steve316 wrote: ↑Tue May 26, 2020 11:10 am
Smaller csa faster speeds; larger csa slower speeds.
That is why average velocity is important and I'm talking localized at the apex.
Chad ,are you talking of measured velocity as in on the bench or calculated velocity .
I 'll give an example of a head I have and calculated . 225cc , 5.437" port center line length , 2.52sg.in avg csa , 2.40"sq.in pinch, 2.70sq.in at the apex .These give velocities of 301 fps avg ,316 fps at pinch and 280 at the apex using 316cfm at my max lift. Are these to fast ? to slow? or acceptable . If you don't what to answer that is fine . I understand not giving away to much information . Dan
steve316 wrote: ↑Tue May 26, 2020 11:10 am
Smaller csa faster speeds; larger csa slower speeds.
That is why average velocity is important and I'm talking localized at the apex.
Chad ,are you talking of measured velocity as in on the bench or calculated velocity .
I 'll give an example of a head I have and calculated . 225cc , 5.437" port center line length , 2.52sg.in avg csa , 2.40"sq.in pinch, 2.70sq.in at the apex .These give velocities of 301 fps avg ,316 fps at pinch and 280 at the apex using 316cfm at my max lift. Are these to fast ? to slow? or acceptable . If you don't what to answer that is fine . I understand not giving away to much information . Dan
I'm talking pitot velocity.
IMO the numbers you posted are tight and that is important because it means it's balanced. However when I go to put a head on an engine I figure what that head wants for an average velocity through the port. Sometimes the MIN ends up a by-product of a balanced port. I also put my pitot dead center of the port and measure it from the opening to as far back as I can get. I have some heads that don't change 10 fps. Calculated is great. But it still depends on how much the head is moving. So head cfm is important.
Steve,
No I have not had the opportunity to own one of those. I only work on my own stuff so my range of intakes has been limited to an Eddy rpm air gap , Single planes manifolds have been Dart Wilson ,Brodix , Wieand team G with 3/4" taller plenum and a GM bowtie all sbc stuff.
Hopefully all goes well this week and next Sat. I get to try out my new W/P motown II at a test and tune . It's a new top end combo on a 383 short block I've put about 100 1/8 mile runs on . Sorry I could not help you out with info. Dan
6.50camaro wrote: ↑Sat May 30, 2020 8:11 pm
Steve,
No I have not had the opportunity to own one of those. I only work on my own stuff so my range of intakes has been limited to an Eddy rpm air gap , Single planes manifolds have been Dart Wilson ,Brodix , Wieand team G with 3/4" taller plenum and a GM bowtie all sbc stuff.
Hopefully all goes well this week and next Sat. I get to try out my new W/P motown II at a test and tune . It's a new top end combo on a 383 short block I've put about 100 1/8 mile runs on . Sorry I could not help you out with info. Dan
All good Dan,
I have a selection of intakes as well but not a motown, i priced one recently here in Australia $700
Good luck at T and T,I would be interested in your results if you want to share
Ok will post some results . Hope it goes better than the last time. 1st run of the year in March before all this Chinese Bat flu bs. My spare parts 350 lost the head off one of the exhaust valves just before the finish line . Holed #8 cylinder wall and head . Run a 1.47-60' 6.95 1/8th . Was tuning to run 7.0 index class it had gone 6.74 @100+ before detuning . The new-old 383 will also be tuned to run the same class . It went 6.96 last time out in 2015 with the same heads intake and carb as the 350 had but with an HR cam . My 6.50 engine is out of the car being updated at the present .Dan
65dragster wrote: ↑Sat May 30, 2020 9:15 pm
I would enjoy hearing Test and Tune results, too!
Not much to share . Made one pass , not a good burn out (car pushed forward while trying to heat tires) 1.59- 60', 7.25 1/8 et 94+ mph . Tried a second pass , an electric glick popped up line loc wouldn't work tranny brake wouldn't engage . Aborted try for a pass .got a growling noise ,sounded like pinion bearing area driving back to pits . 95°+ day loaded car up will try again. Dan
That’s always so disappointing when you spend the time and money to race and bad stuff happens. I am still very interested to hear updates on track times. I sure hope nothing expensive is broken. Fingers crossed for something simple.
