JasonC SBB

Re: Schumacher vs. Rubens:

Wow. Left foot braking allows him to basically virtually control braking balance very quickly. He is modulating the front (braking torque) vs. rear wheel net torque (braking torque minus engine torque). But he is nowhere near as choppy on the gas as Rubens is. Therefore he doesn't need as much "throttle response" as sjmarcy. :-p

Re: Senna.

He chops the gas like a rally driver. The effect of this is like PWM. If you go on off rapidly enough and modulate the durations of the on and the off, it emulates an analog signal.

Unlike Schuey who has good analog control over the throttle (positioning the throttle accurately to get the desired torque), Senna's foot oscillates. The NSX's driveline and suspension filters out most of the high frequency content (the chopping) and delivers an smoothed version of this right foot to the tires. Senna isn't demanding say, a jump from 20% to 80% torque in 100 ms. The car doesn't require that to balance it. The car needs a smoothed version of his right foot, and that is what the car delivers. If the car delivered torque to the tires and caused the car's attitude to change as quickly as his foot was moving, he would spin out.

So my contention is that Senna's driving style doesn't require superfast torque response to the tires, I will say the opposite is required - his style would work equally well on a turbo car.

In control system parlance, Senna's foot is a torque-demand actuator with a lot of 'D' in front of it, so it chatters a lot back and forth, and the system (throttle butterfly to tires) lopass filters this to produce a smoothed version of the torque demand.

-----

When I said my M3 was more difficult to throttle modulate at autox than my turbo miata, I believe it's for 2 reasons:

1) The M3 like any n/a car will develop near max torque at something like 50% throttle at 4000 RPM. The miata with TPS controlled boost target only develops 5 psi (wastegate can pressure) at half throttle, and it's programmed to linearly increase boost to 15 psi at WOT. So the throttle is less sensitive to movement in the miata. Its easier for my right foot to demand 5 psi (~60% torque), than in the M3.

2) Second, my right foot is more like Senna's in that it's not so good at immediately and precisely going to a foot position to get the torque that my brain wants (which Schuey is very good at). So my right foot chops like Senna's, and the turbo smooths it out to shock the tires less.


P.S. Despite accusations of troll-like behavior in this thread, this has been a good one.

P.P.S. Lolz at Sav's recent replies.

sjmarcy

Here is Lewis Hamilton's data in a slower technical area of the course which I blue highlighted. There is less downforce available compared to the faster turns. Hence more driving is needed since the invisible hand is not pushing you down on the track as hard. Bahrain. McLaren F1.

Aggressive driver. I see throttle movement. And steering movement on the viddie. And left foot braking.

Like I've been saying...

sjmarcy

Here is Lewis in Australia. McLaren F1. Examine the green and purplish-blue marked zones. Notice how LH drives in these two technical areas without the cure-all of massive downforce…

I detect a pattern.

blaen99

iTrader: (6)

Wait, Sjmarcy, you just drive a mostly-stock N/A Miata and are trying to argue with Sav about a FI Miata using F1 N/A examples?

Efini~FC3S

iTrader: (4)

You know, after looking at these data traces and the analysis I have to take some issue with it. It seems the author is trying to use the data to show how much faster Schumi is because he left foot brakes. What I see from the data is two drivers taking a different line and different approach to the same corner, as well as driving style differences between a left foot braker and a right foot braker. From the data it seems Rubens is taking the corner quite a bit differently than Schumi.

If you know turn one from Suzuka you know there's quite a few ways to take it. It seems Rubens is over slowing the car for the first apex, and then accelerating the car before braking for the second apex. From the data it looks like Schumi is trail braking throughout the whole corner and carrying more speed through the first apex. So what difference does that make? Well you can't really say that the differences in the data traces are solely from the difference in braking technique. Rubens is going at this corner in a totally different fashion (overslow, back on gas, brake again) then Schumi (trail brake through the whole corner) and that makes for a bigger affect on the difference in the data traces than anything. It seems Michael's approch is the faster way, but that doesn't mean Rubens is slower through the section because he left foot brakes. It means he's slower through the section because he's doing the corner wrong.

Also the author seems to downplay the fact that Rubens is on the gas sooner and has a higher exit speed. Obviously corner exit speed isn't everything but it is very important. Imagine if there were a one mile straight after this corner, over the whole distance Rubens might be faster even though he's losing 0.3s+ in corner entry and mid-corner. As we know, there isn't a one mile straight after this corner. There's a short straight and then a series of sweepers that in an F1 car are mostly flat, at least till the last one. Anyway, what am I rambling on about. Well, without knowing how quickly they both get through the section of track following this corner we can't really know who is faster, Michael or Rubens.

In summary, my big beef is the author choose the wrong data to prove is point. "This is the most spectacular example of Michael's unique driving style". WRONG, this is an example of two driver's taking a completely different approach at driving through a corner, regardless of driving style (that is, if those two things can be entirely independent). There are better examples out there of how Michael's unique driving style helped him at certain tracks be faster than Rubens.

I'm not trying to defend Rubens by any means, actually I think his right foot braking as really hurt him over his career. It hurts the teams he drives for too because they have to set the car up differently for each driver.

Okay, done rambling. Wonder if anyone will read this...

