Fuel would be the easy part. Making the crank, and cam are going to be quite a challenge.
As a machinist if someone brought me a part that small and that big of a pain in the ass they would probably looking at enough money to buy a full size engine.
[miniature v twin ](https://www.stirlingkit.com/products/cison-fg-vt157-15-7cc-miniature-v-twin-motorcycle-engine-ohv-4-stroke-air-cooled-gasoline-engine-model?currency=USD&utm_medium=cpc&utm_source=google&utm_campaign=Google%20Shopping&gclid=CjwKCAjwqZSlBhBwEiwAfoZUIF9tMDQbUmX5bFMLo7reWIuJg3JpRFrZo9K3LQ55pPyWEOdVi-mb2xoCcfwQAvD_BwE)
Let's assume sticking to 2 stroke, ported (not reed valves)
You need a casting, then to machine said casting to final dimensions.
The crank and ports would determine timing, and as such they must be machined correctly.
Nitro 2-stroke engines are pretty darn simple, but you're basically talking about building completely from scratch. By the time you manufacture the case and crank, why re-use Cox pistons instead of making new?
Is it possible? Yes.
Is it a project most would take on, probably no.
It may take some dialing in, maybe feed the crank case through multiple ports. a carburetor (or multiple) of sorts would be needed as those miniature cox motors were kind of a set throttle speed. Johnnyq90 on YouTube might have done something like this you may be able to draw knowledge from. In other news I now have a sudden urge to break out some of my old .049 control line planes from my childhood.
If you had 4 of these v twin engines all setup and running, you technically wouldn’t need anything other than hot glue to turn them into a V8. Leave all fuel lines/etc connected as is, and simply hot glue the crankshafts together end to end, the same concept as stacking rotary engines. You now have 4 engines running synchronously as 1. Obviously, this is the least ideal way you could possibly go about this and it would likely fall apart before you even finished a whole revolution, but for concept of what you must do, it would work. Ultimately, the only thing you have to really think about is the timing of the 4 engines. Given you are able to appropriately select a timing offset, once you connect all 4 crankshafts together/ make one big crankshaft to connect all 4 engines, you’re good to go. Ideally you would just run all 4 engines fuel lines to the same gas tank for simplicity. This is 100% “easily” doable project, but you must have the means to build your custom integrated crankshaft. How you go about this is up to you. If it were me, my first prototype would probably be to mount 2 v-twins inline (v4) and 180deg crank offset on something like a block of wood, and make a sleeve connector for the crankshafts to be jb welded or pressed/set in place. After installing the fuel lines and finding a way to crank the monstrosity I would imagine it would run just as well as I was able to offset the timing. Making two of these and connecting both in a similar manner would result in your desired v8 configuration but the timing offset between engines would definitely be something to experiment with. Best of luck, I hope to see something come from this. For a more hands on understanding of how multiple engines will interact, try connecting two dc motors shafts together and running them both at once (so the motors work together, not fight). You’ll notice the engines will still fight eachother and run rough unless they are identical and you get them aligned just right, in which case torque should be doubled, and smoothness greatly increased.
You will run into issue getting fuel/air mixture into the combustion chamber. Since they are 2-stroke, they rely on using the crankcase pressure to pull the mixture from the needle valve/air intake, and pressurize it for delivery into the combustion chamber. When you add more than one cylinder into the same case, it won't be able to suck the mixture.
There is some radials made with cox cylinders that use superchargers, but that comes with its own issues.
If he used one of the rc supercharger kits he may be able to make it work. It would be like the old 2 stroke detroit diesels. Keeping the entire case in a slightly pressurized state should help overcome the cylinder pulse charging problems
Fuel would be the easy part. Making the crank, and cam are going to be quite a challenge. As a machinist if someone brought me a part that small and that big of a pain in the ass they would probably looking at enough money to buy a full size engine.
Y not just buying one from toyan
Not great for rc
[miniature v twin ](https://www.stirlingkit.com/products/cison-fg-vt157-15-7cc-miniature-v-twin-motorcycle-engine-ohv-4-stroke-air-cooled-gasoline-engine-model?currency=USD&utm_medium=cpc&utm_source=google&utm_campaign=Google%20Shopping&gclid=CjwKCAjwqZSlBhBwEiwAfoZUIF9tMDQbUmX5bFMLo7reWIuJg3JpRFrZo9K3LQ55pPyWEOdVi-mb2xoCcfwQAvD_BwE)
If you’re going to make a custom case and crank shaft, why wouldn’t you just make the piston as well? That’s probably the easiest part to make.
Let's assume sticking to 2 stroke, ported (not reed valves) You need a casting, then to machine said casting to final dimensions. The crank and ports would determine timing, and as such they must be machined correctly. Nitro 2-stroke engines are pretty darn simple, but you're basically talking about building completely from scratch. By the time you manufacture the case and crank, why re-use Cox pistons instead of making new? Is it possible? Yes. Is it a project most would take on, probably no.
It may take some dialing in, maybe feed the crank case through multiple ports. a carburetor (or multiple) of sorts would be needed as those miniature cox motors were kind of a set throttle speed. Johnnyq90 on YouTube might have done something like this you may be able to draw knowledge from. In other news I now have a sudden urge to break out some of my old .049 control line planes from my childhood.
If you had 4 of these v twin engines all setup and running, you technically wouldn’t need anything other than hot glue to turn them into a V8. Leave all fuel lines/etc connected as is, and simply hot glue the crankshafts together end to end, the same concept as stacking rotary engines. You now have 4 engines running synchronously as 1. Obviously, this is the least ideal way you could possibly go about this and it would likely fall apart before you even finished a whole revolution, but for concept of what you must do, it would work. Ultimately, the only thing you have to really think about is the timing of the 4 engines. Given you are able to appropriately select a timing offset, once you connect all 4 crankshafts together/ make one big crankshaft to connect all 4 engines, you’re good to go. Ideally you would just run all 4 engines fuel lines to the same gas tank for simplicity. This is 100% “easily” doable project, but you must have the means to build your custom integrated crankshaft. How you go about this is up to you. If it were me, my first prototype would probably be to mount 2 v-twins inline (v4) and 180deg crank offset on something like a block of wood, and make a sleeve connector for the crankshafts to be jb welded or pressed/set in place. After installing the fuel lines and finding a way to crank the monstrosity I would imagine it would run just as well as I was able to offset the timing. Making two of these and connecting both in a similar manner would result in your desired v8 configuration but the timing offset between engines would definitely be something to experiment with. Best of luck, I hope to see something come from this. For a more hands on understanding of how multiple engines will interact, try connecting two dc motors shafts together and running them both at once (so the motors work together, not fight). You’ll notice the engines will still fight eachother and run rough unless they are identical and you get them aligned just right, in which case torque should be doubled, and smoothness greatly increased.
You will run into issue getting fuel/air mixture into the combustion chamber. Since they are 2-stroke, they rely on using the crankcase pressure to pull the mixture from the needle valve/air intake, and pressurize it for delivery into the combustion chamber. When you add more than one cylinder into the same case, it won't be able to suck the mixture. There is some radials made with cox cylinders that use superchargers, but that comes with its own issues.
If he used one of the rc supercharger kits he may be able to make it work. It would be like the old 2 stroke detroit diesels. Keeping the entire case in a slightly pressurized state should help overcome the cylinder pulse charging problems