Efficiency v2.0

[mobile_bob]

Been doing a bit of thinking and decided to start another thread, actually a two part thread
this coming on the heals of the debate and obvious differences of opinion of what is meant by "efficiency"

first a question presented to the board for consideration and input
with the premise that the lister/oid is an engine and as such is part of a machine,
we cannot fully analize the machine but we can talk about the basic engine, assume consistant fuel, air temp, humidity etc,
only criteria open to chang are with the engine itself, so...

what would i do to increase the efficiency of a lister/oid?
a. get the operating temperature of the coolant up to near 195 degree's F
b. determine that the injection system is atomizing the fuel as well as practically possible
c. set injection timing to proper spec's
d. set valves to proper spec's
e. improve volumetric efficiency, by optimized intake and exhaust runner lengths (possible)
f. reduce internal friction, by proper fitting, finish etc.
g. explore the possibility of reverse flow cooling to equalize temps across the cylinder


what would you do to increase the efficiency of an engine, namely the listeroid?

a. (insert here)


next i would like to discuss the overall efficiency of the machine, which the engine is a part of.

unless one has a view of the machine as an  seperate entity, one has to include himself as part of that machine, in sort
of a symbiotic relationship.
the machine exists to serve us with heat and power, and we need the machine to produce both heat and power.
we don't get heat and power, and the machine does not run if we don't feed it.
we all know that it is far easier to work with mother nature than it is to fight her,

it is very hard for most of us to think of ourselves as a cog in a machine, or not something above or vastly superior.
but that is not the arguement that i am presenting here.

the discussion is one of Efficiency and as such we must step back a moment and see ourselves as part of the machine.

everything we do in life has a cost in "lifeblood" or "life energy" we usually equate it to dollars or yen or rubbles or whatever, but
it is lifeenergy not money.

so where is ole Bob going with all this you may ask?

there is an old adage that goes something to the effect,,," you get 90% of the result with 10% of the effort, and the last 10% result will cost you 90% of the effort"

effort= money= lifeblood= life energy

so if we have a machine that is 90% efficient (remember that the lister was a finely crafted and very efficient engine, that we will have one hell of a time increasing
by any appreciable and measureable amount) and we have invested 10% effort, then it by rule will take an exceptional effort (money, lifeblood, life energy) to increase the efficiency appreciably and measurably. what i mean here is if we assume that a lister engine is 33% efficient making it to 35% is going to take a huge effort, and going beyond that is going to take a monumental effort. remember....

effort= money= lifeblood= life energy

on another post i mentioned the 15 minutes it would take to fuel the example machine, increasing efficiency of the engine while possible would take several magnitudes of effort over what would be gained in less time worked to fuel the engine.

the same amount of time and effort spent improving my employment would have far greater gains returned to me, than investing the time and effort to increase the efficiency  of the engine and by extension the machine.

my point ... i am not advocating setting up a smoking horribly inefficient engine as part of a machine,
what i am advocating is getting the engine and also each component of the machine up to a reasonable standard, to each his own here.

where i part with some is the fight for the last nth of some sort of definition of efficiency ,without factoring in the "life energy" that it will cost.

one can reach a point of diminished returns

thoughts?

bob g

[buickanddeere]

  Add in there a PM geenrator so power isn't wasted making a excitation field.
  D*m, I enjoy you cranky b*ggers discussing various topics . The wife wonders why I prefer this site to the TV. Why ,if given the choice I'll take reality over fiction. 

[Guy_Incognito]

For extra efficiency? I think you've covered it, but with:

c. set injection timing to proper spec's
d. set valves to proper spec's

There could be wiggle room to set these to specs that whilst not "proper", are more efficient than what was supplied. Eg, you might find a combination that provided constant adequate power/torque for the task you need it for, but are hopeless for someone that needs to be able to both run at idle and at full output. It would be fascinating to have a variable valve timing and fuel injection setup on top a of listeroid for evaluation. But that goes into the diminishing returns part of things.

