So which one is better?

Say you are heading down the main straight in 5th or 6th gear and have to bring the speed down significantly to the point you'll go 2 to 3 gears down. At the moment of braking do you clutch in and brake or rather go through the gear and use the engine as well as the brake to slow yourself down.

I believe that you should dissconnect the trans from the engine because the brakes at maximium braking the brakes will go beyond the braking of the engine and now your brakes will have to brake for the forward kenetic energy your carrying and the engine inertia energy.

ps. i brought this up in another forum *cough* *cough* *BMW* and i shouldn't have been suprised with the comments i have gotten.

 

https://honda-tech.com/forums/road-racing-autocross-time-attack-19/rev-matching-heel-toe-opinions-2726429/ read that..because this will probably get the lock down since this is a recent topic that has been covered.

 

In for the theory.

 

I saw the thread but i thought it wasn't covered indepth. Heel and Toe and engine braking doesn't go hand and hand.

Too many people lump Heel & Toe, Rev Matching, and Engine Braking in all one big lump.

 

engine is for accelerating

brakes are for decelerating

"engine braking" is coasting

Coasting=bad

you should be on the brakes, or on the gas as much as possible.

"coast factor" is something that a DAG can/will/might look at.

(note: most of us do it at some time, and i think most DAGs look for something in the 70% or more range. IE the car/driver is coasting less then 30% of the time around the track, not 100% sure on the number though...)

 

I personally agree.

It would seem to me that you are in effect slowing the rate of speed of both the vehicle and the engine, it seems rather obvious that you would want to only slow down one of the two if you had the option.

 

Wrongs everywhere. "Engine braking" is a farce and is indeed covered in that other thread. The engine does little for deceleration compared to the brakes of the car. It is useless as a means to slow the car.

That's it. Brake as hard as possible without locking the wheels, downshift as necessary to get in the proper gear to accelerate from the corner.

The brakes are not held back much at all by the engine. You will not see significant heat/wear in your brakes since you are slowing the engine with the chassis of the car. It is quite difficult to smoothly re-attach the engine torque to the drive wheels from idle, so clutching as you brake and then releasing to add power is not a preferred technique. This is similar to certain drivers not heel-toe downshifting and just grabbing the appropriate gear just before the apex of the corner-- it doesn't work, I promise. You'll always be slowing yourself down somewhere.

As was mentioned in the other thread: If every professional driver in the world has been doing it one way, its likely the right way.

 

Can you say this again, but slower?

 

think about it this way. rev your car up to the limiter(ish) then let it come down to idle on its own. note the time. now think:can i brake from 130+ to 40 that fast? generally no. so the theory about the brakes slowing the engine down is no good. but the entire 'engine braking' shouldn't even be referred to in a track situation because it does nothing. you should be 100% throttle, 100% brakes or modulating cause your in a corner. coasting (engine braking) is useless.

 

Can you elaborate on this.^
Imagine going down the road and having the car in gear vs a car that is just cruising in neutral with no brakes applied in both. Which one slows down faster?

Also at idle at a complete stop if i put it into first gear and slowly release the clutch doesn't the car move forward?

Now the brakes we all know will decelerate better than the engine but if it goes back to the original question of if it does it better and why would i want a engine attach to the wheels that is always wanting to keep it moving?

I think its just as hard as going down gear by gear, it just takes practice. Think about how often you have practice heel and toe through the gears vs the amount of times you've tried to do it the other way.

Well if this is the case wouldn't you rather eliminate the amount of actions you are doing so there would be less chance of mistakes.

-Heel and toe once at the end of your braking zone
or
-Heel and toe 2-4 times all the way through the braking zone?

Which one do you think would have more chances to make a mistake in?

If we all just believed things the majority believes we would still think the world is flat and we would still use leeches to heal all wounds. I would like to see more people thinking for themselves.

 

This is why the topic is:

"Engine Braking+Braking" vs "Just Braking"

and not

"Engine Braking" vs "Braking"

no coasting involved in the discussion.

 

What people are saying is engine braking is essentially coasting because it is not the most efficient way to slow a car. Even if you are "engine braking" and using the brakes, the engine braking is hardly doing anything to slow the car because the brakes are much more efficient (read; "made") to slow the car.

 

I would suggest buying "Drive to Win" by Carrol Smith. It covers this topic very well and gives a couple of scenarios including about down shifting one gear at a time verses all of them at once. Buy the book, it will help you on this and other driving issues.

 

"Free Braking" using the engine is an important component of a drivers "style". You just gotta remember to set your brake proportioning valve correctly or you'll spin out and not get to squeeze the trophy girl's *** while you're flagrantly tongue kissing her on the podium as all your less stylish competitors look on in envy.

Scott, who nevar forgets you gotta always look far ahead when racing...past the next apex...to the podium!

 

Normally when people brake, they are not using any gas, and the engine is above the idle rpm, so the engine creates an additional braking force. It tries to slow the car down via the axle, as opposed to the brake pads. It does not try to keep the car moving.

And yes, you can skip gears while downshifting if you want.

Generally it is a good idea to keep the car in gear as much as possible.

 

It's been awhile since I've seen a real trophy girl. Maybe I would pay more attention to being stylish if you could send down some of your hot trophy girls. I guess it doesn't help that our tracks are located closer to a high concentration of lot lizards that are more likely made famous by their presence on that hit T.V. show COPS. But I digress...but only for a moment.

