Is IC Piston Engine Really Less Than 1% Efficient?

I tried to let the OP know in an earlier post that rotational units were at least part of his problem. It seems that it may be a common error to mess up these units.

Just in case someone is interested in the correct analysis...

Torque [N-m] x Rotational-velocity-in-Radians-per-second [1/s] = Power [N-m/s] = [J/s] = [Watts]

59 [N-m] x 2500 [1/minutes] x 2 x 3.14159 x 1/60 [minutes/s] = 15446 [Watts]

15546 [Watts] x 1/745.7 [horsepower/Watt] = 20.8 [horsepower]

To summarize...

At a peak torque of 59 [N-m], the crankshaft is turning at 2500 RPM producing approximately 20.8 [hp].

Torque usually drops off a bit above this point and up to the rated RPM of the motor. As a rough estimate, IF torque were constant and RPM doubled to 5000, the output power would double to 41.6 [hp]. This is fairly close to the manufacturers rating of 37 to 39.5 [hp] at 5000 RPM. There is NO discrepancy in the calculations. Just use the correct units and it all works out as expected.

This refers to mjb's thread #172, in which it is stated that the Maruti Suzuki engine for which the calculations have been made consumes 225 c.c/min. Meaning that I litre petrol would last for just 4.4 mins at peak efficiency. Or a mileage of 15.4 km/gallon = 10 mpg approx. This might be on the pessimistic side, since the car weighs only 620 Kg or 1364 Lbs. The over evaluation might have arisen from the fact that the fuel per power stroke has been multiplied by 3. (i.e., fuel per power stroke = 0.03 c.c x 3 cylinders). In actual fact in a three cylinder car there are only rpm/2 power strokes, in this case 5000/2 = 2500) So actual fuel consumption would be 0.03 x 2500 = 75 .c.c in one minute. Considering that the average mileage of the car is given as 15 km/l at 60 km/hr. Then 75c.c per minute seems more realistic. This raises another point.

0.03 x (2500/60)= 0.03 x 41.6 = 1.25 c.c petrol/sec = 33000 x 1.25 = 41,250 J/sec = 55.32 hp/sec theoretical value. Therefore efficiency = 39.5 hp manufacturers figure/ 55.32 theoretical figure = an efficiency of 71.4% ! This is bit disheartening, since we have all been led to believe that the efficiency of the piston engine is about 15% on a wheel to road basis. 71.4% at the flywheel gives a lot of room for thought.

I have read the OP from start to finish and I have to say that DDJames might just be right, at least in as far as he claims to be right. He claims that the torque developed by a piston engine is reduced through (a) the angle of attack of the connecting rod (b) the short length of the lever (crank throw) (c) the opening of the exhaust valve before BDC. Checking : Pressure on piston head after ignition equals approx. 35.2 Kg/cm² (Figure as given in text book) area of piston head = 36.72 cm² , force on piston head = 1292.7 Kgf. According to Archimedes this should translate to 1292.7 Kgm torque ( 12,669.2 Nm torque) if the force were applied at 1m distance from the axle (shaft) and at an angle of 90 ⁰ . Manufacturers figures for torque are 59 Nm @ 2500 rpm. Torque and BHP are closely related by the relationship BHP = Torque x RPS x (6.28/550) the last (0.0115) represents rads/sec divided by hp/sec and is a constant. Therefore manufacturers BHP = 59 x (2500/60) x 0.0115 = 28.27 BHP. Whereas theoretical BHP = 12,669.2 x 41.6 x 0.0115 = 6060.9 BHP. Obviously the efficiency would then be (28.27/6060.9) x 100 = 0.46% ! A clever if devious way of proving that the efficiency of the IC piston engine is less than 1% !

Oh Jesus H Christ.

First, BHP is a unit of power that is inherently imprecise since one is never sure which of the mostly similar units of horsepower one is referring to; metric horsepower, mechanical horsepower, electrical horse power, hydraulic horsepower, or boiler horsepower. So if we assume that this is based on aything but boiler horsepower, the relationship difference will not be significantly different.

Next, there is no reference at all to conversion equations. So the accuracy of these questionable relationships cannot be disputed because they have no reference in this universe.

Lastly, many people here have already pointed out the folly of the OP's mathematic precision, methodology and highly inaccurate mixing of units.

If you wish to believe this idiocy go right ahead.

But it is not a good idea to argue with an idiot. Eventually nobody can tell the difference between either party.

Red, I suggest you Google BHP before letting off steam about something you are so emotional about!

