Hi, I have a noob question:

Can be Evo X whp measured on 2WD dyno with Evo´s rear axle lifted (not to find real WHP, but to see WHP difference during tuning)? Could it damage the SAWC system?

 

if you want to risk your car falling, then go right ahead.

 

Of course I am not going to risk this, I just asked about possible issues while one axle has no grip.

 

absolutely not. do not attempt this ever.

 

Just use Evoscan to log and use Brad Barnhills Dyno program to graph it out. Fill it out correctly and it will be super close. Plus if your using it as a before/after program it will tell you everything you need with out the dyno.

 

Is any way possible to disconnect rear diff, so that the 2WD dyno usage becomes possible ??

 

No.

 

Try it let us know what happens.....

 

You can do it, but you gotta lift one side of the car. That way one of the front wheels an one of the back wheels are on the rollers. All this silly talk about lifting the back is for amatures. And you'll want to set the E- brake for safety. Or you can listen to all the people above who aren't named Mitsubixo. Ah, i just noticed you're from the czech republic, perhaps this is something you should do. I googled crazy Czech cars and got alot of good videos. This could be another.

 

Forget it... I'll try getting a Viscous Coupling Eliminator (VCE).
Try this on Youtube.

Shep Trans has it.

 

It's funny how many in this thread said it would damage the car but not one person gave an explanation as to why...

 

Honestly, I think it's "forum fatigue" from seeing the same question over and over again. The OP could have quickly found his answer from a Google search:
http://lmgtfy.com/?q=site%3Aevolutionm.net+2wd+dyno
Page after page of the same question, complete with answers.

But to answer your question, the problem is that disconnecting one driveshaft effectively puts zero torque on that side of the center differential. The other side of the differential has the full torque load of the dyno at that point. The center differential isn't designed to operate with that mismatch, so it's not going to work.

For the pre-ACD cars, you can purchase a viscous coupling eliminator, install that for dyno use only, and use a 2WD dyno that way. But that's a non-trivial operation that must be done at the dyno facility and takes, from what I've been told, several hours on either end of the dyno session. At that point, it's hard to imagine a scenario where someone asking a basic question like this on the forum without doing a search would be better off going with the complicated, expensive, and time-consuming VCE eliminator option as opposed to just driving the extra distance to an AWD dyno.