Best way to slow down.

Can you define what you mean by "engine braking" in this scenario and how this would be used in the wet vs not in the dry? Just not following you.

 

The OP was somewhat ambiguous about street/track driving despite being in the tracking section. That applies more to street driving than track, as its a lot safer to run 3rd or 4th gear on the interstate, than top gear.

In the case of the engine of my 944, the engine wasn't tuned for maximum horsepower, it is not concentrating the power band at the upper end of what the engine can turn over speed wise. The primary purpose of downshifting is to keep the car in the powerband, so with a pure racing engine, there is nothing that could change. The 944, under normal circumstances, I'd be downshifting to a point that the next gear arrived about 5800RPM, within the powerband. I *could* increase engine braking by downshifting to a point 500RPM over red line(7K RPM, a speed the engine can safely spin, but makes poo for power unmodified)

Theres a certain flat section of interstate near me without as much camber for water run off, pretty much a guarantee when the rain dumps to see fwd's scattered around there. They reconnect with pavement with the front wheels turning a completely different speed, spook the driver, driver goes drastically bad, and take a trip into the fence/grass.

 

I don't follow on the interstate. Why?

...and why would you do that (downshift to raise engine speed to 7k) vs just using the brakes?

So you are saying they are hitting their brakes through the water or losing it back out of the hydroplane and onto pavement with traction? That is the first correction I would make - adjust speed leading into the water. So they could brake, drive through on the best line, then get back on the throttle once you are through it. I'm missing what putting the engine to max revs buys you in that scenario. It will slow you slightly, but so would the brakes - and they are both dependent on the grip of the tires. This is actually what you will see taught in driver's education in the US - OMG big puddle, slow down before it, drive straight through off power and off brakes, then make decisions once you have traction back.

Just not following : )

 

+1. I agree that the purpose of downshifting is to select the gear that results in the optimal rev range through and out of the corner.

I guess it is semantics. Braking to me (and most others) is when there is a slowing force inputted by the driver on the rotating, unsprung mass of the car (wheels, tires, hubs, rotors).

In nearly all cases, properly executed and with commitment to achieve highest levels of deceleration performance, the brakes are the most effective tool at the driver's disposal.

If there is excessive (read: almost ANY) period of "engine braking/coasting/slight thrust negative" state, the car becomes unstable and there is no consistent way to administer that state.

At least, that's what 11 TB of data and video from the worlds finest formula, sports racing and GT drivers tell me...

 

pffft what do you know

 

Perfectly stated, thanks!

[/thread!]

I think that's what pretty much *all* of us have been trying to say all thru this entire train wreck!

Cheers,
Ian

 

This! Thanks Coach and Ian....and many others : )

 

To me, this is the key, and probably a large point of the disagreement here.

If by "use engine braking", 4th Gear means "experience engine braking", then I agree. We all experience it.

But, to me, "using" it means it's something that I can control, modulate, etc. (administer!) in order for it to be a tool. For me, it's not.

 

Time to bring this back to life..... lol

In the 3rd Qtr issue of Prancing Horse (FCA rag) there is a lengthy article about the '65 24 Hrs of LeMans. Apparently Ferrari had a few issues with brakes during that race, to the point where the crews were jacking up cars in the parking lot and taking the rotors. The article mentioned how the drivers ended up using compression braking.

 

I rev my engine exactly 500 rpms past redline as I'm slowing down. While that happens, I pump the clutch 10-15 times, on, off, on, off...and so on. At the same time, I do a "star" pattern with the shift rod - 1st, 4th, 3rd, 2nd, 5th, reverse - and repeat that.

I'm still at speed, then forcibly grab the emergency brake with both hands OFF the wheel to induce maximum spinnage.

By then, hopefully I've scrubbed off about 100 mph, at which point I look for the the nearest berm or road sign and make a bee-line to it. Once I slam into it (around 80 mph or so), I then stop with the most efficient and clean way possible.

I didn't see that as one of the choices above, but that's the best way...you heard it from me.

 

Slamming it into 1st, pop clutch out works a treat. Won't damage car since you slowing down anyways.

 

Hmmm, maybe I can work these approaches into the curriculum?

 

^^^^



Post of the thread, right there!

Cheers,
Ian

 

LOL!!

 

On a more serious note - one of the corrections I often observe required is the too early downshifting at the end of a long straight. I am not certain less experienced drivers do this to utilize the braking power of the engine - lower gear - or just because they want to get the car into the appropriate gear to enter the corner as quickly as possible. In fact, you sometimes observe coasting into the corner. In any event, again for most drivers, the early application of brakes and later downshifting results in a smoother and controlled entry into the corner and ultimately results in earlier application of the throttle in or at exit of the corner. Somewhat of an oversimplification - but this whole discussion has often veered away from basics.

Rob in Potomac

 

Oh, come on Rob - everyone knows that middle pedal is something akin to your appendix... nobody knows what it's really there for. It's just an extraneous addition with no quantifiable value whatsoever.

 

Glad to see I'm not the only one!

 

In racing you should either be on the gas or the brakes. NO COASTING!!!

 

that's why you should shift into neutral, and why F1 wheels have the neutral button so close to the driver's thumb

(sarcasm)

I was hoping this thread had worn itself out. Guess not.

 

The appendix is a vestigial structure that used to have a greater role in digestion and immunology, but we've evolved away from needing it and by now it has become superfluous.

Perhaps racecar drivers are evolving away from needing the middle pedal and would only go back to it in the event of a sudden digestive issue... such as the brown overalls that can arise from a rapidly approaching barrier? Maybe we'll get a clearer picture heading into the next millennia.

All the best,
Andrew.

 

I think too many people watch Top Gear...........

 

KILL IT WITH FIRE!!