Wow, I include a link that defines and explains one of my complaints about this sloppy pseudoscience post and how people who accept this drivel refuse to listen to others. Then look at what happens, I get a specific complaint that I should look up what I posted. Did you click on my link and read? Of course you didn't. You have nothing but a completely myopic view that scientists and engineers are hiding the truth of the universe from you. But that is an unfair comment on my part, for I don't actually know which insulting "guest" you actually are. Well my suggestion for you is to stop hiding like a coward and at least generate a pseudonym for your postings. It will help us to evaluate if you have any integrity in your postings. Lastly, so what is wrong with blowing off some steam when people come to this engineering blog with absolutely no respect for our discipline. As one individual pointed out here, this distorted use of mathematics is nothing but a confidence scheme. This should and has been shouted down as the drivel it is.

Redfred!!!

Find a huge rock and try and move it using a 1" lever. I will move the same ropck using a lever 3 feet long. Let's see who is so pseudoscience then !!!!!

Your defintions of BHP show how ignorant you are??

"According to Archimedes this should translate to 1292.7 Kgm torque ( 12,669.2 Nm torque) if the force were applied at 1m distance from the axle (shaft) and at an angle of 90 ⁰ ."

What a great idea! Why not carry it further, and assume that the lever length is a kilometer, so that we can generate some SERIOUS torque? While we're at it, why not a lever a few megaparsecs in length - after all, bogus numbers are free, right?

But the Maruti / Suzuki engine in question was stated to have a 72 mm stroke, giving a maximum lever length of just 36 mm; you'll need to multiply your [highly] theoretical horsepower from that imaginary 1m lever (and it CANNOT be "brake" horsepower when it's theoretical only!) by a factor of 0.036 just to correct for this particular error. It is NOT the only one... but it alone bumps your 0.46% efficiency up to 12.7%.

Please explain the source and physical meaning of "hp/sec".

Your calculation indicates that the manufacturer's numbers say that the engine has less horsepower at the torque-peak speed than at horsepower-peak rpm - EXACTLY as expected - so what?

For many eons the water wheel was the main source of mechanical power around the world. They were made large for a reason! Certainly a water wheel with a radius of 0.03m like the throw of the crankshaft in a modern car, would have developed little power!

That's because they had to use slow moving water. If they had had water moving at anything approaching the speed of a piston in a small IC engine, they would have been forced to use MUCH smaller wheels.

DKWarner,

I am new to this thread, but I am under the impression that water wheels generated quite a lot of power. This statement seems to be borne out by the OP. Could you please calculate the hp generated by a (say) 4m dia water wheel running in a current of water that exerts say 3 Kg, per cm sq. Lets say that the area of the paddle is 1 sq m? hmmmmmm?

Another example of a clear lack of understanding. This guest generated a whole lot of useless inaccurate information completely off of the top of his/her head in a bold attempt to look knowledgeable here. 3Kg is a unit of mass, not force. The only possible useful information is the area of the paddle and the diameter of the wheel. There is no identification about this being an undershoot wheel or an overshoot wheel. The unknowns in this defiantly proposed problem greatly overwhelm any merit to even attempting to answer this.

I say that until this guest can identify how much energy gets released by one cubic meter of water being lowered four meters, he/she won't even be capable of understanding the correct answer.

Don't waste your typing DKWarner.

Just put a 5 Kg weight on your hand and hold it at right angles to your body for as long as you can. Is it a force or a figment of your imagination !!

I find it hard to believe that you could have come out with that in an engineering forum.

But then there has been a lot said in this thread about which I could say the same.

While holding that weight, both the work and the power are zero!

While holding that weight both the work and the power are zero!

This is confusing. You say that while holding a 5Kg weight at arms length, both power and work are zero. So is any force being exerted at all to keep that weight of 5Kg at arms length or not?

You do require a force to keep it at that height. But still you are not doing any work, since the nett result is zero.

But work done (as per physics) = vector dot product of the force and the displacement

Since it is kept there itself, so the displacement is zero and hence though you are exerting force, you have not achieved anything, you have only maintained status quo.

Not only that you walk with the object in your had in room from one corner to other and you have not done any work on the object since the force and distance are perpendicular to each other. (The friction force here is not on the object which is held in your hand and is immobile with respect to it)

I have some doubts about work not being done when a weight is held at arms length. I recently saw a guiness world record on TV where a strong man attempts to hold a 25Kg weight at arms length, he could only hold it for about 30 seconds. So work is being done against gravity, or am I mistaken, it is true that if you were on a spaceship no work would be done because there is no force acting on the weight and you are just holding it stationary.

