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I came across this, might be your answer. "You'd test it the same as you would any other head. Flow it at 28" and see what kind of results you get. The airspeed in the ports on the running engine will be the same regardless of boost since the airspeed is a product of the ratio of bore area to...

I wonder if velocity is around 240 fps at peak torque what would it be at peak hp?

Anyone hear of this formula for tuning (sizing ave. csa of intake and header) for peak torque rpm? Supposedly base on that an engine torque peaks at 240 fps. (obviously there's other factors that influence where it peaks). csa = cid of one cylinder x rpm / 88,200...

I get there's no overall ideal, it's all a series of compromises, I guess by Ideal I mean more in the general sense. I've heard many say they'd sacrifice exhaust valve for intake valve, and hear of making the exhaust side of the cam smaller cause too much of the intake charge is going out the...

Wonder what the Ideal ratio of exhaust port volume, flow and velocity is to achieving higher lbs-ft per cid, I feel it's one of the reasons LS heads do so well, even why I think magnum heads respond well to cams.

Velocity is the speed of the air mass without speed (movement) you got no air flow. The runner is part of the port it's size and shape is gonna aid in velocity and the mass of air, a 360 gonna need about 600-800 cc of air for each power stroke and got less than a millisecond to do it. The...

Do you have a point?

Further ahead than I was before, think I got a few bits of good info to build on. Air flow and it's speed (velocity) obviously plays a big role. But if you look at the acceptable velocities It does cover a wide range 240-320 fps, If you calculate that out to port cc size for 300 cfm that's...

I said you got anything helpful to add, guess not.

I really like Darin Morgan the dude just loves to spill out information and he's really good at explaining it.

Chad from Speier Racing Heads, where I got most of this fps info and formulas from, he seems to be 100% all in on it, I've seen other head ports argue him they seem to think it's more just guidelines. Point is Chad for I think he said for stock eliminator seemed to shoot for 330 fps and he said...

All cleared out.

Now I'm not saying this chart is right, but as I figure out each decent heads port velocities they seem to fall in the 250-300 fps average range and the more impressive heads do seem to be closer to 260 fps. Now I could be calculating wrong, port length and even cc are hard info to come by. Now...

The LS Cathedral ports, if I found the right port length about 5.5", the stock heads seem to be in the average fps of 250-260. 260 is supposedly the ideal 250 seems to be the largest port size you want to go with 240 fps maximum. So if right the LS seem to be on the large side. Eg. If was a...

Your ridiculous. Do you actually have anything helpful to add to the conversation?

So? Who cares the 323 ain't making the same hp per cfm, it's all about the hp curve and the 323 is better, that's what powers your car.

I do understand the context, you might if everything wasn't about your obsessions with the small. You mean cfm ? 2.23 hp per cfm. If everyone could easily get 450-500 hp out of 318 heads, you don't think people wouldn't be champion that. I imagine they could. No **** you act like this...

No, I’m saying it’s got most of what it can get out of these heads by 5000 rpm’s. If your building a 6500 rpm engine like this one it should be making a lot more hp at 6000 rpm’s.

It is a pretty cool little engine but if you look at the power curve every 500 rpms there's a solid hp gain from 2500 to 5000 rpms and then it basically flatlines to 6500 rpms the engine could obviously use more head flow in the real world. (outside the contest)

Porting as in different velocity ? For the same cfms.

The point of building more torque per cid is to make more hp at any given rpm, the torque # in itself ain't overly important it's what it does to the power curve.

Like said before it's an impressive engine, it's not an engine most would be able to build. But yes fits in with the discussion, Say the olds has similar port length as a sbm that's about 260 fps, if look at the chart I made post# 126 that 200 cfm needs about 150 cc to have about 260 fps which...

Yes but what exactly is too big ? Everyone is afraid of too big but no one seems to know what exactly is too big or just right. And yes boss heads are an example of excessive but many have made good power with them, here's a boss 302 vs a chevy 302 both make very similar down low torque...

Calculated recommended head flow cfm for a given cid and rpm. RPM. 4,500.....5,000....5,500....6,000....6,500....7,000 273. 150.........167......184.......200........217......234 cfm 318. 175.........194.......214......233........253......272 cfm 340...

If you look at the calculated fps of stock 273/318/340/360 heads they seem to fall in the 260-280 fps range. And as we modify them for higher cfm velocity goes up not down cause the ease of cfm gain is easier and obviously not linear to volume gain, it lags behind creating higher velocities.

I just subscribed, looks like kewl channel and been keeping yourself busy.

If your buddy regularly pumps out engines that make that much lbs-ft per cid then everything should be fine, not saying he can't. I was just pointing out for the average guy it's a little up there basically that's a decent 340 torque number. And even if you don't still should make 350 hp at a...

If you look at what port size cc is needed for a given cfm to make a velocity of 260 fps are roughly. 225 cfms = 170 cc, 250 cfms = 190 cc, 275 cfms = 205 cc, 300 cfms = 225 cc, 325 cfms = 245 cc. If 260 fps is the ideal for best balance of torque and hp. Supposedly above 320 fps hurts hp...