Engine Braking

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
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Benniau
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Joined: 30 Jan 2007, 08:51

Engine Braking

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First off, apologies if this has been covered in another topic, I searched a bit but couldn't find anything really specific.

Simple question. I've been hearing alot of the drivers complaining about the lack of engine braking coming into corners for the new 2008 regs.

Isn't engine braking simply changing down gears so the driving wheels are restricted by the engine at high revs?

How could they ban that? Have the clutch automatically disengage as they hit the brakes?


Benni

modbaraban
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Joined: 05 Apr 2007, 17:44
Location: Kyiv, Ukraine

Re: Engine Braking

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I reckon the engine braking was very much controlled (and adjustable) by the ECU. With banning the TC and introduction of the universal ECUs that area is mostly beyond teams' control.

CMSMJ1
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Joined: 25 Sep 2007, 10:51
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Re: Engine Braking

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The cars used to have systems that opened the throttle to stop the rear wheels locking up. If you recall the on screen graphics, where you would see the throttle flickering when the brakes were full on, this was the computer managing the engine braking.

As this i now banned, the drivers have to work harder to match downshifts to road speed and engine speed and as they have not got a foot clutch to balance the laods with it is pretty tough!
IMPERATOR REX ANGLORUM

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Benniau
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Joined: 30 Jan 2007, 08:51

Re: Engine Braking

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Surely it wouldn't be that hard to build a clutch that releases slightly when the energy is coming from the wheels and not the engine?
As you downshift and the force reaches a point where the wheels would lock, the clutch releases slightly for moment, a mechanical device, not computer controlled?

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checkered
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Joined: 02 Mar 2007, 14:32

Re: Engine Braking

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That'd be a

pretty significant change, as in current "zero shift" gearboxes the clutch disconnects only while the car is stagnant. David Coulthard did refer to the engine "spiking" during downchanges towards a turn, something that certainly wouldn't make the job of keeping the total of braking forces consistent easier for the driver. Of course there's no telling what teams do to solve these, and other, problems associated with the SECU and I can only presume all kinds of mechanical variations are actively and continuously being looked at.

Fiero Brick
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Joined: 16 Oct 2007, 21:11

Re: Engine Braking

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I can certainly understand the problem! With dynamic compression ratios like a F1 engine and a vehicle that light, engine braking could cause quite a problem with traction... particularly if you're on the brakes when you're in a corner. It will be interesting to see how the drivers and engineers adjust to the change. I have some sympathy for the drivers; I've locked the back wheels of my truck by downshifting into first when I was not paying enough attention or the roads were slick. It isn't a fun thing. Of course, a formula car has better tires and more than 20% of its weight on the back wheels, but they're also going a bit faster...
Benniau wrote:Surely it wouldn't be that hard to build a clutch that releases slightly when the energy is coming from the wheels and not the engine?
As you downshift and the force reaches a point where the wheels would lock, the clutch releases slightly for moment, a mechanical device, not computer controlled?
From what I understand, lots of motorbikes have a clutch that acts like that.

mahesh248
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Joined: 05 Mar 2007, 12:05
Location: India

Re: Engine Braking

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[quote="CMSMJ1"]The cars used to have systems that opened the throttle to stop the rear wheels locking up. If you recall the on screen graphics, where you would see the throttle flickering when the brakes were full on, this was the computer managing the engine braking.

As this i now banned, the drivers have to work harder to match downshifts to road speed and engine speed and as they have not got a foot clutch to balance the laods with it is pretty tough![/quote]

I thought it was because of the burst in RPM when you shift to a lower gear , the RPM would increase when the shift to a lower gear dose it not , Engine Brake is the Frictions loss in speed due to the the friction inside the Cylinder , you dont need ECU for this thing to happen ..

Carlos
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Joined: 02 Sep 2006, 19:43
Location: Canada

Re: Engine Braking

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A solution to the problem of loss of tire adhesion, locking up the rear wheels is available within the F1 regulations. A mechanical solution, used in MotoGP, which has similar problems under engine braking, it certainly should be adequate for F1 as MotoGP translates 230BHP through the tiny contact patch of a single, narrow tire, this article explains the features and the design of the slipper clutch.

http://www.hmstm.com/technology.htm

Gecko
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Joined: 05 Sep 2006, 20:40

Re: Engine Braking

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The engine braking as such is not really an issue. The engine can still be mapped so that the trailing throttle will produce more or less braking torque.

The problem is the loss of active control of the throttle under braking. While borderline legal under the previous regulations, the engine was working as a sort of an ABS system for the rear axle. It basically meant that the drivers never had to fear locking up the rear axle. What is happening now in testing is that the teams still have to update the braking systems in order to be able to cope with the usual braking demands, something that they didn't have to worry about too much in past years, so the drivers are experiencing some issues. I don't doubt that this will all be mostly sorted by the first race.

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Benniau
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Joined: 30 Jan 2007, 08:51

Re: Engine Braking

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So many little bits of technology that you don't hear about often. I guess $400million+ has to go somewhere :P

Fiero Brick
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Joined: 16 Oct 2007, 21:11

Re: Engine Braking

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Kind of like comparing the options list of an economy car from 1990 with a brand new Mercedes. I find myself continually amazed as the number of thinks I would never notice that can be crammed into a car.

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Benniau
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Joined: 30 Jan 2007, 08:51

Re: Engine Braking

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I really keen to find out now if F1 teams use Slipper Clutches.

Speaking of clutches, I've seen clutch paddles on the rear of steering wheels under the gear change padddles. Does anyone know if these are "analogue" or just off/on switches? I'd imagine they would need to be analogue, or variable to stop wheelspins or stalls, but how much travel do the have?
I heard that the accelerator pedal has about 2cm of travel, its pretty much an on/off button. Think about that for a moment... car idles at around 5000rpm... Redline at 19,000. That gives you 14,000 rpm to play with. That's 700rpm every millimeter of accelerator travel.
You'd really need to have strong and sensitive ancles and feet.

I also heard the brake has about the same amount of travel and you practically have to stand on the things to make them work.


Can anyone offer any input as to whether these figures are correct?

PNSD
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Joined: 03 Apr 2006, 18:10

Re: Engine Braking

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Thats not true about the pedals.

They will differ from driver to driver tbh.

Anyone who saw that 5th gear where the rich guy bought an F2001, when at the Ferrari factory choosing his ermm items (ie seat/pedals etc) he chose MS's pedals because they had so much more travel than RB's pedals.

bizadfar
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Joined: 03 Jan 2007, 15:51

Re: Engine Braking

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Yes in other words it is electronically (fly by wire?) tuned. It can be setup to be non-linear for driver taste.

PNSD
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Joined: 03 Apr 2006, 18:10

Re: Engine Braking

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bizadfar wrote:Yes in other words it is electronically (fly by wire?) tuned. It can be setup to be non-linear for driver taste.
yup they are fly by wire, im sure.

I imagine pedal adjustment was one of the first things drivers did when testign without TC.