Hi-lift flow vs Mid-lift flow 2

[Rick360]

When porting a set of heads there are ways to enhance high, mid or low lift flow characteristics. I realize the ideal is to gain at all lifts but sometimes there is a tradeoff.
Which one would you trade for what other one? and why?

I profiled a cam which has .800" net lift thru its entire lift curve to see how long the valve was at what point, the piston velocity, and the flow at that lift. I then calculated theoretical flows throughout the intake stroke to see which lift points made the bigger difference. It seems that .700" and up had a bigger effect. Does this hold true on a dyno? Would gaining 10cfm at .7" - .8" be worth giving up 10 cfm at .5"-.6"?

Rick

 

[CurtisBoggs]

Larry,

Thanks, .. yes I'm going to try a 30, 35 & 37, .. see what happens.

Thanks again,

Curtis

Curtis Boggs
Racing Flow Development

http://www.raceflowdevelopment.com

 

[MaxRaceSoftware]

A few questions, .. the curtain area at .300" how much will that flow?
what's the best possable?
also, .. I'm very bad at math, .. is there a spread sheet available to do the calc's, .. curtian area, .. etc.?
===================================================

Curtis, Darin Morgan has a Excel SpreadSheet available
for you to download and use or at least get an idea of whats important/relevant ?

Darin Morgan
R&D-Cylinder Head Dept.
Reher-Morrison Racing Engines
1120 Enterprise Place
Arlington Texas 76001
817-467-7171
FAX-468-3147
Visit our web site at

http://www.rehermorrison.com

Go to my (Darin's) web site at

http://webpages.charter.net/dsda/

I have uploaded an XL spread sheet showing the discharge Coe.



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

 

[CurtisBoggs]

Larry,

Thanks, .. you ARE the MAN!

Another question, .. perhaps for another thread, ..
I'm thinking about building a F/ED dragester with a Mopar W9 rp cylinder head on a Mopar aluminum 4 cylinder block, ..
do you have any experience with these combos?

Curtis

Curtis Boggs
Racing Flow Development

http://www.raceflowdevelopment.com

 

[Rick360]

Larry,
Thanks for the info. I checked out the spreadsheet to see the formulas involved and I have a question about the disch coef. The basic formula is FLOW/(CURTAIN AREA * 137.7). What is 137.7 for? a constant for something? Is this constant different depending on test pressure?

Rick

 

[MaxRaceSoftware]

Larry,
Thanks for the info. I checked out the spreadsheet to see the formulas involved and I have a question about the disch coef. The basic formula is FLOW/(CURTAIN AREA * 137.7). What is 137.7 for? a constant for something? Is this constant different depending on test pressure?--Rick
-------------------------------------------------

Quote by Darin Morgan =>
"There are many coefficients that I use and CFM/SQin is by far the simplest. The other coefficients you should learn and use are,

(1) Discharge Coe. Based on theoretical maximum such as the SAE factor of 137CFM/SQin or the 146CFM/SQin that most of us use. The equation uses the window area at every lift increment, the theoretical maximum and a ratio of effective area and actual flow area."

Rick for more Info checkout this Link

http://speedtalk.com/forum/viewtopic.php?t=321

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

http://www.maxracesoftware.com/

 

[CurtisBoggs]

Larry,

More discussions, ..

I have a 2" valve, .. data from my portflow software.

.200" lift, 132.6 cfm @ 28" , est valve area 1.257, 105 cfm per sq in.,
flow area sq in. .910, flow coef. .724

.300" lift, 201.1 cfm, est valve area sq in. 1885, 106.67 cfm per sq in.,
flow area sq in. 1.380, flow coef. .732

So, am I missing something or does this seem to be fairly poor??

This is a late model 5.7 Hemi head, .. ported, valve job with wide 60 still using the 45, and flow didn't chamge at all under .400" ????????????

I've gained nothing in the lift range of the cam, ..Help!

Curtis

Curtis Boggs
Racing Flow Development

http://www.raceflowdevelopment.com