Plot of Engine Speed vs. Fuel Consumption

I am looking for a plot of engine speed vs. fuel consumption. Is one
available anywhere? I am not at all picky about what specific engine.

I have seen that graph. From where did the data come?


delbert brecht wrote:

>ecarecar4/12/08
>
>
>
>>I am looking for a plot of engine speed vs. fuel consumption. Is one
>>available anywhere? I am not at all picky about what specific engine.
>>
>>
>While each vehicle reaches its optimal fuel economy at a different speed (or
>range of speeds), gas mileage usually decreases rapidly at speeds above 60
>mph.
>
>As a rule of thumb, you can assume that each 5 mph you drive over 60 mph is
>like paying an additional $0.20 per gallon for gas. Quote from the feds.
>
>Graph he
>http://www.fueleconomy.gov/feg/driveHabits.shtml
>
>

Such a graph must be stupid, of course consumption rises
with rpm

| gas mileage usually decreases rapidly at speeds above 60 mph.
Not necessarily fr 60 mph, big factors incl
[i] exhaust*manifold : cheapo 4-1 short branch * can give
¾ of maximum torque @ low rpm <1000, but gives <½
of maximum torque @>3000 rpm, & even less @ higher
rpm
[ii] voltage & ampere from small single coil ( esp if hot )
drop fast @>3000 rpm : sparks will be too small to
ignite enough fuel before pistons reach b-d-c, esp where
only cheapo carbon core cables are used
[iii] cheapo mineral oil's coarseness are apparent only @ high
rpm when only the most slippery oil ( e.g. synthetic with
fullerene ) can produce high torque.
[iv] gear ratios & axle (tyre) height

Just throwing in some other good discussions for the
archives:

Optimal speed by model (compact, mid-size, van, etc.)
http://auto.howstuffworks.com/framed...ning/speed.htm

Discussion of how resistance (especially wind resistance)
causes fuel mileage to plummet at high (55+ mph) speeds:
http://auto.howstuffworks.com/question477.htm


"ecarecar" > wrote
>I am looking for a plot of engine speed vs. fuel
>consumption. Is one
> available anywhere? I am not at all picky about what
> specific engine.

On Sun, 13 Apr 2008 23:13:02 +0800, "TE Chea" > wrote:
[i]
>Such a graph must be stupid, of course consumption rises
>with rpm
>
>| gas mileage usually decreases rapidly at speeds above 60 mph.
>Not necessarily fr 60 mph, big factors incl
> exhaust*manifold : cheapo 4-1 short branch * can give
> ¾ of maximum torque @ low rpm <1000, but gives <½
> of maximum torque @>3000 rpm, & even less @ higher
> rpm
>[ii] voltage & ampere from small single coil ( esp if hot )
> drop fast @>3000 rpm : sparks will be too small to
> ignite enough fuel before pistons reach b-d-c, esp where
> only cheapo carbon core cables are used
>[iii] cheapo mineral oil's coarseness are apparent only @ high
> rpm when only the most slippery oil ( e.g. synthetic with
> fullerene ) can produce high torque.
>[iv] gear ratios & axle (tyre) height

Needless to say, this guy is wacko. By far the biggest factor in poor
fuel economy at high speeds is wind resistance. Many vehicles (e.g.
big SUVs) run less than 3000 rpm at speeds above 60 mph and get much
reduced fuel economy due to their barn door aerodynamics.

Of the above, only iv. will have any noticeable effect on fuel
economy. To the extent that i. reduces power at high speeds it may
actually reduce fuel consumption.

Is there something not-too-expensive I could plug in to get the data for
myself?


ecarecar wrote:

> I am looking for a plot of engine speed vs. fuel consumption. Is one
> available anywhere? I am not at all picky about what specific engine.

ecarecar wrote:
> Is there something not-too-expensive I could plug in to get the data for
> myself?
>
>
> ecarecar wrote:
>
>> I am looking for a plot of engine speed vs. fuel consumption. Is one
>> available anywhere? I am not at all picky about what specific engine.

c'mon dude - you need to be much more precise with your questions to get
meaningful answers.

1. do you mean engine speed or vehicle speed?
2. what kind of engine?
3. what kind of fuel?

there's more, and it's a long list of highly significant variables.

as for plug-ins, yes, you can use obd output data to compute
consumption, if you know some other data, but it's a non-trivial
exercise, and without knowing a /lot/ more detail, you're pretty much
stuck with getting gas station receipt data, recording mileage between
each fill-up, then driving different speeds.

On Apr 12, 4:49 pm, ecarecar > wrote:
> I am looking for a plot of engine speed vs. fuel consumption. Is one
> available anywhere? I am not at all picky about what specific engine.

I suspect Universities that compete in building very fuel efficient
vehicles (esp. hybrids) would have this information available to the
public.

Marine applications may be a source, too.

Maybe Briggs & Stratton has that info. for their lawn mower engines.

ACAR wrote:

>On Apr 12, 4:49 pm, ecarecar > wrote:
>
>
>>I am looking for a plot of engine speed vs. fuel consumption. Is one
>>available anywhere? I am not at all picky about what specific engine.
>>
>>
>
>I suspect Universities that compete in building very fuel efficient
>vehicles (esp. hybrids) would have this information available to the
>public.
>
>
>
You would think, but, actually, no. They may have it, but it isn't public.

After years - literally YEARS - of searching, I found information that
served my purposes.

This will get you from 0 km/hr to 60 km/hr
http://www.jari.jp/pdf/rt2005/09Fu_eng.pdf

This will get you from 50 km/hr to 140 km/hr
http://www.greencarcongress.com/2006...consumptio.htm

The first, as you might have guess, is from Japan. The second is from
Germany.

On Tue, 15 Apr 2008 04:06:26 -0700 (PDT), ACAR
> wrote:

>On Apr 12, 4:49 pm, ecarecar > wrote:
>> I am looking for a plot of engine speed vs. fuel consumption. Is one
>> available anywhere? I am not at all picky about what specific engine.
>
>I suspect Universities that compete in building very fuel efficient
>vehicles (esp. hybrids) would have this information available to the
>public.
>
>Marine applications may be a source, too.
>
>Maybe Briggs & Stratton has that info. for their lawn mower engines.
>

Here is a plot of Brake Specific Fuel Consumption vs. rpm for a VW TDI
engine.

http://forums.tdiclub.com/showthread.php?t=208125

BSFC is the measure of how much fuel is being consumed per unit power
generated - a true fuel efficiency measurement. To get an absolute
fuel consumption rate, you could multiply the BSFC by power at a given
rpm. Of course this all assumes wide open throttle. If you are
running at a lower power setting, the absolute fuel consumption will
be lower. I would guess that BSFC might be higher or lower depending
on the way the engine is set up.


Maybe the OP could tell us exactly what he wants to know.