Mikey's LR2.4 MIVEC 10:1 Motor Build
Jul 3, 2010, 06:06 PM
#706
Lengthening the R/S ratio slows the speed of the piston around TDC, and increases it around BDC. How can this affect power? In a nutshell ...
When the piston moves faster around BDC, that makes the ideal closing point of the intake valve (the single most important valve timing event) come quicker. So, changing R/S significantly indirectly changes cam timing with respect to piston position.
When the piston moves slower around TDC, that has the effect of increasing the resolution of ignition timing at higher rpm. This is desirable because the piston moves faster than the flame front.
What does this mean in the big picture? I believe it was GM engineers that demonstrated that any change in R/S ratio <5% or so made no discernable difference in power in clinical settings.
FYI
When the piston moves faster around BDC, that makes the ideal closing point of the intake valve (the single most important valve timing event) come quicker. So, changing R/S significantly indirectly changes cam timing with respect to piston position.
When the piston moves slower around TDC, that has the effect of increasing the resolution of ignition timing at higher rpm. This is desirable because the piston moves faster than the flame front.
What does this mean in the big picture? I believe it was GM engineers that demonstrated that any change in R/S ratio <5% or so made no discernable difference in power in clinical settings.
FYI
Jul 5, 2010, 09:07 PM
#708
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) it regulates the oil in the head, which will keep more oil in the pan, which is better for the bearings. The head only require 15psi of oil or w/e it is, and this will help keep the bottom end with plenty of oil. in a nutshell. somewhere in here there is a link to a thread on it. Ill try finding it for you.
Jul 5, 2010, 10:42 PM
#711
that was in PM! I basically said its not really a necessity if you're just building a car to do an occasional pull and not slamming gears on a daily basis at the track in high rpm's. For you, id say you probably wont benefit from it, for me.... i benefit from it.. i slam gears everyday (on the street). It has helped with my blowby in my buschur motor as well.
Jul 6, 2010, 01:33 PM
#715
Thanks for clearing that up! I'm definitely going to grab one now.
PS: are you, Mikey, Lucas, or anyone else running any type of modified oil pan or pickup to fight starvation issues during launching or acceleration?
PS: are you, Mikey, Lucas, or anyone else running any type of modified oil pan or pickup to fight starvation issues during launching or acceleration?
Last edited by dsmfan95; Jul 6, 2010 at 01:37 PM.
Jul 6, 2010, 04:40 PM
#716
We run AMS pans for the most part. Right now since I am not drag racing I pulled it off and have a stocker on it since I dont really need it too much. If I go back to drag racing the car I'll put an AMS back on or modify my stock pan and pickup. For the time being running a 1/2 quart extra seems to be working.
Aaron
Aaron
the neons had the same issue.