NewbVetteGuy
Well-Known Member
Here's a question I've been pondering; it has 2 constituent parts/ ideas that come together to make the question possible so bear with me:
1. Modern SBC "Street" heads like the AFRs and Profilers have been laser-focused on keeping air speeds up and maximizing airflow velocity to improve torque and cylinder filling across the range. Darin Morgan has gone so far as to say that this type of head is "velocity limited" (they're trying to keep the air speed close to the max at which you no longer can make more power and the airflow goes turbulent- so when you start to spin up in RPMs the airspeed gets too high and flow goes turbulent and you don't flow more air and you don't make more power.) -We can see this from the airflow in these head's falling off at high lifts and power falling off even with high speed capable valve trains at high RPMS.
2. Tuned intakes use pressure wave reflections to jam more air into the cylinder in certain narrow RPM ranges; this increases air velocity through the intake path, within this RPM band.
Question: Will a combo that utilizes a modern SBC "max velocity" street head and a tuned intake hit the max power velocity "wall" much faster than a combo that utilizes a normal single or dual plane intake? (and cease to make power at a lower RPM, limiting max HP)
Specific applied example of my question: If your build uses an AFR 180 head or a Profiler 185cc head, that would normally not go turbulent until 6,500 RPM, would a tuned intake that further increases air velocity cause you to hit the "speed limit" at a lower RPM and prevent you from reaching your max power RPM sooner? -Causing your power curve to drop off sooner- not because of valve train issues or lifter bleed down but simply because your max air speed went too high?
(My guess is that the solution would be to pull out PipeMax and to figure out how much you need to port your heads/ increase your heads' CSA at the pinch point to prevent the flow from going too fast until after your desired peak power RPM...) -My other thought on a solution would be to go with one size bigger head if PipeMax calculations are estimating your air velocity to go above the max velocity limit.
Anyone have any dyno charts from say an AFR 180cc head or Profiler 185cc head on a 350 or 383 with a high RPM-capable valve train and something like a Holley Stealth Ram?
-(IF anyone's got them, please post them here if you can so we can all look together.)
Adam
1. Modern SBC "Street" heads like the AFRs and Profilers have been laser-focused on keeping air speeds up and maximizing airflow velocity to improve torque and cylinder filling across the range. Darin Morgan has gone so far as to say that this type of head is "velocity limited" (they're trying to keep the air speed close to the max at which you no longer can make more power and the airflow goes turbulent- so when you start to spin up in RPMs the airspeed gets too high and flow goes turbulent and you don't flow more air and you don't make more power.) -We can see this from the airflow in these head's falling off at high lifts and power falling off even with high speed capable valve trains at high RPMS.
2. Tuned intakes use pressure wave reflections to jam more air into the cylinder in certain narrow RPM ranges; this increases air velocity through the intake path, within this RPM band.
Question: Will a combo that utilizes a modern SBC "max velocity" street head and a tuned intake hit the max power velocity "wall" much faster than a combo that utilizes a normal single or dual plane intake? (and cease to make power at a lower RPM, limiting max HP)
Specific applied example of my question: If your build uses an AFR 180 head or a Profiler 185cc head, that would normally not go turbulent until 6,500 RPM, would a tuned intake that further increases air velocity cause you to hit the "speed limit" at a lower RPM and prevent you from reaching your max power RPM sooner? -Causing your power curve to drop off sooner- not because of valve train issues or lifter bleed down but simply because your max air speed went too high?
(My guess is that the solution would be to pull out PipeMax and to figure out how much you need to port your heads/ increase your heads' CSA at the pinch point to prevent the flow from going too fast until after your desired peak power RPM...) -My other thought on a solution would be to go with one size bigger head if PipeMax calculations are estimating your air velocity to go above the max velocity limit.
Anyone have any dyno charts from say an AFR 180cc head or Profiler 185cc head on a 350 or 383 with a high RPM-capable valve train and something like a Holley Stealth Ram?
-(IF anyone's got them, please post them here if you can so we can all look together.)
Adam