I agree with the point of diminishing returns - there's a limit where it's simply not useful to go any further. Call me materialistic , but I find it's best to break it down to cold hard cash. Your time is valuable - whether it's measured in money, bonding with the kids, whatever. For calcs such as these, it's easier to convert your time to money. Use whatever metric you feel like, but make sure it's fair compensation for your time.

Consider a generator running on waste oil that is supplied free of charge, with more than enough to run it as needed.
If your engine puts out enough of the correct form of energy that you need, and it's running OK, you're done. Efficiency doesn't really matter a damn at that point, the fuel supply is free. Environmental issues notwithstanding of course.

Then you have a generator running 1000 hours a year at 3 litres an hour. Fuel costs $1.33/litre, so that's $3990 a year.

You spend $500 (of labour/parts) to get an extra 5% efficiency. Is it worth it? It depends on your timeframe for payback. You save $200 a year in fuel. After 2.5 years, you break even, and only then do you actually begin to save money. If you convert your machine to WVO before then, you've lost your money. If the engine runs for 10 years with little ill effects, you save $200*10 - $500 = $1500, or $150 a year over 10 years. So your fuel cost is now $3840 a year. Not really a spectacular saving, but it's there. That's a beer or two every weekend. Go celebrate your efficiency gain!

If your efficiency tweak somehow compromises the machine and it breaks down more regularly (eg, it now cooks valves every 500hrs, say with $400 of time and money in repairs), it needs to be factored in. So if you have to replace a set of valves twice a year at $400 a go, then your 5% upfront increase in efficiency has cost you big time. You're now spending an extra $800 a year for valve repair, but you do save $150 a year in fuel, so in this case it only costs you $4640 a year. Which is 15% more than what you started out with. Now you have to give up drinking, just because you tried to be a bit more efficient.

[mobile_bob]

B&D:
GI:

excellent points and you both seem to see where i am going with this,

i have been the guy, that has stiven to achieve max efficiency on occasions, and there is always a tradeoff, a comprimise after a point

at some point you look to other parts of the machine to see where there is relatively cheap (in time/labor/dollars) gains to be made, sometimes there is
another part of the machine that makes more sense to invest in, and realize real measurable gains.

as much as i hate to admit it, i agree with GuyF, on some points, it is in the details that we part company.
i also realize that as a trained, educated, and time served engineer he can at time fall into the trap, of non real world details and outcomes.

an engineer will sometimes at first jump to the conclusion that one cannot get to any meaningful data without sophisticated test equipment.
only when reminded on how these specialized and sophisticated test equipment came from does he back off. (i am not saying Guy falls in this trap, but
it would be second nature to do so)

just as one can compound his error with faulty computations and with faulty input data, he can reverse the process and thru reverse resolution increase his
accuracy with the proper mind set, and careful repetition.

a crude example is the neat little tool that is used to straighten a bent crankshaft on a b&s lawnmower engine, with the resolution of the pointer on the jig, one
can not only straighten the crankshaft in place(in the block) but do so with great accuracy.

in three steps i can place two precision round bars to within one 10 thousands using no test instruments, except to check the final placement, it is done by reverse resolution.

you use the escalation in error in reverse to drive the precision positive.

for example,
to test the relative efficiency of an engine, as was previously posted by others, you need but few things

1. a baby bottle marked off in oz and ml

2 a thermometer

3. enough fuel that is stable in temp to run a full serious of tests from the same batch

4. a fixed load, such as a prony brake, which is fairly easy to manufacture

5. a spring scale

6. a piece of 1/2 inch clear plastic tube

7. a stop watch.

