TheBucketOfTruth

Not who you were asking, but some of that might depend on compression ratio differences. In any case, any time you actually need power to do anything in a Turbo you likely won't be in a zero boost situation.

Dock

I don't think so.

autobonrun

Hmm. I was wondering how much HP and torque is available and being generated when you pull off briskly but the boost gauge only indicates 0 or 0.1. The point I was going to make is if it is at least the same as the NA car, 300+ HP is sufficient for normal driving. But I think you're absolutely right, some level of boost is needed to even achieve NA power just based on the design, compression ratios, etc.

"02996ttx50

thats a great question. take away the snails and i think you're very near what might be the numbers for an n/a 996. but thats just a hunch, i have no idea. the cpl times I've been in limp mode though, it sure feels like a normally aspirated 996 might and my ol 993 with its massive 275 hp felt peppier. lol.

limp mode though is probably further ecu limited than simply "no boost". i dunno.

cdk4219

I would guess that from the engines that I have added turbos to , that the factors directly rated lower hp numbers are, increased backpressure from the turbine side, decrease in airflow on the compresor or cold side ( intercoolers, smaller piping, restrictions from the turbo inlet and outlet without the wheel spinning, lower compression, different timing maps, and camshaft design also don't help either.
I would say that the airflow restrictions in the turbo and piping needed are the biggest culprits, but I would suspect the peak hp number down 10% or so, but low rpm power without boost down quite a bit more.
When I add a turbo to a car, driving it around with the wastegate open seems to dull the reaction and pep of the car, nothing else done, and that is to an engine that was designed to be normally aspirated

"02996ttx50

i know nothing if not very little of the mechanics of any of this stuff. i'm a driver is all, but i marvel and learn often from you guys that have actual experiential data from your own real world tinkering. yes, even from dan lol.

but all that said..? does this mean you agree that an n/a 3.6 pcar might have similar "numbers" vis a vis performance and hp/tq as might our turbo cars without boost?? or do you think it not possible. i am trying to understand.

my only experience with this might be limp mode, as how else can we drive this car without being able to boost? but no one "pushes" their car in "limp" mode lol. or i would hope not !

dprantl

A 996TT with turbos disabled would perform slightly worse than a NA 996 of the same displacement and engine design. The compression ratio of the TT is lower, and the turbos create an exhaust restriction. The intake will not be optimized for running NA, and ECU mapping will also not be optimal on the TT if the turbos are not doing anything. I think cdk's estimate of -10% HP/TQ is a pretty good one.

I have actually experienced this first-hand one time on a Saab 9000T with a T-25 turbo that lost its wastegate rod c-clip and the turbo suddenly did nothing.

Whether the power output of a NA 996 is enough for someone for street driving is completely subjective and depends on the individual. After driving a torque monster supercharged Porsche 928 daily for years (how about an instant 320lb.ft to the wheels @ 1,500RPM), it is a little disappointing. Nothing a turbo upgrade can't fix though...

Dan

rmc1148

Is that an Audi tt just kidding but agree a NA motor because of compression would/should be the better performer. There is no replacement for displacement other then being force fed.

"02996ttx50

that makes complete sense to me, and would've been my "guess" that power level would be similar btw the two cars n/a vs unplugged lol turbo even if the n?a car was tuned or stock for a non boost situation

would not be enough for me. most ALL other cars are in limp mode for me now

thx for the clarification.

Dock

I talked to PCNA and they confirmed that a 996 Turbo engine without any boost available does not produce the same power numbers as a normally aspirated 996.

autobonrun

Thanks for following up.

BryanCO

Compression as well as a bunch of other variables mentioned.

Really, apples and oranges...

dprantl

Wow, it has been a long time trying to get that pic...

Dan

Daytonaman

My 05' "S" coupled to a Tip with a Softronic Tune and an exhaust upgrade, pulled a ZR1 up to about 85.
The Tip allows the car to remain on 1.2 bar thru the power band @ WOT.
Never felt comfortable with power shifting a manual @ WOT. Seems like boost is lost @ shift points.
From a standstill, the low 1st brake torque puts 1.0 bar off the line, and 1st-2nd really slams..
Run what you brung...