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Posted:
Mon Dec 15, 2008 9:22 pmby Half-Inch Stud
So I ask if there is an ideal intake Runner casting that can be described by the folks here. As if to say many benches were built, much results gathered, and compared with the ton of prior art out there to say...the good flowing Intake Runner needs to look like "this" upon approaching the valve stem, and like "that" in the bowl.
For strokes under 3.75"
For Strokes near 4.2"
Or simply, clearly are there some Runner & Bowl shape trends noticed when evolving from short-stroke to long stroke?
Posted:
Mon Dec 15, 2008 10:53 pmby blaktopr
I think we are all still working on that. I been studying the effects of bowl/ central runner shapes to equalize the speeds through the throat and seat, and the effects that has on the wet flow signature in the chamber/cylinder. With some headway.
Chris.
Posted:
Wed Dec 17, 2008 10:42 amby 200cfm
In some reading research I came across a statement that said the longer the stroke the faster the velocity of the air through the port in comparison to a shorter stroke motor. How would that be used in porting?
Posted:
Wed Dec 17, 2008 12:05 pmby 106-1194218389
Posted:
Wed Dec 17, 2008 1:46 pmby larrycavan
Posted:
Sat Dec 20, 2008 9:46 pmby Half-Inch Stud
Well there it is: the Venturi. The necessary shape to allow the mass-air to speed-up to the Valve's backface & flow along the backface into the CYL.
I gots some fundamental advice from some 1976 book on...of all tings flow hoods and ductwork. Show plots, nomographs and scale factors on ductwork.
The advice: Our Intake rectangular ports are killing flow because the "tall runner does the turn causing short-radius flow to pinch-off the Long radius flow by crashing into it. <-- I hope all on this site know this.
Our port-runner shape should be low-height, and wide. If I could UPLOAD a ppt-slide pict, it would be a picture of:
Factory Rect D D like E-Exhaust Factory Rect
ports on their side ports
BEST Good Bad
Posted:
Sun Dec 21, 2008 2:43 pmby CraigAPD
Posted:
Sun Dec 21, 2008 3:08 pmby 106-1194218389
Posted:
Sun Dec 21, 2008 4:47 pmby CraigAPD
:)
Posted:
Thu Jan 15, 2009 4:42 pmby Half-Inch Stud
Aside from CSA concerns for "rate-of-flow" I've boiled it down to the basic displacement:
The CID volume from Bore&Stroke ought pull an Intake track of equal Volume. Such that the "runner" pulls from a pressurized Plenum (or similar Step-in-diameter). Aside from intake pulse timing, this basic makes a case for 8 throttle plates located about 1 CYL volume away from the valve seat huh.
Makes me re-ponder the dual-plane versus a single-plane with a constant diameter "momentum tube" at teh carb inlet. In other words an air cleaner seem to destroy above-carb momentum. 