Hand porting vs Cnc porting
#1529451
11/06/13 01:54 PM
11/06/13 01:54 PM
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Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
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Texas
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Why would a person prefer a Cnc head over a hand ported head done by a talented porter? The cnc head is only as good as the original head that was digitized to program the Cnc mill. Just because someone has a Cnc don't mean they are a head porter. Just courious what the fascination is.
Getting old just means you were smarter than some and luckier than others.
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Re: Hand porting vs Cnc porting
[Re: Crizila]
#1529457
11/06/13 03:02 PM
11/06/13 03:02 PM
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Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
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I agree that the process is awesome and should be able to save the consumer some money on the end product. That is great. But too many times I will be talking to someone about their combination and they will get to the heads and say that they are Cnc ported but when asked by who the answer is don't know, bought them off the internet. Then go on without a second thought. Seems to me a lot of people think just because their heads were cnced it was a professional job. I think not necessarily so.
Getting old just means you were smarter than some and luckier than others.
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Re: Hand porting vs Cnc porting
[Re: dannysbee]
#1529459
11/06/13 04:24 PM
11/06/13 04:24 PM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Comments: 1. Unless the CNC program is run on a dedicated "Pro Port" core, there are still liable to be drop-outs and other casting-related differences between runners on a CNC-ported head. So, in that case the expectation that each port flows identically simply isn't true. 2. CNC programs run on typical production heads (not the raw "Pro Port" cores mentioned above in #1) often require someone to hand-finish areas such as the bowl blend and valve seat transitions into either the bowl or chamber. 3. I've seen "by hand" ported production heads that are as about as close from runner to runner as those production heads that still need to be hand-finished like I mentioned in #2. 4. I like that one of the porters who does a lot of CNC work these days mentions it's his goal that his CNC heads flow w/in 5 CFM of his hand-ported prototypes once they're ready to ship. Right, his CNC'd heads don't flow as well as what they're based on done by hand. 
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Some guys still do it by hand though. 
Very true. CNC porting is a labor saving device, and in that context, they are hard to beat. Repeatability is also good. That being said, IMO, a professionally ported head is still hard to beat. Also IMO, a combo of the two is the way to go. Get them CNC'd and then finished by a professional porter. 
You are correct it takes a professional head porter a lot less time to finish up a set of CNC heads.But you need to make sure you have the right person to CNC the heads at the start.I have found it best to take them to the professional head porter and let them have the cnc work done or tell you who to take them to.