8 tachometer,

9. perhaps a couple of other crude instuments


now we have to have a careful measure of fuel, but we have a baby bottle,,hmmmmm not very accurate, so how do we increase the resolution to allow for more
accurate measurement?

we attach the 1/2 " tube to a stand, and place a valve on the bottom to supply the engine, we fill and purge, run the engine to get all the air out,
we then fill the tube with one oz. of fuel, which will travel up a few inches in the tube, we then subdivide the tube to determine as accurate as we want.

we now have a fairly accurate albeit relative measure of fuel.

we set up the prony brake, bring the engine up to temp and load the engine to a predetermined level that will be constant thru all tests, and time how long it takes to use x amount of fuel.

we make one modification at a time and repeat the test process, and take careful note of each result

we do timing,
we do valve settings
injector spray patterns,
etc etc

at some point we have a peak on our chart that shows what our relative gain has been
based on
operating temp,
temp of fuel
type of fuel
rpm
torque
timeing
etc
etc.

is it worth all the trouble, well that is up to the individual and his needs.
the prony brake could be replaced by the generator, but heat losses in the generator might skew the results, so the gen head would
have to be allowed to return to ambient temp

now had we kept with the baby bottle we would have had a very subjective result as it is very difficult to get meaningful results of one oz
when the miniscus (sp) is 2 inches wide and hexagonal, never mind translucent.
but by means of increasing resolution we get a much better precision in our readings.

step back and look at our prony brake, we used a spring gage with course graduations, we can increase resolution and accuracy by using a
longer arm, thus increase the accuracy of the torque measured

we can also increase the test time, this will increase the overall resolution,

and the list goes on.

now do we have precision that is that of a test lab? no
but for real world work we are likely close enough, and remember we are looking for a relative increase over the baseline engine in efficiency.


in the real world, (and whether of not i or any other folks of the engineering ilk,) most folks are not going to go to even this level of testing
not until someone does it, and comes up with results that would indicate that if one was to go to the trouble he could get results that would
pay  him to do so.

personally i wouldnt do it unless it was demonstrated that i could reliably experience over a 5% increase in efficiency without a sacrifice in
longevity.

there are far easier ways to get that 5% in other area's of the machine, easier, cheaper and likely things that would increase reliability as well.

now if one was to set up such a test system, and from the results published it was shown that for example:

a. replacement of the intake manifold with a 23.2 inch intake runner that was 2.2 inches in diameter, gave an increase of 5% at 650 rpm and 3kwatt load
on a 6/1, then i might very well purchase or install one, and test it myself.

b. increaseing coolant temps to 205 degree's was shown to increase efficiency by 5% , i might give it a whirl

c. etc

but if i didn't see at least a 5% increase that could be replicated, or was faced with results under 5% i would look at them as being within
the margin of error

that is of course if you want to get anal about efficiency in the first place

bob g

[jzeeff]

I agree that measurement is vital in optimizing efficiency.  I'd use a syringe for measuring fuel.

Some things to look at (sorry for repeating some things others have said):

Test overall efficiency at various loads and rpms.  An electric meter called a "Killawatt" is pretty accurate for measuring electric  output.  The goal is "how many KWH can you get from one syringe of fuel?".

Do you have any use for the waste heat coming off the engine and exhaust?

Preheat the fuel for better spray pattern.

Try slightly higher or lower compression.

Use exhaust heat to preheat the intake air.   

Eliminate belts.

Low viscosity oil.

Adjust injection timing.

More swirl in the cylinder.

Tuned intake/exhaust.

More efficient generator.


Does anyone have any figures on any of these?  I'm sure that many are too small to worry about.

[Firebrick]

The biggest improvement in efficiency, almost doubling it, comes very easy actually.  I know that the big cats on a gen are running around 43 percent efficient (mechanical).  They commonly use the hot cooling water to heat buildings in northern europe the efficiency jumps to around 90.  The dutch use landfill gas to power several engines, use the jacket water to heat greenhouses, and remove the CO2 from the exhaust and pump it into the greenhouse to not only help with the solar gain but helps the plants grow faster. So install a jacket around the exhaust and pump it and the cooling water though a radiant floor.  Summer time or live in a hot climate?  Use the heat for domestic hot water or to power an absorption type refrigeration system