Valve seat profiles

Fahlin

with 50 sylable words and ten sentences of geekeeze, you just repeated pretty much exactly what i just said - and what Lenohan hinted at - however you are totally incorrect on one thing - air is a fluid, and behaves like a fluid in every instance. Any real world head porter will tell you that.

Wet flow benchs have already shown that the shear or stall, caused by sharp edges, is beneficial, or detrimental, depending on the port and where the sharp edge is applied in that particular port. Which is why Nascar, and some of the best porters in the world have wet benches - precisely to see where the eddies and vortexes are in a port and what causes them, and how to make them gone or at least modify the cause enough to contribute to better air flow if they cant be eliminated.

Most would kill for just a decent flow bench lol
 
It behaves like a fluid that is why its considered a fluid when studying the dynamics of it, yes. Thank you for pointing things out. Sorry, sometimes I don't talk in plain common words, they grow on you as you study engineering etc etc.

Since we need micro-turbulence either way, this lip that causes shearing how large could we go before it impedes flow due to high level turbulence or maybe causing flow seperation later in the port? Thats what I am thinking about. Regardless testing on both wet and dry flow benches, we all know loud ports obviously have some problems compared to good flowing quieter ports.

I believe the Mach index somewhere around .545 or something close things start becoming into the choking-zone of flow.
 
How about this thought, how much stability is gained or not gained going from a sharp edged angle (machined valve job etc etc) to a radiused contour? I remember reading Smokey Yunick mentioning he argued with Detroit engineers about flow went more efficiently around a set of machined angles than a radius of the same angle.

Surface finish?
Boundary layer condition?
Subsonic or supersonice flow?
Pressure recovery problem?

I see turbocharged heads as a high pressure lower velocity flow therefore this would entail, if my premiss is correct, the total mass of air is more important than flow velocity like Greg Hogue has said in the past on here. If the DI diesel engine uses a slower flow but denser mass then how much could that change your applicable valve angle combinations? From Lenahan's post on angles that have been used in the past it doesn't seem like much a change, the tuned-venturi is pretty interesting to observe. As far as the flow path within the port/runner; turbocharged vs N/A, you could say this path is in a nutshell, similar.:pop:
 
Well I got some seats cut finally. Ended up going with a 5 angle cutter on the intakes and a radius style cutter on the exhausts. I'm happy with how they turned out, will have to see how it runs. Haven't been able to do any flow testing yet.

ImageUploadedByTapatalk1361827417.651412.jpgImageUploadedByTapatalk1361827466.580473.jpg
 
Fahlin Racing said:
Be interesting to see how the flow will be effected with so many combos that can be tried. I haven't chosen what angles I would like to use with the guinea pig 6.0L Ford PS heads I am puttsing around with, I am still porting them.

Have you chosen any cutter yet Jupton?
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Have you started playing with those dmax heads yet?
 
jupton said:
Well I got some seats cut finally. Ended up going with a 5 angle cutter on the intakes and a radius style cutter on the exhausts. I'm happy with how they turned out, will have to see how it runs. Haven't been able to do any flow testing yet.

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looks good. now unshroud the intake valve. theres quite a bit of air to be picked up doing this. just mark your bore size with a scribe and radius it from there. wouldnt hurt to cut down the material between the valves and taper to the injector hole to prevent heat soak. those areas are known to crack.
 
This could be a stupid question, but if the valve face is very near the surface of the head, and it being perpendicular to the bore, doesn't it essentially unshroud as soon as the valve lifts? Theres a value in relationship to the valve dia. that determines the lift needed for complete unshrouding, or it could be my sleep deprevation talking.
 
lenahan05 said:
looks good. now unshroud the intake valve. theres quite a bit of air to be picked up doing this. just mark your bore size with a scribe and radius it from there. wouldnt hurt to cut down the material between the valves and taper to the injector hole to prevent heat soak. those areas are known to crack.
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Ya I plan to blend the seats in the bowls and smooth things up a bit on the deck. Those photos were taken right after I cut the seats. The outside of the seats already overlaps the bore a bit. What's your thoughts on bore notching lenahan?
 
jupton said:
Ya I plan to blend the seats in the bowls and smooth things up a bit on the deck. Those photos were taken right after I cut the seats. The outside of the seats already overlaps the bore a bit. What's your thoughts on bore notching lenahan?
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dont do it. you will gain nothing. why put a big valve in something and then shroud it with the bore? its just never made sense to me why people do this....
 
