Cylinder Heads
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From: Fort Wayne IN
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Cylinder Heads
I've noticed a trend in the LS1 world being everyone uses CNC'd heads and no one seems to use hand finished heads on "gods motor."
I only ask because I can't help but think that one the majority of CNC heads being sold, both stock castings and aftermarket that some hand cleaning up or hand porting an as-cast set would yeild as good or better gains than the CNC programs when done right.
Thoughts?
I only ask because I can't help but think that one the majority of CNC heads being sold, both stock castings and aftermarket that some hand cleaning up or hand porting an as-cast set would yeild as good or better gains than the CNC programs when done right.
Thoughts?
Team Owner
Joined: Mar 1999
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From: At the beach in little Rhody
CNC offers faster production and better reproducability from essentially hand ported heads. Usually a ton of research can be accurately reproduced on the CNC machine. If you read some of Tony's posts on the AFR heads, they spent a ton of time getting the flow they wanted from a small port and CNC is probably the only way to accurately reproduce it and get consistency from port to port as well as head to head.
Drifting
Joined: Oct 2004
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From: Southwest Virginia
Originally Posted by vettenuts
CNC offers faster production and better reproducability from essentially hand ported heads. Usually a ton of research can be accurately reproduced on the CNC machine. If you read some of Tony's posts on the AFR heads, they spent a ton of time getting the flow they wanted from a small port and CNC is probably the only way to accurately reproduce it and get consistency from port to port as well as head to head.
But one of the biggest reasons you see so many CNC heads being used it because that is the way almost every aftermarket head comes. I'm sure the aftermarket head manufactures do a lot of research (hand porting) to get the good flow. Once they do they duplicate that with CNC. There is no way a head manufacture could pay a staff of good experienced hand porting people to hand port every head and still sell the heads at a reasonable price, so CNC is the only way to go for mass production. I'm not saying CNC is better than hand porting, just a lot cheaper and much faster. There is nothing wrong with hand ported heads. I'm sure most good experienced hand porting people could touch up a CNC head and get better flow, but your probably only talking 1-2%. So you have to say, is it worth the expense for that little gain. Most people will say that it is not and simply use the CNC heads as shipped.
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Well, I didn't mean finished from the factory by hand porters, I was talking more along the lines of someone taking a CNC'd or As-Cast head to an independent person to have them finish it off/improve things. Or is it that most people are just THAT complacent with the heads as they come from the manufacturer and the ones that do have things "finished off" simply don't talk about it?
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From: At the beach in little Rhody
I would think one could do more harm than good. For example, the Darts and the AFR's spent a lot of time on the flow bench. The Darts on a very expensive wet flow bench. A hand porter would likely not have access to the same tools or knowledge of the original design, so I would be reluctant to have someone modify the ports.
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From: Fort Wayne IN
2025 C5 of the Year Finalist - Modified
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Originally Posted by vettenuts
I would think one could do more harm than good. For example, the Darts and the AFR's spent a lot of time on the flow bench. The Darts on a very expensive wet flow bench. A hand porter would likely not have access to the same tools or knowledge of the original design, so I would be reluctant to have someone modify the ports.
I will admit that a CNC has one DISTINCT advantage being that you KNOW that all ports are created equal, so there's going to be very little port variance. That's an inherent risk you take with hand finishing.
It just surprises me more than anything that (coming from the LT1 world) the ratio of CNC to hand finished setups is so one-sided.
