NASHVILLE, Tenn. – We’re reawakening the Power of Z with the new Nissan Z Proto, combining 50 years of passion and heritage with modern technology. Please join us at TheNissanNext.com for the Z Proto Digital Unveil on Tuesday, September 15 at 7:30 p.m. CDT.
That's what it should be. No need for naming engine naming convention.
If they stick with the naming convention then it doesn't have to tie with engine displacement or output. Just increment it over time. 400z > 450z > 500z whatever. But really should just be the Z and we can have the internal code name for it.