Cylinder Head Flow numbers

[pbf777]

So...what your saying is every IR carb's set up spits up?

    YES!

    Absolutely, with out exception; though there will be different magnitudes of expulsions in the reversionary act; as in some instances barely visible but under the right conditions of observation, others to the point of creating challenges in engine tuning or even creating an inflammable hazard, this for a number of reasons, but still, always.   

    And, if you still doubt this, for comparison just pop the air cleaner lid on even the common plenum single carbureted engine, that of a standard "bread & butter" sedan type vehicle example, that in which this subject of reversion above the carburetors' venturi is generally of far less concern, and note the burned exhaust carbon collected on the underside, how did that get there?   

    Scott. 

[crossboss]

So...what your saying is every IR carb's set up spits up?

    YES!

    Absolutely, with out exception; though there will be different magnitudes of expulsions in the reversionary act; as in some instances barely visible but under the right conditions of observation, others to the point of creating challenges in engine tuning or even creating an inflammable hazard, this for a number of reasons, but still, always.   

    And, if you still doubt this, for comparison just pop the air cleaner lid on even the common plenum single carbureted engine, that of a standard "bread & butter" sedan type vehicle example, that in which this subject of reversion above the carburetors' venturi is generally of far less concern, and note the burned exhaust carbon collected on the underside, how did that get there?   

    Scott.

Scott,
Really? I have seen and experienced just the opposite. Does it happen, yes. Just not on every engine/every time. Guess you and I have different opinions on this...
Ok, we are getting way off topic here. Lets keep it about flow and cfm flow numbers.

[pbf777]

    O.K., back to "flow & C.F.M. numbers:

Think of it like a fan. Turn the fan on...it just blows all over the place. Now, place a tube in front of it, and viola, it makes more velocity/speed!

    Yes "velocity/speed" perhaps, but that's on the discharge side of the fan, of which has the responsibility of inducing the motion initially, so perhaps the question might actually be: Did the C.F.M. volume as set in motion by the fan actually increase; this as measured on the inlet side of the fan?  Possibly, but more likely, rather due to the now increased in pumping effort instilled with the inclusion of the "tube" in order to facilitate this "velocity/speed" effect, the C.F.M. numbers passing thought the fan actually decrease, as with this increase in the pumping effort by the device volumetric efficiency is generally reduced.  And along with that increased effort is the fact that the energy utilized, in this case as measured in amperage consumption (if the example were an electric motor driven) increases; as nothing is free, and in order to facilitate that acceleration in the movement of the mass of the atmosphere energy is traded.   

     Just food for thought.   
     
     Scott.

[crossboss]

    O.K., back to "flow & C.F.M. numbers:

Think of it like a fan. Turn the fan on...it just blows all over the place. Now, place a tube in front of it, and viola, it makes more velocity/speed!

    Yes "velocity/speed" perhaps, but that's on the discharge side of the fan, of which has the responsibility of inducing the motion initially, so perhaps the question might actually be: Did the C.F.M. volume as set in motion by the fan actually increase; this as measured on the inlet side of the fan?  Possibly, but more likely, rather due to the now increased in pumping effort instilled with the inclusion of the "tube" in order to facilitate this "velocity/speed" effect, the C.F.M. numbers passing thought the fan actually decrease, as with this increase in the pumping effort by the device volumetric efficiency is generally reduced.  And along with that increased effort is the fact that the energy utilized, in this case as measured in amperage consumption (if the example were an electric motor driven) increases; as nothing is free, and in order to facilitate that acceleration in the movement of the mass of the atmosphere energy is traded.   

     Just food for thought.   
     
     Scott.

There is a little thing called 'Velocity stacks'. And yes, they do work.

[pbf777]

There is a little thing called 'Velocity stacks'. And yes, they do work.

      Yep, and most vehicles have a thing called a "tail-pipe" too!    

      And both are mostly about directing an air volume on a desired course; both hopefully with some efficiency with reasonably area and proper transitions to coerce the air volume to flow smoothly and effectively, and in just the same either may present the possibility for improvement in the overall performance output of the engine, often as in the sense of a tradeoff of being a lesser evil as otherwise, but just not for free!   

      I believe your position would be better suited in the example of an efficiently executed true "venturi"; as this is probably as close as one gets to conforming and accelerating an air column, within a distance, this as long as one doesn't with poor execution or excessive intent approach a "choke" effect, and this being with minimal energy loss in the process that might be relevant here.   

      But do realize that since the subject of engine performance realized is not relegated solely that equipment for the purpose of increasing the C.F.M. air flow sums, rather that much of that which is done, particularly that of the inlet side induction, is also about fuel acquisition, this particularly as drawn from a mechanical carburetor, equivalent distribution particularly in multi-cylinder engines and the creation of a homogeneous mixture, aka. fuel control, and as such that at times less leads to actually more!    

      Scott.

[crossboss]

There is a little thing called 'Velocity stacks'. And yes, they do work.

      Yep, and most vehicles have a thing called a "tail-pipe" too!    

      And both are mostly about directing an air volume on a desired course; both hopefully with some efficiency with reasonably area and proper transitions to coerce the air volume to flow smoothly and effectively, and in just the same either may present the possibility for improvement in the overall performance output of the engine, often as in the sense of a tradeoff of being a lesser evil as otherwise, but just not for free!   

      I believe your position would be better suited in the example of an efficiently executed true "venturi"; as this is probably as close as one gets to conforming and accelerating an air column, within a distance, this as long as one doesn't with poor execution or excessive intent approach a "choke" effect, and this being with minimal energy loss in the process that might be relevant here.   

      But do realize that since the subject of engine performance realized is not relegated solely that equipment for the purpose of increasing the C.F.M. air flow sums, rather that much of that which is done, particularly that of the inlet side induction, is also about fuel acquisition, this particularly as drawn from a mechanical carburetor, equivalent distribution particularly in multi-cylinder engines and the creation of a homogeneous mixture, aka. fuel control, and as such that at times less leads to actually more!    

      Scott.

+2. Agreed.