Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
11/13/23 2:33 p.m.

I fell down a YouTube rabbit hole last night and now have a new item for my Christmas wishlist: Instructions to build your very own real, running engine from scratch:

https://www.hemingwaykits.com/category-84

 

Has anybody ever seen these before? I feel like I've been missing out on an even crazier little corner of the world than ours.

APEowner
APEowner GRM+ Memberand UltraDork
11/13/23 2:46 p.m.

I haven't seen that particular engine before but scale model engine building is indeed a fascinating corner of the world. It's also one that I've been deliberately trying to avoid exploring too much lest I fall down an expensive and time consuming rabbit hole.

Tom1200
Tom1200 PowerDork
11/13/23 4:07 p.m.

In reply to Tom Suddard :

Look up a guy named Alan Millyard; he does wild stuff like building V12s by combing two Kawasaki KZ1300 motors and making 4 cylinder two strokes using a Kawasaki triple. 

ShawnG
ShawnG MegaDork
11/13/23 4:10 p.m.

If you haven't heard of John Britten, you should do some googling.

stroker
stroker PowerDork
11/13/23 4:38 p.m.

I'd love to build a V-4 500cc two stroke motorcycle engine...  Just pop the cylinder/architecture off a 250cc motocross bike.  All you'd have to build is the crankcase/crankshaft and then CNC the crankcase to include a compatible gearbox...  

Slippery
Slippery GRM+ Memberand PowerDork
11/13/23 4:41 p.m.
stroker said:

... All you'd have to build is the crankcase/crankshaft and then CNC the crankcase to include a compatible gearbox...  

Easy peasy cheeky

stroker
stroker PowerDork
11/13/23 4:47 p.m.
Slippery said:
stroker said:

... All you'd have to build is the crankcase/crankshaft and then CNC the crankcase to include a compatible gearbox...  

Easy peasy cheeky

It's been done before...

z31maniac
z31maniac MegaDork
11/13/23 4:53 p.m.

I really want to build one of those small engines and put it in an RC car. 

While an RC truck or drifter sounds fun, I don't know if there is anyway where to use them locally. Bashing around by yourself tends to get boring pretty quickly.

APEowner
APEowner GRM+ Memberand UltraDork
11/13/23 4:57 p.m.
stroker said:

I'd love to build a V-4 500cc two stroke motorcycle engine...  Just pop the cylinder/architecture off a 250cc motocross bike.  All you'd have to build is the crankcase/crankshaft and then CNC the crankcase to include a compatible gearbox...  

I wonder if that would be any narrower than an inline 4.  Since the crankcase is part of the intake path you couldn't share crank throws or crankcase sections and by the time you add the required crankcase webbing, seals and crank throws there's likely to be no benefit to the V shape.  Except for what I suspect would be an awesome sound! 

Driven5
Driven5 PowerDork
11/13/23 4:59 p.m.

I still can't see putting the time and effort into building a working 'model' engine, when I could just build it big enough to be a 'real' engine instead. But if that's your thing, you might want to check this place out:

https://www.homemodelenginemachinist.com/

For a full-scale 'build your own engine from scratch' rabbit hole, check out the YouTube channel documenting the work of Pete Aardema and Kevin Braun with their home-built LSR engines:

https://www.youtube.com/@GregQuirin/videos

stroker
stroker PowerDork
11/13/23 5:50 p.m.
APEowner said:
stroker said:

I'd love to build a V-4 500cc two stroke motorcycle engine...  Just pop the cylinder/architecture off a 250cc motocross bike.  All you'd have to build is the crankcase/crankshaft and then CNC the crankcase to include a compatible gearbox...  

I wonder if that would be any narrower than an inline 4.  Since the crankcase is part of the intake path you couldn't share crank throws or crankcase sections and by the time you add the required crankcase webbing, seals and crank throws there's likely to be no benefit to the V shape.  Except for what I suspect would be an awesome sound! 

Kenny Roberts had the freedom to do whatever he wanted with the Proton design, which was the last "factory" 2 stroke in MotoGP.  They went with a V-3.  Yamaha left the TZ750 (inline 4) and went to a V4.  Suzuki had the Square 4 and Honda had a V-3 before Proton did.  All this is memory so don't hold me to it.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
11/13/23 6:24 p.m.
Tom1200 said:

In reply to Tom Suddard :

Look up a guy named Alan Millyard; he does wild stuff like building V12s by combing two Kawasaki KZ1300 motors and making 4 cylinder two strokes using a Kawasaki triple. 

Guy named Foucault (I think) does something similar for some weird rally-like class in France where they have a 2 liter naturally aspirated limit. So he makes crankcases to combine 660cc motorcycle heads with three or four banks, and puts them in a 205 T16.  450hp from a 12 or 16 cylinder 2 liter engine.  They sound like dentist drills.

secretariata (Forum Supporter)
secretariata (Forum Supporter) GRM+ Memberand UltraDork
11/13/23 6:26 p.m.

My wife's grandfather built 2 different working miniature steam engines from scratch. Each was mounted on a dime. Supposedly, one is in the Smithsonian's collection.

NOHOME
NOHOME MegaDork
11/13/23 7:24 p.m.

Was thinking more along the lines of a big metal billet and your milling machine. I thing there is a guy called Steve Morrison who does this with LS style engines and goes very fast down the quarter mile.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
11/13/23 7:39 p.m.
APEowner said:
stroker said:

I'd love to build a V-4 500cc two stroke motorcycle engine...  Just pop the cylinder/architecture off a 250cc motocross bike.  All you'd have to build is the crankcase/crankshaft and then CNC the crankcase to include a compatible gearbox...  

I wonder if that would be any narrower than an inline 4.  Since the crankcase is part of the intake path you couldn't share crank throws or crankcase sections and by the time you add the required crankcase webbing, seals and crank throws there's likely to be no benefit to the V shape.  Except for what I suspect would be an awesome sound! 

Mercury Marine did it just fine with V6 engines.  The cylinders were closed off at the bottom and the rod just went through a little slot.  Exhaust scavenging did the rest.

 

A 2 stroke is the only way to have an even firing 60 degree V6 with shared crank throws, and it appears that MM did use shared crank throws and had a little full-circle divider between the rods, which only adds a small amount of length to the engine.  60 degree 4 stroke V6s have cranks that look a lot like 4 main inline six cranks, these are even shorter.

Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
11/14/23 9:29 a.m.

I was really hoping you all would say "no no that's a terrible idea don't do it!"

DeadSkunk  (Warren)
DeadSkunk (Warren) UltimaDork
11/14/23 9:40 a.m.
Tom Suddard said:

I was really hoping you all would say "no no that's a terrible idea don't do it!"

You must be new here.......we never say don't do it.

WonkoTheSane
WonkoTheSane GRM+ Memberand UltraDork
11/14/23 10:25 a.m.
DeadSkunk (Warren) said:
Tom Suddard said:

I was really hoping you all would say "no no that's a terrible idea don't do it!"

You must be new here.......we never say don't do it.

Agreed.. It's significantly more likely to be "No, no, that's a terrible idea.  When do we start?"

Kreb (Forum Supporter)
Kreb (Forum Supporter) GRM+ Memberand PowerDork
11/14/23 10:26 a.m.

My dad went to high school with a kid who built a working rotary engine in the schools machine shop. He'd be old now, but I always wondered what the career arc would be of someone so talented so early. 

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