The online racing simulator
Brake Bias and Engine Braking
2
(43 posts, started )
Quote from Vain :Because one method screws up your brake-balance and brakes inconsistantly and the other can brake very fluently with a well defined brake-balance.

Vain

So ignore the gears so that you can concentrate on braking. What happens then once you have stopped braking? Ignore the gears and concentrate on the steering?
Most advanced driving teachers, and racing schools, will advise you to be in the appropriate gear for the upcoming corner as soon as possible, which means engaging it whilst braking hard.
#27 - axus
Also, if you are really really pro, you could adjust the amount of blip you to the slope to change your brake balance, but that is more of an instinct - you can't really learn to do it right because you have to be too accurate.
#28 - Vain
@sinbad:
There is a difference between shifting down so your average rpm is about 10 000 rpms and putting yourself into the right gear for the next corner.
You always shift through the gears, the matter is just to which time you shift. Either shift down at the red line for additional engine braking or shift down where necessary to get the right gear for the turn and brake using your brake-pedal.

Vain
Caroll Smith's thoughts are to do with improving a driver. He says that most people can't heel and toe/blip very well, and concentrate too much on it. His test is to show how concentrating on one thing (using the brakes alone) is more effective that trying to do two things less well. There's no doubt that in real life, in LFS and in Mr Smiths head that using engine braking with normal braking is quicker, but in real life most people don't actually left foot brake, and hell and toeing perfectly everytime on the limit under pressure is very very hard.

In LFS it's much easier to do both, because we have no forces acting on our bodies, less noise and vibration, less risk of pain, and no risk of wiping out a car or a competitor that will end up costing real money.
I find that staying on the throttle for a breif instant while clutching to gear down works fine, my right foot can slipoff the accelerator and land on the brake, so for single gear-down situations like many turns I don't have to heel toe, and don't have to worry about RWD cars getting all haywire on me.
Quote from nikimere :it's simple, why use one method of slowing the car down when you could use 2? you stop faster.

It makes absolutely no difference whether or not you use engine braking in a game that doesn't involve weak brakes or brakes that overheat and fade. Since brake force in LFS is always sufficient to lock the wheels if you so desire, there is no excuse for the above rather wrong comment.

As Carroll Smith correctly noted, using engine braking as a matter of course makes things less repeatable and less consistent.

Quote from tristan :
There's no doubt that in real life, in LFS and in Mr Smiths head that using engine braking with normal braking is quicker,

Perhaps in cars with downforce where optimum brake balance changes with airspeed...other than that, why could using both be "quicker"?
Because you can use the engine braking as an extra source of braking. If you're not threshold braking with every wheel you're not braking at full capacity (assuming a straight line), and it's highly unlikely that you'll ever get the master and slave cylinder sizes, bad sizes, effective disc diameter and brake bias perfect for every corner on every track. Thus if you use engine braking you can reduce the pedal braking on the driven wheels and use the extra (and free) engine braking to boost the resulting loss of braking on the driven wheels. Thus you have more perfect braking more of the time.

The downside is that it would take rather more driver skill to make use of this than not, so it's not widely done. And it's not done much on light cars (say single seaters) as they become very twitchy under braking, with or without downforce.

At least that's my understanding.
#33 - Vain
Engine braking can be used to adjust brake bias dynamically, but when you want to brake in a straight line, you could just set your brakes for this matter and brake with perfect bias and perfect strenght.
With turning this gets more complicated. While trailbraking it is desirable to have a higher front bias, or you'll lock the rear wheels. Thus it might be worth trying to use the engine in an RWD car to move brake bias back while braking in a straight line and having the more front-biased conventional brakes on while trailbraking.
But the maximum decelaration allowed by the tyres can be achieved both ways. With or without engine braking. It's a matter of preferance and setup.

Vain
i usually brake hard at the last moment and then trailbrake while engine braking to minimise locking the rear wheels (with auto blip on).

this works a treat and i can outbrake quite a few people = faster times...
Quote from skiingman :It makes absolutely no difference whether or not you use engine braking in a game that doesn't involve weak brakes or brakes that overheat and fade. Since brake force in LFS is always sufficient to lock the wheels if you so desire, there is no excuse for the above rather wrong comment.

As Carroll Smith correctly noted, using engine braking as a matter of course makes things less repeatable and less consistent.


Perhaps in cars with downforce where optimum brake balance changes with airspeed...other than that, why could using both be "quicker"?

Why are you trying to complicate things? The simple answer to which is quicker is... A combination of both engine braking and normal braking together is the fastest way to slow down your car, be it IRL or in a game.
Quote from nikimere :Why are you trying to complicate things? The simple answer to which is quicker is... A combination of both engine braking and normal braking together is the fastest way to slow down your car, be it IRL or in a game.



I dunno. Not just Smith, but very good drivers I trust have suggested making downshifts as late as practicable, unless one has a very good reason to need the extra engine braking. I think the true benefits for experienced drivers were best described by Vain and Tristan.

