CNC ported modular npi heads

96blak54

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The covid vacation opened up a little bit of free play and it was perfect timing too! It gave me the opportunity to map my professionally ported npi heads intake and exhaust port so that i can copy each port with a cnc machine.

I used the cnc as a high tech computer measuring machine to map one of the ports by first setting the head up with the port perpendicular to the table. Most inline with the spindle, keeping the port situated in a way to be machinable all around the port surface.

Then i took the tool of choice to be used, a 6" long 1/2" ball rotary file, and started touching off in multiple locations and recording the points on a cad/cam software. Moving down the port every .100" and then circling around the port in multiple points took FOREVER!!! Hours!! But i was determined!! And i will say the npi port is nothing like what the entry port shape is at the begining!

Not knowing what the actual rewards could be from all this work didnt bother me cause i know the entry to these ports are pinched down quite a bit and then opens up considerably. I remember when i purchased the heads, the guy claimed 210cfm intake flow. Knowing how this little bit of info can be debatable with all the technicality of a flow bench, i do know from the years of watching other npi successors, opening the port begining to the rest of it yields great results...so we're going with that!
 

96blak54

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As you can see, most of the port work is on the floor blended into the sides, the right having more took out than the left. Also a little bit of hand porting is needed to blend the entry.
 
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96blak54

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Gauging the amount of material removed compare to level of porting stages, such as stage 1, stage 2, and the maximum being stage 3. Im going to say the port begining is a stage 3, the port middle is a stage 2, and the port around valve guide and valve seat are a stage 1 with only minimal clean up.... Or at least thats what i see.
 

96blak54

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This is a rendering of tool path lines. Most of the lines are correct. Some of the lines that look out of place are just that and represent nothing only to complete the path.
 

OLD H2S

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This is from my Trick Flow heads.

Are you going for flow or velocity? What RPM? Flow will give hp but velocity will give more torque below 4600. Nice mill..one of my favs. It it was mine I would take a 1/2 inch, 6" long mill and cut 2 little Trick Flow wings on each side of the valve guide boss and work the bowl with a 70 degree taper as long as I could make it. Recut the seat for a 1 mm larger intake valve at least. You want my seat cutters?
I am running monster ports on a 5.4 truck head, stock everywhere else...crap! But I do intend to go nuts nuts nuts when you are set up so let me know.

This is the inside of the Trick Flow ports with the 70 degree taper, non cnc street heads.
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These are my 5.4 truck heads
 

96blak54

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A bigger valve is a great idea! Remember i had to rev limit this last build to 6300rpm, even tho it wanted to do more, tire slippage would cause over rev creating fear in me to regulate it. The same piston speed in a 4.6l is 7200rpm. I got a set of seat cutters too, just no bigger valves.
 

OLD H2S

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Dang...I just got rid of a set of NPI stainless big valves by Manley.
A stock intake will be better for limiting RPM and have more torque down low.
Strange to build engines with limits, the one I am running now is limited to 250 HP to run in NASA and I came in at 244. Running a rev limiter might be easier.
Did you get a valve guide alignment set up tool for the mill to know when your on centerline?
 

96blak54

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I have no valve tooling for the mill...yet. Im just about ready to purchase a 3angle system of some sort for the manual mill. Been looking at Silver Seal products here lately. Then ill be able to deck, valve jobs, spring pockets, valve guides and such.
 

96blak54

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^ DELETE DELETE DELETE!!!

Their was a spammer about porn...click on this blah blah see girls crap
 
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OLD H2S

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This is the tool I have for locating vertical on the mill, the shaft is a valve guide boss for the seat cutters.
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96blak54

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More npi port work.
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Been grinding the npi port opening to a pi port shape so that port transition is smooth and to create a funnel taper shape instead of the pinched port opening tear drop shape. Remember the npi port opening in severly pinched at the port begining.

So a recap,
I mapped my last version steen racing npi heads on the cnc, wrote a program to that shape and cnc cut all the ports in a set of heads.

Now im hand opening the ports and will revist the cnc for mapping the new max port version.

Take notice all the work at the ports begining till around 2" down. The rest is untouch. This castration is what prohibits the npi port.

Oddly enough though, when these heads untouched are paired with pi cams and intake, power production is apples to apples to a pi engine of same compression.
 

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