How about if the weight were sitting on a table. Would the table be doing work to hold it up?

You're mistaking the English language that almost makes work and effort synonyms. It takes tremendous, exhausting effort and strength to hold 25Kg at arms length. But when one applies the Physics definition of work, then since the mass makes no movement the net work is zero.

Alright, here's another useful demonstration of how appropriate unit usage must be adhered to.

5 Kg is a unit of mass in the SI system. A Newton is the unit of force in the SI system. Regardless of any geometry considerations on how anyone holds or places this mass, while on or near the surface of Earth the gravitational field from the Earth applies a force of F=mg. With g being the gravitational constant of ≈9.8 m/s² = 9.8 N/kg. So while on Earth this mass will always have about 49 Newtons of force applied to it towards the center of the Earth. If this mass is not accelerating towards the earth at 9.8 m/s² then another force must be opposing this constant force with the same magnitude but opposite in direction. If this mass were on a smaller body than the Earth, like the moon, then a smaller force would be pulling it toward the moon's center. etc.

This is high school level basic Newtonian physics. If you can't get this right...

Ron is right 5 kg force= 5 x 9.8 N approx. Then so is DD james right when he says that a force of 2681 lbsf is applied on the piston head. So if you hold a 5 Kg weight at right angles to your body and your arm is about 1 m. long that weight is exerting a torque of about 5Kgm (49 Nm) .

That's also why wind turbine blades are so large , more than 25 metres in length for a single blade, put two together and what do you have ???

Of course an 800cc engine with a one meter crank throw would also develop very little power. Why might that be?

Guest, as I stated earlier, this is a scam. I've seen this for years as a cop. It's a classic story.

Con man attacks the status quo, offers "facts" which sound great to support his con, then offers a "solution".

Note at the bottom of the post. He offers an "alternative".

I'm sure he'll be willing to share that, for the right price.

Too many good and knowledgeable people have debunked the "facts" this person presented. Just another bunco scheme.

BHP = Torque x RPS x (6.28/550)

the last (0.0115) represents rads/sec divided by hp/sec and is a constant.

BHP = Torque x rps x (rad/sec) /(hp/sec)

= torque x (rad/sec) x (rad/sec) / (hp/sec)

= [(torque x (rad/sec)) / hp] x (rad/sec x sec)

= (unit less) x rad

_{(torque x angular speed/ power = unitless constant, usually unity if units are properly chosen.}

= rad (which is unitless too)

So BHP = Power = unitless

A clever if devious way of proving that the efficiency of the IC piston engine is less than 1% !

Small edit: A moronic and inapplicable way of pretending to prove that the efficiency of the IC piston engine is less than 1%.

Otherwise your post is OK in terms of visual appeal. The numbers and text make little sense and the basic physics are wrong (hp/sec??), but the overall shape and spacing of the characters has some artistic merit.

Or not.

Hi!

You are the one who is moronic if you can pardon me for saying so. Lets look at what guest posted:

bhp = torque x rps(rpm) x 6.28/ (550/33,000). Sorry for being so esoteric, BUT the above equation gives the same HP , if calculated per/sec or per/min. Now 6.28 is the DISTANCE covered per rotation per se, whether it is calculated per minute or per second. Thus if it hp per minute (550 x 60 = 33,000) and if per sec = 550 ft lbs! This is multiplied by the speed i.e., rps or rpm depending on what you are using. So you have torque multiplied by distance, (i.e., speed x radians/sec) divided by Hp/sec what are U going on about !!! Check it out this is how hp is calculated.

WRONG!

Sorry, but I can't make sense of your post. I get lost at "per/sec or per/min" which I parse as "per per second or per per minute".

If you are writing about cats, it would be "purr per second or purr per minute". Otherwise, mathematically it is nonsense, as is hp/sec, unless you are trying to describe an acceleration in hp... but that acceleration in inapplicable to the current discussion.

Any theories on why all this miscalculation shows up? Is CrimeCrusher right?

Doh! Here we go again with bad units

Please go HERE to read about the correct way to apply units and choose the proper conversion factors.

There is a problem with your pressure units. If you fix that, most of remaining calculations will come out close to the manufacturers ratings and support the ~25% efficiency estimates.

Bad math or improper use of units is not clever. It could be devious if someone is trying to use the faulty calculations to sell fictional goods or get funding for nonsensical ideas (a 200% efficient magnetic engine perhaps? ).

mjb,

These are not bad or incorrect units. In fact the maufacturers fiugures for torque are much less than calculated in the OP b'cos, he does not take into copnsideration the opening of the exhaust valve BEFORE power stroke is ended if you think about it this is a huge consideration!! So the manufacturers figure of 59Nm @ 2500 rpm is the maximum torque for this engine. Go figure!!

mjb,

There is a problem with your pressure units.

