dude in a mirage

With SOHC you have to make sure the cam is ground properly for best power and you cannot tune it as well otherwise (just buy the right cam in the first place and don't worry about it). SOHC has less mass for the crankshaft to spin so less loss of low end as compared to DOHC but has more valvetrain mass so it is less stable at high rpms...and will fly apart easier at high rpms.

With DOHC, like I said two cams, two cam gears means more mass to get moving but the direct (or nearly direct in some cases) actuation of the valves means less valvetrain mass and high rpms can be obtained more safely and held more constantly. Now we all know how to make big power on a small motor right???? HIGH RPMs...yup it takes higher revving to make the most power (non-turbo) out of a small engine. So with DOHC you just make use of the high rpm nature, put cams in that are based for higher rpm breathing, design the ports for higher rpms and then you have a more powerful motor than a SOHC powered engine, but you could easily tune the SOHC for high rpms too...just not AS high and consequently not as much high end power but you still will have a slight torque advantage with SOHC from lower rpm cam tuning and the total amount of mass present.

Did you know that Dodge reverted the Neon from DOHC to SOHC on thier ACR and R/T neons???...see, DOHC isn't all powerful in all applications.

dude in a mirage

just wanted to add that SOHC is much cheaper to upgrade than DOHC...only one cam and one cam gear to buy. Tuning? Well instead of having four possibilities for every degree (one cam stock other set 1 degree advanced, both cams stock, both cams set 1 degree advanced and then the opposite cams set 1 degree and stock) you only have two possibilities (either set it at stock or advance it 1 degree) so dyno tuning goes much quicker and is much cheaper. Less guess work too...