If it's a diesel then probably but if it's a gas burner it's just a heavy built block!The extra weight is just the NOx reduction hardware.
From what I have been reading to reduce the NOx levels on gas engine's they are cheating the air flow and relative compression ratios with the camshaft profiles.
Back in the early days they ran fairly normal camshaft profiles but dropped the engine compression severely to cut NOx and then added air pumps to supply more clean air to the catalytic converters so that they could use it to burn off the pollutants.
The problem with doing it that way was the compression ratio reduction severely reduced the engine's efficiency and let more unburned fuel go out the exhaust into the catalytic converter where it was further burned to reduce the remaining pollutants.
As of now they use camshaft profiles that have even larger intake to exhaust overlaps to pump that extra air and fuel through the engine into the exhaust so the catalytic converters can be kept hot enough to work properly. It works but the big camshaft overlaps reduce the effective compression ratios so that an engine that measures with a 9:1 compression ratio is actually lucky if its effective compression is much over 7:1.
Now with the latest emissions requirements they needed to move even more air through the engine to dilute the exhaust but they have to keep the effective compression ratio down to keep NOx production down.
The only real way to do that is to make the camshaft profiles pump even more air through the engine but to do that without dropping the effective compression ratios down any lower they went and bumped the physical ratios up way higher.
In the case of your Nissan engine they are doing like was done with the Toyota Prius engines and running high compression ratios of 11:1 or more but with huge camshaft bleed off to keep the effective ratios down low enough to prevent NOx production.
From a old school engine builders perspective it's interesting to note that due to the large difference between mechanical compression ratio and effective ratio that most of today's engine can not take having an old school high torque towing type camshaft profile without doing severe damage simply due to the excessive effective compression ratio that that type of camshaft makes.
The only way around that is to replace the pistons with lower compression ratio units or grind out more space in the cylinder heads which then messes up the computer control system because a high-efficiency high torque camshaft and matching compression ratio pistons or head work requires a different air fuel ratio to work properly which happens to fall far enough outside a stock engines computer program settings that it can't handle the engine control properly.
It's some pretty fascinating engineering behind how they make burning more fuel less efficiently to look cleaner works.

