Diffrance Between DOHC and SOHC

[Chanman420q]

Other than the fact theres 2 cams. Whats the advantage to having another one?

[Sick0]

You have more control of the vavles when you rev the motor.

[phatswinn]

and theres more presise tuning abilities

[crashinmatt]

i believe DOHC motors can rev higher. but i also believe they r more to maintain, plus if u mess them up, then u have 2. but other than that i believe they have more potential.

[remlapr]

One of the advantages I believe is that they are more efficient - remember that a motor has to use some of it's power output to keep itself moving, I believe DOHC's use less total energy from the stoke - that means more power to the ground. At least I think that is the deal in cars...

[forum]

Because less moving parts is better. the more moving parts the more energy it takes to run it, And with SOHC you need rockers, also the rockers arn't as presice. With DOHC the valves are directly pushed by the cam. so it will rev more freely

[Sick0]

Well the way I understand it is thata SOHC(crf450f, 400ex, raptor) with rev faster because because of a less spinning parts, and a DOHC(yzf426,z-400, preditor, cannondale) can rev higher because you less problems with vavles because like otheres have said more direct and precice.

If you think about it, all of the SOHC engines have more lowend power and have a smoother power band, and from what I see and read all of the DOHC engines have soft lowends, more two stroke like powerband.

I'm not sure if the DOHC's engines are have less lowend because of the natraul of the design or because of the designers taking advantage of the design and making them for topend.

The one DOHC engine thats porrly design engine is the Kaw 250 mojave. Its dohc and still use rockers which to me defeats some of the advanatages of the 2 cams.

I'm might no be right on every thing I just wrote, but whats every thing I have read, this is whats my understanding it, so if you can give correct me or give me a better understanding.

[400exBro]

raptor is a 5 valve dohc...

the z-400 has a lot more tochy throttle it is on and off, it response awsome when you grab the throttle the is misses bottom end... i like the dohc over single becuase of the snap it will produce... just a perfence thing i guess

[YZROOSTINYA]

raptor is a SINGLE cam with rockers:p

[sparks400]

(dohc) means dual over head cams, which depends on your bike, z400 has dohc, and (sohc) mean that theres only one cam in the head above the cylinder

[wilkin250r]

Two valves will flow better than one, that's obvious. When you have mutliple valves, things become harder to control, synchonize, and also keep them from breaking. Rocker arms bend slightly under load, they wear, ect... Cars can get away with it, because most cars don't see 9000 rpms, and those that do are pretty expensive because of the engineering that goes into them.

Basically, two cams pushing 4 or 5 valves is going to be more precise then 1 cam with rockers, thus allowing the DOHC to rev higher, and last longer.

[400exBro]

Originally posted by YZROOSTINYA
raptor is a SINGLE cam with rockers:p

really?? i always thought it was DOHC ... since it was 5 valve and all..

[Sick0]

Originally posted by 400exBro
really?? i always thought it was DOHC ... since it was 5 valve and all..

It would make sence to have dohc on a 5 vavle motor.