>> There isn't a linear relationship between the rotational speed of the 
>> wheels and the speed of the engine.
> 
> There is, in a (relatively primitive) manual transmission.

Indeed.

> There is not, 
> however, a linear relationship between engine RPM and gasoline usage.

No - that would depend on the smoothness of the road, the inclination, 
wind speed, and a bunch of other factors. Even so, I would expect it to 
be possible to come up with an *approximate* number for fuel used per 
cylinder.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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andrel wrote:
> 
> http://en.wikipedia.org/wiki/Variomatic
> 
> just plugging dutch technology that never really caught on.

It did, when improved enough.

http://www.audiworld.com/news/99/multitronic/content.shtml

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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>> No wonder hitting anything is an instant fatality...
> 
> Hmm, yeah, 110 feet per second, wear your seatbelt.

And won't walk across busy motorways at night while dressed only in 
black. ;-)

Also, DON'T HIT A TREE!

[A nice mature Oak has brunches going up to 30 feet into the air, and 
roots going down to 30 feet into the ground. The entire organism 
probably weighs multiple tonnes. If you hit it, IT'S NOT GOING ANYWHERE!]

> 0.0027 tsp of gas per cylinder. (other factors ignored). 

Hmm, that's actually really small... that's like... 0.015 ml. o_O

That can't be right, surely? That's less than one droplet per cylinder! 
How would you portion out such a tiny amount? Surface tension would seem 
to make this impossible.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Orchid XP v8 wrote:
> 
> No - that would depend on the smoothness of the road, the inclination, 
> wind speed, and a bunch of other factors. Even so, I would expect it to 
> be possible to come up with an *approximate* number for fuel used per 
> cylinder.
> 

Yes, ~1/4 of used fuel is used for one cylinder (but not injected in one 
- it's injected to the air intake before cylinders;). Just multiply the 
~28,75cm with consumption (l/100km) and you'll get the average amount of 
fuel .

Just a side-note: given that IIRC your car is <2l naturally aspirated, 
I'd guess the maximum possible fuel used per minute per cylinder with 
original parts is somewhere around 200cc (the injector capacity), giving 
total of 0,8l/min. OTOH, that much is used rarely, basically only when 
revving with pedal on the floor at the rpm of maximum power.

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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Orchid XP v8 wrote:
> 
>> 0.0027 tsp of gas per cylinder. (other factors ignored). 
> 
> Hmm, that's actually really small... that's like... 0.015 ml. o_O

On one rev the car moves 28,75cm, in that time 2 sparks are launched. 
Google says 40mpg (US, AFAIK it's pretty near 50imperial MPG) converts 
to 5,8l/100km (which is pretty low for 120km/h, but possible, if you 
have a modern diesel with long gearbox and good aerodynamics). 
5,8l/100km makes 
0,058l/km=0,000058l/m=0,00003335l/rev=0,00001668l/spark=0,01668ml/spark. 
Yep, we're on the same line - I'd say the differences comes from the 
roundings and converts.

> That can't be right, surely? That's less than one droplet per cylinder! 
> How would you portion out such a tiny amount? Surface tension would seem 
> to make this impossible.

To get to that consumption on those speeds you'll need a modern diesel 
engine (or a hybrid-system), for example common rail -engine. In those, 
the diesel is packed with very high pressure (>1000bar) on a kind of 
pipe before the cylinders and released to cylinders very precisely with 
piezo-electric injectors. Really fine mechanics, think about a 
manufacturing fault in there...

http://en.wikipedia.org/wiki/Common_rail

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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Eero Ahonen wrote:
> On one rev the car moves 28,75cm, in that time 2 sparks are launched. 

HUGE mistake - on HALF rev the car moves 28,75cm and in that time only 1 
spark is launched, therefore...

> Google says 40mpg (US, AFAIK it's pretty near 50imperial MPG) converts 
> to 5,8l/100km (which is pretty low for 120km/h, but possible, if you 
> have a modern diesel with long gearbox and good aerodynamics). 
> 5,8l/100km makes 
> 0,058l/km=0,000058l/m=0,00003335l/rev=0,00001668l/spark=0,01668ml/spark. 
> Yep, we're on the same line - I'd say the differences comes from the 
> roundings and converts.

... these last numbers DO NOT MATCH, the correct final number being 
0,03335ml/spark.

> To get to that consumption on those speeds you'll need a modern diesel 
> engine (or a hybrid-system), for example common rail -engine. In those, 

Also to be noted, if you really have common-rail diesel or something 
similar (I recalled you have a non-GDI petrol engine), the fuel actually 
is injected to the cylinder, not to the intake.

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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Invisible wrote:
> OK, so here's one for you...
> 
> If I put my car into top gear and set the engine to 3,500 revolutions 
> per minute, my car travels forward at almost exactly 75 miles per hour. 
> So... how far forward does it travel for a single revolution of the 
> engine??
> 
> Similarly, at that speed my car achieves roughly 50 miles per gallon of 
> fuel. So how much fuel does it inject into each cylinder??
> 
> [My car has a four-cylinder, four-stroke internal compustion engine, and 
> is normally-asperated. And runs on petrol, in case that wasn't obvious. 
> Presumably the timing is therefore set so that exactly one cylinder 
> fires for every revolution of the engine.]
> 

The fuel consumption of a vehicle is often quoted (in metric) as litres 
per 100km.  Suppose a medium sized sedan gives 10L/100km to keep the 
maths easy.

So we have fuel consumption as a volume per distance.  That means it can 
be reduced to an area.  Think of it as the cross-section area of a 
cylindrical line of fuel that the vehicle is consuming as it hurtles 
down the road.  Of course when you accelerate the engine guzzles more 
than this average and while cruising at some optimal speed (around 
80km/hour ?) it would sip a bit less so the shape is tapered.  It isn't 
a simple cylinder but rather a lumpy one.

Lets ignore these variations and work out how large this cross-section 
is on average.

Well do the calculation and you get 0.1 mm^2.  That is one tenth of a 
square millimeter!  Depending on the size and resolution of your screen 
and the font size that you use it is about the area of a full stop.

So as you cruise along a motorway your vehicle is slurping a stream of 
fuel about the same size across as a largish grain of sand, burning it 
to produce hot gases and farting them out the rear.

I find the fact that such a seemingly miniscule amount of fuel can be 
used to propel quite massive vehicles along at such speeds quite 
amazing.  The energy density and convenience of petroleum fuels is just 
astonishing.  As someone once said if you were to write down the ideal 
properties of a vehicle fuel you would pretty much define petrol.  High 
energy density but not (terribly) explosive, liquid over a wide range of 
temperatures, cheap (well relatively), easy to handle, not (too) toxic 
or corrosive etc.

Second thought though is that when you add up the consumption of tens of 
thousands of vehicles along a section of major road each day it does 
start to amount to quite a lot.  Those fractions of a square millimeter 
accumulate to something like the cross section of a fire hose or water 
main.  Imagine the threads of each vehicle weaving with others to form a 
massive cable down the center of the road.  Smaller roads might equate 
to a garden hose each.  Sum this across a city and it is a huge web 
spread down every road and tangled across every intersection.

Over the course of a year the sum cross section along a major road would 
be larger than the cross section of a petrol tanker truck.  So it is 
like every highway and major road being lined with tankers parked nose 
to tail.

And all of this is with a liquid that was produced millions of years 
ago.  It is the captured sunlight that fell on forests in the time of 
the dinosaurs.

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> I find the fact that such a seemingly miniscule amount of fuel can be 
> used to propel quite massive vehicles along at such speeds quite 
> amazing.  The energy density and convenience of petroleum fuels is just 
> astonishing.

On the other hand, steam engines are more efficient. (I.e., transform 
more of the available energy into useful work.) But they're really not 
"convinient" at all.

> Second thought though is that when you add up the consumption of tens of 
> thousands of vehicles along a section of major road each day it does 
> start to amount to quite a lot.

Uh, yeah...

> And all of this is with a liquid that was produced millions of years 
> ago.  It is the captured sunlight that fell on forests in the time of 
> the dinosaurs.

Indeed.

Still, you'd think it would be possible to somehow take plants living 
today and transform their tissues into some kind of highly flammable 
hydrocardon with reasonably efficiency. This would seem the obvious 
sustainable solution.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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482fe97c$1@news.povray.org...
> On the other hand, steam engines are more efficient. (I.e., transform more 
> of the available energy into useful work.) But they're really not 
> "convinient" at all.
Stirling engine generator >>> electricity powered wheels...
http://en.wikipedia.org/wiki/Stirling_engine
>
>> Second thought though is that when you add up the consumption of tens of 
>> thousands of vehicles along a section of major road each day it does 
>> start to amount to quite a lot.
>
> Uh, yeah...
>
>> And all of this is with a liquid that was produced millions of years ago. 
>> It is the captured sunlight that fell on forests in the time of the 
>> dinosaurs.
>
> Indeed.
>
> Still, you'd think it would be possible to somehow take plants living 
> today and transform their tissues into some kind of highly flammable 
> hydrocardon with reasonably efficiency. This would seem the obvious 
> sustainable solution.
There are researches on hydrocarbon synthesis directly from CO2 and H2.
This could be a better solution because arid (but close to the sea )and 
sunny (solar energy) zones could be used instead of fertile lands better for 
food production.

Marc

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Warp wrote:
...
>   3500 rpm = 3500*60 rph, and in 1 hour it travels 75 miles. Thus divide
> 75 miles by 3500*60 revolutions, and you have the amount of miles per one
> revolution, which would be approximately 0.0003571428 miles.
> 
>   Given that I'm not sure which whacky units miles are divided into,
...

0.0003571428 mile
= 1 foot + 2 hands + 2.6285678 inches
= 22 and 5/8 inch (and something).

http://www.google.com/search?q=1+foot+2+hands+2.6285678+inches+in+miles
http://www.google.com/search?q=%2822+5/8+%29+inches+in+miles

1 mile
= 8 furlongs
= 80 chains
= 1760 yards
= 8000 links
= 5280 feet
= 15840 hands
= 63360 inches

1 furlong
= 10 chains
= 220 yards
= 660 feet
= 1000 links
= 7920 inches

1 chain
= 22 yards
= 66 feet
= 100 links
= 198 hands
= 792 inches

1 yard
= 3 feet
= 9 hands
= 36 inches

1 foot
= 3 hands
= 12 inches

1 hand
= 4 inches

1 inch
= 1000 mils

-- 
Tor Olav
http://subcube.com

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