INFINITI Reinvents The Gasoline Engine — VC-Turbo
 

they've put it in to production? that's good. Now we can see what kind of longevity they will have.

Uh, an exhaust turbo-charger with controllable waste gate is likewise a 'variable compression ratio' combustion engine...and far less dynamically complicated.

I don't believe they have released any efficiency numbers yet? Bold claims without data at this point. It may very well be more efficient, but at what cost, literally.

Personally I think car manufacturers should be spending MORE money on their engines/powertrains and less on "features". Things like variable length intake runners used to be commonplace, but now are usually cut out because it isn't "necessary". Screw that! Just think of how much BETTER it would be! I would gladly pay a few hundred dollars extra for variable length intake runners.

Fo you have any specs for these variable intake runners for the diy’er?

The expansion ratio is much higher at low load this way. A normal turbocharged engine cannot have both high power and high mechanical compression ratio.

When the engine is at low load and not developing boost, the low compression ratio really really hurts efficiency because the combustion temperature is low and the expansion ratio is low.

It seems really really complicated but if it doesn't cost them much to build then I suppose there isn't a problem. I personally feel like a better solution is to rev an engine higher when you need power and rely on the transmission to do the downshifting to make that happen, instead of trying to maximize specific torque at considerable expense. Electric motors are the future and electric motors have great instantaneous response so you don't need that low end grunt.

Making your own set of variable intake runners is not really in the scale of the DIY'er, thus why it would be awesome for manufacturers to fit them to engines to begin with! It would be more involved than making a set of headers, so if you haven't done that yet, don't even consider it.

My accord V6 has a variable length intake :thumbup:. It changes the sound enough that it sounds like I have two VTEC transitions, one at 4000 rpm, one at 4900 rpm.

Do you know the input parameters? I.e lengths and rpm ranges etc?

I am pretty handy sometimes :)

Could you snap a photo of your intake?

Is it just the intake length after the air filter?

I don't know for sure, but I am going to go out on a limb and say that with variable valve lift and cam phasing, variable intake length may not make a big difference anymore and not be cost effective.