Back to your originally scheduled programming.

sjmarcy

Driving is driving. When you examine the data you can tell, for sure and with no emotion involved, certain facts. For instance if you only ever gently roll onto the throttle you are not truly at the car's limits. I have shown autocross and track data or video for Miatas indicating steering, gas, brake inputs required to control the vehicle at the limit. If you never do this, you are not at the limit. If you do well at your racing class and never do this, then your car is sufficiently superior to those of your competitors that you don't need to push hard. That can still be fun but there is some unused potential which could be utilized.

When you look at the data from Andretti or Schumie in their primes, or Hamilton right now, you see that ultimately they make errors too. Just fewer of them and they catch them earlier before things snowball too badly. That is a large part of the uberfast hot shoes. Fewer and smaller errors. At times I can run, for sure, just as fast as multiple national champion drivers. But I am over my head and so a turn or two will have a slight error lessening my result. I can tell you that when I drive like that, it is pretty busy behind the wheel. Whether I am in a friend's 550 HP street mod Evo, a SC Miata, my own NA car, it does not matter.

Given the difference in throttle response some cars exhibit, this can help or hurt the ability of the driver to control the car when truly at 10/10ths. Since some strategies sacrifice control for output, this means that they can't quite reach the potential their straight line capability suggests. They can be fast and fun as hell of course. But if a mod has the potential to drop lap times by 5 seconds a lap and you can only find 4 even if you are Senna-esque then I am saying that part of the issue is related to throttle response. I have already established that at the very limit during technical maneuvers, many corrections need to be made. Some of those involved the loud pedal.

mgeoffriau

iTrader: (7)

In what world does rolling on the throttle indicate that you are not at the car's limits? Is the idea that a car may have more power than can be put down in a given corner at max throttle entirely foreign to you?

flier129

iTrader: (7)

Double digit HP crew checking in....

I stay WOT thru the whole corner, there-for my throttle response is better.






Am I doing it right? Please think my story is cool and call me bro!

blaen99

iTrader: (6)

...There's only one possible response to that, Sjmarcy.



This video conclusively proves that a turbo has terrible throttle response, and that even a tiny econobox has far better throttle response to a turbo. Just look at the doriiiftttoooo around the FD!

sixshooter

iTrader: (12)

Cool story bro!
I, too, can take a 60 mph corner at 45 mph in my double digit horsepower car while stomping and releasing the throttle thereby demonstrating my throttle response prowess. **** a turbo.

owenwilliams

"At times I can run, for sure, just as fast as multiple national champion drivers."

That's one of the funniest things I've heard in a while. You even added an unnecessary "for sure" like all the F1 drivers. I lol'd... until I realised that I was sitting at home on a Friday night lolzing at a guy I've never met on the internet, then I got sad.

Anyway, everybody has been going round and round in circles for seven bloody pages now. Somebody make it stop please!

Efini~FC3S

iTrader: (4)

Change your settings so that there's more posts per page.

Then it only goes round in round in circles for three pages.

PROBLEM SOLVED!

sjmarcy

I can say "for sure" because we spent time examining the data. Which proves it. One run I was up about 3-4 tenths on a driving god. But in autocross you have just a few runs. And I made a timing mistake which hurt the run so I was beaten by a few tenths. But still had a decent run.

Here is a display of that data. Note the time slip which shows relative result. I was able to use what I learned in a different car that day though, to good effect, so I could nail the final course elements. If you understand time slip then I have made my point. One thing about autocross is that you are on a new course and will never fully master it by the time it is gone. If the courses stayed up for some time or were permanent, times would drop.

On the thread itself you may want to have a word with Sav. He created the thread after all. And other keep referencing it in other threads, you may wish to speak to them too. After all more information and another POV are not needed everything is already known and fully understood. ;-)

JasonC SBB

Because dorifto requires good throttle control, I'll say the popularity of turbos among the dorifto crowd suggests that turbo controllability is fine.

Dorifto naysayers: if it's "easy", can you do it?

sixshooter

iTrader: (12)

Faeflora

iTrader: (2)

.. i i i

I SALUTE THEE GREAT ONE!!!

stinkycheezmonky

Did I miss the part where someone explained how an individual laptime/data plot was relevant to the comparison of NA vs. turbo throttle response?

<--- Wonders wtf is going on here.

For rolling on the gas information, see here: http://roadraceautox.com/showthread.php?t=35569 For those unfamiliar, Mike Skeen is a pro driver currently racing in WC GT and Grand Am something or other (and possibly more series, I'm not certain). He is very successful and fast, and is one of the smoothest drivers I've ever seen. His comments are towards the end of the thread.

P.S. Am I allowed to link to other forums? Not sure what the rules are on that here...

triple88a

iTrader: (2)

Sorry guys i'm a little late to the show but you're talking about the antilag on the end of the 1st page there...

It can be made at idle and can be made while shifting gears while running rich on throttle lift, iac opened fully and timing pulled back by 40-50 degrees into the negatives so the combustion happens when the valves open to keep the turbo spooled. I was actually trying that with my adaptronic before i pulled it however i dont think theres a way to retard timing into the negatives with it...at least its not possible using the ignition map.

spoolin2bars

iTrader: (1)

excellent link/reading in that thread! further proves sav's point of "rolling into the throttle", that any track enthusaiast should already know. i also think some people on here imagine that "rolling into the throttle" means it's gonna span 30 mins. or something, which is not the case.

Laur3ns

Best post ITT