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Re: Hand or CNC Head Porting ???
[Re: moparniac]
#504039
10/22/09 08:38 PM
10/22/09 08:38 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Cnc porting with hand blending... 
 this is what I do... there is quite a bit of
machine lines in the port and I take the machine lines out
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Re: Hand or CNC Head Porting ???
[Re: MR_P_BODY]
#504042
10/22/09 10:15 PM
10/22/09 10:15 PM
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Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
dodgeboy11
super stock
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super stock
Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
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CNC porting is only as good as the information fed into the computer, and even then it still falls short of the hand ported port that was digitized for the CNC program. I would say that on a head that has symetrical ports you could get away with a fairly good CNC ported head. But on a big or small chrysler where you have ports with opposite bias, there's only so far a CNC machine can go IF there's core shift. This is where a good head porter comes in. I like to start max effort port jobs with untouched heads. It gives me an idea of how thick the material is. If I start on a CNC'd head I have no idea how much material is left in the port and whether or not there's any core shift or not.
For something that I just want a quick port job on and consistency, I say go CNC. But if you want the most out of a set of heads, you need a good head porter. As for the debate of hearing when the material gets thin, I have experienced this on several occasions.
If you want the best CNC ported heads out there, go talk to Chapman. They are an example of CNC porting at it's best.
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Re: Hand or CNC Head Porting ???
[Re: MR_P_BODY]
#504046
10/22/09 11:09 PM
10/22/09 11:09 PM
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Joined: Nov 2004
Posts: 2,119
sc
tjmarcus1
top fuel
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top fuel
Joined: Nov 2004
Posts: 2,119
sc
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Quote:
If you want the best CNC ported heads out there, go talk to Chapman. They are an example of CNC porting at it's best.
Chapman did one set of my W-9s.... plus I sent them a
broken W-9 they ported to see if it could be repaired,
it was beyond help... they duplicated my one to
a tee.... I still touched up the machining lines,
they are the ones I picked up 2 cfm for just a short
bit of time
mike, did you have another set cnc'd by someone else, if so do you know the difference?
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Re: Hand or CNC Head Porting ???
[Re: Moparnut426]
#504048
10/22/09 11:55 PM
10/22/09 11:55 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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isn't it proven by jeff at modern that his cnc program on 906 heads outperformed a hand porter on a FAST build getting a 440-6 RR into the 10 second zone while the hand porter was only able to get the A12 RR to low 11's.  i believe thats proof enough that CNC'ing one of these heads works better then hand porting. if i were to do it again CNC'ing is my choice,hands down.
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Re: Hand or CNC Head Porting ???
[Re: TS3303]
#504051
10/23/09 12:17 AM
10/23/09 12:17 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
CNC'ing is not magic just a xerox machine for a digitized hand ported port. Depending on the original it is probably 95-98% as good, add some hand rubbing after to get another 2%. That being said unless your running an all out effort where you need every last hp, CNC'd heads from a top line porter are more than adequate and usually a little cheaper.
would be curious to see Jeff or others post flow #'s of the original hand port versus the digitized copy of the same port. Head type not important. would be willing to bet it is only 2-3 cfm.
and i bet cnc'ing is safer as not to go through the water jacket.
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Re: Hand or CNC Head Porting ???
#504052
10/23/09 12:27 AM
10/23/09 12:27 AM
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Joined: Nov 2003
Posts: 6,293
Rock Springs
Bob_Coomer
master
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master
Joined: Nov 2003
Posts: 6,293
Rock Springs
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My 440-1 heads CNC ported by MCH flow 380+cfm. The car went 144 mph in the 8th mile and 1.07 60ft Mid July heat. Coulda been a bit faster If I had areal converter. My Stock Hemi heads also done by MCH flow 460cfm, I am willing to bet the engine runs good also. Proof to me is the track times..Flow bench numbers doesnt mean squat to me unless the track numbers back them up  Which they have
[color:"red"]65 Hemi Belvedere coming soon [/color]
[color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]
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Re: Hand or CNC Head Porting ???
#504053
10/23/09 12:37 AM
10/23/09 12:37 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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you can see by the answers here that almost everyone's take on this subject is all about peak flow numbers.
so using YOUR logic for a street hemi car with a 2800 stall convertor, 256 @.05 camshaft and 9.5-1 compression, a max port CNC hemi head flowing 460 cfm would be the cats azz? not hardly. the porting needs to match the combo. stop being so one track minded.
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Re: Hand or CNC Head Porting ???
#504054
10/23/09 01:23 AM
10/23/09 01:23 AM
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Joined: Apr 2004
Posts: 1,981
SE Michigan
TS3303
top fuel
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top fuel
Joined: Apr 2004
Posts: 1,981
SE Michigan
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Quote:
you can see by the answers here that almost everyone's take on this subject is all about peak flow numbers.
Dan! This is the last time I'm going to tell you to stay away from the coffee pot this late!  Only saw one post about max flow, yes it's all about the area under the curve for a broad power curve.
Bob whats this 1.07 144 mph car? dragster or PA car?
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Re: Hand or CNC Head Porting ???
#504055
10/23/09 09:20 AM
10/23/09 09:20 AM
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Joined: Jan 2003
Posts: 75,004
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,004
U.S.S.A.
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Quote:
isn't it proven by jeff at modern that his cnc program on 906 heads outperformed a hand porter on a FAST build getting a 440-6 RR into the 10 second zone while the hand porter was only able to get the A12 RR to low 11's.
i believe thats proof enough that CNC'ing one of these heads works better then hand porting.
if i were to do it again CNC'ing is my choice,hands down.
A 10sec pass so far has only happened ONCE , Ed had a killer 60ft and has not been able to duplicate it since .
You should stick to what you know ... BBQ'ing skirt steaks ...
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Re: Hand or CNC Head Porting ???
[Re: JohnRR]
#504056
10/23/09 09:43 AM
10/23/09 09:43 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
Quote:
isn't it proven by jeff at modern that his cnc program on 906 heads outperformed a hand porter on a FAST build getting a 440-6 RR into the 10 second zone while the hand porter was only able to get the A12 RR to low 11's.
i believe thats proof enough that CNC'ing one of these heads works better then hand porting.
if i were to do it again CNC'ing is my choice,hands down.
A 10sec pass so far has only happened ONCE , Ed had a killer 60ft and has not been able to duplicate it since .
You should stick to what you know ... BBQ'ing skirt steaks ...
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