Brake Boosting

[DUHAST]

Hey guys, I am a demo-player, first-time poster, and a turbo'd car owner.

I love how realistic the game is, but noticed you cannot 'brake boost'

'WTF is brake boosting' you ask?

Brake boosting is when you hold the throttle and brake at the same time in order to slow down, but hold boost at the same time.

Example (launch):
From a stop
Holding the brake 100% with 40% throttle to build engine resistance (and boost)
Then releasing the brake and applying 100% throttle (already at full boost)

This will eliminate boost-lag for a launch.

Example 2 (corners):
When coming out of a corner, the brake is released and the throttle is applied. when the throttle is applied boot is built, the driver experiences boost-lag.

If the driver is to apply some throttle while still braking around the corner, boot will build, then when the brake is released, the turbo is already spooled and pushing max psi (bar)

--------------------------------------------
Works on Automatic, Tiptronic, and Manual cars

LFS S2 currently drops the boost as soon as the brake is applied, and will not allow boost to generate is the brake is still on.

[Flame CZE]

I think you are wrong. This should work in cars with turbos only and it works.

[DUHAST]

....im not wrong... it barely works around corners, not well enough to be effective.. it doesnt work at all off launches...

and yes it should only work with turbod cars

[MadCatX]

....im not wrong... it barely works around corners, not well enough to be effective.. it doesnt work at all off launches...

and yes it should only work with turbod cars

And how exactly would you know that 'cause there is no turbocharged car available in demo?

[tristancliffe]

Hey guys, I am a demo-player, first-time poster, and a turbo'd car owner.

I love how realistic the game is, but noticed you cannot 'brake boost'

'WTF is brake boosting' you ask?

Brake boosting is when you hold the throttle and brake at the same time in order to slow down, but hold boost at the same time.

Example (launch):
From a stop
Holding the brake 100% with 40% throttle to build engine resistance (and boost)
Then releasing the brake and applying 100% throttle (already at full boost)

This will eliminate boost-lag for a launch.

Example 2 (corners):
When coming out of a corner, the brake is released and the throttle is applied. when the throttle is applied boot is built, the driver experiences boost-lag.

If the driver is to apply some throttle while still braking around the corner, boot will build, then when the brake is released, the turbo is already spooled and pushing max psi (bar)

--------------------------------------------
Works on Automatic, Tiptronic, and Manual cars

LFS S2 currently drops the boost as soon as the brake is applied, and will not allow boost to generate is the brake is still on.

Both sound like really bad ways to drive quickly. The first one will knacker your clutch and provide minimal boost.

The latter is best done without touching the throttle whilst braking, but instead blipping the throttle through the corner. Of course, this has the downside of upsetting the balance of the car, and only drivers with the talent of A. Senna will master it.

[Forbin]

Just start your throttle application sooner.

Turbos suck anyway. Natural aspiration ftw. Want more power with equal displacement? Tune for revs, the way high performance motorbikes have been doing it for at least 3 decades.

Also: :bananadea

[FPVaaron]

And how exactly would you know that 'cause there is no turbocharged car available in demo?

:something

[Inouva]

Realy, Stop this "Hauting" of demo crakers, maybe hes using patch Y when XRT was demo...

[FPVaaron]

Realy, Stop this "Hauting" of demo crakers, maybe hes using patch Y when XRT was demo...


Join date February 2011

By the way, 100% brake and 40% throttle in order to launch is used for automatics with high stall converters, doing this in a manual is incredibly bad for your clutch and will simply not work for any "modified" cars with ceramic or brass clutches.

[E.Reiljans]

Join date February 2011So? Version X10 doesn't requires registration of account in order to play game, even in multiplayer.

[Inouva]

Join date February 2011



So? Version X10 doesn't requires registration of account in order to play game, even in multiplayer.

This

[Ricerguy]

This

:( So why post an improvement suggestion on an outdated version? :shrug:

[Inouva]

:( So why post an improvement suggestion on an outdated version? :shrug:

We dont know yet what vercion he's running

[BigPeBe]

Before clutch heat was introduced in LFS I used to launch XRT in a similar manner. By hand I held the handbrake on and carefully started to use throttle and release clutch so before lights went green I had full boost and good rpm for launch and just released clutch and handbrake at same time. Of course this is not anymore possible because it would make the clutch unusable.

