Tutorial request: boxer engine (aka flat engine)

I’m building a car and initially I wanted it to have my design of simple thruster based engine (two thrusters attached on the opposite sites of a rod making the rod spin at high speeds and connected with wired clutch to secondary rods which transfer the power to the car’s wheels.)The thing is, this kind of design is unstable unless I add significant weight to the rods. That makes the engine a bit too heavy for the car. Also, let’s not forget that although this design does the job, it’s still noobish.

There are tutorials on youtube explaining how to build engines but the thing is they are usually too big. When I find an engine that’s compact and powerfull enough for my car (which is going to be a small offroad buggy kind of car), there’s no tutorial how to do it. There is sometimes a duplicator file but I don’t want to just take somebody else’s design. I want to make my own design but first, I want to know how. None of the tutorials I found on Youtube, for example, show how to add those realistic engine sounds.

Just so you can understand how small and how powerfull of an engine it has to be, here’s a video to show you what I’m going for:

The reason why I’m asking for a boxer engine is because they are usually the most compact ones. If you have a design of a different engine but one that’s small, please make a tutorial too.

It can be video or just text tutorial with screenshots but please make it a complete one (include e2 codes and instructions how to add the engine sounds).

I know I’m asking for quite a lot here. I imagine making a tutorial isn’t a 5 minute job but once you’ve done that, you will be able to help more people than just me and therefore gather readers/viewers.

Thank you.