Stan Weiss wrote: ↑Wed Mar 07, 2018 10:47 am
Paul,
What I had posted was the calculated MCSA @ each lift point. Using that and its flow I calculated SAE CD and velocity I was only referencing pages 24, 25, 26 of that PDF as a way to calculate the MCSA.
If what you are using is not proprietary. Why don't you post it up so we can have a look and see if it is better or not?
Stan
Stan,
The attached is typical of what I am using to determine flow window area. It's logic is borrowed from the work of ST member Mike Kalbfeld's postings regarding his thoughts on a port flow single effective area. I adapted it to look at velocities at lift in this case. It uses conditional "IF"s to control for the three valve position values in the spreadsheet equations. The first area is determined by the "transitional lift" area, the next by "valve lift" area and the final by "valve throat" area.
Valve flow velocity.xls
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Stan Weiss wrote: ↑Wed Mar 07, 2018 10:47 am
Paul,
What I had posted was the calculated MCSA @ each lift point. Using that and its flow I calculated SAE CD and velocity I was only referencing pages 24, 25, 26 of that PDF as a way to calculate the MCSA.
If what you are using is not proprietary. Why don't you post it up so we can have a look and see if it is better or not?
Stan
Stan,
The attached is typical of what I am using to determine flow window area. It's logic is borrowed from the work of ST member Mike Kalbfeld's postings regarding his thoughts on a port flow single effective area. I adapted it to look at velocities at lift in this case. It uses conditional "IF"s to control for the three valve position values in the spreadsheet equations. The first area is determined by the "transitional lift" area, the next by "valve lift" area and the final by "valve throat" area.
Valve flow velocity.xls
Regrettably, the chart function does not work on the posted spreadsheet. It is looking for its home workbook. I am working on a solution and will post later.
Stan Weiss wrote: ↑Wed Mar 07, 2018 10:47 am
Paul,
What I had posted was the calculated MCSA @ each lift point. Using that and its flow I calculated SAE CD and velocity I was only referencing pages 24, 25, 26 of that PDF as a way to calculate the MCSA.
If what you are using is not proprietary. Why don't you post it up so we can have a look and see if it is better or not?
Stan
Stan,
The attached is typical of what I am using to determine flow window area. It's logic is borrowed from the work of ST member Mike Kalbfeld's postings regarding his thoughts on a port flow single effective area. I adapted it to look at velocities at lift in this case. It uses conditional "IF"s to control for the three valve position values in the spreadsheet equations. The first area is determined by the "transitional lift" area, the next by "valve lift" area and the final by "valve throat" area.
Valve flow velocity.xls
Try this one.
Valve flow velocity corrected.xls
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Interesting!
I plugged in one of my typical ports and found mean velocity of 322 and mean flow index 101. FWIW this is with a 45° seat 38° top.
At flows <.350 lift just over 350fps velocity. If I plugged in numbers of the same geometry but valve not back cut the flow drops and velocity drop to almost a 300fps flat line in the same lift range.
So is this an illustration of low lift numbers are good VS not so beneficial based on too much velocity?
HDBD wrote: ↑Fri Mar 09, 2018 9:35 am
Interesting!
I plugged in one of my typical ports and found mean velocity of 322 and mean flow index 101. FWIW this is with a 45° seat 38° top.
At flows <.350 lift just over 350fps velocity. If I plugged in numbers of the same geometry but valve not back cut the flow drops and velocity drop to almost a 300fps flat line in the same lift range.
So is this an illustration of low lift numbers are good VS not so beneficial based on too much velocity?
I would argue that the flow is choked at lifts below .350" RE; low lift flow, IMO flow at lifts that jive with demand plus lag and fall into that sweet spot that are neither too fast or too slow, provide the greatest benefit, but I am just a hobby racer.
cspeier wrote: ↑Fri Mar 09, 2018 10:12 am
So you guys don't believe the sooner you get that column of air moving the better?
Not when it requires you to remove cam duration in order to keep the required torque.
Up to a point ... every time there is a NEED to use a smaller camshaft, I lose horsepower.
cspeier wrote: ↑Fri Mar 09, 2018 10:12 am
So you guys don't believe the sooner you get that column of air moving the better?
As long as the column of air is moving in the correct direction. And there isn't a piston up the hole for the column to smash into and reflect back into the post.