Perhaps this is the clue we have to unravel to get to the bottom of this conundrum. There is something wrong with the pressure units, but what is it? Perhaps if we could get to the bottom of this then we will be back in the safety zome of 20% or so efficiency. Request that you make the attempt. After all if what OP says is right then in the example being quoted, an initial force of 2681 lbf exerted on the piston head results in a torque of only 43 ft lbs torque being generated, which does seem a pretty massive reduction!

I assume you are writing this tongue in cheak. Post #2 is where this thread should have ended. The only "conundrum" is in the imaginings of DDJames.

I am not questioning efficiency etc. I am just looking for clarifications for myself.

1. In the context of Maruti Car, we had noted that the car develops 39.5 BHP at 5500 rpm. This is declared specifications.
2. 745.7 w = 1 HP.
3. Hence 39.5 * 745.7 w of energy is generated in one second.= 29455.15 w
4. Engine rpm = 5500. This is a 3 cylinder 4 stroke engine.
5. Hence 29455.15/(3*5500/60) w is generated per cylinder in one cycle= 107.1.
6. But there is one power stroke in a cycle of 2 revolutions.
7. Hence in a power stroke power generated is 107.1 *2 =214.2 w.
8. Average Power = Average Pressure * volume. (I think this is right?)
9. Volume = Bore area * Stroke length
1. Stroke length = 72 mm
2. Piston bore area = pi*(d^2)/4 = pi*(0.068^2)/4= 0.00363 meter^2.
3. Volume = 0.00363 * 0.072 = 0.261 *(10^-3) meter^3
4. Hence Avg Pressure = 214.2 w/(0.261*(10^-3)) = 8.2*(10^5) Newton/ meter^2.
5. PV= Constant over the stroke length. Hence peak pressure : Minimum Pressure = about 55:1 during power stroke (Is this ratio roght??)
10. Can some automobile experts confirm to me whether this is the kind of pressure developed inside the cylinder?

Compression ratio is usually about 10:1

ie Usually at the end of the compression stroke, it will be about 10 bar

1 Bar = 10^5 Newton / meter^2 (same as Pascals). Hence 10 bar means 10 * (10^5) Pascals. As per my calculation avg pressure is 8.2 * (10^5) Pascals = 8.2 bar. OK now I am able to correlate various mecahnical physical / dimensional parameters with power output. Thank you.

OK now I am able to correlate various mecahnical physical / dimensional parameters with power output.

No. Wrong. Full Stop. Quit doing this! You keep trying to invent correlations that do not exist!

The pressure at the end of the compression stroke will be ~10 bar before ignition.

It has bugger-all to do with the current discussion.

You are correct through step 2.

Step 3 is wrong! One correct statement of it would be: 'Hence 39.5hp * 745.7 W/hp = 29,500 W (or 29.5 kW) of power is generated.' The Watt (capitol W) is a unit of power, NOT energy, and it's NOT "in one second" That 29.5 kW is being generated continuously over whatever time period the engine is running at that power level, whether it be for one second, one minute, one hour, or one week if the engine could survive that long at that power level.

If you wish to talk about energy, then you can use the relation 1 W = 1J/s, and then 29.5 kW * 1 (J/s)/W = 29.5 kJ/s. That's kilo-Joules per second, and that is energy per time.

If you want to do correct calculations regarding the power of engines, you must understand the meanings of the terms power and energy, or everything falls apart.

dkwarner,

Guests calculations and notation are correct! He IS talking about work and power, rpm, x rad is indeed all about power amd work! Or am I mistaken, please clarify!!

Which of the many Guests are you referring to?

This post (#212) was not responding to any guest; it was responding to post #210 by M S Divekar, as you can verify by looking at the top right corner of post #212.

His statement #3 was "Hence 39.5 * 745.7 w of energy is generated in one second.= 29455.15 w" (my underlining added).

The Watt is NOT a unit of energy, it is a unit of power, so there are no numbers that could make statement #3 correct. Go study the meanings of those underlined words, then re-read post #212. Until you understand the difference between power and energy, it is futile to continue.

Can some automobile experts confirm to me whether this is the kind of pressure developed inside the cylinder?

You might want to read this.

This discussion of MEP and BMEP might help, too.

