And im not referring to the home video electronic. I referring to Nissans new engine technology, I just wanna see a good explaination

 

that's pretty cool, im interested now as well

 

NISSAN | Variable Compression Ratio Piston-Crank System

...not gonna lie, kind of scared that overcomplicating something like that by adding so many more moving parts will yield lessened engine reliability.

 

Saab or volvo accomplished this many years ago by using a tilting head.

 

After reading that link Bosnian posted, the system seems pretty interesting. That engine is going to be a tuning nightmare. Full sweep time from max c/r to lowest will be critical. I would imagine Nissan taking full advantage of the fly by wire system to 'deaden' the users throttle input. ECU aftermarket for this engine will be nill. Looks like our hobby will be fairly dead soon.

 

im afraid to say this but is this gonna be the new silvia motor????

that's the only motor that come's to mind with the turbo and all

 

Uh, wouldn't it be easier to adjust the CR dynamically with cam timing? You know, run it in Miller Cycle under boost and revert back to high-comp Otto cycle while off boost?

I like Vertigo's thinking about tuning.... With all that complexity flinging around, just think of the giant mess you'll make on the dyno if you get it wrong!

 

Whoa noez ! Quick someone let nissan know they screwed up, high compression is for boost and power, low compression is for fuel mileage.

 

static c/r is more than just the compression stroke. The EXPANSION ratio is what contributes a significant amount to the increase in power / efficiency of a high compression engine (although you could probably get away with a slightly higher c/r in a miller engine). The miller cycle does nothing to increase the expansion ratio, and adds cost + complexity. The basic idea behind the miller cycle is, the first X amount of degrees from BDC is the least efficient at compression due to lack of mechanical leverage, so delay the compression stroke X amount of degrees and let some of the intake charge revert back out of the intake valve. In the Mellenia's case, it has the internal friction of a 3L, with the tq of a 2.3. Also remember that engine runs a lysolm twin screw supercharger which is very expensive.

If the c/r sweep is large enough for this motor, and it can stay in the optimal c/r at each load point, it will produce significantly higher efficiency #'s than a miller.

 

Not sure if you are joking.. but high c/r is for fuel efficiency, low c/r is for power on pump gas.