Porting to reach high rpm breathing
- Thread starter Fahlin Racing
- Start date
If we can find an area that pics up some HP/TQ without having to do extensive milling of the port, that a new guy running a couple of pulls/drags on the weekends a few times a year and gets to have some fun with his daily driven street truck.... then thats worth more than any set of heads that cant be run under 30 psi and wont make power till it gets the rpms up over 3500.
I currently have a set of 3.8L Buick AL race heads at my shop waiting to go into a 29 Ford 2 door sedan, that have some stupid sized intake ports that are LARGE by HUGE in size. doing the math after reading the flow sheet, we figure with these heads at a 750 rpm idle there would be ZERO vacuum at the carb/throttle plate. we have decided that a 6-71 sized blower at 30% overdriven SHOULD be just about enough air to get a decent idle and still be able to drive the car on the street.
Yes it would be cool to pull into the local car show with a nitro motor sticking thru the hood, crackling and popping. What is the drivability of that motor on a day to day basis or even as a weekend run-a-bout. Cool Factor 1, Practicality 0, Fun to Drive Factor 1/4.
I currently have a set of 3.8L Buick AL race heads at my shop waiting to go into a 29 Ford 2 door sedan, that have some stupid sized intake ports that are LARGE by HUGE in size. doing the math after reading the flow sheet, we figure with these heads at a 750 rpm idle there would be ZERO vacuum at the carb/throttle plate. we have decided that a 6-71 sized blower at 30% overdriven SHOULD be just about enough air to get a decent idle and still be able to drive the car on the street.
Yes it would be cool to pull into the local car show with a nitro motor sticking thru the hood, crackling and popping. What is the drivability of that motor on a day to day basis or even as a weekend run-a-bout. Cool Factor 1, Practicality 0, Fun to Drive Factor 1/4.
For anyone pondering, when do we stop with roof taper approaching the bowl? is there an excessive angle we must not reach? Is it the same for horizontal tapering? 
opcorn:
Also
Could the drop in the runner floor be explained yet? Its obviously mirrored from port to port and not a complete level floor to the short side. Could it be an attribute to keep a vortex minimally when higher rpms are used to help prevent reversion by high pressure 'bump' so to speak?
I remember Vizard saying something along these lines, don't direct the air where you think it is supposed to go but make some room where IT WANTS to go. Changing a valve design could make a difference in performance too. If someone does not think a loss in flow can happen with just a width change or angle change in a valve job (that is a physically TINY TINY AREA) then there is just the same amount of possibility within the runner itself, worth small or large gains.
Like Stingpuller mentioned he said something about 'running the same' as factory ported heads. Then what have we achieved besides an expensive piece of Aluminum?
opcorn:Also
Could the drop in the runner floor be explained yet? Its obviously mirrored from port to port and not a complete level floor to the short side. Could it be an attribute to keep a vortex minimally when higher rpms are used to help prevent reversion by high pressure 'bump' so to speak?
I remember Vizard saying something along these lines, don't direct the air where you think it is supposed to go but make some room where IT WANTS to go. Changing a valve design could make a difference in performance too. If someone does not think a loss in flow can happen with just a width change or angle change in a valve job (that is a physically TINY TINY AREA) then there is just the same amount of possibility within the runner itself, worth small or large gains.
Like Stingpuller mentioned he said something about 'running the same' as factory ported heads. Then what have we achieved besides an expensive piece of Aluminum?
You are right and I applaud you for trying to make a difference. My earlier comment wasn't directed toward you as much as it was for Ben. Maybe you can find a cheap difference maker although unlikely as it will be but keep trying.For anyone pondering, when do we stop with roof taper approaching the bowl? is there an excessive angle we must not reach? Is it the same for horizontal tapering?
Also
Could the drop in the runner floor be explained yet? Its obviously mirrored from port to port and not a complete level floor to the short side. Could it be an attribute to keep a vortex minimally when higher rpms are used to help prevent reversion by high pressure 'bump' so to speak?
I remember Vizard saying something along these lines, don't direct the air where you think it is supposed to go but make some room where IT WANTS to go. Changing a valve design could make a difference in performance too. If someone does not think a loss in flow can happen with just a width change or angle change in a valve job (that is a physically TINY TINY AREA) then there is just the same amount of possibility within the runner itself, worth small or large gains.
