I am aware of this. But cnc porting in this thread is being addressed as a one size fits all non-custom option. And it doesnt have to be that way. 1. Custom hand port one port for specific application with flow characteristics you want 2.digitize 3. then put them in the heads with the machine. It doesnt mean you have to reuse that program for every head of that make and model

Get it "right?" So every head you have is ported to Prostock levels with welding, epoxy, sleeved pushrod and bolt holes and so forth?

I agree CNC is a production method, but let's not pretend that hand porting is all the same either. There's more than a few hacks and just plain average talents out there. CNC is selling for more than it's worth in many cases because clueless buyers are buying it. And that's fine, probably 75+% of Mopar guys don't need bleeding edge stuff because they're running bracket stuff.

My point was that the shop or porter could benefit from the machine doing much of the "dumb" metal removal. And frankly, there's a few porters who are under pricing their time for levels of performance that are simply beyond the reach of others. If people are paying 100% for 95% CNC and paying that same 100% for 100% from the hand porter, then that porter should be raising his prices. Because there is no substitute for winning, and if you need the "good stuff" to win, then that's all their is to it. Pay the man. S/F.....Ken M

CNC is the cats azz for duplication and reapeatibility.The program for the CNC is the magic.most programs are designed for maximum flow volume,minimum restrictions and optimum alignment.Each program is designed for the maximum effectivness for each particular application application.No one program is for "all" applications.

Continuing from the last post, this is my point. CNC, like much modern technology, is for freeing up men from the drudge of mindless repetitive labor. They're like illegals, without the drunk uninsured driving and knife fights in bars.

People run their gums about CNC stuff in their car because for most people it's not about the racing, it's about the jaw jacking.

Like I said, if a hand porter is doing 100% work for 100% cost, and the CNC guy is doing 90-95% work for 100% cost then the hand porter should be charging more, and he's a dope if he's not and making the fact that his stuff is better well known.

IMO, the "proper" place for CNC in racing (as opposed to bracket) is for doing billet heads and cutting full ports and chambers in unfinished castings (edelbrock pro-ports and the like). In addition to doing all the prep porting for the hand finishing.

And then there's stuff like TFS is doing with heads being designed for and finished on CNC, giving better performance at lower cost than doing the full Monte with aftermarket porting. S/F.....Ken M

Sorry but I'm not getting this post. Duplication yes, but in EVERY case or head I've tested it has been BAD duplication. Flowbench shows it and the track times do too.

John, what do you mean by bad duplication? The machine wont fix a bad design, it has to be good before its copied. If its wrong, its the cylinder head specialist fault for cutting out a junk port. Nothing to do with the machine, its just copying the hack's work.

I'm telling you that EVERY CNC'd head that I have ever tested has been pathetic and needed major work. Upper lifts on every head went turbulent and started backing up in flow numbers. Testing proves short-turn not capable of maintaining control and the air goes straight across the bowl shutting off air flow going across the top of the port. You can hear it happening. (think garbage disposal)

John, what do you mean by bad duplication?



I'm telling you that EVERY CNC'd head that I have ever tested has been pathetic and needed major work. Upper lifts on every head went turbulent and started backing up in flow numbers. Testing proves short-turn not capable of maintaining control and the air goes straight across the bowl shutting off air flow going across the top of the port. You can hear it happening. (think garbage disposal)

I understand what you're saying but I agree with smell, it's only a machine and only as good as the person programming it. Sounds like the CNC guys don't know what they're putting out, just machining a pretty product to sell, and making quick easy money. This happens in a lot of products. Someone does all the R&D then another guy somewhat closely copies the product with no money invested, pure profit, customer screwed because they listen to the hype.
Might add, if you had the CNC machine I'm sure you would not machine those bad areas that you're talking about. Do you think it's possible to duplicate you port work to the fine line, what I'm saying is the machine capable?

BINGO!!!!!!!!!!!!!! And I'm not saying there aren't GOOD cnc'd heads out there. I just haven't found them yet.

John all I can say is thank you again for this post. There will be some here who will bash you now for being so forthright. I have seen this in the past as well. When it happens just ignore them. Your points are valid. The performance of your cars speaks to your ability. I just wish there were more of these types of discussion on this forum. It is a learning experience for me and others I'm sure.

