Sask997

What is the relative torque characteristic of a turbo engine at part throttle [off boost] versus a naturally aspirated engine?

I ask this question because most of the time, we drive our sports cars at more mundane speeds in the city or local roads. At these speeds, you rarely see any boost on the turbo gauge. We are therefore driving a low compression engine. The torque and power curves that are published are usually at wide open throttle.

I used to have a Porsche 997 Turbo. I now have a 911-50. Unfortunately, I have not been able to drive my new car because of the winter conditions. I have however driven several 991 Carrera S cars. In the city, I almost find the naturally aspirated engine easier to drive as it seems to have better throttle response and more than adequate torque. The turbo car had enormous performance on boost. However, this was essentially unusable in the city because of the incredible acceleration. So most of the time, I ended up driving the car gently without any turbo boost.

I am wondering if others have a similar impression?

Gcracker07110

There's really no comparison, turbo wins every time, at 1400rpm you are getting the same ft/lbs of torque rating as an S. you would really have to lug this engine to the point that it would be undriveable. The turbo is making 355 ft/lbs at 1500 rpm and achieves max torque (without over boost) at 2000rpm of 487 ft/lbs. there's really no way that the scenario you are describing would ever occur in reality

LSV

Turbo turns all the time and the boost is regulated even at low rpm (wastegate). Turbo is related with "bad" throttle response, small turbos or twin (smaller) turbos are better than large ones. They are effective @1200rpm, large one could be @4000rpm (spool up need). Old turbo race cars in the 70's had a 2 second lag. N/A engines have no lag compared to turbo.
The pedall position is your demand on torque.

For your question, I've never seen part throttle test with dyno.

Slantnose!

Are they geared the same?

Sask997

Theoretically, I would assume that they are. In reality, I'm simply comparing the two cars mentioned. I'm not sure if the gearing is indeed the same.

LexVan

So your old car had 480 HP and your new car has 430 HP. I'd expect your driving experience to be pretty similar. With the power delivery of the 911-50 to be a little more linear.

ipse dixit

I've driven both the 991 TT and the 991 C4S (which I now own).

No dyno, and at best just a butt dyno, but there's definitely a difference in torque even at partial throttle when driving around town. Even in 1st gear, the TT just sort of springs off the line whereas by comparison the 4S almost feels like it's going uphill in 6th gear. Get it out of 1st and on a roll in 2nd and beyond and I find the linear throttle response of the 4S much more enjoyable as a daily driver around town and even on the freeways.

There's no doubt the TT is a great car, and insanely fast, with low-end torque that makes the 4S seem like your driving with the parking brake engaged. But, and I've posted this before, around town for me the TT just wasn't enjoyable. Twitchy and almost too fast to drive leisurely. It's like you had to concentrate to make sure you don't butt slam the car in front of you.

Both great cars, but if you're talking about torque delivery, TT hands down. No contest, at least based on this person's butt dyno.