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CS Head Build - Bigger Lighter Valves - Process - Progress
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safe  



Joined: 18 Mar 2017
Posts: 441
Location: Sweden

PostPosted: Tue Jan 24, 2023 2:59 am    Post subject: Reply with quote

Mike9311 wrote:

Hopefully in the next few days, while I wait for some parts, material, I can flow the stock NA head and try the baguette on a NA without all my fancy offset larger valve stuff


Interesting note: I was studying several graphs of stock vs ported heads. There are a lot of other style of heads including American V8 heads that make the same flow as mine does at the same lift points.


I don't think the 931 is bad for a 2 valve design with similar bore. The valve size is probably the biggest restriction.
Got an "aha moment" watching Vizard explaining D*0.25 rule. The valve diameter times 0.25 gives where the flow stalls in lift. At that lift you have more curtain area than the valve size can flow. Which matches the 924 pretty good. it begins to "stall" at 0.4" lift which is ~10 mm and the valve is 40 mm (in the NA, same in turbo?).
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Mike9311  



Joined: 14 Dec 2004
Posts: 1487
Location: Chicago-ish

PostPosted: Tue Jan 24, 2023 5:52 am    Post subject: Reply with quote

Thanks Cedric, you get what I am doing. Jacob and I were going back and forth via text and he said "you are scratching an itch" This is so true and exactly what this is

safe, you see how funny my attempt now becomes? Its me jousting at windmills

42mm gives me 10.5mm or .413 inch with that rule

What happens in practice involves so much more that we can't control or don't know. Resonance, reversion, etc.

Fun to at least try
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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Mike9311  



Joined: 14 Dec 2004
Posts: 1487
Location: Chicago-ish

PostPosted: Tue Jan 24, 2023 11:05 am    Post subject: Reply with quote

Interesting, I just learned something. The NA valve spacing is tighter. With Intake moved over more toward center of cylinder like what I am doing here with 931. Not sure exactly how much but it looks like 1.5 to 2mm

Can you tell I just pulled a NA head off my shelf Will be setting it up. Port is a different animal. Will be interested to see what happens

I can already tell you I would do a 46/34 or something bigger for intake valve if I could find one. No luck so far since I want 6mm stem. 46 is a pretty big change. I already have one 46mm valve since I bought it early on in this current project.
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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F3ARED  



Joined: 14 Feb 2022
Posts: 18
Location: Melbourne, AUS

PostPosted: Tue Jan 24, 2023 5:33 pm    Post subject: Reply with quote

Holden V8s ran a bunch of different valve sizes on the inlet from 45mm up to 50mm. Not sure if they are available in a 6mm stem but length is 132.5mm which is .5mm shorter than a 931 valve.

I wonder if adding a curve to the clay vane could possible promote swirl?
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safe  



Joined: 18 Mar 2017
Posts: 441
Location: Sweden

PostPosted: Tue Jan 24, 2023 8:18 pm    Post subject: Reply with quote

Mike9311 wrote:
Interesting, I just learned something. The NA valve spacing is tighter. With Intake moved over more toward center of cylinder like what I am doing here with 931. Not sure exactly how much but it looks like 1.5 to 2mm

Can you tell I just pulled a NA head off my shelf Will be setting it up. Port is a different animal. Will be interested to see what happens

I can already tell you I would do a 46/34 or something bigger for intake valve if I could find one. No luck so far since I want 6mm stem. 46 is a pretty big change. I already have one 46mm valve since I bought it early on in this current project.


Await you results!

I would like both a bigger intake and exhaust (being a turbo conversion) valve in my head.
But it's pretty tight on space in the combustion chamber, no need to go bigger if it starts to shroud itself on the cylinder wall. Custom pistons and a maximum bore, what that could be, 88-89 mm?
EDIT: the big valve kit that Dan sold was 44/37 mm


I have a block bored to 87.5 with pistons.
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Porsche 924 -79 NA, EFI and Turbo.


Last edited by safe on Tue Jan 24, 2023 8:38 pm; edited 1 time in total
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safe  



Joined: 18 Mar 2017
Posts: 441
Location: Sweden

PostPosted: Tue Jan 24, 2023 8:23 pm    Post subject: Reply with quote

F3ARED wrote:
Holden V8s ran a bunch of different valve sizes on the inlet from 45mm up to 50mm. Not sure if they are available in a 6mm stem but length is 132.5mm which is .5mm shorter than a 931 valve.

I wonder if adding a curve to the clay vane could possible promote swirl?


In the NA the valves are 137mm long!
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Mike9311  



Joined: 14 Dec 2004
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PostPosted: Wed Jan 25, 2023 1:29 am    Post subject: Reply with quote

F3ARED, I have been looking at Holden stuff but more for how they were modifying the head. I'll look their too

The first time I hit 196 was with a smaller 'baguette' that was shaped at a slight angle with a hook at the end. Inspired by LS7 development article which has a deflector in the port. The idea is still on the table. Obviously theirs was in a different spot



Safe, the Ferrea valves are 150mm so no worries there. Remember with the new Stern Parner tappets they need to be slightly longer to cover the difference minus the cap/shim.
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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safe  



Joined: 18 Mar 2017
Posts: 441
Location: Sweden

PostPosted: Wed Jan 25, 2023 1:41 am    Post subject: Reply with quote

Mike9311 wrote:

Safe, the Ferrea valves are 150mm so no worries there. Remember with the new Stern Parner tappets they need to be slightly longer to cover the difference minus the cap/shim.

