Saito FA-180 CDI Compression Ratio & Induction Modification Performance Gains
07-19-2016, 03:23 AM
#26
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No need to yell, everything Dan said is based on the fact that our engines already run at or very near their peak/limit of reliability rpm. This DOHC 1.20 four valve Conley turns a 14x6 @ 12,181 rpm. It won't touch a 15x8 without overheating and knocking. It's not a very practical engine.
Otherwise, that yelling sounds like my first wife. 
07-19-2016, 11:28 AM
#28
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to each his own I guess, besides, I was not suggesting that we all start ordering cams that are ground 50, 60 or 70 degrees over stock numbers.
if you back up your statement about "cam aggressiveness" by posting duration numbers at .006" Lift and .050" Lift you would then have told me something
BTW, unless these stock cams are more aggressive than I believe they are, increasing the intake's rocker arm ratio by 1.00 will only change the intake valve's duration by 2 or 3 degrees IF that, hardly much to boast or complain about, yet will increase the idle's smoothness without raising the idle's RPM much at all, as well as producing more power throughout the powerband.. increasing the exhaust's rocker arm ratio will suffer low end torque some
like I said, to each his own
if you back up your statement about "cam aggressiveness" by posting duration numbers at .006" Lift and .050" Lift you would then have told me something
BTW, unless these stock cams are more aggressive than I believe they are, increasing the intake's rocker arm ratio by 1.00 will only change the intake valve's duration by 2 or 3 degrees IF that, hardly much to boast or complain about, yet will increase the idle's smoothness without raising the idle's RPM much at all, as well as producing more power throughout the powerband.. increasing the exhaust's rocker arm ratio will suffer low end torque some
like I said, to each his own
Our engines already turn more RPM than what would allow the utmost efficiency from the practical propeller sizes.
As far as lobe specifications? Having seen a lot of cam lobe profiles on street practical automotive cams, the Saito big block cam has a rather broad nose on the lobe.
https://www.youtube.com/watch?v=T-Sbz2Etl_A
07-19-2016, 05:15 PM
#29
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specifying cam duration at .050" lift will not "erase" anything, yet specifying cam duration at .200" lift along with .004" and .050" will tell us more
"the Saito big block cam has a rather broad nose on the lobe".
you can get a broader lobe nose with less lift on a cam, and then use higher ratio rocker arms to get the lift you desire, these types cams are easy on the cam followers (lifters) and pushrods
"This DOHC 1.20 four valve Conley turns a 14x6 @ 12,181 rpm"
and what does an OS 120 turn at with the "same" prop, maybe one could say the Conley has a more aggressive cam than the OS, maybe
umm, 4 four valves, why 4, could 4 valves flow more fuel/air than only 2 valves
there is always room for more modification
"the Saito big block cam has a rather broad nose on the lobe".
you can get a broader lobe nose with less lift on a cam, and then use higher ratio rocker arms to get the lift you desire, these types cams are easy on the cam followers (lifters) and pushrods
"This DOHC 1.20 four valve Conley turns a 14x6 @ 12,181 rpm"
and what does an OS 120 turn at with the "same" prop, maybe one could say the Conley has a more aggressive cam than the OS, maybe
umm, 4 four valves, why 4, could 4 valves flow more fuel/air than only 2 valves
there is always room for more modification
Last edited by the Wasp; 07-19-2016 at 05:29 PM.
07-20-2016, 04:04 AM
#30
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Four valves are a plus not necessarily because of increased cross section but more because two smaller columns of air/fuel and exhaust are easier to accelerate from a standstill. Getting fuel/air mixture flowing sooner is a big plus. Airflow velocity, in fps, is faster in the smaller passages,increasing the ram tuning effect. That barely skims the surface but presents the idea.
