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Blended chamber looks like a wash, but does give very slight gains where it matters most.

The one thing that has been surprising me with this is how seemly hard it is to have low velocities. If the port length average for all these heads is around 4.95" that makes about a 195 cc as the crossover point where cfm and fps are equal and any ports that has less cc than 195 cc fps will...

Nope, but sounds like I should get it. That's why started the thread hope to get to the bottom of it, not saying anything I calculated above is accurate just a jumping off point.

340/360 2.02/1.88 1st, not sure if the port length is 4.95" ? for these heads but using it for now, as long it's not to far off should be close. From what I understand 340/360 heads are in the 150-160 cc range and flow 200-225 ? (1.88 vs 2.02) Average csa = 1.85"-1.97" Velocity 200 cfm =...

It's six pages deep of course it's off track. Hysterics brought up the Fords, you were debating the OP take on the Fords and I'm adding my take. Port velocity, carb velocity it's all related.

cfm demand = cid x rpm x .0009785 / # cylinders Or rpm = (cfm x cylinders) / (cid x .0009785) Rpm = 6,012 for a 408 cid Min csa = b x b x s x rpm x .00353 / 613.8 2.25" min csa so that's supposed to be the smallest area you have anywhere and that's usually the push rod pinch. I generally...

So eg. Say Trick Flows 300 cfm with a 190 cc port. Is trick flows port length 4.95" ? For now I'm gonna go with that. Average csa = port cc / 81.12 190 / 81.12 = 2.34" ave csa. Port fps = cfm x 2.4 / ave csa 308 fps = 300 x 2.4 / 2.34" To get 260 fps the ave csa and port cc would need to...

So according to these guidelines a velocity of 260 fps according to it's calculated average CSA seems to be the ideal target. And the formula to figure that is Cfm x 2.4 / 260 = average csa. Now to figure a port volumes ave. csa = port cc / (port length x 16. 387), Now I've been going off...

...wrong, feel free to post. But I figured we'd start here with these. Induction Formulas Average_CSA = Port_Volume_CC / (Port_CenterLine_Length * 16.387) MIN CSA = (Bore x Bore x Stroke x RPM x .00353) / 613.8 (.55 MACH) Port_Volume_CC = Average_CSA * Port_CenterLine_Length * 16.387...

It's more efficient to ignore you :)

This is at the edge of my understanding of this so I'm not saying I'm a 100% right but to me the more fuel and air is in relation to the displacement difference, so at say a 100% ve and 10:1 cr a 25 cid cylinder vs a 50 cid cylinder the 50 cid should have about twice the fuel and air but has...

Had an old Suzuki Samurai and the throttle cable broke 3 hours from my house, used a shoe lace to tie the throttle where I wanted it. But after awhile it started to slack a bit and couldn’t do highway speeds so I pull over to redo it and the hood latch cable broke, so I had to take the through...

But my overall point is we're building Mopars and we really don't have huge port heads and if the Cleveland guys can get away using 4V heads on 302-351 I'm sure we don't have to worry as much as people do. Especially people worry about port velocity but seems like not many know how much...

Do you even read what I'm posting, I never claimed larger piston just magically makes Hp, I've said that repeatedly in this thread, we've been talking about force and torque, you keep saying if larger pistons apply more force to the crank its free Hp which is wrong and I've explained why a...

There's people running around with built old school Cleveland's, would they be better off with a modern heads, probably but doesn't mean their not enjoying their cars. Wasn't given exact figures, point is what's important in highly competitive racing not necessarily important to the average dude.

A Dog in a highly competitive race class, I imagine the vast majority of people on this site aren't running in super highly competitive racing where being a 10th of a second off can make a huge deal but for the average guy probably not so much. Most here have a weekend throttle blip burnout...

That runs 20:1 cr.

Again your ridiculous, without context it means nothing.

Doesn't anybody else think its odd this engine hp peaks at just under 5000 rpms ?

That was my exact thought when I read it too. It is utterly ridiculous lol.

You start talking crazy things that look like this for large cube and rpm, 625 cfm pro stock head.

Probably head flow I don't know what those W8 heads are producing flow wise but kind of easy going from stock 200 cfm to aftermarket 300-350 cfm making 1.9-2.3 or so hp per cfm 550-800 hp but imagine gains get exponentially harder and expensive above that.

Keep us updated, keeps everyone on task :) plus it your thread post what you want.

My guess it's harder ($$$$) to get heads with enough area to spin 500 + cid engines.

Bore size is one of the ultimate main limiting factors to hp but for most were not making enough hp to overly worry about it, most aren't even pushing what a 318 bore is capable of and really a 360 bore is less than 3% bigger than a 318 bore and a 340 bore is slightly more than 3% compared to a...

Bewy, hint, to prove us wrong, All you have to prove is for same displacement the bigger piston engine generally has less psi and less psi generally by the percentage difference between the piston area. And not by some old science book but actual examples of automotive engineers or text saying...

Most of us aren't building high effort, highly competitive racing engines, and most of us aren't even close to running port sizes with those cross sections and volumes. I've never heard anyone say the X head was too much for a 340 or that the 1.88 J head was an improvement to a 340 or porting a...

Again were talking combustion psi not lbs of force.

Your thumb is not pressing down on the piston is it, it's the pressure psi from the combustion that is, which has a relatively narrow range of psi based on efficiency not displacement, average car to highly efficient race car 1000-1500 psi a Max effort Pro Stock has 1600-1700 psi.