WOT Braking

[Nick R]

So, I did an experiment, with a few cars. I would be driving down an empty street, floor it, and press the brake down as hard as I could. Borrowed cars from friends for the experiment, as they were curious to see what would happen. This is what happened.

My Focus: Stopped, but the engine did not cut out, the brakes (barely) overcame the engine power in first gear.

2008 Corolla: Borrowed from a friend to test. Same thing, did not cut out under WOT and heavy braking, took much longer to stop than the focus did

2009 Civic: Engine cut out Under WOT and braking

2007 VW Jetta: Engine did not cut out, but it stopped much faster than the others did.

For [censored] and giggles, 2001 Cavalier: Did not stop. Did not cut out, and brakes couldn't overcome engine power in first gear.

2007 Mustang V6 (ours): Engine cut out under WOT and braking.



This was very interesting to me. Only the honda, and our mustang actually cut the throttle off when I hit the brakes. All the others kept pulling.

I predict a [censored] storm.

 

[Slippery_Pete]

Interesting to hear.
I don't think I'd ever let you borrow my car.

 

[CharlieJ]

Did you just step on the brake once or did you pump the pedal?

 

[Nick R]

They are all my co workers. We had been talking about it the other day when we were closing up, and we all wanted to find out what would happen with each of their cars.

 

[Nick R]

Originally Posted By: CharlieJ
Did you just step on the brake once or did you pump the pedal?


WOT, and then firmly, smoothly applied pressure to brake pedal.

 

[Quattro Pete]

Originally Posted By: Nick R
2007 VW Jetta: Engine did not cut out, but it stopped much faster than the others did.

I'm surprised the VW did not cut engine power the moment you stepped on the brakes. Kinda hard to believe that it could stop faster than all the others even with the engine power still applied.

My '01 Audi would cut power, which would be annoying since proper heel-toe wouldn't be possible. But it was a stick shift. Not sure if that had anything to do with it.

 

[mc2lizard]

I lold.

 

[rslifkin]

I haven't tried it in my Jeep, but I know exactly what will happen with the horribly undersized stock brakes. Cable throttle, so it will still be at WOT. It'll slow down a bit, maybe even enough to start a burnout, but probably not. In 4wd, I doubt I could get it below 30mph while standing on the brake pedal.

I did try standing on the brakes at a stop in 4wd once, and then going WOT. The Jeep just started to move forward, and had I felt like cooking my transmission, could definitely have gotten up some speed.

But, that's what happens when you drop a big V8 and higher than average stall torque converter (stock stall is 2300 on these, compared to 1800 for most versions of this Jeep, and trucks with this engine) in a 4200lb brick with brakes the size of an econobox.

 

[Craig in Canada]

It seems like someone needs to explicitly mention that the only cars likely/possibly able to cut power because you touched the brakes will be drive-by-wire cars. If it's not drive by wire, don't even expect it to cut the throttle. I'm specifically thinking of everyone running out to check their 2001 Cavaliers.

Funny, we survived from 1900 until 2010 without cars automatically cutting the throttle because the brake pedal was applied but suddenly now there's a "storm" when it doesn't happen.

I'm surprised at the number of cars that had trouble overcoming their engine power, actually. First, it should be a design criteria that a car be able to outbrake its engine. Second, even when on the road brakes can decelerate a car far faster than the engine can accelerate it even in first gear. I wonder if, perhaps, the difference didn't lie in the brake booster system designs and some vehicles had more or less "power boost" than others as opposed to differences in braking power at the wheels. If one vehicles has a bad or leaky check valve, for instance, it would loose power brakes as soon as the throttle is WOT.

A friend has a 2008 VW and his throttle is cut when he touches the brake, but if he reapplies the throttle it will respond. This is how VW solved the problem of heel/toe rev-match downshifting (which I applaud). It wouldn't shock me at all if non driver-oriented cars like the typical Toyota just wrote the code to say if the brake is applied the throttle shall be closed - period.

 

[Quattro Pete]

Originally Posted By: Craig in Canada
It wouldn't shock me at all if non driver-oriented cars like the typical Toyota just wrote the code to say if the brake is applied the throttle shall be closed - period.

Especially after the whole runaway Toyota paranoia that struck last year.

 

[Nick R]

I knew full well that the cavalier wouldn't cut out, but it was interesting that it couldn't outbrake the engine. My own cavalier wouldn't brake to a stop at WOT either. I was just surprised that these supposedly "modern" DBW cars didn't cut out.

 

[Thermo1223]

The VW should have I don't get that.

Our old Rabbit did it everytime.

Heck when I went through a large rain puddle I shorted out the wiring to my DBW accelerator in my TDI.

That resulted in 1200RPM only regardless of pedal input for at least 2-3 miles until I could pull off the road and get it to dry out.

 

[ARCOgraphite]

I never had a car that would overcome its brakes** - even a '70 455 Buick Electra convertible. One 4th of July evening, many moons ago, in town Andover, MA, I attempted a "burnout" or "smokeshow" using the brakes to hold the car. The car had Posi. The front brakes held, but when the rear tires got stickey, the rear traction was great enough to slide the front tires - even though they were locked! That's Torque. 2&1/2 tonne car too.

** if they were in good service order, 89 caddy was an issue.

 

[ARCOgraphite]

Nissan seems to advertise lately and often that their cars won't run away.

 

[Volvo_ST1]

Originally Posted By: Nick R
So, I did an experiment, with a few cars. I would be driving down an empty street, floor it, and press the brake down as hard as I could.


Why?

 

[Nick R]

Originally Posted By: Volvo_ST1
Originally Posted By: Nick R
So, I did an experiment, with a few cars. I would be driving down an empty street, floor it, and press the brake down as hard as I could.


Why?


I've explained why. Apparently it's not important to know if your engine cuts out if you slam on the brakes, for whatever reason.

 

[SteveSRT8]

Try that in my car and the computer pulls the throttle bad.

You can do a nice burnout, but if there's any road speed it cuts the throttle severely.

 

[ARCOgraphite]

Nissan: Brake override technology

http://www.topspeed.com/cars/car-news/ni...al-ar95582.html

 

[Landrew]

I've heard there is another way to get the car safely slowed down when the engines at WOT. I'm going to do a bit of research and see if I can find it again someplace........

 

[eljefino]

Next time use both feet on the brake, and pull upwards on the steering wheel for even more pressure.

Have a friend use a cane or stick or something to floor the gas.

One foot was higher than the other, I assume, in your comparison, not a great way to get maximum force applied. You may have also subconsciously gone easy on something to avoid damage, something adrenaline will overcome in a life or death scenario.