cnc or reg head
Thread Starter
Intermediate
Joined: May 2004
Posts: 41
Likes: 0
From: Jacksonville fl
cnc or reg head
what is the difference between cnc combustion chamber heads and regulear heads and are the cnc heads worth 200 extra dollars
What does cnc mean anyways?
What does cnc mean anyways?
Last edited by mpick; Jan 22, 2005 at 10:45 PM.
Racer
Joined: Jun 2002
Posts: 411
Likes: 0
From: Palm City FL
The cnc heads are modeled after a sucsessful set of ported and flowed heads. The research has already been done and there is very little room for improvement on that particular brand head. If you bought that particular head non cnc'd, it would cost you probably between $600-$1200 in profesional porting to get them to work as well.
Thread Starter
Intermediate
Joined: May 2004
Posts: 41
Likes: 0
From: Jacksonville fl
235 cc flowed 292 cfm's @ .500 lift
235 cc flowed 310 cfms' @ .600 lift
235 cc flowed 318 cfm's @ .700 lift
These are the numbers given on the cnc heads.
235 cc flowed 310 cfms' @ .600 lift
235 cc flowed 318 cfm's @ .700 lift
These are the numbers given on the cnc heads.
Last edited by mpick; Jan 22, 2005 at 11:00 PM.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
It depends in part on what engine those heads would go onto along with the remainder of the setup.
To get the most out of a set of heads both flow and port volume are important considerations in the big picture.
Instructor
Joined: Jan 2005
Posts: 153
Likes: 0
From: Sacramento CA
CNC = computer numerical control, allows flow consistency for all heads without human error, or slight deviations. When heads, intake, or any other machined part is CNC, the level of consistency is almost 100% congruent to optimal specs.
Thread Starter
Intermediate
Joined: May 2004
Posts: 41
Likes: 0
From: Jacksonville fl
Originally Posted by 65Z01
It depends in part on what engine those heads would go onto along with the remainder of the setup.
To get the most out of a set of heads both flow and port volume are important considerations in the big picture.
I want to change my stock heads with oversized valves for some good high performance heads.
I would consider changing the cam if it would help. The 220 cc cnc heads flow 264 cfm's at .500. Can't decide whether 220 cc or 235 cc. Both have 64 cc chambers
I am also going to switch to crane gold rockers 1.6 instead of my 1.5's I have now.
Any advice is certainly appreciated
Last edited by mpick; Jan 23, 2005 at 11:24 AM.
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Le Mans Master
Joined: Jun 2002
Posts: 6,097
Likes: 0
From: High Plains Drifter Fayetteville, AR
Do you want torque or horsepower?
Big runners like you're looking at will have the potential for more horsepower, but significantly degrade the torque of the motor at low rpms.
If it were my 383, I would look for a more balanced head in the 190cc range with good cfm throughout the range of lift. The flow you've posted at .5, .6 and .7 is good, but you will not be taking advantage of that flow on a street motor. How do those heads flow from .1 to .5? I would suspect not so well if they are only giving you flow specs for .5 and above.
Big runners like you're looking at will have the potential for more horsepower, but significantly degrade the torque of the motor at low rpms.
If it were my 383, I would look for a more balanced head in the 190cc range with good cfm throughout the range of lift. The flow you've posted at .5, .6 and .7 is good, but you will not be taking advantage of that flow on a street motor. How do those heads flow from .1 to .5? I would suspect not so well if they are only giving you flow specs for .5 and above.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Originally Posted by mpick
I have a 383 with 214/220 cam, forged rollers, 9:1 flatops and 24# Bosch injectors.
I want to change my stock heads with oversized valves for some good high performance heads.
I would consider changing the cam if it would help. The 220 cc cnc heads flow 264 cfm's at .500. Can't decide whether 220 cc or 235 cc. Both have 64 cc chambers
I am also going to switch to crane gold rockers 1.6 instead of my 1.5's I have now.
Any advice is certainly appreciated
I want to change my stock heads with oversized valves for some good high performance heads.
I would consider changing the cam if it would help. The 220 cc cnc heads flow 264 cfm's at .500. Can't decide whether 220 cc or 235 cc. Both have 64 cc chambers
I am also going to switch to crane gold rockers 1.6 instead of my 1.5's I have now.
Any advice is certainly appreciated
those heads at 220cc and especially at 235cc will be WAY WAY too big for that motor. Your compression is way low at 9:1 and you definately don't want to put a huge head on that.
I would get a set of 180 or 190 AFR heads if you can find them. Their base heads 70% cnc will serve you well with that combo.
Those big heads will be NO GOOD>
Read the post about the 18* heads going on, it will shed some light on this thread as well.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Take a look at the following site, you will have to copy the site address, nut sure how to get this to go directly to the site. These sites show flow numbers for a wide varity of heads.
1) http://users.erols.com/srweiss/tablehdc.htm
This site shows just about everything for all heads made. You can also do searches on thr forum to see what others have experienced. You will see a lot of varried opinions based on experience and DESIRE. There are several things to keep in mind. What is your base engine and what is the best rpm range you will be spinning. If your range is 5000 or less and 350 ci you would want to stay at 195 or less for intake cc. If you have a high rev above 350 ci then go with more cc for the intake.
