991 turbo - turbo lag
#31
Racer
All that is true, but it you're not standing on it most of the time, the engine longevity shouldn't be compromised.
The added power really only kicks in when you're in it for somewhat more than part throttle.
If you're tracking the car, that's a whole different story though...
The added power really only kicks in when you're in it for somewhat more than part throttle.
If you're tracking the car, that's a whole different story though...
#32
The 991 TT/TTS is about as turbo lag free as you will find. Perhaps the 991.2 Carrera will be better, but we won't know for sure until March 2016.
Honestly, most modern turbo setups are so advanced that to complain of turbo lag you're either Walter Röhrl, and just showing off, or you're one of those super creatures that can hear facial hair grow.
Honestly, most modern turbo setups are so advanced that to complain of turbo lag you're either Walter Röhrl, and just showing off, or you're one of those super creatures that can hear facial hair grow.
In general, increasing engine displacement and decreasing peak boost pressure will decrease lag (increased energy in exhaust gas flow vs decreased energy required to fully spool the turbos).
The only way to SIGNIFICANTLY alter lag with a 3.8tt making 500-600hp is to use electric motors i.e. Maclaren style "torque fill".
#33
The most pronounced turbo lag I feel is when I accelerate off the line from a dead stop. Is it simply a split second or less of lag? Perhaps, but I still feel it and I don't like it. And no, I don't go around drag racing at lights or anything but I'm just trying to see if there's a solution to 2 annoyances I have with what easily is the best city driving car I've ever owned 😀
#34
All that is true, but it you're not standing on it most of the time, the engine longevity shouldn't be compromised.
The added power really only kicks in when you're in it for somewhat more than part throttle.
If you're tracking the car, that's a whole different story though...
The added power really only kicks in when you're in it for somewhat more than part throttle.
If you're tracking the car, that's a whole different story though...
Last edited by speed21; 11-29-2015 at 08:29 PM.
#35
I drove a 991S (PDK if it matters) for 3 days straight a few months ago on backroads and on track so I am familial the 991 NA engine. Off the line, although slower than the TT in acceleration, it seemed to have a more gradual and predictive increase in torque along the curve. And perhaps, as pointed out by some on this post, I am either imagining things or am going out of my way to say that I can pick up incredible subtle levels of turbo lag. But in the event that I am not imagining things or making things up, and someone else experienced the "lag" and have found something that helped with this deficiency, any input would be helpful and most appreciated
#36
I am very sensitive to turbo lag. The 991 TTS has noticeable turbo lag (I've driven several, and every one I've driven has displayed this trait); strictly my opinion and no offense intended to anyone. It's the only car I've ever driven that has actually made me appreciate non-linear acceleration. I still can't stand Turbos in any other cars, but the TTS is just a damn special car and for whatever reason, it doesn't bother me in the least that I feel turbo lag every time I step on it between 2500 and 3k, for about .7 seconds.
#37
Racer
You can't change the laws of physics. Turbo only engines will always suffer from turbo lag. Blowers do a much better job when it comes to FI, but are nowhere near as efficient. N/A cars are nowhere near as efficient either; hence, turbocharging.
The 991 is a beast, and although has some lag, is still very tolerable - to me.
My FGT was upgraded to a Whipple 4.5 liter blower, making over 1000 HP, but still can't take my 991 TTS off the line...or even at 80....
It has no lag, develops instant thundering power from the get go that can cause the tires to literally light up, but can't put it down to the ground. It gets 2-3 MPG under WOT and it's one of the coolest cars around...but my TTS will destroy it from a standing start, turbo lag and all.
I'll just have to "suffer" through the turbo lag I guess. LOL
The 991 is a beast, and although has some lag, is still very tolerable - to me.
My FGT was upgraded to a Whipple 4.5 liter blower, making over 1000 HP, but still can't take my 991 TTS off the line...or even at 80....
It has no lag, develops instant thundering power from the get go that can cause the tires to literally light up, but can't put it down to the ground. It gets 2-3 MPG under WOT and it's one of the coolest cars around...but my TTS will destroy it from a standing start, turbo lag and all.
I'll just have to "suffer" through the turbo lag I guess. LOL
#39
RL Community Team
Rennlist Member
Rennlist Member
A 3.8 making 20# of boost with turbos sized to make 650hp or more is going to have lag. Technologies such as VTG help, but there simply isn't sufficient engine exhaust energy to fully spool the turbos at low revs. Look at a graph of boost vs RPM, it's unavoidable.
In general, increasing engine displacement and decreasing peak boost pressure will decrease lag (increased energy in exhaust gas flow vs decreased energy required to fully spool the turbos).
The only way to SIGNIFICANTLY alter lag with a 3.8tt making 500-600hp is to use electric motors i.e. Maclaren style "torque fill".
In general, increasing engine displacement and decreasing peak boost pressure will decrease lag (increased energy in exhaust gas flow vs decreased energy required to fully spool the turbos).
The only way to SIGNIFICANTLY alter lag with a 3.8tt making 500-600hp is to use electric motors i.e. Maclaren style "torque fill".
By that account, one could (or should?) also use an electric motor to torque fill a NA engine b/c anything short of instantaneous torque (through an electric drive train) would have lag.
#40
Agree. Everything could be said as having some form of lag, depending upon gear and throttle command. This new car is as good as it gets...until Porsche brings us something even better...and even "less lag-ier" (if that is a fair or applicable comment).....like say the .2tts from what I'm reading today. I mean how much better can it possibly get now!
No doubt I will be standing corrected after I drive it...
No doubt I will be standing corrected after I drive it...
#41
Racer
A 3.8 making 20# of boost with turbos sized to make 650hp or more is going to have lag. Technologies such as VTG help, but there simply isn't sufficient engine exhaust energy to fully spool the turbos at low revs. Look at a graph of boost vs RPM, it's unavoidable.
In general, increasing engine displacement and decreasing peak boost pressure will decrease lag (increased energy in exhaust gas flow vs decreased energy required to fully spool the turbos).
The only way to SIGNIFICANTLY alter lag with a 3.8tt making 500-600hp is to use electric motors i.e. Maclaren style "torque fill".
In general, increasing engine displacement and decreasing peak boost pressure will decrease lag (increased energy in exhaust gas flow vs decreased energy required to fully spool the turbos).
The only way to SIGNIFICANTLY alter lag with a 3.8tt making 500-600hp is to use electric motors i.e. Maclaren style "torque fill".
#42
Turbo lag is the delay form throttle application until full boost. In general, the smaller the engine and the greater the peak boost the greater the lag.
A car that does not make boost, by definition, cannot have turbo lag.
I am not an advocate of torque fill via electric motors in any application. I'd rather deal with turbo lag than the weight and complexity of batteries and electric motors.