Just thinking today while sitting at my porting table. After I have one port finished and off multiple trips to my flowbench its time to crank up the stereo with some Stevey Ray Von, Doors, or some other favorite CD and start the usually 2 day process of finishing the other ports. At these times ones mind tends to wonder. Now for the discussion. I personally have been able to pick up a minimum 15cfm and as much as 30 plus cfm on CNC'd heads. I've had guys bring there heads in for flow testing after their car hasn't performed anywhere near what they were told the heads are capable of flowing and the numbers aren't even close to what they were told. Several years ago I would have said CNC is the future of our sport but if the hand ported head isn't a GOOD blueprint, now what? Hand porting is becoming a lost art with many of the true blue teachers passing away and few are interested in pursuing it for full time work. My Son for example has no interest in giving it a try and I even paid for him to go to Darrin Morgans 2 day theory class. Look at Edelbrock for example trying to release a new head and all the issues they are having. I personally see performance issues taking a step back in 10-15 years. What are your thoughts?

CNC will never replace hand porting for getting to most out of a set of heads. I like It for the fact that you can get alot of the material out of the way easily and then finish the ports off by hand and save some time. There are definately going to be less people who are good at it, but as long as there are people who want the most out of there heads and are willing to pay there will people doing it by hand.

This is coming into a lot of different areas... fab work
is going down hill.... hand porting is also... the big
thing with CNC is you have to have a master to scan from
so if no one whats to get dirty anymore... its hard to
get a good master... at least I still see a few people
that are still willing to try to build headers... hell
I offered 2 different guys on how to build headers...
neither wanted to even try... that went right along with
building complete exhaust for cars or cycles... that was
the reason I sold all my chassis bending equipment... no
one wants to work

been fighting the CNC crap for a long time. One company ( a big name head company) called me a crook and a liar because their heads were CNC ported and didn't flow any where near what they said. The ports were so turbulent you couldn't read the manometers.

Then the customer is pissed because they paid for CNC and the big name companies tell them not to finish the ports by hand. I have NEVER seen a port that was CNC finished that didn't improve with hand finishing.

In 10 years I'll probably be dead and so will performance automotive stuff. It's got one foot in the grave and another on a banana peel right now. If a kid is under 15 right now, they will NEVER understand performance cars. Ever. They are indoctrinated from day one in school (and every day on TV, in the papers and on the web) to hate cars. I was born in the wrong generation for sure.

The heads you ported for me performed better than some big $$$ heads I paid for. Don't give up just yet, there are some young un's that would like to learn.

Maybe true BUT some of the GOOD cnc stuff is profiled AFTER a bad ass port is achieved so it does have it`s place but too many lies follow and the #`s don`t line up as stated........Oh, my heads were hand ported by me and approved by Ed Mosler fwiw.

My Eddy's were ported By Jeff at MCH and I think they move pretty good for what I do. Is there more in them? not sure

I'm sure there have to be some good CNC'd stuff out there but honestly I have been really disappointed with the ones I've tested.

With modern computer flow simulations you should have a good idea what a cnc port will do before the head is ever ported. It is the future, because there are places that will teach you how to do this.

Trying to learn the art of hand porting from someone is like trying to get the chicken recipe from KFC.

I'll believe it when I see it.

The numbers for computer simulation must have meaning or everything you do with them is WORTHLESS.

A rudimentary understanding of such things as laminar flow, Reynolds numbers and a bunch of other stuff is required or what you design is junk.

There are many "rules of thumb" I use that still work to this day...I suppose you could program those into simulation programs.


But herein lies the crux of the matter. Today's generation think the computer has revolutionized the world, that we are doing things now that have never been done and that is 100% arrogant horsecrap. Go find an early Oakland engine and look at what those engineers did WITHOUT CNC. And, evidently, we have forgotten/ignored or are ignorant of what was accomplished by THIS country WITHOUT computers during WWI and WWII.

All CNC means to me is that whatever you have that is CNC'd will be almost exactly alike, warts and all. The tool path is copied exactly the same, every time, even if there is no material there, or there is more metal there and you have tool deflection. All errors are copied as well.

As I see it, the public is getting screwed with CNC porting. By the time you fix the CNC work, you have the same money in the heads as you would if they were hand ported. And this is why the big companies tell you to leave them as is, they can't sell you a semi-finished head for retail.

There are exceptions to this rule, but the rule is correct none the less.

John...I am quite happy with my hand ported Victors. Radar Lechtenberg did them along with matching the Indy intake. He learned the trade in the late 70s from Gary Ostrich. Worked for him a while before setting out on his own. He used to do a lot of Top Fuel stuff till it got to be too much work for him. Radar is still doing cylinder heads but he is getting up there in years and has slowed down a bit. The guy does a heckuva job and I am proud to have a set done by him!

And this too is a big part of the puzzle. PORTED INTAKE MANIFOLDS. I ported a set of Chevy Dart Platinum's for a Friend that started out flowing 260 then backed up from high air-speed. When I finished porting them they were flowing 315-320 so we bolted his stock Victor Jr on them and they were now flowing 260 cfm. He was flabbergasted and said we didn't gain anything but I then said to him, what do you think they were flowing with the intake bolted on before the porting work. I charged him another 200 dollars as he NOW wanted the intake ported to match the heads but not before he spent another 400 dollars to buy a Dart intake and it was just as bad as the Victor Jr. 6 months later he dragged over the Dart intake to have ported. LOL

The computer HAS revolutionized the world, for good or bad is the opinion of the person. Most older generations would say bad. Most things that have been accomplished in the past could of been aided by a computer for a quicker POSSIBLY better outcome. One of the greatest accomplishments of WW2 involved a different country, creating and using a computer.

We might not be at the point that CNC programs and simulations come close to what a hand porter can accomplish but we will one day as long as there is money to be made.

It is all just a matter of economics. If the sales volume justifies it then there is no reason that a CNC port can't be just as good as the best hand port. All it takes is time and money to duplicate the ports.

I thought the essence of a CNC port was really so you could essentially purchase a slightly more economically priced mass produced ported head based on an intricately digitally mapped and 'science out' hand ported (and flowed) model. To think the CNC would be 'better' than the hand ported model it was based on would be a stretch, I thought cnc was just applying modern mass production technology to a hand science as a means of keeping the unit cost and lead times down. I would think hand finishing a CNC set would be beneficial in terms of ultimate bench flow numbers but we're probably talking only 10ths of a percent impovements overall in practical terms. Ybut by hand porting above CNC you maybe pushing the safe limit envelope if the heads are nearly maxed to begin with.

But they aren't maxed out. Heck they weren't even thought out in my eyes if a head goes turbulent above .600 like most of them do. When air is traveling at 400 plus FPS across the whole short turn that port is BEGGING for more area which in turn will give you more flow.

Once someone has a good flowing hand ported set then its
the number of steps/transitions that is involved.. I had
a set of CNC heads done(W-9s) then had them flowed... then
I went over them with hand bits... it picked up 3 CFM on
the mid to full lift... same numbers down low.. but I will
say there was some big steps/transitions per step

The article HERE brings up some of what you're talking about, too.

I think you hit it there on the head, people want miracles. Say CNC they think 4 seconds faster. Your early duster ran fast but I bet it took awhile trying different combinations till it ran the fastest. Open up the heads to big flow, and the rest goes out the window, everything will be changed to work with that flow. Chrysler had those combinations pretty much figured out for us back then, we're on our own now and very few with the knowledge. In my business I spend almost as much time educating the customer as doing the work. To much misinformation everywhere.