In order to program a computer to CNC port any cylinder head, you have to hand port it and test it. Also, most places that CNC port heads start with aftermarket cast heads with thicker walls, designed to be custom ported. Stock castings, especially the ones I deal with are not something you could easily setup for CNC porting.
Hand porting still has advantages over cnc porting but for the money you are better off doing CNC work on a large number of heads and then finishing them up per application. Its almost the same theory as saying x head is good for y application when you really have more than 1 application you are trying to market for but its not “optimal”.
Calling people names or repeating yourself isn’t going to educate anyone on cnc vs hand porting. I have considered having some CNC work done for heads but in te end I can do it by hand AND check my work with a flowbench and ccing for much less. The more experience I get, the easier it is anyway. I don’t have the luxury of aftermarket support for cast heads. We are lucky to have the possibility for a new cast manifold.
whats the chance of hand porting and all the runners flowing the exact same… and chancing it without a flow bench? i say slim to non that they are exact… but finally someone that has a clue about porting unlike a few posting in thsi thread
GM high tech perfomance did a test of the top 5 heads for ls2s they commented on them being a CNC head with a very nice hand polish finish. i never said they do that to equal the flow. learn to read, i said they did that to make em look nicer, and get rid of the cnc lines left behind from the CNC machine
yes cnc programs come from hand porting, but they find the best flowing hand port that they did on a flow bench and run with that for there CNC to follow, then from that, the know every runner will be the exact same as the best one they got from hand porting. and like you said, u can do hand porting cause u have a flow bench to check each indiviudal runner, which is awesome. but if u didnt have a flow bench would you hand port them still?
Why is everybody busting his balls??? The guy does top notch work on everything he touchs and when he tries something out you guys jump all over him. C’mon that’s kid’s shit. Like he said the “customer” is happy with it and he noticed a difference that should be all that matters. And another thing, if you guys were talking about Hybrids, JJ’S, or First try or anybody else no one would be doubting there abilities so whay are you doubting his?? Maybe I am out of the loop or something
I spend about 3-4 days doing a street/strip type port job on 3400 heads. If I “flow match” them on my flowbench, it was taking me 3 weeks to do this when I first started. Last time took me 4 more days. Now I don’t work 8 hours non stop as my wrists won’t take it. I also do more than port work. My flowmatch is 2% variance max between 6 ports. The flowbench I use has 1% repeatability, proven in magazines and my own testing so that leaves 1% for my error. I try to go as close as possible without chasing my tail past where I want the shape to be but I have got them as close as 1% max variance (.5% from the mean value). That is average for all values from .050 to .500 in .050 increments. While I do my best at each measurement, the casting difference between heads/cylinders makes it difficult to do that. Its interesting to note that if I turn the screw a little, I can usually get the values desired. To do a true graph of matching, you need to measure in tighter increments…say .010.
I was told cnc can do some crazy % variance, like .005 or something. I don’t know so I won’t comment on that. I am not trying to say a human can beat a well programmed cnc machine because of all the variables. Popular engines for modding will get that sort of aftermarket attention because there is money to be made. CNC is faster for repeatability and from that stand point is far superior. You can’t really compare that with a custom hand porting though.
Oh yeah, forgot to add that my non matched heads generally flow 4-5% though that was early on. When I am done with this set of heads I can tell you what my ‘first attempt’ variance is. I never send my first attempt out though but its probably the closest you will get for an experienced porter doing the work without a flowbench.
Your tripping if you think that I was supposed to understand your horrible sentence structure. I would have to unlearn how to read if you want me to follow what your saying. Depending on where your ment to put the peroid, that run-on could mean a couple different things.
a lot of lsx porters esp dart, do cnc porting then come in by hand and smoth it out just a little more, they do this soo all runners flow the same,(If you put the period here your saying they hand finish to flow match) then smoth it out a little more by hand, dont do any porting by hand
oh shti its the inter mother fucking web. Asshat. If i cared to make a complete sentence on here, i would fucking do so. or u just tryin to hate on me cause u have got nothign so say fucktard?
Anyone on here that is so addament about flow bench testing has no experience with flow benches. They have no clue about the variences of eye sighting maniscuses of the vaccum tube, and the flow tube. There are variences with your dial indicator. What if you have it just a bit off angle. Basically they think they know, but they just don’t. I don’t know your process of porting but mine has alot of steps. I devide the runners up into about 4 or 5 areas. I’ll start with the bowl, and then do all the bowls. Then profile the valve guide boss on all of them. Then smooth the long radious. Then smooth the short side. Then gasket match. Then slim the pushrod guide bulge. I do them in small portions so that my overall varience is minimal. Some people just don’t understand how well you get to know the ports when you work with them so long. People that work with dolphins can tell them all apart. The all look the same to me. People that port heads can pick out minute variences and fix them.
When the hell did CNC become a debate point? Just cause some dumbass brought is up as being an exellent alternative to hand porting (if you have the money) doesn’t mean anyone disagrees that its a great method. Come on newbies lets do some research before we post so we don’t look so foolish.
If you are a 2% Variance and the machine is a 1%…wouldn’t that make a possible variance of UP TO 3%? Not that it makes a difference, just wanted to point that out (I am somewhat of a #'s nerd)
I went through all that in my research phase. I have pages written out of where I made a change and recorded the differences. Then reverse the pattern and see if it still holds true if you do something else first. I don’t use a dial indicator to measure lift. I use a set screw that sits on the valve stem (adjustable) and then I use .050 shims, numbered for consistancy. Yes, lots of variables and I am sure I haven’t figured them all out by any means. I have also tested with different tubes for exhaust and clay molding for intake. I prefer to test with the manifolds on for NA though to keep things simple and more “real world”, even if its only 28" of water.
I need a better setup so I can go really high depression (90s would be cool) and also a water injection setup with dye so I can see the atomization pattern.
I can’t think of any benefit to polishing the intake port of the heads.
I’m almost speachless. Your dumbass perpetuated the argument, and when proven completely wrong you digress to this level? I don’t believe I have ever hated on you. I retorted and called spades, spades. If you want to post something stupid, then your stupid. If we cant be defined by our actions then what are we. Just don’t think you have any ground to stand on when your sentence structure is the misleading factor in a debate your trying to win.
Yeah, it could be 3%,which would be 1.5% + or - from the mean. Its not very much, thats about all I know:P I have never actually had a whole 1% difference though. Its the rated max but I thought I should include it.
90" of water? I like the water injection idea. I put a bit of polish on all the runners mainly for the apperence. That and I don’t see any down side to a little finer finish on an injected engine.
no, all i ever asked to see was ur numbers from ur head porting job, thats all, then u get all worked up. u said porting a small block chevy head is the same as porting a LSX head. DEAD WRONG. u can take i belive up to 6mm out of a sbc head to make it flow great, wiht a lsx, its only takin up to 2mm out. then u said porting ur set of lsx heads, that u dont even need a flow bench to check ur numbers at all. when hand portin u should, and i would have a flow bench to check numbers. then i said that Dart CNC’s there heads and then smoth out by hand.