07GtS197
Well-Known Member
I’d like to see the flow numbers on these compared to stock npi, pi and trick flow heads.
On a side note, you guys remember patriot heads?
On a side note, you guys remember patriot heads?
CNC ported modular npi heads
- Thread starter 96blak54
- Start date
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I do remember them.
My steen race ported head was supposedly 220cfm at .600" lift. I never recieved any document with the heads, only hear say by the original purchaser.
My steen race ported head was supposedly 220cfm at .600" lift. I never recieved any document with the heads, only hear say by the original purchaser.
07GtS197
Well-Known Member
It’s too bad trick flow is the only aftermarket head manufacturer. Patriot was a cast of cnc ported pi heads. People used to rag on them but no one had any actual experience with them. The thing is, I bet there is room for improvement in the design of the 2v head. In your opinion, do you think it’s the small displacement that limits the power output or the intake volume? I don’t see why a 2v head couldn’t flow similarly to 4v heads, given a redesign of the water jackets and more intake runner volume.
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Well...a trailer queen, factory svo head 2v 4.6l has been 9.5sec in the quarter consistently. Thats a 1.840" intake diameter. That places the engine in the 450hp - 475hp ballpark. Not to shabby if you ask me.
The pi heads in my opinion are not an all out naturally aspirated performing head. More oriented towards factory performance along with meeting government mandated gas mileage. And with its big exhaust valve to be better suited for forced induction. Perhaps the better of them all untouched and a bolt on performing head in any aspirations, but not for full on out naturally aspirated. This is only my opinion.
Engine displacement does play a huge roll in naturally aspirated power. Adding displacement to the 4.6l will stall out the intake port sooner. If the 4.6l made 450hp at 7500rpm, the same engine senario but with more cubes will produce the same hp but now at a lower rpm. This is why a big bore stroked 4.6l is nothing great. This is why the 5.4l swaps are really nothing to brag about. I have yet to see any factory head 2v 5.4l swap produce any more hp over what the 4.6l can do.
The pi heads in my opinion are not an all out naturally aspirated performing head. More oriented towards factory performance along with meeting government mandated gas mileage. And with its big exhaust valve to be better suited for forced induction. Perhaps the better of them all untouched and a bolt on performing head in any aspirations, but not for full on out naturally aspirated. This is only my opinion.
Engine displacement does play a huge roll in naturally aspirated power. Adding displacement to the 4.6l will stall out the intake port sooner. If the 4.6l made 450hp at 7500rpm, the same engine senario but with more cubes will produce the same hp but now at a lower rpm. This is why a big bore stroked 4.6l is nothing great. This is why the 5.4l swaps are really nothing to brag about. I have yet to see any factory head 2v 5.4l swap produce any more hp over what the 4.6l can do.
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07GtS197
Well-Known Member
Do you think trick flow heads on a 5.4 will be the ticket to more power?
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It will allow more power over stock 2v heads, but again, the same power can be had with the 4.6l. Only it will be at a higher rpm.
07GtS197
Well-Known Member
Ok I get it.
On a side note, there’s a guy on another forum who did a 5.4 3v swap in his new edge. He adapted a 4.6 plenum onto the 3v manifold. Probably a bit of a choke point but it’s a start. I’m interested to see what it puts down when finished.
On a side note, there’s a guy on another forum who did a 5.4 3v swap in his new edge. He adapted a 4.6 plenum onto the 3v manifold. Probably a bit of a choke point but it’s a start. I’m interested to see what it puts down when finished.
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Pm me that forum page if you would mind. Id like to see what he got going on
07GtS197
Well-Known Member
OP
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More npi madness
Ive recently been forced into a situation beyond my control and it has free'd up some of my time to play around.
Shown is the latest cnc npi port cut. It does look like crap. And in some ways, it supposed to, but the major is the machine has done most of the porting work and will be consistent in each port.
Will i smooth out the machined cuts....nope. the lateral cuts as you see it was my main goal. The port bowl under the valve seat still needs hand work
I plan to cut this port in half and check out material thickness.
Ive recently been forced into a situation beyond my control and it has free'd up some of my time to play around.
Shown is the latest cnc npi port cut. It does look like crap. And in some ways, it supposed to, but the major is the machine has done most of the porting work and will be consistent in each port.
Will i smooth out the machined cuts....nope. the lateral cuts as you see it was my main goal. The port bowl under the valve seat still needs hand work
I plan to cut this port in half and check out material thickness.
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ttocs
Post Whore
really cool pic and info blak.
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Here are a few comparison pics with a 4v exhaust valve as a representation of difference. The valve diameter is 30mm or 1.185"..... 1-3/16"...how ever you interpret. Like i have always said, the npi port begining is the restrictions. All the work is done at the beginning and then blended as the port opens up on down the hole, just before the short side radius.
Attachments
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I should note with the ported head, that valve drops all the way down. Where as before porting the valve wouldnt enter the port.
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Impressive. Love reading this info.
I wanna pick some of y’all’s brain with our sons build…
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We all here. Ask away
Silver95bird
Active Member
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Neat work, glad to see you're still kicking blak. The pictures really don't do the npi heads justice. The PI heads do a much better job of tapering as they go further from the valve. The NPIs have this weird pinch like 1" or so in, that the cutaway pic is better at showing. People see the port at the gasket and assume that's the big difference. Not so. The NPI also has this weird casting that makes the intake port kind of ovaled, like a tongue shape. I can also tell you they aren't all the same size. They're roughly 1.10 x 1.50 iirc, I'm not sure how that changes the airflow. Perhaps trying for more swirl?
When I started doing the quick job on my 96, I used a 1/2" drive impact socket until I found the one that would just barely pass through the tight spot, and then I ported all 8 ports so that the next size bigger would both pass through, and slide across side to side at that point. Could I have taken more? Maybe, but I didn't want to break through, so I took what I could get. Blak would be better able to say how far is safe without cutting the wrong spot too thin.
My humble opinion is that on an npi casting, you would have to be very thin in a few places to make oversized valves worth it. The ID of the seat is enough to support a fairly ported port as is, given that the seat really needs a 15/30/45 angle port. Bigger seat IDs require bigger ports to support it. Starting at the seat, there should be a 2% taper each inch back. The mapping of the ports can show you the area at each point back, so you can calculate the area of each level and see exactly where and how much needs to be cut. You'll find that at the gasket face you really don't even need to cut for flow, you're cutting for mating the intake to it.
When I started doing the quick job on my 96, I used a 1/2" drive impact socket until I found the one that would just barely pass through the tight spot, and then I ported all 8 ports so that the next size bigger would both pass through, and slide across side to side at that point. Could I have taken more? Maybe, but I didn't want to break through, so I took what I could get. Blak would be better able to say how far is safe without cutting the wrong spot too thin.
My humble opinion is that on an npi casting, you would have to be very thin in a few places to make oversized valves worth it. The ID of the seat is enough to support a fairly ported port as is, given that the seat really needs a 15/30/45 angle port. Bigger seat IDs require bigger ports to support it. Starting at the seat, there should be a 2% taper each inch back. The mapping of the ports can show you the area at each point back, so you can calculate the area of each level and see exactly where and how much needs to be cut. You'll find that at the gasket face you really don't even need to cut for flow, you're cutting for mating the intake to it.
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I forgot to post pic of the other half
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I found 2 sets of 5.4l npi heads local. Picked them up cheap. I got one head stripped down and set up on the mill to get cut out. Im still tweeking the tool paths and process.
