F1, motorcycle, short stroke type engines.

[hetfield]

1/2 the scale doesn't mean 1/2 the ccm but you already know that, your engine will be 375ccm

Good point! I didn`t even think about it!

I would have done it in full-scale, but my 5axis mill isn`t big enough!
Maybe it would be pointless to spent so much time, for so little power!
And if i would rev it, at 40 000 rpm. It means that i have to forge the pistons and conrods.

Hmm... back to basics!

[Adaware]

You do realize that if you are going to follow the exact dimensions of the engine even when you scale it down, that Ferrari uses pretty exotic materials that comes with a exotic price and you might need special tooling to fabricate the parts and many of the parts may be forged or in other ways special hardened. You cant get all the important details of each component just by looking at pictures and even if you did it would be a hell of a job to make them. CNC is a neat thing but it its not better than the man who programs them and you need vast enginering experience to tackle this but, for all i know you might have that experience and i sincerely appreciate your effort

I have never made an engine before and i'm not shure i can get started and actually have a running engine but hey, it's a hobby.

Ps, if you scale the horsepower to the displacement of the engine, you can in theory be pushing 100hp on 375cc's.....

[hetfield]

You do realize that if you are going to follow the exact dimensions of the engine even when you scale it down, that Ferrari uses pretty exotic materials that comes with a exotic price and you might need special tooling to fabricate the parts and many of the parts may be forged or in other ways special hardened.

I already have the materials, even gr5 titanium for the rods and valvetrain.
And the tooling isn`t a problem.
Slightly bigger problem is, that i don`t have a underpressure tempering furnace (normal version, i do have) for titanium forging.
And the forging mould for the crank, would be so complex, that it is not worth of doing just one piece!

Maybe i have to get, a little more information about engine designing (not exactly my strongest sector, as you might guess!)

As you said, it`s only a hobby.

[Adaware]

You can still make a racing style engine you know but alittle more simple, you allready have training in drawing so why not take a swing at it?

I am pretty courious on how you where going to make the long thin parts like valvestems and so on, any thoughts about it?

[65ShelbyClone]

Slightly bigger problem is, that i don`t have a underpressure tempering furnace (normal version, i do have) for titanium forging.
And the forging mould for the crank, would be so complex, that it is not worth of doing just one piece!

Depending on your target RPM for the engine, the rods and valves probably don't need to be forgings. If you are shooting for 30,000-40,000 rpm, that might be different, but 18,000-20,000 should be a lot less difficult to build for. Regarding the crankshaft, I would bet money that it is a billet piece and not forged.

I don't know how true to the original you want it to be, but think you could also save some headache by using coil spring valvetrain. Many of the 250cc Japanese 4-cyl bikes have factory redlines in the 18,000-19,000rpm range and that's with heavier steel valves.

[hetfield]

I am pretty courious on how you where going to make the long thin parts like valvestems and so on, any thoughts about it?

There is two way to make the valves.
The other way is turning and grinding.
But if i use Nimonic 80A steel. easiest way again is forging, and then grinding.

[elmerfud]

Hetfeild, your work is almost factory cad in appearance.
You have put me in the shade pal.
Keep up the good work!

[hetfield]

Hetfeild, your work is almost factory cad in appearance.
You have put me in the shade pal.
Keep up the good work!

Thanks!
I have runned a little calculations with one cylinder 37.5cc. And best performance is 7.38 kw @ 35000rpm and 3.15 nm @ 5000rpm.
With following cam:
Intake opens 5dec closes 20dec
Exthaus opens 55dec closes 10dec

[dynosor]

Thanks!
I have runned a little calculations with one cylinder 37.5cc. And best performance is 7.38 kw @ 35000rpm and 3.15 nm @ 5000rpm.
With following cam:
Intake opens 5dec closes 20dec
Exthaus opens 55dec closes 10dec

I can see how one can calculate power as a function of air pumped and fuel burned, multiplied by some overall volumetric and thermal efficiencies, but how did you determine the RPM at which peak power would occur? Your torque peak RPM seems low compsred to the peak power RPM - does your design have variable valve timing?

[hetfield]

I can see how one can calculate power as a function of air pumped and fuel burned, multiplied by some overall volumetric and thermal efficiencies, but how did you determine the RPM at which peak power would occur? Your torque peak RPM seems low compsred to the peak power RPM - does your design have variable valve timing?

No i don`t. It would be difficult to design.

[elmerfud]

Wow, 35k rpm, 20.7 stroke valves say 21mm or so.
Maybe a desmo setup could hold the revs, a steel spring I feel would not.
Maybe a single cylinder test motor to prove valvetrain before you build all ten.
If you are building pnuematic valves the discoveries you make for sealing them reliably I would keep top secret, a patent or a business idea.
Pnuematic valves are still distant from mainstream and i consider them exotic. (if that counts for anything)
35k, you'll get a job at ilmor or cosworth, exciting stuff!

[hetfield]

Wow, 35k rpm, 20.7 stroke valves say 21mm or so.
Maybe a desmo setup could hold the revs, a steel spring I feel would not.
Maybe a single cylinder test motor to prove valvetrain before you build all ten.
If you are building pnuematic valves the discoveries you make for sealing them reliably I would keep top secret, a patent or a business idea.
Pnuematic valves are still distant from mainstream and i consider them exotic. (if that counts for anything)
35k, you'll get a job at ilmor or cosworth, exciting stuff!

Yes. the sealing might be a little challenge!
But the camshaft is rotating "only" at 17000rpm, and the valves are so light that it might work!

I am going to build a single cylinder proto. Because there is so much to learn, before it runs!

PS:Megasquirt doesent support revs over 19000rpm. any suggestions?