 2 cams over 2 bank of pistons la?! -
lol.... confused,...... need for enlightment.......
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err, u said it urself, number of cams above each bank of pistons. if i had said the number of cams above each pair of cylinder banks, then i would be slapping myself in the face. anyway, there is NO SUCH THING AS QUAD OVER HEAD CAMS or QOHC.Originally posted by brisance:By your own definition, "how many cams are operating above each bank of pistons", since there are 2 cams above 2 banks of pistons, then it should rightly be called quad cams. -
so u're saying that the odd engine type toyota altis is usin is a quad cam?