And the ability to make boost before accelerating out of corners of course is car related, some cars pick spool up faster than others so it's not exactly unrealistic if it's hard. Tho I have to say when I race TBO (usually XRT) I don't have problems picking up boost. Good gearing + right driving style works. I always aim for the earliest possible accelerate out of corner so I apply full throttle quite early.

[E.Reiljans]

:( So why post an improvement suggestion on an outdated version? :shrug:Cause changelogs of versions Y/Z/Z28 didn't mentioned anything related to that.

[Rotareneg]

I just checked 0.04Q and holding the brakes and throttle down to build boost has worked even that far back. The OP must be mistaken, or doing something wrong, or whatever.

[zazzn]

break boosting works, it's just the turbo physics of the game are wrong.

even at 6 k it takes for ever for boost to come back online and the way boost builds is wrong the first few PSI should be slow to come on until you hit the turbo threshold at which point you should instantly pop up to the max desired boost.

My biggest problem on the FXO/XRT/RB4 and other turbo cars is the lag on them is unrealistic. No production car gets full boost at like 5k unless you are talking about a 450 HP evo MR. Any production car running small amounts of boost like 7 PSI will make full boost at like 3500 RPM.

Don't get me started with the GT cars which run 26 psi of boost spool slower than a jet turbine and have a redline of 6k

:P

[xfirestorm]

Both sound like really bad ways to drive quickly. The first one will knacker your clutch and provide minimal boost.

I'm sorry, but I really don't understand how can applying throttle while braking cause damage to the clutch?
It's like applying normal throttle but the brakes are "generating" some resistance to wheels causing the car to have trouble to accelerate or even prevent it from doing so. So it's like going up a steep slope where the gravity provides the resistance instead of the brakes and the throttle does the usual thing.
Is this not so?

[Whiskey]

If an engine develops 300 bhp, the clutch is not really holding all of those because the car will be accelerating. But if you apply your brakes the clutch will hold all those horses.

It's hard to explain in English, sorry :shy:

[xfirestorm]

If an engine develops 300 bhp, the clutch is not really holding all of those because the car will be accelerating. But if you apply your brakes the clutch will hold all those horses.

It's hard to explain in English, sorry :shy:

Yes I understand this, but, you're not applying full brake in the middle of the corner. At least I haven't been able to pull this of in any corner to do 100% braking and turning through the corner at the same time.

[Forbin]

If an engine develops 300 bhp, the clutch is not really holding all of those because the car will be accelerating. But if you apply your brakes the clutch will hold all those horses.

It's hard to explain in English, sorry :shy:

Bollocks.

Force is force, whether it's going through the drivetrain and acting on the ground or on the chassis through the brakes.

Along those same lines, clutches are not rated based upon horsepower capacity. They are rated based upon torque capacity.

[tristancliffe]

This is about a standing start. Not braking into a corner against a throttle, which is quite common even in normally aspirated (read: better) cars.

Revving an engine with no load generates little boost. To hold a car at, say, 8000rpm with no load only requires a few percent throttle - no heat is generated for the turbo to gather. Flow on it's own doesn't drive a turbo (and with the throttle pretty closed there isn't much flow either). More throttle won't work, as the car will bounce off the rev limiter, which will cut sparks and/or fuel, and hence reduce the heat output into the exhaust. A massively retarded ignition might work to throw heat into the exhaust, in the form of a crude anti-lag system whilst at a standstill.

So, to generate boost at a standstill we need some load. That load can't come from the mass of the car, as we are at a standstill. We need to generate load against the brakes. That means slipping the clutch (wheels not moving, engine revving - something has to give), but not too much as otherwise it won't provide any load (100% clutch slippage = zero load, 0% clutch slippage = engine stall (or movement if the brakes aren't strong enough!)).

So, as the car is sitting there generating load via the clutch against the brakes, the clutch becomes more and more like the surface of a star. And stars are, as we all know, useless as clutches.

[Seb66]

brake boosting does work, that's what people (including myself) do in the turbo GTR cars at on rolling starts of league races:razz:. You go full throttle 2nd gear, then hold the brake to control your speed to the rolling start pace of about 80 - 90kph, this also spools the turbo to max pressure, then when the green flag comes out.. let the brake off :)

[tristancliffe]

But in that case your wheels are moving, so the clutch can be fully engaged. You just use the brakes to add resistance (load). If you're not moving, you MUST HAVE slip between engine and drivetrain, but also some load - hence a lot of clutch slip. I don't think it's possible to do it at a standstill without destroying a clutch in double quick time.

