http://www.infamousnissan.com/...=6598

It fell short of his expectations.
Modified by seang at 2:00 PM 9/12/2009

its because of the cam... his cam is going to basically lower the compression so that the shaving of the head basically just brings it back to stock... so with the sidedrafts needing re-jetting its gonna run pretty much stock... thus its no different for him than before

if he re-jets it... and gets a less aggressive cam he'll be where he wants to be

I don't see how the more aggressive cam would lower the compression ratio, would you please explain?

i've never understood it either... i think its more of a 'relatively speaking' term

but... the cam has too much duration and is on too narrow of a lobe separation angle for such a low compression engine... the engine needs a lot of timing to compensate for the terrible combustion at low and midrange speeds (VERY poor cylinder filling with the valves open too much)

I kind of see what you mean, but he said the head was shaved and his comp ratio was now like 10:1. Maybe its really not 10:1 at all.

yeah... i'd say the compression isn't quite that high

he could test it... but my guess is they ripped him off on the head

a guy locally is a 'carb genious' and he autocrosses his old '77 yota truck... he made 67whp stock... and with the sidedrafts and an exhaust he makes over 85at the wheels at 5,400ft above sea level... so my guess is if he jets the carbs right he'll be doing pretty well

The compression lowers because of the valve overlap. The duration is too long, so some of the extra compression added goes out the exhaust or seeps back into the intake. To make full use of the cam, the headers would need to be tuned (4 into 1, 4 into 2 into 1, the length of the runners, the side of the piping for the headers and the type of collector), the length of the intake from the carbs to the head (the shorter the more power high rpm, but less power lower rpm) but the worst thing is these engines naturally does not rev that high. 5200 is the highest i've heard with aggressive cams.