Hirth
The well regarded Hirth line of small engines out of Germany continues mechanically unchanged in 2023. What has changed, as we first reported last year, is new Hirth engine sales are now handled by Phil Yager at Northwest UAV in Oregon. Hirth engine service, such as parts sales, overhauls, used engines and Blue Max oil, continue to be handled by longtime Hirth specialist Matt Dandar in Ohio. Dandar reports he sold approximately 3000 Hirth engines to the ultralight and VLA market while he was the Hirth distributor and he wants to stay available as long as possible to help keep those engines running.
Just after our Engine Buyer’s Guide went to press last year, Hirth had a substantial price increase as general inflation took hold, so customers have had to digest that. Luckily, Yager reports stability since then. Costs are about the same (but Yager must quote on a per-engine basis due to fluctuating exchange rates so we can only give estimated guidelines here in our guide) and lead times remain normal. The challenge is shipping costs, which have nearly tripled.
As for the powerful, precision-built two-stroke engines themselves, they are mostly offered with or without a gearbox (with many gear ratios to choose from), and could have other important options such as adding a centrifugal clutch to the drive, an electric starter or oil injection or electronic fuel injection (We’re displaying the base engine for each model in our charts.) Furthermore, there can be tuning differences within an engine model line, meaning power and torque peaks can be selected between “high” and “low” options depending on if maximum peak power or maximum cruise fuel efficiency is more valued. Lower power Hirth engines are air-cooled while the larger engines are water-cooled.
Rotax
All two-stroke Rotax engines dropped out of production in 2021 except the 582 UL, which went out of production last year. There is still “a good supply” of 582 UL engines in stock, however, so they can still be purchased new from Rotax dealers, but now only in E trim and only with the 2.62:1 gear reduction. Our guess is new 582s will be available into 2024; likewise parts support should continue for some years. This venerable two-stroke manages to carry on.
| Model | Drive Type | Horsepower | Weight | Price |
|---|---|---|---|---|
| BRP Rotax | ||||
| 582 UL inline WC twin | geared | 65 hp @ 6500 rpm, carbureted | 104 lb w/o radiator, w/ E gearbox and exhaust | $8149 E drive |
| Hirth and www.recpower.com | ||||
| F-23 opposed twin | belt drive | 50 hp @ 6150 rpm | 71 lb, free air w/ starter, exhaust | $9800 w/ electric start |
| 3202 inline twin | gearbox | 55 hp @ 5500 rpm | 79 lb, fan cooled w/ starter, exhaust; opt. gearbox adds 19 lb | $10,100 w/ electric start |
| 3203 inline twin | gearbox | 65 hp @ 6300 rpm | 79 lb, fan cooled w/ starter, exhaust; opt. gearbox adds 19 lb | $9380 w/ electric start |
| 3503 inline WC twin | gearbox | 70 hp @ 6500 rpm | 79 lb, w/o radiator, w/ starter, exhaust; opt. gearbox adds 19 lb | $10,300 w/ electric start |
MZ 201 and 202??
Next year you might want to consider adding Polini and Vittorazi to this list. A number of ultralight manufacturers have already switched over to them to fill the gap left by Rotax.
I double up on the MZ line of engines…….