One of the things I see as an obvious problem is feel. A good braking/steering system gives a lot of feel for what is going on at the front corners of the car. In my experience, the feel as to the braking at the rear is more vague because it isn't as dominant and isn't hooked up to the steeering. With engine braking, you need to be a left foot braker in order to modulate both brakes and engine braking at the same time. I think the benefits of engine braking show up in situations like tristan describes, because you cannot adjust brake bias for every corner perfectly, but can do a much better job if you can modulate engine braking to modulate the effective brake bias.

This is not something that is easily done. Its stupid/pointless/impossible on the streetable cars I race that have synchromesh gearboxes. For them, the benefit of engine braking is saving the inevitably undersized brakes from abuse.

In LFS, it seems to me that since the feel of braking is lacking compared to the real thing, you have to rely on either lots of practice or secondary clues to know when you overdo the engine braking and cause understeer/oversteer depending on drive configuration. Since there is always plenty of brakeforce in LFS, aggressive use of engine braking seems to me to uneccessarily complicate things at the expense of consistency.

However, for people looking to run WR times, the ability to dynamically adjust brake bias without twisting a knob/punching F12 has obvious benefits. I wonder how large they are. I imagine the benefits are greater on the cars with downforce because their apparent mass distribution changes with airspeed. Reason number 13516 it would be nicer for everyone if racecars had the wings loading the uprights instead of the chassis.
A mixture of engine and brakes for braking is best for me. but be careful not to shift down a gear to many at high speeds, it ruins your engine as you lot know no doubt
A perfect example of using engine braking to help turn in is in the hairpins on AS North using Race_S setup on the FZ50. I was used to trail braking into those turns in 2nd gear, then I realised 1st gear was long enough, so I started using 1st, and boy did it turn in a lot better Then for other corners where the back is already feeling a bit loose, I'll turn in on the brakes in a higher gear, to keep from getting sideways. So, it's nice to have a variable brake bias for different corners on the track... I know this has already been discussed, but I thought I'd bring up this example of it
It depends on the car. In real life, many racing cars have their clutches setup to limit the amount of engine braking, probably for two reasons: 1. to keep the rear tires from sliding; 2. to keep the engine from over-revving.

The other issue is that the amount of engine braking depends on what gear you're in and the engine rpms. It isn't consistent. However, I have a tendency to brake a bit early and modulate the throttle while approaching the apex of a corner, but for slow speed turns, I'll sometimes leave the car in 2nd gear until past the apex before downshifting into 1st.

Note also that just cornering hard consumes energy and slows a car down. When cornering hard, my guess is that cornering slows down a car more than engine braking does. I do use the throttle to control how fast the car slows down in a turn, while approaching the apex.

When watching an analisys of a fast lap, I've heard the the expression, "no hint of a lift, just the g forces slowing down the car" more than once, as in this video. I get the impression that F1 cars don't rely on engine braking at all, based on the when the downshifts occur.

spaf1.wmv
Quote from JeffR :It depends on the car. In real life, many racing cars have their clutches setup to limit the amount of engine braking, probably for two reasons: 1. to keep the rear tires from sliding; 2. to keep the engine from over-revving.

Like motorcycle slipper clutches? In the cars you are talking about, is this done through electohydraulic clutch control, or a mechanical system like the motorcycles? For anyone not familiar with the idea, here is a good link : http://www.sigmaperformance.com/slipperclutch.html
Quote :
I get the impression that F1 cars don't rely on engine braking at all, based on the when the downshifts occur.

spaf1.wmv

Yeah I have that understanding too. I think they do add more engine braking to the throttle-closed ECU settings when they have good reason.
Quote from nikimere :
no racing driver in their right mind would just brake into a corner and then select the right gear before the apex or before you go on the power.

I was wondering why it would be so ridiculous for a driver to do this if he had his brake power setup so hes able to lock the wheels with little effort with only foot braking (and therefore threshold brake without help from the tranny)? Of course i can understand why you wouldnt put it in gear after turning in, but im wondering why it would be so insane to brake with just the brakes until reaching a safe speed to put it in the right gear for the corner, and then turning in?
Quote from KurtG85 : Of course i can understand why you wouldnt put it in gear after turning in, but im wondering why it would be so insane to brake with just the brakes until reaching a safe speed to put it in the right gear for the corner, and then turning in?

Its not insane in the least.

As is kind of alluded to above re: slipper clutches, this is pretty much exactly what happens in racing motorcycles. Engine braking is limited to just about nothing, in the interest of consistency and smoothness.

As is made obvious with the new BF1 in LFS, the ECU is used in racing cars for a similar effect, although more easily adjustable.
Quote from skiingman :this is pretty much exactly what happens in racing motorcycles. Engine braking is limited to just about nothing, in the interest of consistency and smoothness.

Are you trying to say they don't use engine braking in motorcycle racing??????

If yes that's an insane opinion,
if not, sorry!!!!
2

Brake Bias and Engine Braking
(43 posts, started )
FGED GREDG RDFGDR GSFDG