Managed to get a near-full parts list for the project I had in mind. It will likely cost me about 400 euro's, and that's excluding unforseen issues. So I won't be building this project.
What the project plans were:
I had planned to put a "RHB31/VZ21" turbo onto a 3hp 127cc briggs and stratton engine. This engine would produce way too little cfm to get this turbo to spool, and I found a theoretical way to get passed this: intentional valve float.
I had planned on weakening the exhaust spring, so I would be getting horrible valve float. That would kill both gaining more RPM and more power. But as I had planned it to be a static party trick, the nosedive in power, wasn't an issue. If I'd managed to get horrible exhaust valve float around 3300 rpm, I'd still be getting a tiny bit of boost from the turbo. This would mean that the exhaust gasses WOULD get expelled from the cylinder. Meaning there WOULD be an RPM gain possible. And because the power gains wouldn't matter (only the sounds and fire spitting of this turbo and engine setup), it should still be able to boost-loop to the moon. According to my research, I'd have to add a rev limiter (with a spark cut system lust like a kill switch), set to about 4200 rpm. That way, doing 10 second runs, all the internals should last long enough. Running 1:50 2-stroke fuel mix, would cool down the valve seats some, and would reduce the bad effects of "valve banging". (valve banging on the seats with the horrible valve float) With the carb infront of the turbo, you'd need to keep the intake valve perfectly closed during ignition, hence the question about better intake valve springs. And to keep the boost going up and up and up, you'd also want an very hot exhaust, so the gasses would keep maximum pressure. So you'd have to mount the turbo almost onto the engine block itself. Which should work decently well, with these ancient flatheads. Tape around the exhaust from the engine to the turbo too.
This way, the turbo pressure could creap up to 10-15 psi. But it would actually cripple hp output when the exhaust valve starts to float. A basic car alternator would have been a perfect dummy load, to keep everything working as intended. This setup would have been crazy loud, spit big near constant flames, have all the turbo spool noises and be rev-banging non-stop.
Can't find anyone having done this before, so in these days, that's kinda rare. But I'm just not able to afford the price for the components to make it all work. Good luck if anyone wants to take this idea and call it their own!
