Hi there! I’d like to share with you my write-up and idea for modifying the small ETZ engines using a piston from the Polish SHL 175 M11. The videos are in Polish, but I tried to add subtitles, and nowadays the automatic translation works pretty well too.
Historically, the idea for this modification, as the older folks say, comes from paragliders, who converted small ETZ engines to power propellers. The modification was never widely developed, and since I built the first engine with this piston 12 years ago—which still runs today and has proven durable and reliable, at least in terms of the crank assembly—I recorded a few videos together with my son just for fun, showing how we rework this little engine.
As for the modification itself, it’s a really successful combination. The engine doesn’t lose any of its usability, the useful RPM range stays the same, but the power and torque curves are significantly higher. The carburetor and exhaust remain stock, with only the main jet in the standard Bing 53 changed from 105 to 112 according to Bing specs.
In the videos, I show the whole process—from calculations to the 3D design of the cylinder head. There are ready-to-download models as well. If this caught your interest, you’re welcome to check it out. I’ve added links to the dynocharts below.
https://www.youtube.com/watch?v=vpbuCvc ... E0bhHxP4wz - playlist
https://intr.usermd.net/pliki/175/wykre ... esult2.pdf - dynochart
