Re: Looking for some DOHC horsepower

Posted by shinyribs on Apr 21, 2012; 5:24pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/Looking-for-some-DOHC-horsepower-tp3928486p3928558.html

I have been wanting to do something similar to my SOHC. I'm not sure if the HP gains of an 836 kit are worth it. You see where people buy and sell them,but you never hear what they are worth. Dyno charts would be nice too look at,but I cant really find any. If you do the math,break it down by hp per cc.,using the factory hp rating on my bike,which yours is probably higher than mine already,an 836 kit would be worth about 9 hp.

67hp divided by 736cc= 0.09103 hp per cc

additional 100cc's @ 0.09103 hp/cc= + 9.103 hp

Thats above a 10% hp gain which is not too shabby,but is it worth it.

What does it do to the torque curve?Who knows

I dont know if this hold true in the real world or not,but that is the math. There would be other things that an overbore would create. It would help improve cylinder head flow by unshrouding the valves,but a larger bore always give you inherent frictional losses (cylinder wall drag/increased heat)that cannot be avoided just due to increased surface area.If you buy heavy forged piston that would increase rotating mass,which costs you hp. So if you factor in the inherent frictional losses and the rotating weight you could pickup that 9hp could drop to about 7 hp or so. But who knows really.

And the cams listed are just funny. They are described as "race","hot street","heavy duty"...i dont want adjectives.I want hp numbers. Show me a dyno chart where your cam makes more power than the other guys! Too bad these engines dont get the attention they deserve.