Fuelly Forums - Confucius say EOC inevitable

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I think that DFCO is the best option in most situations. If you have a long stretch of road with no cars, pedestrians, or animals; and DFCO causes too much engine braking for you to make it, then I could understand. But I think it's just a matter of time until some kid runs out in front of someone who is going to wish they had their power brakes.

Quote:

Originally Posted by DRW (Post 106063)

I figure it's better to rob the momentum directly from the car rather than involve the electrical system which has more efficiency losses.

All other things being equal, that would be an interesting question, and I'm pretty sure I know the answer. To electric start, you have to convert rotational motion into electrical energy, store it, then convert it back. To bump start, you use raw rotational energy. Converting it twice and storing it in-between is bound to be more wasteful.

suspendedhatch, about braking: My power brakes and steering work fine with the engine off, though the brakes run out of stored pressure after 3 or 4 uses and then I have to put part of my 220 pound body into it -- and that's still enough for decent braking. However, I've tested quite thoroughly, and in my car Pulse & DFCO is the least efficient option, even worse than just cruising normally. Pulse & Glide with the engine on and transmission in neutral saves lots of gas.

Those are my measured observations, not theories. Pulse & DFCO just doesn't work, at least in my VW.

Anyway, the places where I would EOC do not have children, or pets, or people, or other cars; I drive some nice empty roads through the woods on the way to work:
https://lh4.ggpht.com/ronanian/SDleut...6/IMG_0908.JPG

Yes, I take a chance of hitting a deer/coyote/fox, but that is my own risk and I'm happy to take it.

I eoc if it's going to be > about 10 seconds. I would probably go shorter, but my scangauge takes a couple seconds to come back online and the reported numbers are inaccurate if I do it too quickly.

I bump-start any time unless I'm actually stopped. A quick up-down pulse in 5th to fire the engine, then choose the gear and let it out again. There's little-to-no jolt or momentum lost that way.

OK, on the question of the difference in enrichment for warm electric start vs. warm bump start: I hooked up the meter and found out for sure. Bump start definitely uses less fuel than electric start.