How short of a coast will you bother to EOC?

[davelobi]

Ive been doing a lot of eoc and enjoy the free miles.
I always key start up rather than bump start. Why bump? Just to save wear on starter motor?

Back on subject..
I have a few spots where I can eoc about 8/10 of a mile and love those. They feel great. Sometimes just a hill will motovate me to coast down and rather than just clutching it or bumping to neutral I'll kill the engine. Some of these end up being short so I don't drop too much speed with other traffic behind me.
Is 2/10's of a mile worth shutting off the engine? 3? 1?

I'm getting good at anticipating the lights and killing for them.

Maybe off topic but also, assuming no cars in rearview mirror, how far down the speedo will you eoc? On the 55 mph roads I have been sneaking up to about 60 then killing the engine and coasting down to about 43-45 mph. Below that speed I have to drop to 4th gear instead of staying in 5th (my HF has really tall gears).
What I mean is, is it worth eoc down slower, say 35mph in my case, and having to start back up in 4th gear instead of 5th? If nobody in sight would it be worth coasting all the way down to say 10mph and starting off in 2nd gear? The 60 down to 45 feels the most economical because I gewt to stay in 5th.

Love to hear your thoughts and experiance.
thanks

[Frank Lee]

Why bump? Just to save wear on starter motor?

That and to not burn fuel to turn the alternator to recharge the battery after that crank.

Back when I P&G'd I found that the Tempo could pull away cleanly from a bump start from as slow as 20 mph in top gear- but the 2.3 is a real torque monster. So my cycle was 20-60 all in 5th gear, traffic permitting.

[wmjinman]

Yeah, I think you wanna be able to stay in top gear during all of it.

[alvaro84]

Originally Posted by davelobi

I always key start up rather than bump start. Why bump? Just to save wear on starter motor?

I also use the starter on Teresa, but bump start the YARDIS. It's because I just can't smoothly bump start a relatively light bike with a (big in comparison) 650cc single and I suspect that regular bump starts contributed to the early death of the last drive belt.

OTOH, long FAS sessions with starter use stress the battery. The question is, which hand of mine I should bite? (I vote on the battery. That's possible to recharge time to time and easy to replace if fails.)

[cbaber]

Bump starting has been discussed many times. The conclusion and the truth is that it is not going to prematurely wear your clutch, done properly. Properly means in top gear. Lightly release the clutch pedal until it grabs, then quickly press the clutch in again. Then rev match and let out the clutch to accelerate. None of this should feel jerky. Done properly a passenger wouldn't even notice.

That being said, most of the top hypermilers on here have the strategy of "all or nothing". Meaning that their default driving mode is EOC. They only use the motor to stay within a predetermined speed range. No matter how long the coast will be, they pulse at a determined engine load and then EOC once a certain speed is reached. This is repeated over and over as long as traffic and condition allow. So really the goal is to only use the engine to give yourself a boost. While the engine is running, it is always running at the most efficient load.

[alvaro84]

Originally Posted by cbaber

Bump starting has been discussed many times. The conclusion and the truth is that it is not going to prematurely wear your clutch, done properly. Properly means in top gear. Lightly release the clutch pedal until it grabs, then quickly press the clutch in again. Then rev match and let out the clutch to accelerate. None of this should feel jerky. Done properly a passenger wouldn't even notice.

Silky smooth in my car. Even smooth with our 250cc bike. Not with our 650. The best I could ever do was 'not too jerky'.

[justme1969]

Originally Posted by cbaber

Bump starting has been discussed many times. The conclusion and the truth is that it is not going to prematurely wear your clutch, done properly. Properly means in top gear. Lightly release the clutch pedal until it grabs, then quickly press the clutch in again. Then rev match and let out the clutch to accelerate. None of this should feel jerky. Done properly a passenger wouldn't even notice.

That being said, most of the top hypermilers on here have the strategy of "all or nothing". Meaning that their default driving mode is EOC. They only use the motor to stay within a predetermined speed range. No matter how long the coast will be, they pulse at a determined engine load and then EOC once a certain speed is reached. This is repeated over and over as long as traffic and condition allow. So really the goal is to only use the engine to give yourself a boost. While the engine is running, it is always running at the most efficient load.

I couldnt have said it better myself really!
I do tend to slightly disagree with the clutch wear issue though.
I have replaced clutch slave 1x already and the neutral pedal switch.
this could be attributed to normal wear but its not normal unless your stuck in bumper to bumper traffic to engage a clutch and disengage it every 40 to 160 seconds. Nor does a throw out bearing enjoy its extra duty cycles.
Lets get it straight foremost these are wear componants and each cycle is wear.
Will I stop doing it probbably never the maintenance will come and I will roll again. Most cars wont see all or most of these issues before the transmission synchros go out or other failures happen, and this is why we dont put cars back together with worn wear componants anyhow. As said most here will experiance some failure at some point because these are wear componants but Ive got 45k miles on the POS KIA and basically doubled the F/E with $75 bucks in clutch parts, It is a non issue but it will happen not just murpheys law here its fact.

[PaleMelanesian]

I still had the original clutch in my Civic when I traded it at 200,000 miles. That last third of that included HEAVY use of bump-starting, multiple times per mile.

The longer you can glide the better your results. The magic of P&G happens in the glide, not so much the pulse. So you want to design your cycle to have long glides. Then, the question of "how short to EOC?" isn't so much of an issue. That being said, my cutoff is somewhere in the 5-10 second range. Not worth the key-off-bump-start cycle for something so quick.

[Fat Charlie]

In the Bobsled I'd try to do 1/2 a mile or longer. The Albatross is such a pig that even my favorite 2 1/2 mile EOC is less than a mile long glide and I have to pulse at least once during it. So I'm not EOCing these days. Basically, hypermiling is a very busy way to get somewhere- and my glide has to last long enough to give me the time to shut down and restart. I'd also like to spend some time in that glide, and my current rig doesn't give me that.

The Bobsled's clutch lasted 8 1/2 years for 207,000 miles. Vicious bumper to bumper commuting the whole time with 6 years of vigorous trips up and down through the gearbox and very enthusiastic starts and 2 years of bump starting. I've said it before- if you're hard on your clutch, then you're hard on your clutch no matter how you turn the engine over. If you're smooth with the clutch, it doesn't matter if you're shifting or bumping- you're smooth with the clutch.

[elhigh]

I'll EOC for as little as 50 yards. In traffic I can spend as much as 30% of the time with the engine off, sometimes paused but usually still moving. I prefer not to take it out of gear if I don't have to, I've determined by experimentation that keeping the engine spinning prevents backfires and their associated negative effects.

On a short EOC it helps to actually pick up a tiny bit of speed, then key off and roll in gear. When the time comes, if I've timed it right, I'm arriving at the stack of traffic just as it's beginning to move, and I can key back on. No jolt to my passengers, no wear on the starter. Half the time my passengers don't even notice I've done it. Drop down to 2nd or 3rd and off we go.