How big a cam before going open loop idle?
08-21-2013, 01:35 PM
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How big a cam before going open loop idle? Just wondering how much overlap you can run before you guys force open loop idle? My car is fine in closed loop right now, but if I decide to change my cam out this winter I really do not want to be forced into open loop idle.
My cam specs a 242/250 113/109
My cam specs a 242/250 113/109
08-21-2013, 02:46 PM
#2
There are a few other variables that come into play besides cam size. Header length and O2 locations on the headers will affect how well the o2's will work at idle also. If you set up OL idle only its not that big a deal IMO. Most cam only setups thought can run CL at idle, the bigger stroker motors with alot bigeger cams usually are the ones with idle O2 problems.
08-22-2013, 12:10 PM
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Control of idle mixture is key; beyond that you
might have to play with the P, I, D settings for
idle loop to get stability with a far-different motor
response. Over-rich mixture (a common consequence
of camming up) makes the motor "soggy" beyond
what the stock control-loop parameters are set up
to accommodate. But I'm just a hack when it comes
to control theory, not to mention that the params
and loop algorithm are evidently not classical P, I, D.
Still, you have those "*****" if you get mixture
right and stable and still have the wow-wow-wow.
might have to play with the P, I, D settings for
idle loop to get stability with a far-different motor
response. Over-rich mixture (a common consequence
of camming up) makes the motor "soggy" beyond
what the stock control-loop parameters are set up
to accommodate. But I'm just a hack when it comes
to control theory, not to mention that the params
and loop algorithm are evidently not classical P, I, D.
Still, you have those "*****" if you get mixture
right and stable and still have the wow-wow-wow.
08-25-2013, 08:07 AM
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Cool, I am thinking about changing my cam already. Over the winter. Should be around 28 degrees overlap, from the 20 degrees I have now. Going from a 113 to 112 LSA.
08-25-2013, 11:01 AM
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