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Old 08-26-2014, 02:51 PM   #1 (permalink)
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Talking racers line and ecoline minutia

It seems racers line is a general term that to some people means cutting the curve at the shortest radius to the end up with the shortest distance traveled.
This definition has little to do with what racers actually do, (although I am not a racer)

This makes sense only on the highway with big sweeping S curves and little traffic. I take advantage of this when I can also.

As some have stated on exits, entrance ramps and curves, maintaining inertia and momentum is best achieved by staying off the brakes and taking the outside of the curve at the max radius and safe speed.

As smart combination of when to employ which line can make a big difference.

Also, the cross section of most road lanes is shaped like subtle "W" with the two tire tracks at the bottom. In some cases on asphalt in MI with heavy truck traffic this can be substantial, sometimes a couple of inches which creates a side slope angle or "banking" . I try to use this banking on curves without forcing the wheel. Sometimes I cut the corner line and then let the car float to the very outside and pick up the banking on the outside lane.
Left tire just left of the center of the lane and the right tire just short of the right edge. Many times the car tracks without any input from the steering. Less resistance.

Taking this W to city driving, I move to the top of the W at stop signs and traffic lights if I can, making sure the car is stopped heading in the exact direction I want to accelerate in . The tire resistance of turning at slow speed helps stop the car and avoiding any turning during accel helps too.
Raising a 4000# car an inch or 2 burns off energy and this is recovered moving to the tracks at the bottom of the W.
At stop signs where I am going to turn at, I make as much of the turn when stopping as I can so there is less of a turn during acceleration. When accelerating I go as straight as I can and delay finishing the turn to the edge of the lane. Minutia I know, but it has become a habit and I don't think about it much, except that if everyone did it it would save a bunch of fuel

More minutia, drive to the top of the W at the bottom of hills and bottom of the W at the top of hills.

A movement for a legal "energy stop" would be great. Make it OK to slow to 2 mph a minimum of 20 ft from a stop sign and roll through. Even if it was just when there is no other traffic at the stop sign. Topic for another thread

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Old 08-26-2014, 03:00 PM   #2 (permalink)
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The racing line is not travelling the shortest distance, but making sure you go as fast through a corner as possible. What means that the racing line goes from outside of corner to inside (apex) and to outside again. The biggest radius is achieved this way. By taking th biggest radius through a corner there is also less tire drag and more momentum to take out of the corner.
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Old 08-26-2014, 03:02 PM   #3 (permalink)
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It's the same, most of the difference is when I am driving I sometimes make my wife gasp. When I'm racing she would pass out and I would be gasping. If it was me I'd get rid of every stop sign in residentail areas and half the lights on the main roads. Got snagged today by a red light that is so stupid, the guy that tripped the light made a legal right hand turn on red, the light only served to make several cars going 45 slam on their brakes. There are whole areas of tidewater va that I generally avoid because they couldn't time a light if their lives depended on it.

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Old 08-26-2014, 03:12 PM   #4 (permalink)
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Quote:
Originally Posted by Joris View Post
The racing line is not travelling the shortest distance, but making sure you go as fast through a corner as possible. What means that the racing line goes from outside of corner to inside (apex) and to outside again. The biggest radius is achieved this way. By taking th biggest radius through a corner there is also less tire drag and more momentum to take out of the corner.
Exactly, Thanks for the clear definition I think many where confused.
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Old 08-26-2014, 03:32 PM   #5 (permalink)
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Normally people slow way down to make a turn it is annoying. I think us hypermillers make up the time from going a little slower on the straightaways in the corners.

I really try not to brake before a turn because I know all of my speed will drop in the turn. I will try to slow down before if I am going to fast. I love it when a fat SUV is on my bumper going 45MPH in a 45MPH zone and its a sharp turn I make a huge gap again just for them to floor it to catch up.
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Old 08-26-2014, 11:02 PM   #6 (permalink)
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Re: the W cross section.
The ecoline is different and probably better than the racing line or cutting the corner for FE given the rut tracks in the road. We are generally much slower than the road can handle. I think it is better to stay in your own lane and bank within the lane on the "W". Crowd to the right of the lane on a left curve and crowd to the left of the lane on a right curve. This is opposite of intuitively cutting the corner which causes negative banking from the "W" and crossing lanes can cause the car to dance a bit and require more steering input and scrub off speed.
I am sure this should be posted in a hypermile thread instead of here. sorry
Does anyone have an opinion of whether P&G would be effective at all with an automatic transmission and not doing neutral coast or EOC? I know this may be very vehicle dependent.
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Old 08-27-2014, 11:27 AM   #7 (permalink)
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I have a lot of fun on one route home. I turn off at a sharpish corner and go into tighter corners, small hills and whatnot. I'll hold near 40 all the way through, and it's a couple miles after that turnoff before there's enough straight that the guy that was riding my bumper even comes back into sight.

And before that turnoff, he was probably complaining that I don't know how to drive.
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Old 09-06-2014, 10:49 AM   #8 (permalink)
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You don't want to use "racer lines" to hyper mile.
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Old 09-06-2014, 02:49 PM   #9 (permalink)
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You don't want to use "racer lines" to hyper mile.
Can you explain why you don't want to do that?
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Old 09-06-2014, 04:44 PM   #10 (permalink)
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Actually the best racing line through a corner is not the line with the biggest radius!

It would be if the speed was constant before, during and after the corner; which makes it a good approximation of the ideal line for hypermiling.

But in a race you enter the corner still braking, and exit it while already giving it throttle.
The speed in the apex needs to be slightly lower, so you can brake longer before the corner and accelerate going out.

I did not win 3 F1 Championships, but take it from someone who did:
Now its not just the line you take, but also the speed at which you (try to) take it. The closer the speed comes to the limit of what the tires can bear, the higher the friction will be trying to slow you down.
You can compensate that with gentle throttle, but hypermiling is all about maintaining momentum through efficiency, not extra throttle.

If your speed was already low enough to go round the corner without tire squeal the biggest radius would be close to ideal.
If you have more speed you might choose a line that starts at a bigger radius (entering the corner slightly earlier at higher speed) and allow the friction to gently reduce the speed, and radius, throughout the corner; especially so if you do not need to speed up in the section after the corner.
Then there are corners where the road surface is not even, like the OP pointed out. Better run that ridge if it does not violate the ideal line too much...

There is no simple rule of thumb to prescribe the ideal throttle, line and speed for hypermiling corners, just like there is none for racing them; because in both cases there are too many variables at work.
Which makes hypermiling a true skill, just like racing.

There is a lot we hypermilers can learn from racing.

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Last edited by RedDevil; 09-06-2014 at 05:26 PM..
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