Marvel's Hydra Coupe 1/12 scale full scratch build

[François]

Yup, that's exactly what it is. A totally useless gadget. But it will be cool to see it turn with the engine. Providing the micro gear motor I'm planning to use is strong enough to rotate 16 pistons plus the drive train plus some other gears. I'm starting to have some doughts !!

 

[François]

Did a bit more work on the V16 engine. That is a lot of pistons! It will be fun to watch if ever I'm able to pull this off and have a running engine. Like I said before, there's very little info on the Auto Union V16 so to get a somewhat realistic firing sequence, I found a little youtube that explains the sequence for the new Bugatti V16.

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[Dave @W]

Francois - did you look at the 1930 Cadillac V16 as well? There seems to be a fair amount of information available for that 'monster'. I know that you will do a great job on the one you are making now but this may be worth at least getting some ideas about how these work:https://www.motortrend.com/vehicle-genres/cadillac-v-16-engine-history-photos-specifications/ and https://en.wikipedia.org/wiki/Cadillac_V-16

 

[François]

Made some progress on the valve train today. It's a fairly complicated system. The cam shaft is located on top in the center, between the 2 heads. Each head has a set of 8 rockers actuating the outside valves (exhaust). These rockers are actuated via 8 horizontal rods( or close to horizontal) going towards the cam shaft, not too sure exactly how these rods are moved but I suspect that they are directly in contact with the cam shaft. And positionned just beneat the cam shaft there will be another 16 rockers, 8 to activate the the left side intake valves and 8 for the right side valves. My goal is to try and have working valves but really not sure I'll be able to. I will print every part so at worst it will be static.

Here is a cross cut of my ref engine where you can see the valves, rockers and horizontal rods.

And here's where I'm at. The red line would be the cam shaft.

 

[François]

Ok, so the valve train is all done and it's a thing of beauty! And it works! Well at least in Inventor it works... This is one complicated system. It's one thing to reproduce it with todays design tools but imagine doing this back in the 30's. These guys were good. I did print a few test parts and I do have one working valve/rocker. Up next is the camshaft drive which I will base the design on the Bentley's. Here are some pictures, screen shots and videos of the finish valve system.

test valve and rocker arm

Test piston and crank



the full valve train in motion
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And test valve and rocker arm in motion
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[François]

I made another test print to see if the valves could be actuated via the camshaft. It appears that they can but I only put in 4 valves. I'm a long way from having 32 working valves. The test did show me where I need to make design modifications. All in all, I'm happy with the result and it was really fun to do but still not sure if it will go into the final engine.




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[François]

After a month off, I'm back on the hydra coupe.

Althougt the design is not 100% done, I started printing some parts. Back on october, I printed a test engine head with a few valve and rockers. I learned a lot from it and made a few design changes. So I reprinted the full head and after a first fail, I think I have something that should be good. I'm still aiming on having a working valve train and this adds to the precision and level of detail I need to but in. I'm always impressed by what comes out of the printer. This is really a case of 'garbage in, garbage out' so I must be feeding the printer good stuff because the results are very nice!!

 

[Daniel20]

Thats incredible detail François. I know something of what it takes to draw that up in 3D.

 

[François]

More work done on the engine head, I printed a boat load of small parts. I actually have 2 head castings printed, one is perfect and one has a few flaws. I'm using the flawed one as a test bench to make sure my fits are good and that what needs to move move's correctly. So I fitted a partial camshaft along with the bevel gear setup and one rocker/valve and hooked it up to my dremel and let her rip. It ran like clockwork. Here's a little video showing the rocker mouvement. I had to slow the video by 50% in order to see it move.


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And here are some pictures of the different parts printed

Valves

Rockers

The cam shaft (not final yet)



And the bevel gear housing (I borrowed the turret idea from the bentley blower)

 

[François]

I made good progress on the head today. All 32 valves are made and in place, painted the head casting flat aluminium and added some engine grime in the concaved areas, assembled and painted the camshaft complete with simulated grounded lobe surfaces (I used a chrome pen for this) and installed the exhaust valve rockers. The black finish on the rockers is done with a permanent marker, easy to apply, close to zero thickness and dries very fast.

I also made 16 aluminium push rods with spherical heads at both ends. These rods need to be exactly 1.000in long with both spheres in place, I was able to get them all within +- .002in.



To make the valve stems, I used flat headed stainless steel needles that I had to cut to the correct lenght (.530in). The lenght has to be precise if I want the valves to seat correvtly. To do this, I made a simple jig using a piece of hardwood that was cut to .530in thick. I then drilled a series of .030in diaand inserted the needles. My dremel with a cutting disk made quick work of it. I also made a small jig to cut the valve springs to lenght.





All valve components ready for assembly

And assembled



Painted camshaft

head assembled

remember, this is not a kit!!

 

[Peter Voogt]

I made good progress on the head today. All 32 valves are made and in place, painted the head casting flat aluminium and added some engine grime in the concaved areas, assembled and painted the camshaft complete with simulated grounded lobe surfaces (I used a chrome pen for this) and installed the exhaust valve rockers. The black finish on the rockers is done with a permanent marker, easy to apply, close to zero thickness and dries very fast.

I also made 16 aluminium push rods with spherical heads at both ends. These rods need to be exactly 1.000in long with both spheres in place, I was able to get them all within +- .002in.



To make the valve stems, I used flat headed stainless steel needles that I had to cut to the correct lenght (.530in). The lenght has to be precise if I want the valves to seat correvtly. To do this, I made a simple jig using a piece of hardwood that was cut to .530in thick. I then drilled a series of .030in diaand inserted the needles. My dremel with a cutting disk made quick work of it. I also made a small jig to cut the valve springs to lenght.





All valve components ready for assembly

And assembled



Painted camshaft

head assembled

remember, this is not a kit!!

Now you owned a VERY BIG WOW, François. Impressive scale technique.
Regards, Peter

 

[Daniel20]

You have created a truly amazing realistic look with that engine head.