1/3 scale DOHC V8 Engine

satech04 · Jun 12, 2024

Hi all,

After building Steve's wonderful Demon v8 I decided to try building an engine of my own design. Having built a pushrod v8, I decided to try a DOHC engine... with 32 valves. We'll see if I regret that decision. I'm about 1/4 of the way through designing it up in CAD, then I'll start on the fun part: machining!

The engine is based off of a Ford Coyote 5.0. I'm going to try building a helical supercharger to go with it.

Specs:
1.2" bore x 1.2" stroke so 178cc
Full oil and water systems
HUGE valves at .479 intake and .415 exhaust
.120 valve lift

One head almost finished, except for oil and water porting.

Crank and pistons are basically done

More detail on the head. It's going to be a very complex part

GreenTwin · Jun 12, 2024

That is a nice start.

I would think the 4-valve design could be challenging, but I think it is possible, and you never know what is possible until you try something.

Good luck.

.

gbritnell · Jun 13, 2024

So shim under bucket design? A ton of work there!

satech04 · Aug 10, 2024

It's actually got a shim on top of the bucket. It sits in a little pocket. Hopefully it'll stay put!

satech04 · Aug 10, 2024

Long time coming, but time for an update. I enjoy the actual machining far more than sitting and doing CAD... but it has to be done.

I've made a good bit of progress on the motor. I've gotten the water pump, oil pump and related passages done, finished up the various covers, and started on the timing and serpentine belt arrangements. I like seeing the belts move, so I decided to do the timing externally.

Detail on the water pump. I'm trying an impeller design, hopefully I can get enough flow. It's 1.5" in diameter, and I'll be spinning it at about 1.25:1 to the crank.

Oil pump:

It took a while, but I figured out how to model a proper gerotor oil pump. We'll see if I can manage the tolerances needed:

satech04 · Aug 10, 2024

Still a lot left to be done! CAD says there's already over 700 parts, but about 250 of them are fasteners. A lot of this will be CNC milled, because as much as I enjoy manual machining you can do a lot more with CNC.

I've started my research on the supercharger. I want to do a real screw-type blower, which means some crazy complex shapes for the rotors. I'll have to see if I can find somewhere to have them 5-axis machined, maybe one of those Chinese machining/3d printing sites?

I found this compressor online, even though it's 3d printed he actually gets a little bit of boost!

Sparky_SC · Aug 11, 2024

satech04 said:
Still a lot left to be done! CAD says there's already over 700 parts, but about 250 of them are fasteners. A lot of this will be CNC milled, because as much as I enjoy manual machining you can do a lot more with CNC.

I've started my research on the supercharger. I want to do a real screw-type blower, which means some crazy complex shapes for the rotors. I'll have to see if I can find somewhere to have them 5-axis machined, maybe one of those Chinese machining/3d printing sites?

I found this compressor online, even though it's 3d printed he actually gets a little bit of boost!

I am wondering if you could pull it off on the lathe using a form tool and a threading operation? Probably another of my crazy ideas.

Adaware · Aug 15, 2024

Looks like an interesting project

Just machining and no casting?

The gerotor oil pumps used in various Chinese GY6 engines engines can be found dirt cheap and the quality seems OK. I have one on my desk (for a GY6 50 139QMB engine) that I can measure if you want to test it in your design.

GreenTwin · Aug 15, 2024

The 3D modeling looks great.
Watching as this engine progresses.

.

mayhugh1 · Aug 15, 2024

First class modeling. What are you using for source documents? Do you have one of the Tritons to work from? - Terry

satech04 · Aug 16, 2024

mayhugh1 said:
First class modeling. What are you using for source documents? Do you have one of the Tritons to work from? - Terry

Thanks. I've just been using a spec sheet I found online, and lots of pictures. It's probably not a perfect scale replica, but pretty close.

satech04 · Aug 16, 2024

Adaware said:
Looks like an interesting project

Just machining and no casting?

The gerotor oil pumps used in various Chinese GY6 engines engines can be found dirt cheap and the quality seems OK. I have one on my desk (for a GY6 50 139QMB engine) that I can measure if you want to test it in your design.

