ROTAX 915 iS vs 916 iS
The engine choice on every ARGON order
Nineteen horsepower and 800 hours. The ROTAX 916 iS gives 160 hp for take-off against the 915 iS's 141, and it is overhauled at 2,000 hours against 1,200 - for 3.6 kg more weight and a higher price. Everything else is close enough not to decide anything: both are turbocharged, fuel-injected, four-cylinder engines running on ordinary road petrol, and their maximum continuous power is 135 and 137 hp respectively. Every figure here is ROTAX's own, from their published datasheets.
This matters to anyone ordering an ARGON, because the engine is the single biggest line in the build. The 916 iS is standard on the ARGON GTL and on the three-seat GTL Triple; the 915 iS is standard on the lighter ARGON 915 iS. Each is available as the option on the other.
Side by side
| ROTAX 915 iS | ROTAX 916 iS | |
|---|---|---|
| Take-off power | 141 hp (104 kW) at 5,800 rpm | 160 hp (117 kW) at 5,800 rpm |
| Maximum continuous | 135 hp (99 kW) at 5,500 rpm | 137 hp (101 kW) at 5,500 rpm |
| Weight, engine with gearbox, turbo and intercooler | 82.2 kg | 85.8 kg |
| TBO, time between overhaul | 1,200 hours | 2,000 hours |
| Full take-off power up to | Not published separately | 15,000 ft |
| Maximum operating altitude | 23,000 ft | 23,000 ft |
| Fuel | MON 85 / RON 95 / AKI 91 minimum - ordinary petrol, or AVGAS 100LL | The same |
| Certification | iS: ASTM compliant. iSc: certified to EASA CS-E | The same |
Where the 19 hp actually goes
Not into cruise speed. A gyroplane cruises on a fraction of its available power, and at 5,500 rpm the two engines are within two horsepower of each other - the ARGON GTL flight manual gives 23 litres an hour at 150 km/h at 3,000 ft whichever is fitted. The extra power is a reserve, and it is spent in three places: getting off a short or soft strip, climbing away two-up on a hot day, and carrying weight. That last one is why the three-seat Triple is a 916 aircraft.
Turbocharging is what keeps that reserve as you climb. Both engines are turbocharged, so they do not lose power with altitude the way a normally aspirated engine does - ROTAX publishes full take-off power up to 15,000 ft for the 916 iS.
The 23,000 ft figure, and what it is not
ROTAX's datasheet for the 915 iS carries the line "full take-off power and a service ceiling up to 23,000 feet", and it has been copied onto specification tables across this industry as though it were the aircraft's ceiling. It is not. It is the engine's maximum operating altitude - how high the engine keeps working.
The aircraft's ceiling is set by the airframe and written in its flight manual: for the ARGON GTL, FL180 physically and FL100 verified. In practice neither number governs a British flight - how high a gyrocopter actually flies is decided by airspace and by the absence of oxygen on board, and that answer is usually between 2,000 and 5,000 ft. We had the engine figure in our own 915 iS specification table until September 2026, and took it out.
The overhaul interval is the money
The 915 iS is overhauled at 1,200 hours, the 916 iS at 2,000. The ARGON GTL flight manual repeats 1,200 hours or 15 years for the 915 iS installation, whichever comes first - the calendar limit catches most private owners long before the hours do.
At 50 hours a year the difference is theoretical. At 150 hours a year it is one overhaul you do not pay for, and it belongs in the sum next to the higher purchase price rather than being waved away - our cost of a gyrocopter page sets out where the overhaul reserve sits among the other lines.
iS or iSc, and one bulletin to know
Both engines come in two forms: iS, which is ASTM compliant, and iSc, certified to EASA CS-E. The letter follows the aircraft's certification route rather than the owner's preference, so it is decided with the order.
One piece of maintenance history applies to both: in September 2026 BRP-Rotax issued an Alert Service Bulletin on the turbocharger valve housing for named serial numbers. If you are buying a used aircraft with either engine, check the serial against it - what the bulletin says and how to check is written up in full.
So which one
Take the 916 iS if you will fly two-up from short or soft ground, in heat, or if you are ordering the Triple; and if you expect enough hours for the 2,000-hour interval to pay for itself. Take the 915 iS if you fly mostly solo or light from a normal runway and would rather put the difference into avionics or into the flying itself. Neither choice is a mistake, and both engines run on the same fuel you put in a car.
We will do the sum with you against the way you actually intend to fly, and say so if the cheaper engine is the right one.
Frequently asked questions
What is the difference between the ROTAX 915 iS and the 916 iS?
Nineteen horsepower and 800 hours. The 915 iS gives 141 hp for take-off and has a 1,200-hour TBO; the 916 iS gives 160 hp and has a 2,000-hour TBO. The 916 iS is 3.6 kg heavier. Both are turbocharged, fuel-injected four-cylinder engines that run on ordinary petrol, and continuous power is nearly identical at 135 and 137 hp.
Which engine does the ARGON GTL use?
The ROTAX 916 iS, 160 hp, is standard on the ARGON GTL and the three-seat GTL Triple; the 915 iS is the option. On the lighter ARGON 915 iS the 915 is standard and the 916 the option. The engine choice is the single largest line in the build price.
Is 23,000 feet the ceiling of the aircraft?
No, and this is the most misquoted figure in the class. 23,000 ft is the engine's maximum operating altitude as ROTAX publishes it - how high the engine will keep working. The aircraft's ceiling is a different number set by the airframe and the flight manual: for the ARGON GTL, FL180 physical and FL100 verified. No gyroplane in this category carries oxygen, and UK airspace keeps most flights below 5,000 ft in any case.
Does the bigger engine burn more fuel?
In cruise, barely - the two engines are within 2 hp of each other at 5,500 rpm, and the ARGON GTL flight manual gives 23 litres an hour at 150 km/h at 3,000 ft. The 916 iS costs its extra fuel where it gives its extra power: take-off, climb and full throttle.
Which one should I order?
If you fly two-up from short or soft strips, in heat, or you are ordering the three-seat Triple, take the 916 iS: the margin is in the climb. If you fly solo or light from a normal runway and want the lower purchase price, the 915 iS does the job and has done for years. The 2,000-hour TBO tilts the sum towards the 916 if you expect to fly a lot.