HOWQUICK

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by headbam:
<strong>Thanks for bringing up this topic. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Could you tell us what portion of the intake and exhaust ports are machined by the CNC? Chambers worked on too?
Miles points out an interesting fact about percentage gains. I notice that they are in the useable lift curve for most hyd. roller cams. Very potent. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
As for consistency among each CNC finished head, there should be very little change in flow from port to port. We see the biggest variable is the profile of the valves. Backcut angles will produce two very different flow curves.
How that translates to power to the ground has yet to be determined. <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />
Cheers,
Richard</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">my point exactly...inch either side of the valve...can a CNC tune here? Naaa....flow bench and time... <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

John@PACE

headbam - This post wasn't meant to be a CNC versus hand porting topic. It just so happened my example was CNC. Let's see some other numbers from various heads and their info. Heck, someone want to build a database?

Anyways, you brought up valve seats. Yes, they were done. As HowQuick says, flow bench and time. This particular seat machine can do any angle upto and a complete radiused seat if needed.

Other info, the flowbench is a SF-1020.

So, say a set of heads gains 30rwhp, but has been milled and larger valves. Now another set of heads gains 25rwhp and has stock valves and hasn't been milled. Yet the first set making 30rwhp claims more "flow." Which do you by? <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Richard@WCCH

iTrader: (3)

Sorry John. Didn't mean for this to be a CNC vs hand porting issue. The point I was trying to make was that with the consistency and precision of CNC porting, a significant reduction in time spent on the flow bench testing each and every port is not necessary. An experienced hand porter can achieve the same consistency, however they will spend more time equalizing port flow. I guess you can say it gets down to time vs money. For me, the reason for going with CNC is that as I'm getting older I'm spending less time in the porting room and even less time to find or train competent porters. I know that when I reach 50 (in not too many years) I doubt I'll be hand porting much at all. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
As HOWQUICK pointed out correctly, "......an inch either side of the valve......" demands that much bench time be spent testing seat and valve profiles.
In the end, the dyno or track will tell the story. One thing is for sure, ongoing development will continue.

Cheers, <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Richard