my si hatch needs a new power plant but i dont know which engine is better(a dohc zc or sohc zc) or has more capabilities.any help would be appreciated.

 

SOHC has more options, no decent cams/exhaust/intake for the DOHC.............

 

DOHC

 

would it be better to keep the sohc zc head on there or would you change it for a vtec head?

 

DOHC ZC has better quench areas, slightly higher CR I think and makes more power out of the box. Crespo makes Cams and Delta ReGrinds. Crespo has been know to be shitty in the past, but since then they have bumed up Quality Control. Exhuast Manifolds, Headers, Are Almost the same, The intake is different, but that is easy to get around.

If it had to come to it, I would instantly select the DOHC.

 

i have the sohc zc, and ive never been happier. Also if you plan to change anything later on the dohc u cant.. Such as dif heads and such. you can swap any sohc head on the zc. and usually wield higher cp anyways. I think 1 of the vtec heads on the sohc block brings you to 12.** compression. a nice all motor combo.