Early Release 2000 MX Z 700

Drop your HO, the 700's got all the power and less weight
RELATED TOPICS: ENGINES | SNOWMOBILES
We have to admit, when Ski-Doo rolled out the MX Z 670 HO last season,we were stoked. The proven 670 Rotax mill had been finely machined to crankout the kind of power aftermarketeers shoot for. Our Shoot-Out sled registered a whopping 129 hp right out of the box. The MX Z 670 HO was even voted ourAmSnow Online Sledder's Poll Sled of the Year by our cyber sledders. Itwas love.

But, as all good love affairs go, we were forced to abandon the HO andlook to a newer, lighter, more invigorating model when Ski-Doo unveiledits latest Summit and MX Z 700 in January. We were nervous about the newRotax Series 3 700cc engine. It had big shoes to fill in the power department.The 600 we had last year was a good preview, but the proof would be in theseat of our pants and on the dyno bench. We rode it and it felt good. Nowwe have a full dyno run to tell us why it felt so good: 126.1 horsepowerat a usable 8100 rpm.

Ski-Doo told us that one of the prime concerns for the new cylinder reedengine project was improved fuel economy. By looking at the data chart,we can see that the brake specific fuel consumption (BSFC) is in the .5range. On any other engine, that would be running on the ragged edge, butthe Rotax 700 doesn't seem to bat an eye. "We jetted down to adjustfor the ambient conditions," noted Dynoman Rich Daly. "We testedmany different jet sizes and found that this particular engine was not asjet-forgiving as the 600 we did last fall. But that could be a factor ofwarm weather testing.

"We moved up two jet sizes to see what it would do," continuedDaly. "It spiked the BSFC up into the .6 to .7 range and we lost twohorse, but the torque was about the same. The 600 didn't even flinch whenwe changed jets a size up or down, but this 700 responds to it. Althoughfor the average trail riding snowmobiler, the power change would be barelynoticeable."

The MX Z 700 we used for testing was out of the original 1999 1/2 runwhich Ski-Doo released in mid-January. Like the MX Z 600, the 700 has afour-hour break-in period during which the onboard computer retards theignition timing. "The particular sled we tested had about 200 mileson it," added Daly. "If it would have come without being brokenin, we probably would have seen about three horsepower less."

The early run engines do differ slightly from the full 2000 models. "Weused a sand-cast engine for the first batch," said Ski-Doo's NorthAmerican Communications Manager Dave Thompson. "For the full productionrun, Rotax will die cast the engines." Thompson explained that thedie-cast engines will be more efficient at dissipating heat and will runa little stronger than our test unit, though he wouldn't say how much better.

Looking at the test results, consumers will have an easy time clutchingto the power band. At 7700 rpm, the torque curve hits its peak at 82.3 ft/lbs,and the horsepower just cracks over the 121 mark. The power creeps up fromthere to full strength at 8100 rpm.

Ski-Doo consoled us at the spring test by saying that even though the670 HO was gone, its replacement would offer a similar power to weight (ptw)ratio. But based on our dyno results and our seat of the pants testing,we tend to think that the 700 will spank the HO in that consideration. TheHO pulled 129 hp and weighed 502 factory pounds for a ptw factor of .256.The 700 spins at 126 hp and is considerably lighter at 472 factory pounds.That makes its ptw factor of .267. They're close, but the MX Z 700 has morepony per pound than its predecessor.

To sum it up in one sentence, those who were sad to see the HO go shouldn'tbe; the new 700 is all that and more. For full test riding impressions,see our 700 Single Pipe comparison report on page 80 and our Summit 700Long Term Test report on page 96. AS

Thanks to Bowen's Ski Doo in Ilion, NY for providing the MX Z 700.Phone: 315/894-1128

2000 SKI-DOO MX Z 700
Air Density: 93.0
Fuel: 94 Octane Pump Gas
RPM CBT CBHP BSFC FUEL
H2O
6600 74.1 93.0 .543 48.3 91.5
6700 74.1 94.5 .538 48.7 92.5
6800 74.3 96.2 .543 49.9 93.0
6900 75.3 98.9 .545 51.5 93.5
7000 77.5 103.3 .530 52.8 94.0
7100 78.8 106.6 .530 54.0 94.5
7200 79.8 109.5 .527 55.2 94.5
7300 80.6 112.1 .521 55.8 95.0
7400 80.9 114.0 .518 56.5 96.0
7500 81.1 115.7 .530 58.4 96.0
7600 81.9 118.5 .530 59.9 96.5
7700 82.9 121.5 .524 61.0 97.0
7800 82.3 122.2 .550 64.3 97.5
7900 82.0 123.3 .570 66.9 98.0
8000 82.6 125.8 .560 67.3 98.0
8100 81.8 126.1 .559 67.4 99.0
8200 80.2 125.2 .546 65.4 99.0
8300 77.7 122.8 .539 63.3 99.5
8400 73.3 117.2 .578 64.8 99.5

RPM: Engine crankshaft speed.
CBT: Corrected Brake Torque.
CBHP: Corrected Brake Horsepower.
BSFC: Brake Specific Fuel Consumption.
FUEL: Actual fuel flow pounds per hour.
H20: Water temperature in degrees F. 
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