And to the other contributors on this thread. Thanks for your input. Jim

CNC porting has become a sales gimmick of sorts, and 99% of the heads on the market are fairly generic. As has been stated in this thread already, if the port being copied isn't great, the machine isn't going to make the head any better. That said, a cnc ported head will be more consistent from port to port than a hand ported head.

I can think of two CNC programs out there I know are good
W5 CNC program at Modern
Small block Eddie CNC at Modern
I would wager there are plenty more, but can verify as fact only these two, based on track results, which to me is all that matters.

That info Don has posted is the kind of info I would like to see others offer. Thanks Don for sharing.

Here's a letter I received from a good Friend, Tim Bowman of Bowman performance. He doesn't post very often as he is usually busy teaching or in the shop building well thought out, high horsepower race engines. He was taught by one of the best so read this on his thoughts.



Been HAND porting heads 40+ years
Got to spend some time with probably one of the best hand porters out there, Joe Mondelo, RIP Joe I miss your input.
Proper hand porting has become a lost art.
Been flow testing for over 30 yrs of those 40 yrs
Its and ugly unrewarding job until you put them on and engine and make power.
I have never flow tested a cnc head Brand x or Mopar that ever flowed the claimed numbers AND didn't have major issues in the flow curve.
I'm with you on this one John, upper lift flow on a big head that should do it. Joke!
Garbage disposal? Sounds like someone took big crap in front of a big fan. That's what you got,crap
I promote cnc head sells, only with the plan than additional work needs to be done, and i charge on top of that.
cnc gets the rough work out of the way, John knows the time it takes to port n flow heads.
Repeatably JOKE! 40 cfm spread on the same head? That includes Hemi heads
Valve jobs as delivered, Lets not even go there. This is a big part of the final product
Also, on a cnc head, there are times where you can,t fix a problem they created without re- weld or sometimes epoxy
Cnc has a place in the market for those that do not have the skills to port heads, absolutely not offense intended to them.
But the product is not where it should be in this day and age.
Some of the cnc porting final finish looks like they cut lose a rabid beaver in there, come on Really?
Got so many cnc duplicate heads in here that are not even close to each other, wtf? is your equipment that wore out? Got any QC going on here ?
if your going to port heads for power/in all different applications better have a flow bench. Any novice can improve a cylinder head with in reason.
If you work with a flow bench, you need time to interpret what it is telling you also , it takes time and experience, I know John knows!
Lastly, there are a boat load of top self cnc heads being supplied out there, doing what there supposed to do, you just got to know who they are
and they are spoken of on Moparts.
My input John, feel free to post this, As for hand head porters, keep on grinding. Tim Bowman, Bowman Performance

^ good stuff. Now all this thread needs to balance itself out is a good head porter who actually has a centroid and does more than copies cast ports and puts little shiny cutter marks in everything.

I think what some of the problem with CNC heads are most of the mass produced stuff is its more of a shine job than a real performance head.

No way would I hand port w9s or w8s but my CNC stuff all gets some hand finish work

Just valve job and blend can kill a good CNC port if done wrong.

I have updated some HAND PORT w9s and port to port before we recut them did not look bad but after you can see how far off hand port stuff can be.

Here is some pictures of bad a$$ CNC WORK. (Note valve job blend not done)
This is TRD cup head cut in house by Toyota.

Just like hand porting most of the time you get what you pay for.

$1000 CNC job most of the time will need some work to make good.

If you start out with bare Indy 360-whatever and hand port to max potential it would take 40 plus hours at $50.00 per hr. = $2000.00


The other deal with CNC castings have thin spots all the time to make money you can't junk lots of heads so most mass produced heads are backed off little vs what hand port master was.

My w9 program is on the "edge" gets little thin but it's not mass produced

I also have 3 intake programs for that same head to fit wide range of builds.
So you can cut smaller port and hand finish for application or cut the big one and add the weld that's needed with the customer knowing up front heads will have holes into water when done and need weld.

Some of my CNC cut heads with quality valve job.

I really like the one line your friend said... which is
VERY TRUE... porting gets the bulk of the work out of the
way... then its the fine tuning... most people not realize
that it takes just a minor bit to change things... thats
when you either know things or not.. a bit too much and you
can screw it up also... believe me I know when I started

I like the directional lines in the Toyota head...