S54 Header Design talk

[Bry5on]

That looks great but it's already longer than the target. Are you able to pull out 100mm and keep the equal lengths? I think we should design shorter so we can easily add length and tune it as needed. It's very easy to continue bundled parallel primaries.

Also a few small things: you probably need to space your primaries in their cluster more so that you can get a 15 degree merge angle. I think tight now your merge would end up very narrow. Maybe I'm just visualizing that wrong and you am still get a clean 15 degree merge?
I have been designing around a 50mm OD to give room for different engine configurations. Cams, stroker kits, etc. just making extra space so it's as flexible as possible.

I did another revision on mine before bed last night and I got the delta much smaller but cylinder 1 is still the issue. It's down to around 25mm total but the merges are about 25mm out of sync now. I'm also not really sweating it because I don't think you will be able to hear that difference.

Yeah, very easy to shorten them. I think I have a method now as I’ve experimented with a few techniques. I’ll start over for the next rev and it should have pretty flexible CAD.

I modeled this with 3 straight tubes into the merge plane based on your last comments that you were struggling with that. When you say the merge would be narrow, and you’re targeting 15 degrees, what do you mean exactly? Straight primaries into a 15 degree merge cone for collector, 7.5 from centerline? Or a 30 degree cone, 15 degrees from centerline? Or by pointing the primaries themselves at a 15 degree axis? All doable, there’s plenty of space to get to sub-millimeter accuracy it seems.

My plan for a merge is to gradually transition from circular cross section to three orange-slice sections to get closer to a merged circle to make the collector tight. I packed the circular tubes pretty tightly with this in mind. Are you planning for a 1.5mm wall thickness, or something thicker? 50mm OD/47mm ID seems pretty big.

edit: what length are you targeting? I’m catching back up and couldn’t find it quickly

[ApexPothole]

If you look at this video from Burns Stainless, they talk about modelling their geometry after an ASME Venturi, and mention that the rationale for increasing the angle to to avoid a very long transition is to decrease wall losses. Also, it looks like the merges that he's showing off are at 15^o though the inlets all look coaxial, and the whole thing looks like it's packed as tight as practical while still affording welding clearance. If you retain the linear lead-in from Bry5on's design it would be easy to lengthen/shorten the linear section to adjust tuning length to different applications

Also, could I steal someone's chassis scan data? I'd like to try messing around with this a little, and I don't have time to get under my car and scan it myself rn.

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[Bry5on]

This is an interesting engineering exercise but I do believe the solutions that exist for this chassis at this moment in time, exist for a reason.

V1's have been tried and true and don't cost 5k.

It would be cool to see something 3D metal printed and run to see how it performs but the amount that would cost vs. how many people would actually buy it makes this a very bad business idea lmao

Wise guy I think we’ve clearly outlined why this approach differs from everything that’s on the market, but I’ll recap:
1) true equal length primaries
2) true equal length secondaries
3) open source design, tunable in steps, length and diameter
4) 3D printable from stainless at similar cost to existing options

Nobody in here is trying to make a business from this collaboration, we’re all doing it to learn and contribute to a collective best design that can even be optimized for custom motors. Once the files exist, anyone can order them printed without going through another forum member.

I also very much dislike my SS V1s, on a personal note. Crappy tolerances and a shit leaky pain in the ass slip joint top my dislikes. I started my project because of these

[Bry5on]

If you look at this video from Burns Stainless, they talk about modelling their geometry after an ASME Venturi, and mention that the rationale for increasing the angle to to avoid a very long transition is to decrease wall losses. Also, it looks like the merges that he's showing off are at 15^o though the inlets all look coaxial, and the whole thing looks like it's packed as tight as practical while still affording welding clearance. If you retain the linear lead-in from Bry5on's design it would be easy to lengthen/shorten the linear section to adjust tuning length to different applications

Also, could I steal someone's chassis scan data? I'd like to try messing around with this a little, and I don't have time to get under my car and scan it myself rn.

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Shoot me a PM with your email. We can find the best way to share the scans then I can upload here.

[3staxontheradio]

Ill add my chassis scans to the github. Bry5on happy to make a folder for you on the GitHub too

[Bry5on]

I’ll didn’t add my chassis scans to the github. Bry5on happy to make a folder for you on the GitHub too

Why didn’ti think of git. Would you mind adding a link to your repo to the initial post? I can make a merge request after cloning.

[3staxontheradio]

Bry5on
I added the github link to the first post. I'm targeting 550mm but I would like to design it shorter so it can be adjusted easily by adding to the bundle and the comparative lengths and packaging issues wouldn't change. I have my version at like 490mm +/- 5mm except for #1 which is 510mm

I have pipemax configured for primaries for 7900 rpm peak horsepower and collectors at 4900 rpm peak torque.


