cnc roughness?
Thread Starter
Staging Lane
Joined: May 2002
Posts: 73
Likes: 0
From: indianapolis indiana
cnc roughness? i just got my 5.3 stg 2 heads. i was just wondering why the ports are so rough? would smoothing them out make any difference?? (they came from a sponsor on here and are cnc machined)
Re: cnc roughness? I have seen some SBC AFR heads the same way...no one ever said anything about them other than being awesome. I think as long as the bowl work is good and flows into the chamber smoothly it would be fine, but I know little about head work.
Re: cnc roughness? Intake airflow is subsonic speed. It actually helps flow out a bit if there is some sort of surface texture. This texture will reduce the thickness of the flow boundary layers over the surface. Much like how a golf ball will not fly as far without it's dimples. CNC machine path lines might appear a bit rough, but aren't really too bad. If anything could be "touched up" on CNC ported heads, it would just be the blending/smoothing in the valve bowl area.
Exhaust flow is supersonic speed however, and a smoothly polished surface is better for flow at those speeds.
Tony
Exhaust flow is supersonic speed however, and a smoothly polished surface is better for flow at those speeds.
Tony
Re: cnc roughness? My TEA heads had very obvious CNC maching marks. TEA basically said what Nine Ball said. Brian @ TEA also said he didn't think there were gains to be had with smoothing the maching marks out but even if their are slight gains in smoothing the machine marks out, there is a very real risk of getting a dimple near the valve when smoothing out the marks. If you get a dimple, it will kill the flow. Getting the marks perfectly smoothed out is something that takes some skill and time to avoid doing more damage than good. Brian said the tooling marks do not encourage carbon build up etc.
If I had it to do over, I would have had SRP smooth and polish all the areas like SRP suggested on my TEA heads, the ones Nine Ball mentioned and a few other things.
If I had it to do over, I would have had SRP smooth and polish all the areas like SRP suggested on my TEA heads, the ones Nine Ball mentioned and a few other things.
Re: cnc roughness?
Intake airflow is subsonic speed. It actually helps flow out a bit if there is some sort of surface texture. This texture will reduce the thickness of the flow boundary layers over the surface. Much like how a golf ball will not fly as far without it's dimples. CNC machine path lines might appear a bit rough, but aren't really too bad. If anything could be "touched up" on CNC ported heads, it would just be the blending/smoothing in the valve bowl area.
Exhaust flow is supersonic speed however, and a smoothly polished surface is better for flow at those speeds.
Tony
Exhaust flow is supersonic speed however, and a smoothly polished surface is better for flow at those speeds.
Tony
I agree 100% with Tony, that is the reason that I chose CNC'd heads over "smoother" hand ported ones. In my OPINION, the best heads have a "rough" CNC'd intake, smooth bowl, and slick "hand finished" exhausts.
