Great information in this video if you understand it at all about math formulas and knowing them thanks for sharing your knowledge wish i had better math skills
Hi Chad I was trying to work through your formula for cfm demand and I can’t get it to work out to the 424cfm you came up with is that number right or am I just not working it out right 🤷thanks
I go for port velocity over bigger cfm ant day , learn this the hard way 30 years ago , i test fps at half lift too , because the 4 cycle motor is at half lift twice & full lift twice
How do you decide on FPS ? I worked your formulas on a set of sbm trickflows with a 367 & 410 cid and got 6750 rpm & 6019 rpm respectively and a FPS of 318, is that decent for a street strip type of deal ? and what kind of torque per cid if setup right ? On that 1025 hp @ 8700 rpm 435 was that getting around 1.58 torque per cid ?
I have 2 doubts Chad, 1 because in your sheet of cross sections and speeds in the other video it says that 330fps speed is very high, and 2 if these formulas can be used with a small block as much as a 5.0. Thanks for the help
then you have track performance:) clutch, converter, rear gear, driving, chassis, and on and on. sometimes you might have to make some adjustments to port area to make the combo happy at the track. i have seen great dyno power (both hp and tq) in a reasonable rpm range, and disappointing track performance so…bring the head/manifold/cam where the car/driver is at. shouldnt have to, but sometimes its necessary.
Mr Speier, why did you choose to use 800 lift when measuring the velocity at the mcsa in the pinch? Is it because that's the max lift the engine will see? Thank you for your time.
I suspect... 1) get away from anomalies of seat flow by testing way past the 1/4 x valve diameter mark, and.. 2)map velocity near peak cfm - as seen where runners and bowls influences are determining behavior. Not all heads have the clearances to test past 0.800" lift, so its a convenient benchmark to use on nearly anything made..
Thank you so much Chad its so hard to find any real world info like this anymore I really appreciate what you're doing🙏🏽🙏🏽🙏🏽
Bingo!!!! You got it. Best head port video ever!
Great information in this video if you understand it at all about math formulas and knowing them thanks for sharing your knowledge wish i had better math skills
Awesome Chad, always learn great things from your work, thank you.
Dayam! thats like drinking from a fire hose!! Thanks Chad!!
Thanks for posting these videos!
Thanks for these videos Chad.
Unbelievable real good info.
Fantastic
Thanks. Great info.
Awesome, as always.
Good Stuff!
great video chad thank you
Hi Chad I was trying to work through your formula for cfm demand and I can’t get it to work out to the 424cfm you came up with is that number right or am I just not working it out right 🤷thanks
I go for port velocity over bigger cfm ant day , learn this the hard way 30 years ago , i test fps at half lift too , because the 4 cycle motor is at half lift twice & full lift twice
How do you decide on FPS ?
I worked your formulas on a set of sbm trickflows with a 367 & 410 cid and got 6750 rpm & 6019 rpm respectively and a FPS of 318, is that decent for a street strip type of deal ? and what kind of torque per cid if setup right ?
On that 1025 hp @ 8700 rpm 435 was that getting around 1.58 torque per cid ?
Is the 2.4 a constant in the lower formula you have written? Thank
I have 2 doubts Chad, 1 because in your sheet of cross sections and speeds in the other video it says that 330fps speed is very high, and 2 if these formulas can be used with a small block as much as a 5.0. Thanks for the help
330fps is very high. It's all application specific. And not sure what the other doubt is.
@@SpeierRacingHeads My second question is if these formulas would work for me on my small block with my gt40p heads.
How do you adjust cfm demand calculations for a boosted application?
you don't. gets the same cylinder head
then you have track performance:)
clutch, converter, rear gear, driving, chassis, and on and on.
sometimes you might have to make some adjustments to port area to make the combo happy at the track.
i have seen great dyno power (both hp and tq) in a reasonable rpm range, and disappointing track performance
so…bring the head/manifold/cam where the car/driver is at.
shouldnt have to, but sometimes its necessary.
I've slowed the FPS at the short side apex 20 cfm and found around .08 in ET in a max effort engine.
Do you have any tips or tricks for measuring cross section and accounting for corner rad? Especially in the bowl and short side
yes, pitot tube and convert to csa. CSA = ( Flow_CFM * 2.4) / FPS
Mr Speier, why did you choose to use 800 lift when measuring the velocity at the mcsa in the pinch? Is it because that's the max lift the engine will see?
Thank you for your time.
I suspect... 1) get away from anomalies of seat flow by testing way past the 1/4 x valve diameter mark, and.. 2)map velocity near peak cfm - as seen where runners and bowls influences are determining behavior. Not all heads have the clearances to test past 0.800" lift, so its a convenient benchmark to use on nearly anything made..
Chad what is , .55 Mach = 613.8,,,,, Mach 1 @ Sea Level is 767 MPH ,,,,,, .55 Mach = 421.85 MPH , Me Confused ???
convert mph to feet per second.
Thank You, Sir
ever use this?
rpmx bxbxs/180000=mcsa
yea, appears to be 690 fps.