Here is a spec sheet for commercial diesel engines, which show the expected variations in specific fuel consumption from engine model to engine model. From these you can figure efficiency in just a couple steps. If it takes you longer than 30 seconds, you are doing something wrong. (Remember to use the fuel energy density figures for diesel, not petrol.) If you can avoid math and physics mistakes, you will get precise efficiency percentages for these engines. The numbers you get will be completely different than DDJames got, because they are based on reality, rather than on inapplicable theories, non-existent units, bad math, and bad science.

PV= Constant over the stroke length. Hence peak pressure : Minimum Pressure = about 55:1 during power stroke (Is this ratio roght??)

If PV were constant (which, of course, it is not, because the temperature changes from fuel burn, conduction and gas expansion) then we would need a 1:55 expansion ratio, right? Does that seem reasonable in an engine with a 9:1 compression ratio?

Thank you so much for the link to computing efficiency for diesel engines.

Regarding PV = constant. I do agree to what we were taught in college PV/T = R (is it?) - forgot it was 40 years ago. or is it PVR/T = constant? So under constant temp and constant R, PV = constant. Forgot Charles Law, Boyle's law etc etc

Hi,

I would just like to point out a mistake made by Guest in his #203 post. In order to use that formula it is necessary to convert Nm into foot pounds. But he is correct when he says that : "Torque and BHP are closely related by the relationship BHP = Torque x RPS x (6.28/550)." Although this is more often written as Torque x rpm/5252. The figure 5252 is arrived at by dividing hp/min by 6.28i.e., 550 x 60 = 33000/ 6.28 = 5252 approx.

In the example quoted 59Nm @ 2500. Nm should be convertedto ft lbs torque or 59/1.35 approx = 43.5. Then the equation would read 43.7 x 2500/5252 = 20.8 hp. This works equally well using 43.7 x (2500/60) x 6.28/ 550 = 20.79 hp. Click here for a more detailed explanatiion.

This works equally well using 43.7 x (2500/60) x 6.28/ 550 = 20.79 hp.

And, of course, this result does not correspond to the manufacturer's quoted hp, which is measured at a different rpm, at which torque is lower.

If you had used the link I had posted, you would have seen that the crossing over point where HP begins to exceed torque is around 5252 rpm. I think I am working from the figures posted for maximum torque i.e., 59Nm @ 2500 rpm whereas the figures for maximum hp were 39.5 @ 5000 rpm or something, in anycase the torque does not go down by all that much ast least in the two cases being discussed. In the two cases above, a torque of 43.7 ft lbs @ 2500 rpm produces 20.7 hp while torque of 40ft lbs produces 39.5 hp @ 5000 rpm.

If you had used the link I had posted, you would have seen that the crossing over point where HP begins to exceed torque is around 5252 rpm.

Strange as it may seem, many people are aware of that fact, whether or not they read the link you provided. Of course, hp and torque are never equal, because one is a force and the other power. But yes, its true that at 5252 rpm the number values are the same if lb-ft is used as the unit for torque (provided the engine can turn 5252 rpm). For the same reason, the hp value is double the torque value when both are measured at 10,504 rpm.

The only reason I mentioned the fact that the manufacturer's hp specification is not calculated at the peak torque rpm, is that I feared you were going to claim that post 203 is otherwise correct (in respects other than the unit conversion problem you mentioned). The author of post 203 makes many mistakes, the most ludicrous being the assignment of a meter long lever as being the basis for the "theoretical hp" the engine would produce if it were not .46% efficient.

Do you have an NSX?

Let me just state before anything else, that this thread has exceeded all of my expectations! Let me also apologise for the ludicrous thread title: "Is the IC piston engine more than 1% efficient." The reason for that heading was the complacency that everyone feels about this outdated monstrosity of an engine design, my intention was to, and I think I have succeeded, shake things up a bit. Lets look at what we have, in the example given of the Maruti 800 (I'll use American notation since there seems to be an inherent suspicion of the metric system). Diameter of piston = 2.7 ins approx. Area of piston head = 5.72 sq ins approx. Pressure after ignition = 500 psi approx. Total force exerted on piston head = 2861 lbsf. This results in a maximum torque of just 43.7 ft lbs.

Take a look at this design which you are so proud of. The leverage is ludicrously short, the connecting rod exerts pressure on this ludicrously short lever at an impossible angle throughout its journey down the cylinder, the pressure is prematurely released before ever the piston reaches BDC and to top it all you have the constant friction of the piston traveling up and down the cylinder touching the sides of the cylinder all the way! This is the design that most of you, claim can still be improved. This is the engine design for which you claim anything from 20% - 50% efficiency and get so cut up about if it is ever questioned. Look leave alone every thing else, the energy in the fuel produces a force of 2861 lbsf on the piston head yet only a fraction of this force 1.5% is translated into motive power. These facts are clear. As for a metre long lever being used in an engine being ludicrous, try to think out of the box, make it happen, don't sit back satisfied when you know something is terribly wrong. .

