CNC ported sylinder heads
#1
10-22-2008, 03:12 PM
CNC ported sylinder heads
Long time listener, first time caller.....
Has anyone installed CNC ported cylinder heads on their 5.7 Hemi? Some aftermarket dealers that sell them, supposedly from Mopar, but my dealer never heard of them, list them for $3199.00. A supercharger would probaly be more effective for HP gain but that is another thread.......so has anyone bought these and is it worth the trouble to maybe get 50 HP out of $3199.00?
Thanks
Has anyone installed CNC ported cylinder heads on their 5.7 Hemi? Some aftermarket dealers that sell them, supposedly from Mopar, but my dealer never heard of them, list them for $3199.00. A supercharger would probaly be more effective for HP gain but that is another thread.......so has anyone bought these and is it worth the trouble to maybe get 50 HP out of $3199.00?
Thanks
#2
11-08-2008, 10:01 PM
Hall Of Fame
#3
11-09-2008, 07:43 AM
in the following article Dodge engineers were advising David Vizard the whole time he was porting 5.7 cyl heads by hand:
(go to the last page and look at last pictures)
http://www.popularhotrodding.com/tec...iew/index.html
the 30 cfm gain on the intake side very roughly means a 30 hp increase
sample quote
Flow Capability
We can see that Chrysler's engineers were targeting the best two-valve head possible. There are two important questions that need to be asked here: How well did they succeed for the head in stock form and, since no aftermarket heads are available, what is its porting potential? The graph, Fig 3, gives the answers here and you are going to like them. First, the intake port. The stock port with its 2-inch valve flowed a whopping 270 cfm at only .600-inch lift. It hit the peak flow figures, which are produced at .700-inch lift on a stock LS6, at only about 375 thousandths lift. This is good news but there is a lot more. Peak figures are not the whole story. Good mid-range figures are also important. The new Hemi did extremely well here. At 250 thousandths lift, the stock head was nearer a $10,000 Winston (Nextel) Cup head than it was to even a good modified parallel-valve head.
A check on the intake port velocity (Fig 4) showed the intake to be a super high-speed port with valve-to-port areas very similar to what is seen in Formula One. Velocity probing showed 90 percent of the port flows at a velocity greater than 90 percent of maximum. This is far better than a typical 23-degree performance head for a small-block Chevy or, for that matter, the LS6.
The exhaust port showed the same high-function trend by hitting 161 cfm at 600 thousandths lift through its 1.55-inch valve. It also had a far better than average port velocity and velocity distribution (Fig 5).
We spent a day and a half on the flow bench in an effort to find out what this head does or does not like in the way of port mods. We are sure there is much still to come, especially with some bigger valves, but we did find what it took to produce, at 600 thousandths lift, some 302 cfm on the intake and 195 cfm on the exhaust. As the nearby photos show the work to achieve this proved simple. In essence, the porting involves little more than just tidying up what Chrysler's engineers provided in the first place (great job guys).
(go to the last page and look at last pictures)
http://www.popularhotrodding.com/tec...iew/index.html
the 30 cfm gain on the intake side very roughly means a 30 hp increase
sample quote
Flow Capability
We can see that Chrysler's engineers were targeting the best two-valve head possible. There are two important questions that need to be asked here: How well did they succeed for the head in stock form and, since no aftermarket heads are available, what is its porting potential? The graph, Fig 3, gives the answers here and you are going to like them. First, the intake port. The stock port with its 2-inch valve flowed a whopping 270 cfm at only .600-inch lift. It hit the peak flow figures, which are produced at .700-inch lift on a stock LS6, at only about 375 thousandths lift. This is good news but there is a lot more. Peak figures are not the whole story. Good mid-range figures are also important. The new Hemi did extremely well here. At 250 thousandths lift, the stock head was nearer a $10,000 Winston (Nextel) Cup head than it was to even a good modified parallel-valve head.
A check on the intake port velocity (Fig 4) showed the intake to be a super high-speed port with valve-to-port areas very similar to what is seen in Formula One. Velocity probing showed 90 percent of the port flows at a velocity greater than 90 percent of maximum. This is far better than a typical 23-degree performance head for a small-block Chevy or, for that matter, the LS6.
The exhaust port showed the same high-function trend by hitting 161 cfm at 600 thousandths lift through its 1.55-inch valve. It also had a far better than average port velocity and velocity distribution (Fig 5).
We spent a day and a half on the flow bench in an effort to find out what this head does or does not like in the way of port mods. We are sure there is much still to come, especially with some bigger valves, but we did find what it took to produce, at 600 thousandths lift, some 302 cfm on the intake and 195 cfm on the exhaust. As the nearby photos show the work to achieve this proved simple. In essence, the porting involves little more than just tidying up what Chrysler's engineers provided in the first place (great job guys).