Like Stingpuller mentioned he said something about 'running the same' as factory ported heads. Then what have we achieved besides an expensive piece of Aluminum?
Forgot I still had this piece laying around from the cutaway. Thought provoker....
Look how the runner converges to the valve bowl, look how much change is with the floor changes and roof as it approaches the LSR and SSR. If my finger tip can be seen just as a finger tip through an oval shape prior to the valve yeah I would say pinch point.
Imagine what the flow is doing not just in bulk (cfm) but local speeds (velocity) and direction changes at the mouth as well as the short side as well as the divergent side into the cylinder. Whats up ahead I am sure many know, will effect what is happening earlier in the head/intake. :beer
Look how the runner converges to the valve bowl, look how much change is with the floor changes and roof as it approaches the LSR and SSR. If my finger tip can be seen just as a finger tip through an oval shape prior to the valve yeah I would say pinch point.
Imagine what the flow is doing not just in bulk (cfm) but local speeds (velocity) and direction changes at the mouth as well as the short side as well as the divergent side into the cylinder. Whats up ahead I am sure many know, will effect what is happening earlier in the head/intake. :beer
In this image you provided, air flow is moving from left to right, correct?
And the porting you provide smooths (levels/evens out) the floor (bottom) of the runner and removes the "bump" at the roof (top) of the runner seen there between the arrows, yes?
And how much do you charge for this service? Cuz that looks like one helluva restriction...
Sorry if the cost has been addressed already, it's a long thread and I haven't been following it...
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Yes the flow is left to right. I haven't put thought into doing someone else's heads, just working this one for now and the 6.7 Cummins I have laying around. I am done with my 6.0 Powerstroke project, that just needs to be flow tested. Maybe sometime in the future I may get things inline to do other peoples cleanup work. I am planning my Pro Street drag head next here once I get a few things done and that will take up quite a bit of time. As of a price, nothing thought of yet.
GMC this is a LMM head from what Guy told me. Where that severe 'dip' on this wall is where the wall actually starts to have some oval like shape to it in this area from how I see it. This could be widened IMO.
As far as port opening, what are you specifying as small and large, GMC?
If you look at how the roof and the floor dip, fuel feed above?, there could have been better shaping at that point. Perhaps the entire length of the runner.
I have been thinking fluid flow pressure verse wall texture which I suppose won't make much of a difference, however I haven't looked into micro-turbulence with elevated pressures yet (you know I think too much lol). I know it much but a little nugget for everyone, Joe Mondello won't use anything else but 80grit for porting, RIP Joe. I heard that in an interview I listened to a while back.
I think I will try to find a valve and take my telescoping gauge and compare the area right at the short side radius to compare and see what these heads are.
Other head-flow discussion is welcome pertaining to high rpms, as always.
In general on these heads, I plan to make a silicone mold or two hopefully sooner than later and also have a stock runner velocity-mapped to see how busy we are through the port.
If someone is serious enough on having something done, I just may put it into a more serious thought on basic runner clean up. I know JKholder may be on the Ford stuff if hes still kickin' around.
Simple thought provoker...... look down the runner with a light at the valve for those who don't do it much. What do you see.
GMC this is a LMM head from what Guy told me. Where that severe 'dip' on this wall is where the wall actually starts to have some oval like shape to it in this area from how I see it. This could be widened IMO.
As far as port opening, what are you specifying as small and large, GMC?
If you look at how the roof and the floor dip, fuel feed above?, there could have been better shaping at that point. Perhaps the entire length of the runner.
I have been thinking fluid flow pressure verse wall texture which I suppose won't make much of a difference, however I haven't looked into micro-turbulence with elevated pressures yet (you know I think too much lol). I know it much but a little nugget for everyone, Joe Mondello won't use anything else but 80grit for porting, RIP Joe. I heard that in an interview I listened to a while back.
I think I will try to find a valve and take my telescoping gauge and compare the area right at the short side radius to compare and see what these heads are.
Other head-flow discussion is welcome pertaining to high rpms, as always.