"As for a metre long lever being used in an engine being ludicrous, try to think out of the box, make it happen, don't sit back satisfied when you know something is terribly wrong."

A meter-long lever is fine when we talk of steam engines with 4-meter diameter flywheels, and capabilities of at most a few hundred RPM. We could build a gasoline/petrol engine the same size - but it wouldn't run any faster. One of the limitations [aka "the box"] is that the piston must now travel a huge distance, and the relative velocity of piston and cylinder wall will exceed the P/V limits for those parts. And many individual components will be larger than the Maruti-Suzuki itself - but hey, let's just mount the engine "outside the box"! Though that won't help with the fact that the engine weight will exceed the conceivable payload of the vehicle, so that it cannot actually be moved under its own power.

The enormous surface area of the cylinder will mean fuel condensation, guaranteeing that efficiency will DROP relative to normal practice. Emission of unburned hydrocarbons will set back environmental efforts by several decades. Rotating mass will be huge, ensuring that the engine will have poor throttle response. But maybe that will help offset the long pauses between power strokes, and reduce the resulting thump.

In addition to reading up and actually attempting to COMPREHEND the math, kinematics, the units and physics behind them, as RedFred has suggested, may I add: read up on engineering history, especially with regard to engine design. MAYBE you'll someday understand that engineering in the real world requires use of actual materials (with their limitations), built upon actual tooling and machinery (with attendant limitations), sold to actual people who are at least physically in the real world, for real money, running upon actually available fuel, driven under a variety of conditions, and subject to conflicting laws in every market. Those are just a few of the "walls of the box". Until you understand what they are, why they exist, and why no one has ever gone beyond them, you will have no chance of seeing what tradeoffs can be brought into the picture. To paraphrase Otto von Bismarck, "Engineering is the art of the possible".

Please feel free to dream of fantasy-land - but quit trying to pass it off as fact.

Ron,

Have a look at the fans on a Boeing 747 engine , They are huge, more than 2 metres across, and they rotate at much more than the speed you have in mind !! What makes you think a 1 metre span can't raotate as fast? Get real .

Oh, no problem that a fan - or a disconnected crankshaft - can rotate that fast (though it is FAR more difficult to handle the offcenter masses, bending moments, etc. for the crank). But I didn't say that (I said that the PISTON will be the limiting factor). It will need to go from stopped to full speed and back, traveling 2 meters (for the 1 meter throw) twice per revolution. An auto engine these days will normally have a redline of at least 5,000 rpm, even for [inherently unbalanced] inline fours without balance shafts. So, two strokes of 2 meters each is 4 meters' travel, times 5,000 revolutions per minute, or 20,000 meters of sliding travel per minute (20 km / minute). Peak speed will be double this, or 40 km/minute (667 meters/second). Engine designers use a rule of thumb that piston speed should be limited to about 60 feet/second, or 18 meters/second. ONE limiting factor, even if you had a "magic material" for rings and cylinder walls, is that the flame front can't keep up with the piston, and you will get NO energy from combustion... And that doesn't get into how you can fill the cylinder without having flow through the valves exceed the speed of sound, etc. The side-to-side motion of the connecting rod big ends will also be 667 meters/second for this imaginary engine, and imbalance forces will be, umm, difficult to control.

Working backward, if peak piston speed is 18 meters/second, your limit is about 135 rpm. If the rule of thumb is taken to as average piston speed, you can reach 270 rpm for a 1 meter crankshaft throw length.

This is presumably a thread that is anti piston engine, who said you need a piston to make an engine work? This seems to be the main problem with this thread, that most people are thinking in terms of piston engines while OP seems to be thinking on some kind of new lines.

I have to disagree. Most of the math and science discussed in this thread would apply to turbine engines as well, or to other possible systems.

If the OP would tell us what he has in mind (of anything significantly better than the current IC engine), perhaps we would all have a 'why didn't I think of that' experience (or more likely not). Until he does, I believe it is time for us to let this thread die. I'll watch for a while, but I doubt if I'll be back on this thread.

Dick

Hear! Hear! I second dkwarner's suggestion. The OP was too large and unwieldy to begin with, and since then it has only got worse. A positive aspect is that the whole subject has been discussed indepth, bringing to light some new ideasand information.

