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Discussion Starter · #1 ·
i read this today on the supertrax website,

New Rotax 800?
(Thursday, January 20, 2005)

Look for a new 800 series engine from Ski-Doo in the near future. We think it's safe to assume any new engines from Ski-Doo will be equipped with the SDI certified emission system.

For this year the Rotax Series III 800 twin will certify 2006 EPA with carburetors and a knock sensor. However, we suspect if Ski-Doo is going to stay in the 800 class, it will need a new 800cc block with liquid cooled cases.

2- stroke engines with either SDI or Direct Injection require liquid cooling of the crankcases in the absence of fuel being scavenged under the piston as in a carburetor or Throttle Body Injection (TBI) system. 2-stroke engines have traditionally relied on fuel to cool the crank, cases and rods.
 

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Yes, that's why they did away with the 800SDI. They were concerned that it would not cool properly, hence the new 1000 design.
 

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I don't believe the 600 sdi has a liquid cooled case. I also think the article said that the heat problem is a concern at power levels of 800cc and higher which would mean at 135hp and higher there is a heat concern.
 

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The way I understand it, DI motors have fuel injected into the head where the spark plug is. So there are two spark plug looking holes in each cylinder. It is a more precise way to add fuel to the cumbustion chamber, cutting down on emissions and fuel consumption. The yellow part of the cutout would be air only, which only mixes with fuel in the cumbustion chamber. I am not sure how everything gets lubricated on the lower end but imagine it is something different since they need cooled cases.
 

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RenegadeRider said:
Ok here is a cutaway pic of the 1000 SDI Mach Z motor.
I see the blue section around the cylinders where the coolant is, what is the yellow section for??
What is actually removing the heat from the crank and bottom end??
Is the bottom end being lubricated by anything??
Looks to me as it is still a fuel/oil mixture that finds its way into the bottom.
[snapback]275031[/snapback]​
Th yellow is the air that enters the engine.
 
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