I talked to several machine shops in my area that did custom porting. The best known in the area took me back into the shop (clean as a computer room and well organized which tells you alot about their quality). They showed me several heads that were in process of being ported and polished. Very good work. The bottom line was that they could take any head, stock or after market and get it to flow better for a PRICE. They also showed me a set of Air Flow Research (AFR) heads they had just gotten for a customer. They were right out of the box and they were going to do nothing but mark up their cost and sell they to their customer. They really looked good, CNC chambers and valve pockets. They told me that for the heads that were on the market this was one of the best for pulling out of the box and bolting on. By the time I figured the cost of other after market heads and then the cost of porting the AFR's were dollars less. I ordered a set from JEG's (not Summit...I had them on my mind in another post) and had delivery in 6 days from the date of the order. You can go on the JEG's web site and research them to see what you get for your $$. When I talked to the machine shop, they indicated it took them 5-12 weeks to get the AFR heads from time or order to door step.
Good luck in your project.
1) http://users.erols.com/srweiss/tablehdc.htm
This site shows just about everything for all heads made. You can also do searches on thr forum to see what others have experienced. You will see a lot of varried opinions based on experience and DESIRE. There are several things to keep in mind. What is your base engine and what is the best rpm range you will be spinning. If your range is 5000 or less and 350 ci you would want to stay at 195 or less for intake cc. If you have a high rev above 350 ci then go with more cc for the intake.
I talked to several machine shops in my area that did custom porting. The best known in the area took me back into the shop (clean as a computer room and well organized which tells you alot about their quality). They showed me several heads that were in process of being ported and polished. Very good work. The bottom line was that they could take any head, stock or after market and get it to flow better for a PRICE. They also showed me a set of Air Flow Research (AFR) heads they had just gotten for a customer. They were right out of the box and they were going to do nothing but mark up their cost and sell they to their customer. They really looked good, CNC chambers and valve pockets. They told me that for the heads that were on the market this was one of the best for pulling out of the box and bolting on. By the time I figured the cost of other after market heads and then the cost of porting the AFR's were dollars less. I ordered a set from JEG's (not Summit...I had them on my mind in another post) and had delivery in 6 days from the date of the order. You can go on the JEG's web site and research them to see what you get for your $$. When I talked to the machine shop, they indicated it took them 5-12 weeks to get the AFR heads from time or order to door step.
Good luck in your project.
Safety Car
Joined: Feb 1999
Posts: 4,724
Likes: 16
From: Little Elm TX
I personally think "CNC" heads benefit the Porters more than the customer. As previously mentioned a CNC stands for Computer Numerical Control. Which is the Computer that controls a machine tool.
The CNC has two primary jobs, 1) Control the I/O of the machine via an on board programmable logic controller 2) Execute a G-code programs. The G-code program is the program that contains the actual coordinate position values expressed in X, Y, Z, A, B axes for a typically 5 axes machining center. You can also create your programs right on the CNC keyboard, however, typically for 5 axes programs the data is created offline via a cad/cam program and then downloaded to the CNC via Ethernet, disk or rs 232 serial port.
The CNC controls the Servo Systems speed via either small incremental analog commands or digital signals. Based upon the reported position of the Servo's using a linear or rotary encoder, the control system varies the command to the servo's thus staying within a theoritical tool path tolerance.
What does all of this mean? it means once a porter has a combustion chamber that they feel is good, they can digitize the port utilizing a Renishaw probe system. By digitizing, they have copied the surfaces they intend to machine.... after massaging this file with feed, speed and m-code commands, they now have a good program that they can turn around and use for all future cylinder heads, typically using the same file for each cylinder, but they will use a part zero offset to step over to the next chamber.
In otherwords, after they have a good program, they can simply mount a cylinder head and press cycle start and go have coffee while the head is machined.... in otherwords, hours and hours of tedious hand porting is not necessary, and you can pay somebody 6 bucks an hour to clamp the head in and press a button.
The benefit to you, is that in "theory", every chamber is identical. Reality is probably much different with many porters for a lot of different reasons I won't go into right now.
With hand porting, you're paying somebody to sculpture your cylinder head tediously by hand.... it really depends on the individual if you're getting a great result. With the CNC porters, you have made life much easier for them when you purchase CNC porting. The reason for the additional cost is because 5 axes Machining Centers are very expensive... with even the most cheaply made 5 axes machining centers starting at over $ 100,000
good luck with your decision.
cheers,
Beach Bum
The CNC has two primary jobs, 1) Control the I/O of the machine via an on board programmable logic controller 2) Execute a G-code programs. The G-code program is the program that contains the actual coordinate position values expressed in X, Y, Z, A, B axes for a typically 5 axes machining center. You can also create your programs right on the CNC keyboard, however, typically for 5 axes programs the data is created offline via a cad/cam program and then downloaded to the CNC via Ethernet, disk or rs 232 serial port.
