If it's to be eggs with eggs, I'd like to point out that '240Z' didn't mean just *one* thing (there were some pretty radical differences between sub-variants, markets and regional spec) and it would be fairer to quote 'S30-series Z range' and a chosen period for comparison. I choose 1969 through 1973 as an example.
I think it's important to remember the variations of the '240Z' specs. Anybody looking to buy a good condition 240Z these days - and that includes any DDK forum refugees - might well be forced to look at ex-USA market cars as their best options economically. That means an arguably softened-up and dumbed-down spec that might well require a fair bit of modification to bring it up to expectations. Worth bearing in mind.
Alan - you're surfing the waves, one minute down then up high - no stability to your 'agruments ! And anyone buying a clean-chassis Porsche will certainly be looking to import (same as) from the States.
Firstly you says that the 911 was comprised of various models so we shouldn't just say 911 vs 240Z (but you forget to mention your usual and correct discours that the 240Z is different depending upon which destination market and even then what does '240Z' mean - it should be S30........THEN you remind us all again of that same fact - but ultimately you're just sharing your very personal point of view - you like 911Ss. And this from an early age (I was but 5 in 1970). Ok but life is choices and you could have had one and still can if you empty your garages..............but you won't so ipso facto - the Porker isn't good enough for you to drop owning a Z ! But your liking a 911S has no relevance in this discussion - sorry.
And no-one has yet mentioned the 914s and 914/6s !
You've compared the 240Z at 2.4 litres with the 911 range at 2.2 litres in 1971. Well, in 1969 (the year the S30-series Z range was launched) the 911 range was pegged at 2.0 litre capacity. By 1971 it was 2.2 litres - as you have pointed out - but by 1972 the 911 range had 2.4 litres and in 1973 the Carrera RS model debuted with a 2.7 litre engine and 210bhp. .
A modest 'article' published on the Datsun Europe FB page 12x montbhs ago :
Sean Dezart à Datsun Europe Cars & Parts & Tech
16 avril 2017 ·
Porsche 911 vs. Fairlady (Z)
Once upon a time there was a 356 but it wasn't very sportive. Then came along Nissan with the (export) Datsun SPL310 with a similar (1500cc) engine and then the SPL311 (1600cc) - NOW we're rocking but Porsche fought back with the 911 2.0. Never fear, Nissan too can make 2.0s and behold - the SRL311 - the giant killer !
Porsche thinks and produces the 911S but Nissan, after the merger with Prince shows off the Z432 and the (export) 240Z and JDM L20....and Porsche ups the 911s's capacity to 2.2 to match the outperform the S20 and finally reach 2.4 and Efi for 190bhp......JDM Zs are still winning races in Japan in many guises aginst several Porsche models and in GrpIV and V are tackling the prototypes elsewhere.
Back to ground level and dealer forecourts....the 911 L T and E are trying to compete against the lighter SRL311 ...in 1970 against the 240Z (at the same weight) they grow to 2.2 to match the performance, 2years later the cars increase again to 2.4 and between 130-165bhp. In 1973 they up again to 2.7ltr and 148bhp.....topping the 260Z but shortly the 280Z arrives in 1975 with 140bhp (DIN) and sells like crazy !
In 1978, Porsche again up their capacity to be more competitive and it finally is...until 1981 when Nissan exported their 280ZXT with an equivalent 180bhp.
Porsche cruised until 1984 with the unveiling of the 911 Carrera 3.2.....in direct competition with the Z31 300ZXturbo and similar performances.
My point here is to reflect upon the facts that Porsche has consistently reacted to Datsun's (later Nissan badges) sports-cars to stay ahead in their customer's eyes.....Datsun pushed Porsche to become more powerful, faster, more expensive and Datsuns consistently outsold them and where they clashed, out performed them.
Only Porsches ongoing committment to worldwide competition has kept them in the limelight as 'the' reference.......but even Porschistes are beginning to look towards and buy 240Zs now !
;-)