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

[Big John]

It is easy to lose site of how really massive the car actually is even when compared with the Bentley.

Edited September 28, 2024 by Big John

[François]

The 3d model is slowly progressing.  I started the v16 engine bloc. I'm basing the design on the Auto Union type C engine but like pretty much everything else on this project, documentation very limited. All I have are a few pictures of a totaly assembled engine so the dimensions and inner parts will all have to come from my imagination ( no problem there, that's even more). I inserted a few bentley pistons and conrod just to have a better feel. Should be ok.

Block in car

Block with bentley parts in just for fun

 

I also finished the radiator assembly which includes the radiator cowling, rad core and blower.

Speaking of the blower, there's a schene in the movie where you can see the blower being activated. And when activated, the blower's front dome starts to spin. I would like to reproduce this and have it spin while the engine runs. Now the easy way to do this is to simply have the dome in line and coupled with the crank. But that whould be boring. What I did instead is to slightly offset the dome from the crank and added a few gears to speed up the dome's rotation in relation to the crank. I was able to get a 2.5:1 speep up ratio.

Here's the dome on the prop car

And here is mine

With a few gears added

And the completed radiator 

[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. 

 

 

 

 

 

[Kenmojr]

Wowzer, this is incredible...

[Mattilacken]

Nice work! Great details! i have several engines with such details thanks to GrabCad, and nice to be able to print them in 1:12!

[François]

Grabcad do have nice 3d models but unfortunately they don't seem to have a V16 that fit my needs and they are stactic. I wan't mine to have rotating parts.

[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. 

[BK9300]

That's intensely detailed!

[Big John]

Wild valve train detail and a very unique intake duct work being an integral part of the heads. Is this roughly based on a real layout or are you being tres creative? Wild stuff.

[François]

Thank you everyone. 

Big John,  the design is strongly based on the Auto Union V16 engine.  But, like stated before, aside from a few pictures there's very little info on the engine.  So I did get very creative. I have most of the rockers done, still need to do the cam shaft. I'll post some pictures tomorrow.  I'm test printing a partial bloc and head with a couple of pistons and valves to see if everything fits. Working pistons is a given, I'm getting pretty good at making these work at 1/12 scale but a working valve train is another ball game. Even though the car and it's engine are massive, they are still at 1/12 scale so the valves, rockers and cam shaft are relatively small. If I pull this of, it might be a first at this scale !!

Edited October 15, 2024 by François

[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

 And test valve and rocker arm in motion

 

 

 

[BK9300]

Not sure when you sleep . . .amazing!

[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. 

   

[Big John]

Very Cool, but how do you adjust the valve lash on the intake rockers?  Just kidding.  Looks like you are having too much fun.

[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!!

[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.

 

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 !!

 

Edited November 22, 2024 by François

[Bugatti Fan]

MARVELlous !

[François]

Today marks another step towards a fully working engine.  I printed a small portion of the engine bloc,  the clutch and the crank bevel gear. The reason fot this is to see if I can rotate the camshaft by rotating the clutch. Here's how the system work. A bevel gear is mounted on the crank shaft which is directly linked to the clutch.  This bevel gear rotates a vertical shaft going up to another set of bevel gears mounted on the camshaft. This is exactly the same system as found on the Bentley blower but with a few differences. First, it's a lot bigger, about twice as big. Second and most important difference is that on my Bentley model, these bevel gears rotated a simple shaft acting as the camshaft.  Nothing else happens. On the hydra engine,  there's an actual camshaft that, if everything goes to plan, will actuate 32 valves. Now we've seen that the valves can be actuated via the camshaft,  well at least one can as seen in this little video. 

 But to have a fully working engine, I need to be able to turn the camshaft by turning the clutch. 

So here's the bloc I printed with 2 pistons in place

and the clutch 

And here's the test I did where I was easily able to turn the camshaft by turning the clutch. 

 And a final picture showing the know painted camshaft housing and head bolted on the bloc.

So far so good!

[chris chabre]

amazing

[François]

After many hours of testing, modifying, reprinting and assembly, I finally have a fully working 1/12 scale V16 engine head!! 32 valves, 32 rockers,  16 push rods, 1 camshaft and some gearing. All working together. I'm really really happy with the result. 

I did have to make certain modifications and compromises.

I redesigned and reprinted all rockers with a different contact face to8 the valves.  I also redid all valve spring washers to better guide the springs and finally, I had to shorten all valve springs because there was too much combined pressure on the camshaft to easily rotate it.  The drawback to this is that some valves have very little mouvement.

Old rockers and valve on top

New ones on bottom

Some assembly pictures 

Pictures of completed head

And my 3d model

Video of valves moving,  you have to watch very carefully to see the movement 

 And video of valve train in action (accelarated x4)

 

[BK9300]

Fabulous feat in miniature, François - hope your camshaft holds up against the hard surface push rod ends!  Hard to imagine all the knowledge brought to bear to make this actually work.

[Big John]

Wild, François! Perhaps you can have the camshaft machined so the lobes don't wear away so quickly.  You are just having too much fun.

[François]

So far, the plastic did not wear. The resin I use is very hard and the groove that you see on the lobes is the chrome paint being rubbed off, there's aslo a little bit of grease that adds to the wearing effect. Naturally,  this thing is not meant to be run often so I'll have to control myself because it's really fun to see those little rockers move!!

[CrazyCrank]

Dropped my jaws on the floor, again ! 👍