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Traction control

 
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TwinTurboM3



Joined: 21 Mar 2008
Posts: 488

PostPosted: Tue Jul 28, 2009 12:10 pm    Post subject: Traction control Reply with quote

Did anyone activate TRACTION CONTROL on a turbocharged car, 1000-1200 whp?

How does Motec`s Traction Control function?

Does the car still accelerate forward or gets slower due to ignition cut?

Thanks
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Gadgeroonie



Joined: 24 Aug 2004
Posts: 1723
Location: UK

PostPosted: Tue Jul 28, 2009 12:39 pm    Post subject: Reply with quote

traction control works by montoring the front and rear wheels speeds and then cutting ign progressively till it is back under control

there are other strategies you could try

limit the boost depending on the gear you have selected

or some ecu's have a form of launch control where the ecu cuts power if the engine accelerates past a predetermied level - stopping the car breaking into tyre spin

are you wanting really good traction whilst driving- or looking to get the car off the line

a company that has always done a really good version of traction control is racelogic

http://www.racelogic.co.uk/?show=Traction_Control

i have been in the car that is show in the link and i can vouch that it really works well (it works by slowly cutting the injectors one by one )
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TwinTurboM3



Joined: 21 Mar 2008
Posts: 488

PostPosted: Tue Jul 28, 2009 1:06 pm    Post subject: Reply with quote

MIke,
thank you for the answers.

I have a racelogic, got it 3 years ago, and it does not cope with the ABS sensors of E46 M3.

Other than that, i have a Pectel ECU, and Pectel has a programmable menu for TC.

My goal is to accelerate from 40 to 160 mph, not off the line, with a 1000 whp Dynamics Shoot Out, car.

What do you advise?
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Gadgeroonie



Joined: 24 Aug 2004
Posts: 1723
Location: UK

PostPosted: Tue Jul 28, 2009 1:33 pm    Post subject: Reply with quote

if you have the racelogic system, then i advise you get it fitted with your own wheel speed sensors

a set of slick tyres will help no end, as will drag radials and a tubbed rear end

are you reading any wheel speed at all with your ecu ?
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TwinTurboM3



Joined: 21 Mar 2008
Posts: 488

PostPosted: Tue Jul 28, 2009 1:35 pm    Post subject: Reply with quote

need to install old style M3 wheel speed sensors.

Yes I do read rear wheel speed with Pectel.
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Gadgeroonie



Joined: 24 Aug 2004
Posts: 1723
Location: UK

PostPosted: Tue Jul 28, 2009 1:42 pm    Post subject: Reply with quote

if you are reading rear wheels speed - can you move the sensor to the front wheels ?
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TwinTurboM3



Joined: 21 Mar 2008
Posts: 488

PostPosted: Tue Jul 28, 2009 1:44 pm    Post subject: Reply with quote

pectel is reading from rear ABS sensor.

In order to make the TC menu active, I need connect all corners` ABS signals to PECTEL.

So there is no racelogic, just Pectel.
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IJ.



Joined: 10 May 2007
Posts: 75

PostPosted: Tue Jul 28, 2009 3:28 pm    Post subject: Reply with quote

I run TRAC in the M800, we tried a LOT of different strategies to try and control slip, the car is only 500rwhp but was making a lot of torque that came on very hard around 3500.

Retarding timing and cylinder cut had little effect other than to do the pretend antilag thing and increase boost (had boost reduction dialled in as well so net result was no change)

In the end I changed to DBW and finally got brilliant TRAC (I had a couple of the boys from MoTeC Aus helping to get it to work every step of the way)

I did a run on a gravel road at 10psi and could just nail it the whole time.
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TwinTurboM3



Joined: 21 Mar 2008
Posts: 488

PostPosted: Tue Jul 28, 2009 3:50 pm    Post subject: Reply with quote

IJ. wrote:
I run TRAC in the M800, we tried a LOT of different strategies to try and control slip, the car is only 500rwhp but was making a lot of torque that came on very hard around 3500.

Retarding timing and cylinder cut had little effect other than to do the pretend antilag thing and increase boost (had boost reduction dialled in as well so net result was no change)

In the end I changed to DBW and finally got brilliant TRAC (I had a couple of the boys from MoTeC Aus helping to get it to work every step of the way)

I did a run on a gravel road at 10psi and could just nail it the whole time.



I had DBW, and removed as it was easier to set the system.

Do you mean that it is not possible to take advantage of TC without the DBW?

Basically, the DBW closes up to a certain degree, and dont allow air to enter the cylinders.

Would you please explain how the system works better with DBW?
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IJ.



Joined: 10 May 2007
Posts: 75

PostPosted: Wed Jul 29, 2009 12:21 am    Post subject: Reply with quote

I found it to be far smoother than everything else we tried in my car, as I mentioned last post when you pull timing/cut cylinders in a turbo motor it seemed to have the opposite effect and you were back to wheelspin.