Thanks, and yeah, everything will be completely billet. I don't have much experience with casting yet.

That's an interesting idea about the oil pump gears, I have worked with that engine quite a bit. I currently have the outer gear at 1.35 in, not sure if the GY6 gears are about that size?

Adaware · Aug 17, 2024

satech04 said:
Thanks, and yeah, everything will be completely billet. I don't have much experience with casting yet.

That's an interesting idea about the oil pump gears, I have worked with that engine quite a bit. I currently have the outer gear at 1.35 in, not sure if the GY6 gears are about that size?

Nah, for this particular engine it's smaller. Perhaps more suited for 1/4 size engines.
Outer gerotor ring gear has a diameter of 23mm and the width is 8,75mm.

Ghosty · Aug 18, 2024

That's an interesting idea about the oil pump gears, I have worked with that engine quite a bit. I currently have the outer gear at 1.35 in, not sure if the GY6 gears are about that size?

Have you thought about motorbike oil pumps, this is one out of a Yamaha 500 single, 29mm dia, only problem is it is 12mm thick. Just a thought.
Cheers
Andrew

truyentu · Sep 5, 2024

hello Satech04,can you help me how did you make calculation to make the profile of the camshaft (base radius,flank radius,..).these genius math equations and kinematics is so hard so me

http://www.makalesistemi.com/panel/...b5e2d4b7f8963e7535d45e7aa/37506f903036f02.pdf

satech04 · Oct 29, 2024

truyentu said:
hello Satech04,can you help me how did you make calculation to make the profile of the camshaft (base radius,flank radius,..).these genius math equations and kinematics is so hard so me

http://www.makalesistemi.com/panel/...b5e2d4b7f8963e7535d45e7aa/37506f903036f02.pdf
View attachment 159504

I found a nice spreadsheet on one of these forums somewhere that calculates the cut dimensions from the base dia, flank radius, etc.
As far as the calculations for the cam geometry, I just guessed

satech04 · Oct 29, 2024

It's time for an update!

The CAD is basically done. I have the blower, cooling passages, flywheel, crank sensor, pulleys...
I still have to figure out the coil packs, and figure out what carb I'm going to use.

For the headers, I'm planning on bending some thin-wall 316 tube and welding. I did that on the previous engine I built and it worked pretty well.

Supercharger:

I have gears in the back for timing, and the front bearing plate has lots of cutouts for intake. I found some ceramic resin for resin 3d printers that should be temperature resistant up to 250c, so I'm going to try printing the rotors out of that.

satech04 · Oct 29, 2024

Also, I got itchy to start making stuff again so I started on the machining.

Intake manifold:

Intake manifold lid:

Lots of 3d profiling on the lid. It has a gentle curve just to look extra nice:

After a light polish:

I started on the crank too. I made this block to hold the crank blank in a 3-jaw so I can machine the offset journals. I can use the set screws to hold the blank in place, and the scribe line matches up with lines scribed on the outside of the blank for clocking:

Drilling the center holes:

I first tried turning the crank journals on the lathe, but that didn't end up working out too well. The parting tool I was using didn't like the interrupted cut, especially out of harder 4140. My previous crank was 1144, which is much easier to turn. I ended up setting it up on the rotary like a crude 4th axis:

I'm planning on grinding the journals in when it's done, so I'm not too worried about the bottom not being flat.
The first journal turned out pretty good:

I then proceeded to index the blank 90 degrees the wrong way... so I'll have to try that one again... We'll call it a practice run

Also got the rear cover and intake risers done:

satech04 · Oct 29, 2024

The block and heads are by far going to be the most challenging parts I've made yet. There's so many angles and setups. To make that easier, I'm going to try using a dividing head to index the part around and then run lots of different operations on the CNC. We'll see how it goes.

The stock for the block needs to be 6"x6"x8", very challenging to find cheap. I have a few ideas in mind, hopefully it works out.

So many passages and angles in the head! It should all be doable, but I count at least 16 different orientations.

stevehuckss396 · Oct 29, 2024

This should be good!

1/3 scale DOHC V8 Engine

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