Ron,

What is this talk about fans and disconnected crankshafts rotating fast enough. A Boeing 747 weighs in excess of 150,000 lbs and its engines generate about 63,000 pounds of thrust. It doesn't sound in anyway disconnected to me.

Please re-read the first two sentences of post 275, several times. First, I said "OR", not "and". The shaft of a pure jet engine is NOT a crankshaft (CRANK shaft), but a straight shaft, and that STRAIGHT shaft can be balanced together with the multiple fans affixed to it to permit very high rotation rates.

The eccentric masses will impose bending moments upon a CRANKED [i.e., bent] shaft, even before you attach connecting rods & such (and yes, I'm ignoring the fact that the balancing done to an IC engine's crankshaft accounts for a part of the reciprocating masses). It is easy enough to consider the simplest case of something akin to a hand-crank, with a single throw, single joining link, and single centerline shaft segment - rotating it fast will make the throw bend away from the centerline, imposing bending moments within itself and the link, with forces countered by the bearings. Let's go up a couple of steps: three in-line bearings and segments, two throws each supported by two links and 180 degrees apart, so that we have a single-plane crank (CRANK) shaft, which is inherently in static balance. It is easy to see that at high speeds, the two throws are STILL attempting to move outward, now placing tension loads on the links. Within the length of each throw, there is a bending moment which the links must counter. Even if we choose to place the axis vertical to eliminate changing gravitational stresses during rotation, we will reach a limiting speed far, FAR, FAR earlier than if we had a straight shaft through the three bearings. "Or", not "and".

But that is before we even add the connecting rods, which attach to the pistons, which FROM THE BEGINNING I stated were the real limiting factors! (now go read it yet again, and try to comprehend)

Saying what a 747 weighs, or how much thrust it produces, has no discernible relationship to anything preceding this statement. It is a "straw man" argument: try to look at the post itself.

Hi! This refers Blinks post # 250. I did not expect something so , well Juvenile, from some one who claims to know his physics. Let me ask you 'blink' (1) Does the length of the lever matter at all ? (2) Does the angle at which pressure is applied matter at all ? (3) Does the fact that the exhaust valve open 15 degrees before BDC make any difference. ? (4) Does the fact that the piston rings are scraping all through their journey up an down the piston matter at all ?? Apparently not. Instead you use epithets like : I quote "gibberish" . Should I really BE "BEHIND BARS??? " "Your persistence in propagating gibberish (which you have done since your first post here, years ago)"

Well, let me ask you what is your definition of 'gibberish', does it encompass you not answering the facts as presented !! Wake up man! Further which toddler can't tell the difference between an elephant and a mouse ?? Let alone a twelve year old. What exactly is the difference between 2861 ft lbs and 40 ft lbs. Wake up man !!! Answer honestly, does a short , very short lever, make a difference??/ If force is applied to that lever at some crazy angle , does it make a difference ?? If pressure is suddenly released, does it make a difference? Stop ranting and address the questions that have been posed. You are a hypocrite!!!! I am DD james by the way !!

Hi Mr. James,

I sense you found my note unhelpful. However, if you were to take my advice and pedal your wares on Peswiki, I am almost certain you would find the reception much better there. Why put up with the stress of having to make sense (which is a requirement to be taken seriously here)? You can see that my advice is well-intentioned even if you find it currently unvaluable. I can sense, from the tone of your rhetoric, that things are not going well for you here. Perhaps they would go better elsewhere.

You asked several questions:

(1) Does the length of the lever matter at all ?

Definitely. Not in the way you have stated, but it matters nevertheless. Let's assume, for the sake of simplicity, that our Maruti is really 800cc, and therefore 266.6cc per cylinder. If the stroke is lengthened to 2 meters (a 1M lever arm), its piston area would need to be 1.33 sq cm. Thus, the bore would have to be 1.3 cm (13 mm) (about 1/2 inch for those who prefer inches).

I doubt that you can understand the problem here, and probably do not appreciate the mechanics involved in simply transferring force and making the engine turn. But perhaps you can appreciate the fact that one cannot get enough airflow into and out of a 13mm cylinder (through valves of about 6mm dia) to make meaningful power. An engine is, first, an air pump and its power is very strongly related to the rate at which it pumps air. An engine with 6mm valves cannot pump air at a high rate.

There are both oversquare and undersquare modern, efficient, successful engines, But the percentage variation one way or the other from "square" is small. Millions of hours of testing have shown where the benefits of one over the other begin to fall off when the ratios get extreme in either direction. Lengthening (or shortening) the stroke by an order of magnitude or more does not help.

(This applies to your pinwheel engine as well. You can make the lever arm longer, but then a given cylinder charge will move the lever through a smaller part of a revolution. Most of the people reading this thread understand this intuitively. In principal is is little different than the use of gearing: the power into a gearbox is exactly the same as the power out, [if we exclude the very small losses from friction].)

I understand that you know little about how engines work, but you have had ample time to find out how they work since your first posts here, which were every bit as nonsensical as your current posts. You have, apparently, either: 1. failed to do learn the basics of physics or 2. are deliberately failing to be truthful.

Posting in another forum as McQueen, you claimed that our suggestion to build a prototype would be too costly to implement. (I'd suggested building just a single combustion chamber for your pinwheel engine to show that the thrust would be a tiny fraction of the thrust claimed) You also claimed we had offered to take up a collection to help you with the project.* I don't recall that. Building a combustion chamber in aluminium would cost you almost nothing, if you have any mechanical aptitude at all. It seems implausible that you have gone on for so long without creating a proof-of-concept prototype. It is almost as if you want to avoid demonstrating the truth.

(2) Does the angle at which pressure is applied matter at all ?

The angle at which force is applied matters. Pressure is generally taken to act normal to the surfaces affected.

(3) Does the fact that the exhaust valve open 15 degrees before BDC make any difference.

This is not a fact. Exhaust valves open at various times (from one engine design to another) and now, even at different times (for a particular engine) according to operating conditions. However, the beginning of the opening phase is always before bottom dead center, so that the valve can be well open as the piston moves upward. The timing of opening and the rate of opening is an optimization. At c. 15 degrees BBDC, the remaining (low) pressure in the cylinder is making a nearly negligible contribution to torque.

4) Does the fact that the piston rings are scraping all through their journey up an down the piston matter at all

This is not a fact. The piston rings to not travel "up an down the piston."

Should I really BE "BEHIND BARS??

Only you and your courts can answer that. In the US, it is wise to avoid making unsupportable claims if one is seeking investors. If you are not seeking investors, then I think it extremely unlikely that you should be behind bars. I would hope there are no laws against writing science fiction in India. That people here may be "thinking" that you should be behind bars has little bearing on the legal issues. Dennis Lee is famous in the US for perpetrating frauds, and has been convicted of fraud, but has spent little if any time in jail. Some here have suggested that you should seek psychological help. Rest assured that these are only the sorts of thoughts that go through peoples' minds -- don't take them to heart unless you feel it would benefit you to do so.

Well, let me ask you what is your definition of 'gibberish', does it encompass you not answering the facts as presented !!

My definition of gibberish is pretty standard, I think. Here is one from Wikipedia:

• Gibberish is a generic term in English for talking that sounds like speech, but carries no actual meaning. This meaning has also been extended to meaningless text or gobbledygook.

Many of your statements carry no meaning, because the words, phrases, abbreviations, and math are not used in ways that can be said to be meaningful. For example, you write:

Ok! So 37 bhp = 37 x 550 = 20,350 ft lbs approx.

This makes no sense whatsoever. It is an example of gibberish.

Answer honestly, does a short , very short lever, make a difference??/

Yes. See above re overquare/undersquare.

If force is applied to that lever at some crazy angle , does it make a difference ?? If pressure is suddenly released, does it make a difference?

I take these two questions to be rhetorical. It is hard to know what you consider a "crazy" angle, but it goes without saying that the angle at which a force is applied makes a difference in something, and that a sudden change in pressure can also make a difference in something.

No amount of whining will make your contention that current engines are less than 1% efficient true, or remotely close to true. You seem awash in negativity. Perhaps you have some solution to low efficiency in internal combustion engines. If it would make you feel better, please feel free to post that solution in another thread. I understand that your postings about the rotary pulse engine did not go well, (principally because the claimed thrust produced is off by more than an order of magnitude) but perhaps your new idea is better.

If your new idea is based on sound physics, then this is a great place to receive kudos. I hope you find this post more helpful and encouraging than my last.

* You wrote: The CR4 engineering site were stumped, I can tell you that I had received about 400 e-mails from the forum while the subject was hot!!! Unfortunately the most positive aspect of the discussion was that they wanted me to build a working proto-type!! Well you all know how expensive that is!!! Apart from that opinions were divided. One great plus point is that they even offered to pass around the hat , so that I could build a prototype.

Let's assume, for the sake of simplicity, that our Maruti is really 800cc, and therefore 266.6cc per cylinder. If the stroke is lengthened to 2 meters (a 1M lever arm), its piston area would need to be 1.33 sq cm. