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Old 02-10-2009, 10:31 AM   #7 (permalink)
PaleMelanesian
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Join Date: Dec 2007
Location: Texas
Posts: 2,321

PaleCivic (retired) - '96 Honda Civic DX Sedan
90 day: 69.2 mpg (US)

PaleFit - '09 Honda Fit Sport
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You rang?

What I'm talking about is lower THROTTLE in the low gears and at low rpm, and higher throttle at higher rpm. At low rpm, it takes less to fill the cylinders, since the valves are open longer. (lower rpm = longer time for each cycle) Watching the MAP and LOD gauges on the SG, I aim for ~50% throttle, building up to 80% as the rpms climb. If you're in the gear for more than a few seconds, definitely taper it (heavier) as you gain speed.

Gears:
Your shifting scheme looks pretty good. You can go a little lower on the rpm, shifting a little sooner. If it growls/rumbles a bit, that's fine. As long as it can gain speed it's ok.

I hardly use 1st gear. On a downhill start, I don't - I go straight to 2nd. On flat/uphill starts, I only use it to get rolling, and shift to 2nd about as soon as it's fully engaged. (3mph or so?)

The transitions between pulse and glide are a small part of the whole, but when you do them so much, I guess it can make a difference. If you can minimize the number of P&G cycles, they matter less. I finish my pulse, clutch in, and 1/2 sec later key off, right as the revs reach the lowest point. Even the Scangauge can't measure at a fine enough resolution to show the best method here. My reasoning is that this way I have the shortest time in the key-off position, since the low-rpm engine dies that much sooner.

For the pulse, I do recommend getting a vacuum gauge. I've seen that ~80% load on the Scangauge is about 12psi MAP, so you can aim for that.

If your rpm is low enough, shifting with both quickness and smoothness is really really easy.

As for BSFC charts, the colorful one in this article seems to be good enough for my purposes. Just aim for the red zone. Article: Browser Warning

Overall, I find that getting the very best pulse less important than getting the best glide. You can do a 1:1 pulse to glide ratio, with a light pulse, or you can do a heavy pulse with a glide 3x as long. Both will give you similar results. Gauge the terrain, traffic, and other conditions to get the best glide you can. If that means pulsing on an uphill, do that. You can then coast up and over the peak and down the other side. You have to fight the urge to "do something", and just wait it out.


Ok, rambling done. Hopefully some is useful.
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11-mile commute: 100 mpg - - - Tank: 90.2 mpg / 1191 miles
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