lenahan05 said:
dont do it. you will gain nothing. why put a big valve in something and then shroud it with the bore? its just never made sense to me why people do this....
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I was under the impression the purpose of a bore notch was to attempt to unshroud the valve where it is close to the cylinder bore?
 
bore notches were to accomodate larger valves that would otherwise hit the edge of the cylinder - it does nothing to alleviate shrouding
The amount you would have to remove for shrouding purposes would take you through the cylinder wall before you had any kind of gains
 
I have seen several gassers where the valves fit fine inside the bore but to un shroud the valves the combustion chambers are opened up past the edge of the bore and the tops of the bores are then notched to match the chambers. This is what I thought the purpose of bore notching was but someone correct me if im wrong. If you put valves in a 12v head that are too big for the bore I don't think you could notch far enough into the bore without getting into the top ring anyway?
 
jupton said:
I have seen several gassers where the valves fit fine inside the bore but to un shroud the valves the combustion chambers are opened up past the edge of the bore and the tops of the bores are then notched to match the chambers. This is what I thought the purpose of bore notching was but someone correct me if im wrong. If you put valves in a 12v head that are too big for the bore I don't think you could notch far enough into the bore without getting into the top ring anyway?
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-i'm not saying your wrong. that is very likely. yes that is part of the reason behind it.

- if youve ever been on a flowbench with something like this you will see that the cfm gain is not even worth the time. the gain in power would be slim to none. you dont want air directed towards that side of the cylinder anyway and the percentages that exit near the bore barely showed up when flowed. if you ever get time on a bench to flow some stuff, allways keep in mind you want to bend and move your air in the port to exit closest to the center of the bore. if you have access to a wetflow bench with these heads, spend your time on it, you will learn much quicker where the air is exiting the port/valve.

-flycuts and bore notching that are going to be deep enough for top ring issues are going to give you issues....fuel running over the cut and onto the ring and bore notch, will likely cause piston failures.

-keep in mind, these are just my opinions from what i have seen in the past. if its something you want to try, i say go for it. nothing wrong with trying. if you want more flow out of these heads, keep it simple and just go to a bigger bore/valve combo. pm me your number. ill send you a few pics of some 12v 6.7 bore ports and flow numbers.
 
DirtyMaxx03 said:
Have you started playing with those dmax heads yet?
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Nope, I have yet to buy a set of cutters for aluminum and I have recently picked up an altered/front end dragster chassis too so things are becoming busy, plus my car club stuff.

Jupton, your valves don't seem to be too close to the bore by judging your valve location in what you have (i could be off though). I will agree with Lenahan05, don't bother bore notching. Modify the valve-head to continue a smooth flow leaving the valve into the chamber. The cuts look very clean btw!

The wall will act as a swirl dam when you get closer it a way. Have you measured how close the valve is to the bore once you positioned the head on the block? Theres been differences in valve to bore proximity from .100" plus some and to .060" from the bore wall for keeping flow in the right department. If you need to, why not move the valve over slightly.
 
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Fahlin Racing said:
Nope, I have yet to buy a set of cutters for aluminum and I have recently picked up an altered/front end dragster chassis too so things are becoming busy, plus my car club stuff.

Jupton, your valves don't seem to be too close to the bore by judging your valve location in what you have (i could be off though). I will agree with Lenahan05, don't bother bore notching. Modify the valve-head to continue a smooth flow leaving the valve into the chamber. The cuts look very clean btw!

The wall will act as a swirl dam when you get closer it a way. Have you measured how close the valve is to the bore once you positioned the head on the block? Theres been differences in valve to bore proximity from .100" plus some and to .060" from the bore wall for keeping flow in the right department. If you need to, why not move the valve over slightly.
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I haven't measured exactly how far the valve is from the cylinder wall. But to give you an idea the fire ring groove in the pic is about 4.340" ID and it's roughly 4" bore. So the valve is pretty close to the wall. The recessed area in the head around the valve is overlapping the edge of the bore right from the factory on these
 
Yeah, it may take a moment to do this idea, but put the block on a engine stand that rotates and install the head tight enough to where it won't move when you flip the engine. With the valves installed, open the valve with a fixture and flip the engine and measure how much you actually have and mark the head in that place, whichever place you decide to position the head once you have plans to assemble.

I have a question for Lenahan or anyone else, with Jupton's larger valve, if someone were to go large enough to have to move the valve towards the center, what are the circumstances we run into if we dig into the port for our injector. As long as the valve doesn't effect our injector stability, would it be ok to have the divergent area of the valve pocket overlapped partially the injector hole?
 
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