[Ball Bearing Turbo]

Depending on engine & turbocharger design, you could generate quite a bit of boost at WOT in the time it takes to go from idle to redline - some can basically hit max pressure but many can get almost all the way there. At least for a vehicle that behaves well as an everyday driver; I'm not talking about about an 800hp 3L inline 6 with a turbo the size of a beachball obviously. So for a standing start, timed right it wouldn't really matter too much with many modern engines. I posted a video a while back of someone's car able to max out at basically 1 bar very easily just by revving in neutral. It really depends on the engine's characteristics (flow characteristics, ignition mapping, turbo geometry, manifold design blah blah blah)

As stated before, the turbo model in LFS is extremely simplistic and behaves somewhat like the worst design you could think of from the 70s. But at least it has an attempt at one so that's a start.

[logitekg25]

tristan your explinations are spot on every time :thumb:

and people are debating different things, tristan is saying you cant really brake boost from a standstill in a manual (automatics can, my brother has done it), and everyone is saying you can, but they are saying while moving anyways.

so technically i think almost everyone is right; the amount of realism in using the technique in the example situation is questionable, but in theory would work.


off topic: today my friend on demo asked me what the numbers in the dash were...i said gears and he wondered what i was talking about. this world is going to sad places :(

[xfirestorm]

There is one more thing that I don't understand about this turbo thingy generating less psi under no or little load.
The way I understand it, the engine produces exhaust which in turn drives the windmill on the "exhaust part" of the turbocharger, and the windmill of the "exhaust part" is connected to the windmill located in the "intake part" of the turbochargers and turns it as more exhaust fumes are moving through the exhaust headers, and "intake part" sucks in more air with the help of its windmill.
But then, why would it be more difficult to spin the windmills if there is no load on the wheels? Is the car using up less fuel and thus generating less exhaust if there is no load? Or what's the trick that I'm missing here?
I'm sorry for so many questions that might seem obvious to you, but I'm really confused about this whole turbo part. I know my way around the car to the length that I can change my own oil/brake pads/disks/etc, but this turbo thingy is just Chinese to me.

[tristancliffe]

Okay, maybe load is the wrong term. Think of throttle opening. The greater the throttle opening the more gas flow through the engine, and the greater the exhaust heat. Turbos are driven more by the heat energy in the exhaust that the rate of flow (although that does come into it slightly).

At a standstill, in neutral, it doesn't take much throttle before the engine redlines. With a heavy flywheel you could open the throttle 100% and within a second or two be bouncing off the rev limiter. To hold, say, 5000rpm for a launch only requires say 10% throttle - and not much boost is generated at 10% throttle.

If you have a small enough turbo, and time it right so that you're at full throttle, with the revs climbing and the boost building, then you can be at high boost (if not max) as the lights go out for a quick start. You don't need to hold the car on the brakes for this!

But if your timing is out you'll either be too late (in which case your revs will be low and the boost will be low) or too early (in which case the engine bounces off the rev limiter, the boost drops and you have a boost-less start).

A bigger flywheel (so the engine revs slower) might help. A racing car, with the lightest flywheel that can be used, will rev very quickly, so there is little chance of building boost at a standstill without slipping the clutch against the brakes (effectively to slow down the engine revving up at full throttle, allowing boost to build).

Of course, some ECUs will have been mapped so that full throttle at very low speeds (standstill) will retard the ignition and lean the fuelling so that more heat is generated in the exhaust, which will also reduce power causing the engine to rev up slower.

In short, the best way is to use the right size of turbo, time your launches, and accept that high-boost as the lights go out isn't very likely, but will occur a second or so later. I don't think any car modified after manufacture has used a correctly sized turbo - everyone bolts on the biggest one they can find thinking it'll be better.

[Psysim]

DUHAST, sadly if you ask for help on this forum, people will look for a reason to flame you. Anyway, I always understood 'brake boosting' as reducing the required pressure needed on the brake pedal by using a vaccume source from the engine on one side of the diaphram.

But it would seem from the posts, your asking about the turbo? and about it being ready for your exit of the corner? If you want to keep the turbo spinning up.... left foot braking!

Anyway, to the point, this is JUST a simulation and is far from the real thing, keep that in mind when considering your expectations!