996tt power curve
Discussion
Now that a couple of thousand miles have passed beneath my arse in the tt it looks like the optimum place to change gear is around 5000/5500 because after that the torque is falling quickly. But it doesn't quite seem to be in the power though in the next gear. Can't help wondering why there's another thousand revs before the limiter though... The M5 used to pull right into the limiter.
Looking at power curves, it seems they do drop off sharply at this point, but I can't help thinking there should be a little more just to make sure you're north of 3750-4k in the next gear.
Should I expect there to be pull right into the redline? I think the C4S seemed not to fade at the top (shape wise even though it was obviously lower down the graph)
SM
>> Edited by supermono on Tuesday 24th January 15:10
Looking at power curves, it seems they do drop off sharply at this point, but I can't help thinking there should be a little more just to make sure you're north of 3750-4k in the next gear.
Should I expect there to be pull right into the redline? I think the C4S seemed not to fade at the top (shape wise even though it was obviously lower down the graph)
SM
>> Edited by supermono on Tuesday 24th January 15:10
I get the same boost as you,so that seems normal.I rarely take it beyond 6000 revs, as you say it seems pointless,however its still going pretty quick at that level.Im surprised you find it drops power between upchanges because i find that its stongest point is the constant torque and power delivery at that time.Most cars i have owned lose a bit of pace as you change up however the tt gives ann almost seemless delivery...more like a big jap bike.
The engine torque at 6000rpm is around 85% of the peak torque (at 4600 rpm) and so the acceleration is also only 85% (asuming you stay in the same gear). Turbos often have this characteristic (lots of low down torque fading somewhat at high revs)
The reason to rev highly in the 996tt though is not to get into the power band in the next gear, as it has pretty much peak torque from about 2500rpm and so will acclerate as well at 3000rpm as it will at 4000. The real reason is that by staying in gear you are using a lower ratio, which multiplies engine torque better and so the acceleration is also better. To get the best from the car you need to rev to at least peak power, even though the acceleration drops off somewhat in the upper range.
Paul
The reason to rev highly in the 996tt though is not to get into the power band in the next gear, as it has pretty much peak torque from about 2500rpm and so will acclerate as well at 3000rpm as it will at 4000. The real reason is that by staying in gear you are using a lower ratio, which multiplies engine torque better and so the acceleration is also better. To get the best from the car you need to rev to at least peak power, even though the acceleration drops off somewhat in the upper range.
Paul
Maybe the engine's still a little tight ?
I reckon it takes around 3,500 miles (2,000 miles post run-in) before everything is truly starting to loosen up.
I find the engine temperature guage is a fair indicator --- which is why I do like the oil teperature reading on BMW's M series ...
I reckon it takes around 3,500 miles (2,000 miles post run-in) before everything is truly starting to loosen up.
I find the engine temperature guage is a fair indicator --- which is why I do like the oil teperature reading on BMW's M series ...
Looking at some dyno graphs stock torque peak is relatively early (around 3600rpm) but i smore or less held for 2000rpm before it drops off. Peak power is up at around 6500rpm although it starts leveling off around 5500rpm.
This graph I'm currently looking at has a 996tt ib both stock and performance modes, with revo performance on torque at 6500rpm is still more than the stock peak torque level... great to drive as well!
This graph I'm currently looking at has a 996tt ib both stock and performance modes, with revo performance on torque at 6500rpm is still more than the stock peak torque level... great to drive as well!
There are several tuners out there that can do the work. DMS, AMD etc etc.
Most claim torque up on a standard TT to 490lbs & power to around 480bhp.
With this extra I would expect a couple 10ths of the 0-60 time. AMD do a before & after rolling road session, so you can see exactly where the extra power & torque comes in, stays for, etc.
I have resisted the urge myself, but have to say I experience non of the above "problems"
R.
Most claim torque up on a standard TT to 490lbs & power to around 480bhp.
With this extra I would expect a couple 10ths of the 0-60 time. AMD do a before & after rolling road session, so you can see exactly where the extra power & torque comes in, stays for, etc.
I have resisted the urge myself, but have to say I experience non of the above "problems"
R.
Speaking from little experience of tuning a 911 Turbo, but from lots of observations, most of the usual tuners of any moderately tuned turbo car, just up the mid-range urge.
Look at any stock dyno and they have an artificial plateau from roughly 2.5k to 5.5k rpm on the 911 Turbo, which is quite a nice spread of torque. This also gives the illusion of little lag because the turbo's don't spin up too much before then opening their wastegates.
If you up the boost on stock turbo's, all you do is boost for longer and to a higher pressure, making the lag (albeit to a higher output) more noticeable, and run the turbo's alot hotter. 0.6 bar to 0.8 bar is quite a jump in % terms.
So, you fill in that plateau, by adding a splodge on top, and holding that boost a bit longer through to the redline, to add a bit more top end power. However, the perception of "drop off" to the redline will be still noticeable, even more so infact.
