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
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 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
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..
