Fünfzig

I'm not sure if the question was posed earlier in the thread or not (nor am I willing to go back in look), but the most important question when considering turbo vs naturally aspirated is whether you live at sea level or altitude - that should settle it!

achildofthesky

Pressure and density altitude are more good points that I don't think were brought up on this thread, I could be wrong about that though.

PA gain, as in altitude gain in a "standard atmosphere" (29.92 barometric pressure, 15c/59f degrees temperature and a standard lapse rate of appx 4f degrees cooler cooler per 1000' of elevation). DA is PA corrected for a non standard temperature.

Hot, High, Heavy and Humid are all factors that negatively affect IC engines. Turbocharging greatly ameliorates this effect.

Going from sea level to say the Rockies here in the US especially west of Denver or a similar altitude change elsewhere ROW will see a utterly massive difference in output. A NA engine loses on the order of 3% hp per 1000' of altitude gain from sea level. Electronic engine management automatic mixture controls and other magic box fettling may possibly help some in the first few thousand feet of gain but a forced induction engine is at a great advantage in these situations losing much less power than an NA engine.

Just additional food for an evenings thought... Thanks to Fünfzig for broaching the subject.

Be safe
Patty

chuck911

With your background I'm sure you know this but its not forced induction per se but turbo alone that maintains power at elevation. Superchargers suffer right along with normally aspirated from the same problem, lower air density. Turbo's avoid this because, being driven off exhaust gas, part of the design includes a waste gate. Turbo's in other words are designed with excess capacity. This is also why it is so easy to increase horsepower from a turbo- simply dial up the boost.

TAch Miami

Gee, makes one wonder what made the P51 Mustang with its supercharged engine so fast.

achildofthesky

Chuck911:
Correct you are. Superchargers are also a parasitic drag on the engine (higher rpm = higher drag, relatively speaking) and to paraphrase an old saw: "speed cost hp how fast you want to go"?

Also, on another related front, a reason for intercoolers to raise the density of the charge by cooling the compressed air (compressional heat and compressor turbine heat bleed over, etc...) in a turbocharged engine. On and on the process goes... Solutions for problems and then their cause and effect problems needing solutions, an endless mirror array.

Have a fine evening and be safe
Patty

chuck911

I know next to nothing of aviation history, but based on what I know of engines in general my bet would be that even back then they knew a turbo would be better but in war you use what you got and so… oh the heck with it how hard could it be to google this and find…. yup not hard at all…. skipping a bunch of stuff about the availability of tungsten we get to...

TAch Miami

Reading a bit further....The definitive version, the P-51D, was powered by the Packard V-1650-7, a license-built version of the Rolls-Royce Merlin 60 series two-stage two-speed supercharged engine, and armed with six .50 caliber (12.7 mm) M2 Browning machine guns.

But either engine with FI, whether supercharged or turboed is going to compensate for high altitudes and lower air densities.

chuck911

Define "compensate".

Dirk1370

Turbo hands down in my humble opinion. The other added benefit of the Turbo is there is still a lot of unleashed horsepower that can be had by a chip flash if you so desire. Drive them both and you will quickly be able to answer your own question!

destaccado

You mentioned money IS an issue;

Gut your insane options list by getting rid of the powerkit and PDCC, get a black interior, then wait a year and get the 2016 991.2 C4S ; more power, better sound, the new steering wheel, hopefully the improved EPS feel and GT3 PDK, and the better looking car (in my opinion)... ...and start planning your european delivery so you can enjoy the car on the Autobahn and take a spin on the Nurburgring and SPA before you go home.

After the Turbo lost the Mezger in 2009 it became an overpriced, ugly Carrera with boost.

One thing I've noticed over the years is that the options you select have very little to do with the resale values (other than color combos)...