2/27/11 Lexus LFA Experience w/Scott Pruett - Infineon Raceway
#16
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no, it's quite harsh. it jerks you totally. on paper it's very fast, but in reality, i can see what scott means it "feels" slow, coz' every shift comes in 2 stages. first choke to shock you, and then another choke to push you. i don't know if that's what lexus wants. but if they want owners to feel the shifting, yes, you absolutely do
#17
no, it's quite harsh. it jerks you totally. on paper it's very fast, but in reality, i can see what scott means it "feels" slow, coz' every shift comes in 2 stages. first choke to shock you, and then another choke to push you. i don't know if that's what lexus wants. but if they want owners to feel the shifting, yes, you absolutely do
Perhaps the harshness you describe is the sheer nature of Scott's driving and high g-forces that result, which is actually very smooth in terms of performance driving but violent in comparison to what most people experience on a usual basis? In the passengers seat, in LFA, these forces certainly does rock your helmet clad head quite hard at each shift and braking points.
Of course, also, in comparison to a more usual electronic AT based paddle shift car like the ISF, where there is still a torque converter to soak up any shocks, the feel may seem harsher in the LFA?
For a standard positive engaging clutch MT based paddle shift, I felt it was one of the most smoothest and predictable shifting cars I have been in. That includes the R8, 996, M3 SMT, Gallardo LP560 and F355/430 all examples of non-AT based paddle MT.
#18
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no, it's quite harsh. it jerks you totally. on paper it's very fast, but in reality, i can see what scott means it "feels" slow, coz' every shift comes in 2 stages. first choke to shock you, and then another choke to push you. i don't know if that's what lexus wants. but if they want owners to feel the shifting, yes, you absolutely do
#19
http://www.club4ag.com/Events_Pages/...Impression.htm
Some stuff I wrote in detail on the experience...
Some stuff I wrote in detail on the experience...
I`ll have to show my wife the safe aspect of this car to convince her that it`s not a widow maker.
#20
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Any shift especially downshift will decelerate a car with positive clutch meet and complete off throttle condition. But in sport driving at limits, that usually happens when you are on the brakes and during the process of aiming for the apex. While most competing cars in this category like the Gallardo LP560 will engage the clutch after a brief blip and harsh engagement that actually is enough for a driver to prepare and correct the line, the LFA in comparison was much milder and no more upsetting than if operated by a manual clutch pedal with an experienced driver. The paddle shifts are to that effect, very smooth as a standard manual car.
Perhaps the harshness you describe is the sheer nature of Scott's driving and high g-forces that result, which is actually very smooth in terms of performance driving but violent in comparison to what most people experience on a usual basis? In the passengers seat, in LFA, these forces certainly does rock your helmet clad head quite hard at each shift and braking points.
Of course, also, in comparison to a more usual electronic AT based paddle shift car like the ISF, where there is still a torque converter to soak up any shocks, the feel may seem harsher in the LFA?
For a standard positive engaging clutch MT based paddle shift, I felt it was one of the most smoothest and predictable shifting cars I have been in. That includes the R8, 996, M3 SMT, Gallardo LP560 and F355/430 all examples of non-AT based paddle MT.
Perhaps the harshness you describe is the sheer nature of Scott's driving and high g-forces that result, which is actually very smooth in terms of performance driving but violent in comparison to what most people experience on a usual basis? In the passengers seat, in LFA, these forces certainly does rock your helmet clad head quite hard at each shift and braking points.
Of course, also, in comparison to a more usual electronic AT based paddle shift car like the ISF, where there is still a torque converter to soak up any shocks, the feel may seem harsher in the LFA?
For a standard positive engaging clutch MT based paddle shift, I felt it was one of the most smoothest and predictable shifting cars I have been in. That includes the R8, 996, M3 SMT, Gallardo LP560 and F355/430 all examples of non-AT based paddle MT.
actually i should be clearer. on the down shift, i think they did a fantastic job on the lfa. like you said, mild, you feel it, but it doesn't disrupt any driving dynamics at all, everything is well under control.
the harsh shift i talked about is actually more when upshifting at redline. that hard choke to your whole body. same with scott, when talking to him and asking him about his comment on the "slow shift", i think he meant when upshift
yes, that's why i keep on saying it "feels" slow. in reality we all know it's very fast. but that sensation and feeling gives you a different perspective. it does feel a lot like hard manual shifting with gearbox. and i believe that's what lexus wants, main reason why they selected single-clutch vs dual-clutch design
#22
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This is why is never a good idea to base your 'perception' of speed, whether it comes from shifts or acceleration, on that alone. That is the most biased source of info and cannot be taken seriously in debate. I'm glad you got to experience this first hand. Everything is not always as it 'seems'.
#23
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This is why is never a good idea to base your 'perception' of speed, whether it comes from shifts or acceleration, on that alone. That is the most biased source of info and cannot be taken seriously in debate. I'm glad you got to experience this first hand. Everything is not always as it 'seems'.