Think of what you're trying to achieve with TRAC then look how the engine responds, there's always a little delay between say pulling a pile of timing and the wheelspin stopping, add to that the pretend antilag bumping the boost back up and you get into a loop where not much happens.

Now look at how this all works using the DBW throttle, it wheelspins the throttle closes enough to catch it and that drops a little boost the car hooks up and the throttle opens again up to your preset slip allowance.

For wet conditions I also have it control boost so it catches the slip faster.

These are just my findings after many many hours of testing/logging/retesting after getting a modified file back from the guys at MoTeC.

Not sure if any of this is at all applicable to 1000>1200 hp though as controlling that is going to be a big ask.
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Gadgeroonie



Joined: 24 Aug 2004
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Location: UK

PostPosted: Wed Jul 29, 2009 12:47 am    Post subject: Reply with quote

is the dbw a replacement fly by wire throttle system ?
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APEX Speed Technology



Joined: 13 Nov 2004
Posts: 740
Location: Venice, CA

PostPosted: Wed Jul 29, 2009 9:01 am    Post subject: DBW Reply with quote

DBW IS Fly by wire.

You can use DBW for torque reduction on both MOTEC and Pectel; We've done several including BMWs, Porsche and Nissan VQ35 with throttle reduction. We've handled traction control tuning for motorsports teams worldwide, as well as many high-horsepower project cars, including ones with over 1000hp like yours. The keys to good traction control are:

1. Slip target compensation - the ability to change how the slip target is calculated for different gear positions, throttle and speed ranges. You need to be able to vary WHEN the TC engages so it does so only when necessary.

2. Power reduction management - this is where DBW comes in - a good traction control system has complex algorithms to allow the proper amount of torque reduction for maximum control and acceleration. A proper system uses a complex ignition cut, ignition retard and fuel reduction to manage this. The amount of power reduction, how aggressively it comes in and out, and the maximum levels are all very important.

Many cars we do use ignition cut only. Some use retard then cut. The only times we bother with throttle reduction is when we want to "hide" the traction control. Otherwise, per-cylinder torque reduction always results in a smoother and more immediate cut.

A car like yours is going to need a lot of torque reduction very quickly. You're not going to accomplish that with a throttle-based system.
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Gadgeroonie



Joined: 24 Aug 2004
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Location: UK

PostPosted: Wed Jul 29, 2009 10:07 am    Post subject: Reply with quote

if he is running pectel, how do you program the dbw - does it have its own ecu ? or is it simply canbus compatible
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Martiens



Joined: 21 Mar 2008
Posts: 352
Location: Pretoria, South Africa

PostPosted: Wed Jul 29, 2009 10:30 am    Post subject: Reply with quote

Ive done TC with Motec and its very successful.

Ive used both IGN cut and also retard then cut. DBW TC is more complicated to set up. When you use retard you will have to measure on a dyno what amount of retard gives what amount of torque reduction.

For a 1000Hp I would feed the TC power reduction channel into the boost control setup. Ign retard on high power turbo cars could cause excessive EGT`s.

Regarding your wheelspeeds, E46 and E90 BMW ABS pumps output each wheels speed through separate pins.

8
10
12
14

They are digital squarewave outputs.

Hope it helps.

M
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IJ.



Joined: 10 May 2007
Posts: 75

PostPosted: Wed Jul 29, 2009 3:07 pm    Post subject: Re: DBW Reply with quote

APEX Speed Technology wrote:
DBW IS Fly by wire.

You can use DBW for torque reduction on both MOTEC and Pectel; We've done several including BMWs, Porsche and Nissan VQ35 with throttle reduction. We've handled traction control tuning for motorsports teams worldwide, as well as many high-horsepower project cars, including ones with over 1000hp like yours. The keys to good traction control are:

1. Slip target compensation - the ability to change how the slip target is calculated for different gear positions, throttle and speed ranges. You need to be able to vary WHEN the TC engages so it does so only when necessary.

2. Power reduction management - this is where DBW comes in - a good traction control system has complex algorithms to allow the proper amount of torque reduction for maximum control and acceleration. A proper system uses a complex ignition cut, ignition retard and fuel reduction to manage this. The amount of power reduction, how aggressively it comes in and out, and the maximum levels are all very important.

Many cars we do use ignition cut only. Some use retard then cut. The only times we bother with throttle reduction is when we want to "hide" the traction control. Otherwise, per-cylinder torque reduction always results in a smoother and more immediate cut.

A car like yours is going to need a lot of torque reduction very quickly. You're not going to accomplish that with a throttle-based system.

^ that is why I wrote this >
Quote:
Not sure if any of this is at all applicable to 1000>1200 hp though as controlling that is going to be a big ask.

I had hoped Neel would jump in as he helped me out and answered a lot of my questions when I started out with TRAC.
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