11-06-2014, 03:14 PM
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#11 (permalink)
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Quote:
Originally Posted by Ecky
When BSFC charts are made, what is taken into account? Is this at the flywheel? Accessories attached?
I would imagine that, in practice, EoC probably provides a little more gain than can be predicted by these charts, depending on how they're made.
That said, I don't EoC in my Insight as I figure the savings, in absolute terms, are probably peanuts compared with driving at 80% load in lean burn.
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I'm not entirely sure what is taken into account. I'd imagine the alternator is on the engine, but I'd highly doubt if they have anything else attached.
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11-06-2014, 03:16 PM
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#12 (permalink)
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Quote:
Originally Posted by Old Mechanic
At 10 inches of vacuum steady, try pulsing at 2-3 inches and gliding as much as you can. Super shallow grades can allow you to store energy at higher bsfc. You get more power from the same amount of fuel at 3 inches, maybe even up to 5.
On sustained uphills but very shallow grades, you might even pulse the flat spots and use inertia as much as you can on the uphills.
If you are using engine on pulses, then go a little higher on your peak speed which increases your mileage in the glide.
regards
mech
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Its not actually 10.5 inches of vacuum. Its 10.5 psi of absolute pressure in the manifold. 14.5 would be WOT at sea level. So, the chart is telling me peak efficiency is ~4 psi of vacuum. This is the equivalent of the engine being 73% loaded as shown on the chart. |
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11-06-2014, 03:24 PM
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#13 (permalink)
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Master EcoModder
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Awesome writeup. Thanks! I just wish someone could dig up a Honda D series BSFC chart... unsurprisingly no luck on Honda-Tech.
Maybe one of these years I'll get an MPGuino and finally drive informed.
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11-06-2014, 03:59 PM
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#14 (permalink)
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Hypermiler
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I've found that an average of the charts out there works pretty well except in special cases like lean-burn or diesel.
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11-06-2014, 04:32 PM
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#15 (permalink)
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Not bad for a machine
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What if you have much higher RPM's? 2800 at 60MPH?
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11-06-2014, 04:46 PM
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#16 (permalink)
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Master EcoModder
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Quote:
Originally Posted by dirtydave
What if you have much higher RPM's? 2800 at 60MPH?
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P&G should help even more, the worse the gearing. In my Del Sol, in places where I could cruise at ~30mpg steady state, I could get 50+mpg with aggressive P&G because of the huge losses from screaming down the highway at 4000+rpm with low load. |
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11-06-2014, 04:57 PM
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#17 (permalink)
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Batman Junior
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Quote:
Originally Posted by dirtydave
What if you have much higher RPM's? 2800 at 60MPH?
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Upshift!
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11-06-2014, 05:05 PM
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#18 (permalink)
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Not bad for a machine
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I wish I had a 10 Speed!!
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11-06-2014, 05:08 PM
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#19 (permalink)
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Furry Furfag
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Quote:
Originally Posted by dirtydave
I wish I had a 10 Speed!!
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One time in stop and go traffic and I think you would change that tone :P. My dad does over 600 shifts a day (roughly) in a semi. Maybe this is why he drives automatics for his commute car? Lol.
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11-06-2014, 05:26 PM
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#20 (permalink)
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Not bad for a machine
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lmao I have driven a truck too and I'd rather have a 10 speed over the terrible 6 speed auto's the new freightliners / internationals have.
I cannot do the stop and go!! I will leave a 10 car gap and just Idle down the road!! I'm looking at you Richmond VA!!
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