 

Oh Johnny Mac...I only ever saw but a few trophy girls back in the day, and only once got my trophy from one on a podium...there was no kissing and that was I'm sure a relief to the poor girl. Times have changed a bit though, and not that long ago I was at the Thursday night races and the guests of honor were a bunch of Hooters girls doing various promotional activities probably including trophy girl duty and photos. Back in the day the only real attraction was the occasional racers hot sister or sisters hot friend. I remember one of my friends sister brought an adorable friend one night that caught my attention but she disappeared early in the evening. I learned later that she'd left the track that night impregnated by an up and coming mini expert.

Scott, who thinks that sometimes things really do work out for the best even if they don't seem that way at the time...

 

ok, so take out my coasting statement. the rest of the post is relevant.

 

I'm merely saying that there is a fairly insignificant amount of deceleration in a performance driving situation via the engine. Yes, there may be a small variation between attaching drive torque and not, but it is likely only a few degrees in brake pad temperature, so who cares?

I have had to come to a fast stop a number of times on the race track with engine damage where there was essentially no drive torque (in either direction). The sudden loss of some form of non-gravity "back pressure" was enough to often lock the brakes since most systems are made to sufficiently slow both the engine's drag and the weight of the vehicle at any speed. This is also a job of the prop. valve, as was mentioned previously and the sudden loss of torque often locks just one set of wheels, often the bad set!

This is incorrect. It takes one MASSIVE blip to miss (at most) 5 gears than it would to just do it 5 times. If you've ever used a microscope, this would be trying to focus on a something using only the course adjustment and ignoring a few turns of the fine adjustment. It is far more difficult to perfectly match 1 massive gear change than 5 small ones. I have been given rides by many people and have NEVER felt a smooth skip-shift.

The downshift at on-throttle was covered in depth in the other thread. It was also mentioned that it is absolutely impossible to extract 100% out of your car on the track while leaving room off brakes to downshift.

One large shift at lower speed to skip 5 gears would likely be very rushed. The blip would have to be so well placed (toward the VERY end of braking to take into consideration such a large ratio change) and so large that it would be quite difficult to pull off very gracefully. As a racer, I am confident that multiple small downshifts are the way to go.

True. It is in our nature to question and investigate routine. The act (and art, if you as me) of properly downshifting while decelerating is one that does not need further investigation. I used this example in the other thread: There are probably pretty valid reasons why all the pro basketball players don't granny shoot all the time. It is a similar situation with professional race car drivers and their downshifts. I'm sure if it helped race cars go faster or last longer Formula 1 teams would devise a means to drop their gearboxes into neutral while braking and then pop them back into gear before they accelerate. It would be an inefficient use of engineering time and money since the pay off wouldn't be much (maybe a slight increase in brake pad use) and driveability would be impacted extremely (sudden loss of drive torque under braking, sudden return at corner apex).

 

I'd say equally both. Sure, you are having more motions to screw up when going through the gears vs. just selecting one gear, but it normally helps to establish a rhythm, and continual downshifting offers just that. You know the spacing of the gears and the rpm you are using and it falls into rhythm. You don't get that rhythm with just doing it once, and in a sense, you HAVE to make sure you know how to match the mph to the rpm you are about to release the clutch.

Edit:

Exactly what my post was referring to.

 

if i had sig room id sig it!

 

You say "establish a rhythm" but you can can do this as well without releasing the clutch each time you go down a gear. This is something I sometimes do where i'll still go gear to gear down and even heel and toe "without releasing the clutch pedal" to have that rhythm. Also if your heel and toeing all the way through the braking zone you can better modulate your braking because your right foot is only concentrated on braking and not the gas pedal.

It's just practice i don't think one is harder than the other. This is also side track on the real question of engine braking+braking vs just braking.

p.s. I'm really loving the responses i'm getting about the subject and enjoy the level of maturity.

 

Ok so we have a few more temps higher in the brakes because the drivetrain is connected (go along with this). Most race pads can more than deal with this but then also you have to factor in the tires as well. If the brakes have to work harder so is the tires. The tires grip now have to deal with the kenetic energy and the inertia energy of the engine (just like the brakes) which is alot less forgiving.

If 100% is the maxium amount of grip the tires can take before failing and 99% of is used to slow the kenetic energy and 1% is from the drivetrain, wouldn't it be just better to just the 100% of the tires grip for the kenetic energy of the moving car.

Every little thing helps.

It wouldn't be a massive blip because by the end of the braking zone your drivetrain will be slowed down to the point that as long as your going for the correct gear it will be the same blip (maybe a slight higher) than you would if you went through the gear.

 

I'm no racecar driver or anything but I have played with autox a bit and I think I know enough about this to partake

To me, I think coasting in neutral while braking vs being in lets say 5th gear and braking hard before the corner entry then heel toeing into lets say 2nd would be much better as it seems the car would have more grip as there is not such a jolt to the chassis.

If one was to just lift off throttle in 5th to brake would that not cause the car to lift the rear end too much and want to spin?

Like others have said too, being able to downshift from 5th to second while braking seems to be a little more un-natural compared to heel-toeing down throgh the gears. You would have to be spot on in the rev range otherwise time is lost.

 

Dude. This is HT RRAX. We are nothing if not mature