Ski-Doo's 1996 Formula SLS featured an all-new Rotax 499cc powerplant.
Bombardier promised that it was the most powerful liquid-cooled twin in its class. Since the other three manufacturers would also like to lay claim to that title, it seemed that this would make for an interesting test machine. And, so without further ado, it was off to the brutally honest dynamometer for the moment of truth.
DYNOTECH replaced the stock 320 main jets, which are normally safe to zero degrees, with 290s to cover the 70-degree F environment of the test chamber. The machine was fueled up with 93 octane unleaded gas with a splash of leaded racing fuel-shaken not stirred.
This combination gave a marginally safe mid-60s pound/horsepower Brake
Specific Fuel Consumption that might be too lean for oxygenated fuel. Luckily,
there probably is some high-speed enriching from the combination of underhood venting of the carbs and the cold air intake behind the windshield that should make the fuel flow higher and safer than what was produced in the
lab.
Although the airflow readings are lower than actual, for whatever reason, they remained consistent from test to test.
The owner of the SLS had purchased a second airbox, which he had modified
before he brought the machine to DYNOTECH. He had removed the shelf from
the box, which opened up the air passages to the engine and allowed it to
breathe a little better, even at lower revs. Considering the difference in the peak power RPM from test to test, some of the increase in midrange power can be credited to a slightly cooler pipe during this particular run. The compression and timing were unchanged throughout the session.
Because of the slight increase in carb venturi pressure with the gutted box, the main jets had to be increased five to 340s to maintain adequate fuel flow at 70 degrees.
DYNOTECH pulled 90.8 horsepower out of the Rotax spinner with a little modification. Very impressive.
1996 Formula SLS 500
290 Main Jets
Data for 29.92 inches Hg, 60 deg. F dry air
Test: 100 RPM/ Sec. Acceleration
Fuel Specific Gravity: .750
Vapor Pressure: .30 Barometer: 29.86
| RPM | CBT | CBHP | FUEL | AIR | A/F | BSFC | CAT |
| 5250 | 41.5 | 41.5 | 40.6 | 81.6 | 9.2 | 1.00 | 71 |
| 5500 | 44.7 | 46.8 | 42.3 | 85.3 | 9.3 | .92 | 67 |
| 5750 | 48.8 | 53.4 | 43.0 | 89.8 | 9.6 | .83 | 70 |
| 6000 | 48.7 | 55.6 | 41.6 | 93.3 | 10.3 | .77 | 72 |
| 6250 | 52.4 | 62.4 | 51.2 | 100.7 | 9.0 | .84 | 71 |
| 6500 | 53.9 | 66.7 | 55.5 | 703.9 | 8.6 | .85 | 71 |
| 6750 | 56.4 | 72.5 | 61.2 | 108.0 | 8.1 | .87 | 71 |
| 7000 | 58.0 | 77.3 | 56.1 | 112.9 | 9.2 | .74 | 70 |
| 7250 | 60.0 | 82.8 | 53.5 | 117.6 | 10.1 | .66 | 69 |
| 7500 | 61.6 | 88.0 | 56.1 | 123.0 | 10.1 | .65 | 69 |
| 7750 | 60.3 | 89.0 | 62.4 | 125.3 | 9.2 | .72 | 71 |
| 8000 | 56.5 | 86.1 | 65.2 | 127.0 | 8.9 | .78 | 72 |
| 8250 | 40.6 | 63.8 | 62.8 | 125.8 | 9.2 | 1.01 | 70 |
1996 Formula SLS 500
340 Main Jets
Data for 29.92 inches Hg, 60 deg. F dry air
Test: 100 RPM/ Sec. Acceleration
Fuel Specific Gravity: .750
Vapor Pressure: .30 Barometer: 29.86
| RPM | CBT | CBHP | FUEL | AIR | A/F | BSFC | CAT |
| 5250 | 46.5 | 46.5 | 42.5 | 89.5 | 9.7 | .94 | 70 |
| 550 | 50.5 | 52.9 | 44.5 | 94.4 | 9.7 | .86 | 69 |
| 5750 | 50.7 | 55.5 | 43.3 | 99.5 | 10.6 | .80 | 69 |
| 6000 | 54.4 | 62.1 | 47.0 | 106.5 | 10.4 | .77 | 69 |
| 6250 | 57.0 | 67.8 | 50.4 | 111.1 | 10.1 | .76 | 70 |
| 6500 | 58.9 | 72.9 | 55.1 | 115.3 | 9.6 | .77 | 69 |
| 6750 | 60.4 | 77.6 | 55.4 | 118.9 | 9.9 | .73 | 69 |
| 7000 | 62.4 | 83.2 | 54.0 | 123.2 | 10.5 | .67 | 70 |
| 7250 | 63.5 | 87.7 | 54.8 | 128.3 | 10.8 | .64 | 69 |
| 7500 | 63.6 | 90.8 | 56.3 | 132.2 | 10.8 | .63 | 69 |
| 7750 | 60.7 | 89.6 | 61.2 | 134.3 | 10.1 | .70 | 70 |
| 8000 | 50.6 | 77.1 | 62.7 | 135.3 | 9.9 | .83 | 70 |
RPM: Engine crankshaft speed.
CBT: Corrected Brake Torque.
CBHP: Corrected Brake Horsepower.
AIR: Airflow cubic feet per minute.
A/F: Air/Fuel Ratio.
FUEL: Actual fuel flow pounds per hour.
AIR: Airflow cubic feet per minute.
A/F: Air/Fuel Ratio.
CAT: Carb Air Temperature