It's this whole "levelled" off torque curve mid-range that makes cars like this feel flexible, but also open to huge tuning potential for outright torque. Look at the Audi RS6 and RS6 plus. If you actually draw out their curves, the ONLY difference is a slightly lower drop off from the peak torque plateau end to the peak power, over about 500rpm. 450bhp to 480bhp never looked so feeble on a dyno!
The RS4 was the same, quite a flat mid-range, allowing a nice linear shove and nice driveability. Most tuners can get quite alot from this lump in boost upgrades, but cheap chipping can open up that torque for big gains in the mid-range, but not add much power, only exemplifying the apparent lag and the rapid drop off approaching the still reasonable peak power.
Ultimately, my advice is rev it more stock, you'll be even more tempted to change lower with a "torquey" remap!
Dave
Look at any stock dyno and they have an artificial plateau from roughly 2.5k to 5.5k rpm on the 911 Turbo, which is quite a nice spread of torque. This also gives the illusion of little lag because the turbo's don't spin up too much before then opening their wastegates.
If you up the boost on stock turbo's, all you do is boost for longer and to a higher pressure, making the lag (albeit to a higher output) more noticeable, and run the turbo's alot hotter. 0.6 bar to 0.8 bar is quite a jump in % terms.
So, you fill in that plateau, by adding a splodge on top, and holding that boost a bit longer through to the redline, to add a bit more top end power. However, the perception of "drop off" to the redline will be still noticeable, even more so infact.
It's this whole "levelled" off torque curve mid-range that makes cars like this feel flexible, but also open to huge tuning potential for outright torque. Look at the Audi RS6 and RS6 plus. If you actually draw out their curves, the ONLY difference is a slightly lower drop off from the peak torque plateau end to the peak power, over about 500rpm. 450bhp to 480bhp never looked so feeble on a dyno!
The RS4 was the same, quite a flat mid-range, allowing a nice linear shove and nice driveability. Most tuners can get quite alot from this lump in boost upgrades, but cheap chipping can open up that torque for big gains in the mid-range, but not add much power, only exemplifying the apparent lag and the rapid drop off approaching the still reasonable peak power.
Ultimately, my advice is rev it more stock, you'll be even more tempted to change lower with a "torquey" remap!
Dave
Thanks for all the info. First of all, I want to sell this car some day and when I'm looking to buy a car anything that's been titted around with I won't go anywhere near, so I don't consider chipping to be an option.
The car doesn't feel exactly slow, and the engine is pretty flexible as is (though still not as responsive as my E39 M5 was from low 2's, but I guess it can't be).
All I was wondering was whether I should expect it to tail off at high 5s when there's about another 1000 revs to go. And from the replies I can see that yes I should, my car is probably working right.
I'll just need to get more accustomed to this engine. Actually by changing gear faster I'm noticing an improvement. I seem to have turned into a bit of a grandad from driving the lazy M5 for a while, and my long ponderous gearchanges are letting the turbo stop I reckon. Being just a little more decisive with the change has already improved things dramatically.
SM
The car doesn't feel exactly slow, and the engine is pretty flexible as is (though still not as responsive as my E39 M5 was from low 2's, but I guess it can't be).
All I was wondering was whether I should expect it to tail off at high 5s when there's about another 1000 revs to go. And from the replies I can see that yes I should, my car is probably working right.
I'll just need to get more accustomed to this engine. Actually by changing gear faster I'm noticing an improvement. I seem to have turned into a bit of a grandad from driving the lazy M5 for a while, and my long ponderous gearchanges are letting the turbo stop I reckon. Being just a little more decisive with the change has already improved things dramatically.
SM
Thats the only thing, going from a 5.0 V8 with similar torque and power, to a forced induction version of the same thing but with 3.6 litres, you going to notice a difference in delivery.
The problem with the 996TT is that it does deliver the goods so well in the mid-range, that the drop off in punch you get to the last 1000rpm is still LOTS of punch, just relative to the torque it feels weak. This is the nature of turbo torque curves to some extent, but the 996 Turbo does a good job with the controlled output.
Note cars like the new Astra VXR have been tuned so the turbo boosts up but delivers peak torque late on, so it kicks harder as you rev for longer, making the delivery more like a powerfull NA high revving lump.
Like several people here have said, your car is still quite new anyway, when it loosens up it'll probably rev better at the top end which is maybe what you are noticing more than anything at this stage.
Happy driving... lucky bugger
Dave
The problem with the 996TT is that it does deliver the goods so well in the mid-range, that the drop off in punch you get to the last 1000rpm is still LOTS of punch, just relative to the torque it feels weak. This is the nature of turbo torque curves to some extent, but the 996 Turbo does a good job with the controlled output.
Note cars like the new Astra VXR have been tuned so the turbo boosts up but delivers peak torque late on, so it kicks harder as you rev for longer, making the delivery more like a powerfull NA high revving lump.
Like several people here have said, your car is still quite new anyway, when it loosens up it'll probably rev better at the top end which is maybe what you are noticing more than anything at this stage.
Happy driving... lucky bugger
Dave
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