The CNC controls the Servo Systems speed via either small incremental analog commands or digital signals. Based upon the reported position of the Servo's using a linear or rotary encoder, the control system varies the command to the servo's thus staying within a theoritical tool path tolerance.
What does all of this mean? it means once a porter has a combustion chamber that they feel is good, they can digitize the port utilizing a Renishaw probe system. By digitizing, they have copied the surfaces they intend to machine.... after massaging this file with feed, speed and m-code commands, they now have a good program that they can turn around and use for all future cylinder heads, typically using the same file for each cylinder, but they will use a part zero offset to step over to the next chamber.
In otherwords, after they have a good program, they can simply mount a cylinder head and press cycle start and go have coffee while the head is machined.... in otherwords, hours and hours of tedious hand porting is not necessary, and you can pay somebody 6 bucks an hour to clamp the head in and press a button.
The benefit to you, is that in "theory", every chamber is identical. Reality is probably much different with many porters for a lot of different reasons I won't go into right now.
With hand porting, you're paying somebody to sculpture your cylinder head tediously by hand.... it really depends on the individual if you're getting a great result. With the CNC porters, you have made life much easier for them when you purchase CNC porting. The reason for the additional cost is because 5 axes Machining Centers are very expensive... with even the most cheaply made 5 axes machining centers starting at over $ 100,000
good luck with your decision.
cheers,
Beach Bum
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by mpick
what is the difference between cnc combustion chamber heads and regulear heads
Originally Posted by mpick
235 cc flowed 292 cfm's @ .500 lift
235 cc flowed 310 cfms' @ .600 lift
235 cc flowed 318 cfm's @ .700 lift
These are the numbers given on the cnc heads.:
235 cc flowed 310 cfms' @ .600 lift
235 cc flowed 318 cfm's @ .700 lift
These are the numbers given on the cnc heads.:
Originally Posted by mpick
Here are the specs on the non cnc'ed heads
235 cc flowed 274 cfm's @ .500 lift
235 cc flowed 292 cfms' @ .600 lift
235 cc flowed 312 cfm's @ .700 lift:
235 cc flowed 274 cfm's @ .500 lift
235 cc flowed 292 cfms' @ .600 lift
235 cc flowed 312 cfm's @ .700 lift:
Ports with 235 ccs? What are you planning to build? A 472 blown on alcohol??? Read some past threads. Bigger is not always better.
RACE ON!!!
Thread Starter
Intermediate
Joined: May 2004
Posts: 41
Likes: 0
From: Jacksonville fl
I found these 192cc heads on ebay for 249 a piece
What do you think about them?
INTAKE FLOW SPECIFICATIONS
0.200" Lift 117.8 cfm
0.300" Lift 168.7 cfm
0.400" Lift 214.3 cfm
0.500" Lift 238.5 cfm
0.600" Lift 258.7 cfm
0.700" Lift 254.5 cfm
EXHAUST FLOW SPECIFICATIONS
0.200" Lift 85.8 cfm
0.300" Lift 119.9 cfm
0.400" Lift 146.2 cfm
0.500" Lift 159.2 cfm
0.600" Lift 162.2 cfm
0.700" Lift 159.8 cfm
What do you think about them?
INTAKE FLOW SPECIFICATIONS
0.200" Lift 117.8 cfm
0.300" Lift 168.7 cfm
0.400" Lift 214.3 cfm
0.500" Lift 238.5 cfm
0.600" Lift 258.7 cfm
0.700" Lift 254.5 cfm
EXHAUST FLOW SPECIFICATIONS
0.200" Lift 85.8 cfm
0.300" Lift 119.9 cfm
0.400" Lift 146.2 cfm
0.500" Lift 159.2 cfm
0.600" Lift 162.2 cfm
0.700" Lift 159.8 cfm
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
A good place to look is flow at .400.
Those don't flow well at all using low and mid lift numbers.
.400 should be well over 230 CFM on the intake.
On the exhaust flow should be over 160 CFM @ .400
Those don't flow well at all using low and mid lift numbers.
.400 should be well over 230 CFM on the intake.
On the exhaust flow should be over 160 CFM @ .400
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by JAKE
A good place to look is flow at .400.
RACE ON!!!
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Look at the head chart I listed above. The Edelbrock streel legal performer heads with 70 cc chanbers and 170 cc intake (compared to your 192 above) flows 238 at .400 and 244 at .500. Doesn't look like the ebay heads are that good except for dollars invested for a USED head. 
The AFR 190 cc street flows 245 at .400 and 260 at .500. Canfield 195 cc flow 247 at .400 and 258 at .500. Dart 200 Iron Eagles (out of the box non ported cast iron) 200 cc heads flow 229 at .400 and 261 at .500. You might be getting what you pay for.
The AFR 190 cc street flows 245 at .400 and 260 at .500. Canfield 195 cc flow 247 at .400 and 258 at .500. Dart 200 Iron Eagles (out of the box non ported cast iron) 200 cc heads flow 229 at .400 and 261 at .500. You might be getting what you pay for.
Last edited by John A. Marker; Jan 23, 2005 at 04:49 PM.