As far as tubing diameters go it scales with VE/power output. When I have pipemax set up to output a design for ~350 crank horsepower it wants this for 3 steps: *diameters from pipemax are all ODs with assumed 1.65 wall
1st Step Diameter mm= 40.936 Length= 136.076 to 150.364 mm
2nd Step Diameter mm= 44.111 Length= 136.076 to 150.364 mm
3rd Step Diameter mm= 47.286 Length= 272.153 to 300.728 mm

At 4 steps it adds another large diameter:
1st Step Diameter mm= 40.936 Length= 136.076 to 150.364 mm
2nd Step Diameter mm= 44.111 Length= 136.076 to 150.364 mm
3rd Step Diameter mm= 47.286 Length= 136.076 to 150.364 mm
4th Step Diameter mm= 50.461 Length= 136.076 to 150.364 mm

If we aren't doing steps and just straight tube diameters it wants: 40.936 -to- 44.111


If I add a bunch of VE to get to built 3.6L stroker territory the 3 step looks like this:
1st Step Diameter mm= 46.284 Length= 136.076 to 150.364 mm
2nd Step Diameter mm= 49.459 Length= 136.076 to 150.364 mm
3rd Step Diameter mm= 52.634 Length= 272.153 to 300.728 mm

and 4 steps like this:
1st Step Diameter mm= 46.284 Length= 136.076 to 150.364 mm
2nd Step Diameter mm= 49.459 Length= 136.076 to 150.364 mm
3rd Step Diameter mm= 52.634 Length= 136.076 to 150.364 mm
4th Step Diameter mm= 55.809 Length= 136.076 to 150.364 mm

and for a non stepped header it wants:
46.284 -to- 49.459



For collector dimensions:

Stockish 355 crank horsepower engine:

--- Collector Specs : Merge Collector • Straight Tube ---
Peak TQ Diameter Range = 64.794 -to- 67.969 Best Length= 490.671 -or- 981.343 mm
Best Mid-Range Diameter = 67.969 Best Length= 490.671 -or- 981.343 mm
Peak HP Diameter Range = 67.969 -to- 71.144 Best Length= 490.671 -or- 245.336 mm




3.6L stroker:
--- Collector Specs : Merge Collector • Straight Tube ---
Peak TQ Diameter Range = 73.606 -to- 76.781 Best Length= 490.671 -or- 981.343 mm
Best Mid-Range Diameter = 76.781 Best Length= 490.671 -or- 981.343 mm
Peak HP Diameter Range = 76.781 -to- 79.956 Best Length= 490.671 -or- 245.336 mm



Also choke sizing for the merge/venturi is something I haven't finished looking into. I think about 1.5x the primary tube CSA is in the ballpark. Then a megaphone before returning to the collector size.

[Bry5on]

You think the extra effort of package protecting for 3 and 4 steps and a 3.6L are worth it? Seems that if a stroker is limited to a 2 step and a stock displacement limited to 3 step we can really simplify the packaging problem without giving up much. This would keep us to packaging 48-49mm max which would help a lot I think.

[3staxontheradio]

I think if it's configurable up to about 49/50mm OD that allows for a lot of flexibility and covers 99 percent of us. Someone needing maximum peak power out of a 400whp stroker setup can modify the design if it's holding them back.

[digger]

This is an interesting engineering exercise but I do believe the solutions that exist for this chassis at this moment in time, exist for a reason.

V1's have been tried and true and don't cost 5k.

This raises a good point that at some point the system needs to be compared to probably euros and V1s and you need good data to do that on some kind of healthy controlled test mule of representative level of modification. Pretty much all of the exhaust roller chassis dyno test data is questionable if you want to see small gains which is potentially all that we are looking at for most engine specs.

[Bry5on]

Anyone know of a good used engine dyno for sale? I’m sure George Hill wouldn’t say no to one if we all covered the cost.

[George Hill]

Luckily IIRC 3staxontheradio ultimately plans to work with Partee Racing on these and I thought they had an engine dyno in the works. If that ends up realizing I will definitely ship my Kromers to compare if thats an option.

[George Hill]

Anyone know of a good used engine dyno for sale? I’m sure George Hill wouldn’t say no to one if we all covered the cost.

If it wasn't for my location I would definitely be wearing out a dyno right now. That's the dream, just to loud for my area.

[Cronenberged]

Engine masters dyno engines all the time and for good studies I’m sure we could hit them up and they would use it for of their cool content videos.

[Sharocks]

Wise guy I think we’ve clearly outlined why this approach differs from everything that’s on the market, but I’ll recap:
1) true equal length primaries
2) true equal length secondaries
3) open source design, tunable in steps, length and diameter
4) 3D printable from stainless at similar cost to existing options

Nobody in here is trying to make a business from this collaboration, we’re all doing it to learn and contribute to a collective best design that can even be optimized for custom motors. Once the files exist, anyone can order them printed without going through another forum member.

I also very much dislike my SS V1s, on a personal note. Crappy tolerances and a shit leaky pain in the ass slip joint top my dislikes. I started my project because of these

Thanks for the recap, it's helpful in navigating this.

This is one of those projects that sound great but in reality we would all need to see side by side dyno comparisons to even justify it.

I'm not loving my V1's either but they work for my cammed built head car.

If these are better, i'm down to spend.