#24
I am surprise that the engine sound is not mentioned as a contributor to speed perception. To me, a screaming redlined V10 should be equated to high speed by the brain. I guess I will have to experience it for myself.
#25
Lexus Connoisseur
Thread Starter
I'm glad you chimed in....Thank you!
http://www.club4ag.com/Events_Pages/...Impression.htm
Some stuff I wrote in detail on the experience...
Some stuff I wrote in detail on the experience...
#27
Lexus Champion
It's so gradual it just gets there before you even know it? Of course you will know it, but the car is smooth enough that it sort of isolates you? It seems from what I've heard so far, it's more about the connection with the LFA. It seems like it's a car that doesn't really have you on edge, in a good way, but comforts your driving. I remember reading reviews and owner comments about the 550 and 575 Ferrari's, and how they'd make you seem like a good driver because of their computer systems. Is the LFA different from that in the sense that it's more about the car and not down to the stability and traction control systems?
#28
Lexus Test Driver
Perception of speed comes from "peaks and valleys" in the torque curve. Such is the case in the turbo cars where turbo lag causes the car to not respond and suddenly surge ahead creating a false sense of rate of change of acceleration.
LFA's dynos show, it has absolutely no peaks and no valleys in the torque. Just a straight line going from 3000 rpm to 9500 rpm with over 95% available from 3000 rpm to 9500 rpm.
I know it well because my car has the "infamous Celica GTS VVTL-i lift". At 6000 rpm, when the car switches cam, the car jerks and throws you back in the seat when the torque curve suddenly surges about 25 - 30 ft-lbs of wheel torque within 200 - 300 rpm. The effect is like a big surge in power and then it stays in lift till 8400 rpm.
Also, you mentioned the transmission system, you have to remember the LFA engine (like the Porsche Carrera GT) and unlike any other supercar today has no internal inertia. If you want some of the Justin Bell videos, you can see on part throttle how the needle is shaking because the engine is so sensitive to throttle inputs.
The flywheel is an inertia storing mechanism that allows smooth starts and smooth shifts since the weight of the flywheel gradually speeds and slows down due to the weight rather than suddenly in the case of a light flywheel.
Inertia in a heavy flywheel keeps the revs from falling when the engine and transmission system connect especially for cars that are intended to tow a lot of heavy weight. Obviously, in racing it is quite the opposite where the car needs to respond as quickly as possible at the cost of progressive feel of the engagement.
With a car having no internal inertia, it gives incredibly sensitive throttle response at the cost of drivability and smoothness.
The downside is, it will almost be impossible to get a smooth shift especially at 9500 rpm when it is spinning so fast and then suddenly loses speed when it gets disengaged or getting off the line smoothly since the engagement due to lack of inertia will tend to bog the car down, if it does not have sufficient revs off the line. I hope it makes sense.
p.s. I drive a car with only a 7 lbs Fidanza flywheel so I have first hand experience of driving a car with very little internal inertia.
While I lift off the throttle shifting at 8400 rpm making it a bit more gradually into the next gear, Lexus LFA (as you kept the throttle WOT and never lift off the throttle) slams it into the next gear (flat shift). I could imagine how brutal it must be with such a light flywheel suddenly engaging the transmission with the powertrain that is essentially spinning at full speed.
Last edited by 05RollaXRS; 03-04-11 at 05:29 PM.
#29
LOL! In the USA, anything with four wheels and paint on the skin that costs $400,000 is a widow maker. That is unless you are of middle eastern descent and have ordered 6 of them at once for each of your spouse, or if your wife's name is Danika.
#30
Correct.
While I lift off the throttle shifting at 8400 rpm making it a bit more gradually into the next gear, Lexus LFA (as you kept the throttle WOT and never lift off the throttle) slams it into the next gear (flat shift). I could imagine how brutal it must be with such a light flywheel suddenly engaging the transmission with the powertrain that is essentially spinning at full speed.
While I lift off the throttle shifting at 8400 rpm making it a bit more gradually into the next gear, Lexus LFA (as you kept the throttle WOT and never lift off the throttle) slams it into the next gear (flat shift). I could imagine how brutal it must be with such a light flywheel suddenly engaging the transmission with the powertrain that is essentially spinning at full speed.
If anything is a testament, the older of the LFA touring the USA, the dark gray one, has seen tens of thousands of track abuse at these events with hundreds of test and sample drivers as well as Scott Pruitt doing hard laps for the last 10 months. I was surprised to see that it was still on the same clutch plate installed at initial production!!
The downshifts are very well timed without much delay, and more importantly very intuitive and consistent, which helps to assure confidence when on track, and all contact patches are loaded on a fine balance on fairly peaky set of street tires like Potenza 01. The engagement speeds and touch are programmed differently for each condition and especially during downshifts on turn-in, things just work smoother than any paddle shift car I have driven.