Post by Good-old-whats-his-face on Jan 5, 2018 18:47:45 GMT -5
No Serial Number Tag, 339.2cc, Bore 2 x 59.5mm, Stroke 61mm, Type 354 engine, 103 hp @ 10,800-11,200 rpm (modified)
This engine represents the highest level of development of the central rotary valve, liquid cooled Bombardier-Rotax engine. This engine would have been built in 1984. This engine, or a prototype like it, powered Michel Gingras’ twin-track racer that won the 1985 Eagle River World Championship.
The engine was a prototype for the Rotax Adjustable Variable Exhaust, or RAVE valve. While Rotax had been working on the RAVE valve system with Can-Am motorcycle engines, 1985 was the first time people had seen such a variable exhaust port on a snowmobile engine. Winning at Eagle River the first time out of the box while all other competitors were racing non-RAVE Rotax 354s certainly proved its value.
Johann Holzleitner, head of Rotax’s high performance department, personally attended to the engine at Eagle River. While setting up for the race, he was not certain both valves were opening at the same time. He added the piece of channel that connected the valves mechanically to ensure that they did open together.
The exhaust ports are the triple design that were added to racing engine concepts by Holzleitner in 1973. Holzleitner’s design has a large center exhaust port with two auxiliary exhaust ports above the transfer ports on each side of the large exhaust port. The design allows a very rapid blow down of the combustion chamber before the transfer ports open.
The spark plugs of this engine are not in the center of the cylinder bore. They have been moved 11.5mm toward the rear of the cylinder. This places the majority of the squish band toward the front of the cylinder, enabling it to remove heat from the hottest portion of the combustion chamber more quickly.
The combustion chambers in this engine are removable separately from the cylinder head, which is effectively the water jacket. Chambers could be interchanged quickly to change compression ratios easily and inexpensively. The cylinder head can accommodate a thermostat.
While testing the engine, it was noticed that the magneto side crankcase was running hotter than the PTO side crankcase. It was determined that the mass of the magneto and flywheel along with no ventilation to the magneto side were allowing heat to build on that end of the crankcase. This is why you see the openings around the magneto housing and recoil starter. A breakerless ignition system is unaffected by moisture flying around so the openings were made to allow air flow to the magneto end of the crankcase.
The type 354 racing engine is one of the highest specific output engines ever built. This little 339.2 cc engine, running on 100 octane gasoline and naturally aspirated, produced 295 hp per liter of displacement!
This engine represents the highest level of development of the central rotary valve, liquid cooled Bombardier-Rotax engine. This engine would have been built in 1984. This engine, or a prototype like it, powered Michel Gingras’ twin-track racer that won the 1985 Eagle River World Championship.
The engine was a prototype for the Rotax Adjustable Variable Exhaust, or RAVE valve. While Rotax had been working on the RAVE valve system with Can-Am motorcycle engines, 1985 was the first time people had seen such a variable exhaust port on a snowmobile engine. Winning at Eagle River the first time out of the box while all other competitors were racing non-RAVE Rotax 354s certainly proved its value.
Johann Holzleitner, head of Rotax’s high performance department, personally attended to the engine at Eagle River. While setting up for the race, he was not certain both valves were opening at the same time. He added the piece of channel that connected the valves mechanically to ensure that they did open together.
The exhaust ports are the triple design that were added to racing engine concepts by Holzleitner in 1973. Holzleitner’s design has a large center exhaust port with two auxiliary exhaust ports above the transfer ports on each side of the large exhaust port. The design allows a very rapid blow down of the combustion chamber before the transfer ports open.
The spark plugs of this engine are not in the center of the cylinder bore. They have been moved 11.5mm toward the rear of the cylinder. This places the majority of the squish band toward the front of the cylinder, enabling it to remove heat from the hottest portion of the combustion chamber more quickly.
The combustion chambers in this engine are removable separately from the cylinder head, which is effectively the water jacket. Chambers could be interchanged quickly to change compression ratios easily and inexpensively. The cylinder head can accommodate a thermostat.
While testing the engine, it was noticed that the magneto side crankcase was running hotter than the PTO side crankcase. It was determined that the mass of the magneto and flywheel along with no ventilation to the magneto side were allowing heat to build on that end of the crankcase. This is why you see the openings around the magneto housing and recoil starter. A breakerless ignition system is unaffected by moisture flying around so the openings were made to allow air flow to the magneto end of the crankcase.
The type 354 racing engine is one of the highest specific output engines ever built. This little 339.2 cc engine, running on 100 octane gasoline and naturally aspirated, produced 295 hp per liter of displacement!
