any pics of a good port job?

[71chally416]

Porting techniques and flow figures and discussing thermo dynamics is fun, but ET slips are always the final judge of things not easily explained or understood with pictures. We can all agree on that 

[Roppa440]

Porting techniques and flow figures and discussing thermo dynamics is fun, but ET slips are always the final judge of things not easily explained or understood with pictures. We can all agree on that 

I don't agree with that.
I think you are assuming porting is always done to get max power and the faster the ET the better the job. This is not so.
A ported head for a car that launches at 4000rpm and runs to 7500rpm is a totally different animal to one built to run best from idle up to 6500rpm. The head work has to suit the intended use of the engine.

A head should only just low enough for the rest of the engine combo. If it flows more than that you start going backwards by loosing things like throttle response and mileage. Mixture quality will suffer too. Meaning average power over the rpm range being used will be down.

[moper]

Unfortunately, a flow bench, an engine dyno, a chassis dyno.. they are all simply tools. There currently is no way to physically simulate a running engine environment. There are formulas for everything from the seat angles and valve margine to the volume of the intake plenum. All based on generalities and results in the past. But add temps, fluids, interia and fluid dynamics (Pressure waves) and it gets off the chart. And when push comes to shove, the way a car is measured is the ET or MPH. The only wany to KNOW is to run it eventually. So while I agree they are useful tools and can give you a strong idea of what and how it will perform in a car, until it's in the car, it's atill unproven.  I am a firm believer in "smaller is better" for street cars.

[Chryco Psycho]

 
 Tottaly , I port more for velocity , to reduce turbulence & increse swirl & mixing than I do for peak flow #s

[moper]

roppa, on the notching, I generally relieve the chambers to the fire ring, but I don't notch bores 98% of the time. I use a smaller valve instead. On a 360, or 383 bore, especially with a higher output expected, I will notch them.

[71chally416]

On a N/A motor at high RPM you get little more packing the cylinders but what is contained in the head ports. When you consider the volume of a 440 cylinder at BDC, including the head gasket and chamber volume, how does that swept volume of over 1,000cc's  measure up to a stock BB Chrysler production head that has a 200cc Intake port? It will take nearly half the contents of the intake port just to fill the uncompressed 88cc combustion chamber of a stock head. Knowing that, can a stock production 440 head ever have "too much volume" if modified within the constraints of the stock casting? Why do all the aftermarket heads that make so much more HP all have so much more port volume? The smallest Indy heads have 270cc ports. You'll be lucky if you end up with 250cc's on a fully ported stocker, or less than 1/4 of the swept volume of the cylinder. Some food for thought. 

[Roppa440]

If the port was as big as you think it should be you would have very little air passing through the carb. So the carb would not work correctly.

You need a good velocity through the carb for it to work. You need to maintain that velocity to keep the fuel in suspension. Otherwise it drops out and runs down the port sides.

Think of it this way. If you move 1000cc of air through a large port it only moves slowly.
If you move 1000cc through a tighter port it has to speed up.

There is another advantage to high intake velocities.
The air/fuel mixture has mass. The faster that mass moves the more inertia it has. So even when the piston has stopped pulling the mixture down the mass of the mixture keeps it pushing into the cylinder. Which fills it more than it would with no mass or slower speed.
This is how a tunnel ram works.

[moper]

Swept volume needs to be divided in half. The port volume is not a number like "you need 2 gallons to fill a 2 gallon jug". It's more of a method of "feeling out" how much air in the same TIME can get thru. Cubic feet / minute is flow rate... if you can get the air moving like Roppa and CP said, it will more than fill the cylinder right up until it can't. That's the rpm where the engine lays over. It's VERY easy to go too large in the mopar head. more precisely sections of the mopar head. And then the air gets all turbulent and the port stalls. There is a lot of really bad porting out there..lol.

[71chally416]

There is a lot of really bad porting out there..lol.

  Timecards don't lie.

[71chally416]

Yet another opinion on the port volume requirements of a big 446 motor by Steve Dulcich. The goal for this build was to make 600hp at 6,000rpm with a smooth idle. The motor dynoed at 607hp @ 6,000 with a stock-like idle at 850rpm.

"Things really get interesting with the EZ casting treated to Indy's full Windjammer CNC porting of the intake, exhaust, and chamber.
Measuring in at 295 cc, the Indy 440 EZ-295 CNC, affectionately called the Little Easy, scales intake port flow up to a lofty 355 cfm, while still utilizing standard factory-spec rockers. The fully CNC-ed Little Easy, at 355 cfm, was just too tempting for us to pass up in our project, offering awesome power potential, simple installation, and plenty of port volume to make our 446 really come to life.''

http://www.moparmusclemagazine.com/parts/mopp_0508_indy_440_head/index.html

[Roppa440]

Timecards don't lie.

There you go again.

They do!

They only show the engine is making big power in a specific rpm range. usually a very narrow rage when you talk big numbers. A drag car only operates in that narrow rpm range. What works on a drag car is completely usless on a street car.

[Roppa440]

roppa, on the notching, I generally relieve the chambers to the fire ring, but I don't notch bores 98% of the time. I use a smaller valve instead. On a 360, or 383 bore, especially with a higher output expected, I will notch them.

I didn't notch the bores either until my last build. On this occasion I matched them exactly to the valve reliefs and cut down half way to the top ring. Just to take that step out of the way to get better flow around the back of the valve.

I have plenty of cylinder pressure so I was not worried about dropping the compression a slight amount.

I figured it couldn't hurt.

[71chally416]

There you go again.

They do!

They only show the engine is making big power in a specific rpm range. usually a very narrow rage when you talk big numbers. A drag car only operates in that narrow rpm range. What works on a drag car is completely usless on a street car.

Me and guys like David Vizard and Bob Mullen and Tom Hoover and Steve Dulcich will agree to disagree with you about that. You've obviously stumbled upon something that's eluded us all for the last 40 years. 

[Roppa440]

Sorry. I must be confused what a "timecard" is then. Can youexplain the term "Timecard"?

David Vizard and Bob Mullen and Tom Hoover and Steve Dulcich all try to make as much power as possile from a head as far as I know? Engines designed to work at WOT or a limited rpm band only? Or am I mistaken? Are they building dailydrivers that operate mostly in the 1000-4000rpm band??

[moper]

71, which issue has the cam specs and the dyno results? Can you post that link too?