Alright!
I use those tappets with original valves, lash caps between 2.2 - 2.5 mm.
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Mike9311  



Joined: 14 Dec 2004
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PostPosted: Wed Jan 25, 2023 10:28 am    Post subject: Reply with quote

Notice anything? Chose an interesting head from the shelf





Cleaning valves for the head. Hard to find NA valves in all my stuff
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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safe  



Joined: 18 Mar 2017
Posts: 441
Location: Sweden

PostPosted: Wed Jan 25, 2023 9:55 pm    Post subject: Reply with quote

For a carbureted car?
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morghen  



Joined: 21 Jan 2005
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PostPosted: Wed Jan 25, 2023 11:12 pm    Post subject: Reply with quote

I dont think sense has anything to do with most of our activities surrounding these cars.

Finally had the time to do a sketch of what i meant.
Ports could be machined straight for a certain height with either a round or a custom shape (to ensure perfect alignment).
Insert can be CNC'd thin walled to avoid having to drill too much into the heads (1.5-2mm?) and containing the "velocity franzella".
The outside of the insert should match the dimensions for light press fit.
Insert can be glued to the head and one or two small holes can be made into the insert where a dab of weld can be added for extra peace of mind.
Then the weld can be leveled by hand and voila, you've just resurfaced the head port and added a feature that will increase the flow significantly.

The only difficulty i see is the machining of the heads needs to be spot on, so references need to be taken locally to avoid the impact of the old heads production tolerances and years of wear.
2mm of wall thickness of the insert and careful referencing of the ports to position the machining pocket should allow for any misalignments to be kept under 0.5mm and sanded smooth after pressing the insert and having the glue cure.

Note: this is a hand drawn sketch of what i immagined the feature would look like from the side by looking at Mike's pictures.
I dont know how long (deep) the feature needs to be, how tall or what is the exact position...thats for Mike to explore if he choses to go this way with his efforts.

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Cedric  



Joined: 27 Aug 2004
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PostPosted: Thu Jan 26, 2023 12:14 am    Post subject: Reply with quote

Wouldnt it be easier to make the baguette longer so it could just be tack welded at the port entry and thats it? If it works from a flow perspective and dont vibrate loose . No intricate machining required, with ports positioned a bit all over the place, which they are. if the baguette has a tricky shape couldnt it be reasonable to just print it in aluminium from some online company like PCBWAY, small stuff is often not crazy expensive.
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safe  



Joined: 18 Mar 2017
Posts: 441
Location: Sweden

PostPosted: Thu Jan 26, 2023 12:37 am    Post subject: Reply with quote

A little unrelated, but when you have a boosted engine and increase boost there must be a point when "porting" doesn't matter, just hog out the biggest possible port, right or wrong?

Watched youtube yesterday and saw a Steve Morris Engine big block on the dyno. Spinning to 9500 rpm, 60+ psi of boost and probably 5000hp (in the video it made 3000@22psi). In a previous video he showed the heads and the ports are just an enormous hole thru the head...
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morghen  



Joined: 21 Jan 2005
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Location: Romania

PostPosted: Thu Jan 26, 2023 12:58 am    Post subject: Reply with quote

Cedric wrote:
Wouldnt it be easier to make the baguette longer so it could just be tack welded at the port entry and thats it? If it works from a flow perspective and dont vibrate loose . No intricate machining required, with ports positioned a bit all over the place, which they are. if the baguette has a tricky shape couldnt it be reasonable to just print it in aluminium from some online company like PCBWAY, small stuff is often not crazy expensive.



Easier yes, i also thought about that..but then i asked myself if i would drive that car for hundreds or thousands of km away from home knowing that there is a bit of aluminium tacked in each of my intake runners
Also welding inside the runners may be more challenging than machining the ports. But if it can be done, sure it would be easier than what i described earlier.

Actually this whole discussion gave me maybe a better idea.
We can precision drill at the bottom of the port for a round key slot.
The insert would just slide into that key and have a light weld tack at the outer end where its easy to weld and clean.
Only thing is to take care of the water channel below the port.

931_port2 by m0rghen, on Flickr
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Mike9311  



Joined: 14 Dec 2004
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Location: Chicago-ish

PostPosted: Thu Jan 26, 2023 1:39 am    Post subject: Reply with quote

I like all of this and I get both ideas clearly. So far the baguette is farther in than I would want but both ideas solve the issue easily. Even if the tip has to extend over the sleeve or key into the port with either idea

AMC head that I grabbed without thinking. Same as NA but not injected. Only one I have broken down right now. Really curious how a vane / baguette will change things with the port shape differences to 931. We shall know shortly!

Super close now to getting velocity readings. Closer to knowing what is happening

The idea is to get more air into the head more efficiently. Should be same power level with less boost. Should also mean getting more air in faster which is what I hope I am doing here. Only so much time to fill a cylinder.
I think we are a different use case than all out drag race power. My last curve should act like a fatter / wider cam lobe I would think

Morghen sounds like a good test case. He feels like he is hitting a wall. Also just higher boost could become the enemy of the system. Everything needs to hold up to the additional boost. Obviously boosted cars are different. More forgiving and flexible

Not sure what will happen today but I am working on it. Setting up the NA head as well as getting ready for another ported head test. With every improvement from valve lift control to measurement something else needs help. Really need to decide where to cut a groove in stems so setting up could go easier
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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