In general on these heads, I plan to make a silicone mold or two hopefully sooner than later and also have a stock runner velocity-mapped to see how busy we are through the port.
If someone is serious enough on having something done, I just may put it into a more serious thought on basic runner clean up. I know JKholder may be on the Ford stuff if hes still kickin' around.
Simple thought provoker...... look down the runner with a light at the valve for those who don't do it much. What do you see.
Well that's too bad for any and all of us that might be interested in having some port work done, it would seem like you've got a pretty good handle on what needs to be done and it's always nice to have options available
:thumb:
good luck man, I look forward to seeing some finished results of your effort!
:thumb:
good luck man, I look forward to seeing some finished results of your effort!
For now I suppose its a bummer (sorry guys and gals). I will see what my tool situation is, I know I don't have too many porting tools to end up not having a delay in them middle of the headwork, you know have to wait on order stuff. Like I said, I get down the road here a little more I may stock up on porting accessories Jason and go from there so I will keep it in mind.
I do know I need to buy one of the small Makita grinders if I can find one still, its a little easier to handle than the big Milwaukee I am using. I remember LT saying to me using a steel specific bit with lube, which I have been using works great. It doesn't cut as much as the specific aluminum bits which is nice when you need something between sand paper and large cutting teeth. KEEP YOUR CUTTING TOOL and MATERIAL lubricated.
One thing for those wanting to try and tackle things yourself, I am not sure if I mentioned it yet but here is what I found in a book I purchased a while back.
Here is a process that Burgess & Gollan state in their book for porting.
1.Carbide use (cutting down large areas quicker)
2.Mounted point (stones) (not for aluminum)
3.Fan grinding
4.Flapping, restores proper finish for fuel suspension and air flow boundary layer.
5.Hand finish if needed w/ emry cloth
Valve area per valve, add together to get our total valve area of usable flow area that we try to utilize and form our flow curve lift-off to set-down in either tract for those reading/thinking.
Valve area on one exhaust valve
Stem dia. 7mm or .275591"
Valve dia. 31mm or 1.2195" on the valve I am measuring
(1.2195 squared x .7854) - (.2755" squared x .7854)
1.1680 - 0.0596 = 1.1084" area
Valve area on one intake valve
Stem dia. same as above
Head dia. 33mm or 1.2936" on the valve I am measuring
(1.6734" x .7854) - (.2755" squared x .7854)
1.3142 - 0.0596 = 1.2546" area
Now if we measure the area that seems to be a oval-like shape near the short side and compare CSA.
GMC502 look at post 69 on page 5. I posted both halves however I did not make a point of the shape change at that point.
I do know I need to buy one of the small Makita grinders if I can find one still, its a little easier to handle than the big Milwaukee I am using. I remember LT saying to me using a steel specific bit with lube, which I have been using works great. It doesn't cut as much as the specific aluminum bits which is nice when you need something between sand paper and large cutting teeth. KEEP YOUR CUTTING TOOL and MATERIAL lubricated.
One thing for those wanting to try and tackle things yourself, I am not sure if I mentioned it yet but here is what I found in a book I purchased a while back.
Here is a process that Burgess & Gollan state in their book for porting.
1.Carbide use (cutting down large areas quicker)
2.Mounted point (stones) (not for aluminum)
3.Fan grinding
4.Flapping, restores proper finish for fuel suspension and air flow boundary layer.
5.Hand finish if needed w/ emry cloth
Valve area per valve, add together to get our total valve area of usable flow area that we try to utilize and form our flow curve lift-off to set-down in either tract for those reading/thinking.
Valve area on one exhaust valve
Stem dia. 7mm or .275591"
Valve dia. 31mm or 1.2195" on the valve I am measuring
(1.2195 squared x .7854) - (.2755" squared x .7854)
1.1680 - 0.0596 = 1.1084" area
Valve area on one intake valve
Stem dia. same as above
Head dia. 33mm or 1.2936" on the valve I am measuring
(1.6734" x .7854) - (.2755" squared x .7854)
1.3142 - 0.0596 = 1.2546" area
Now if we measure the area that seems to be a oval-like shape near the short side and compare CSA.
GMC502 look at post 69 on page 5. I posted both halves however I did not make a point of the shape change at that point.