Intake Runner Taper 2

[Dookie]

Hi all,
I have a question regarding intake manifold runner taper. I have read somewhere, don't remember where, that adding a taper to an intake runner has the effect of shortening the runner. The example I remember seeing said something to the effect of: a 2* taper on a 14 inch long intake runner will make the engine see an 11" runner. Is this correct?
If so how do you calculate runner taper to runner length to determine it's effect on cylinder filling at various RPM's?
Any help is greatly appreciated.

 

[MaxRaceSoftware]

If so how do you calculate runner taper to runner length to determine it's effect on cylinder filling at various RPM's?
==========================================

its pretty easy after you've done a lot of Research and Developement on Dyno and DragStrip

best results will be from 1.3 to 1.4 times intake valve area in sq. inches

you can make taper area larger, but start to loose runner length "tuning" effects.

the only reason to make Taper Area greater than 1.4 Ratio would be to try to get plenum's runner entry as much under carb throttle bores as possible

then it would be trade off/compromise between mixture distribution and correct runner length

Max_Taper_Area = Int_Valve_Dia * Int_Valve_Dia * .7854 * 1.4


safer;
Max_Taper_Area = Int_Valve_Dia * Int_Valve_Dia * .7854 * 1.3

inside plenum area max area = Max_Taper_Area


min recommended Taper Factor = 1.2


Larry Meaux (maxracesoftware@yahoo.com)
Meaux Racing Heads - MaxRace Software
ET_Analyst for DragRacers
Support Israel - Genesis 12:3

 

[ColinMe]

Larry, just to clarify, does the Max_Taper_Area parameter specify the inside diameter of the runner at the far end? Sorry, just a little confised.

Thanks in advance,
Colin

 

[MaxRaceSoftware]

the "Max_Taper_Area" would be the "intake manifold runner inside area" at the very beginning of the intake manifold runner starting point inside the plenum area ...this then would taper to or converge to valve seat/ bowl area inside the cylinder head




Larry Meaux (maxracesoftware@yahoo.com)
Meaux Racing Heads - MaxRace Software
ET_Analyst for DragRacers
Support Israel - Genesis 12:3

 

[MaxRaceSoftware]

one more thing =>

"diameter" ....its not the diameter ...but the area

the area is directly calculated
the diameter can be indirectly calculated from the area

Diameter = (Max_Taper_Area ^ .5) / (.7854 * Taper_Factor )

Taper_Factor = 1.4 max recommended 1.3= OK 1.2= minimum



Larry Meaux (maxracesoftware@yahoo.com)
Meaux Racing Heads - MaxRace Software
ET_Analyst for DragRacers
Support Israel - Genesis 12:3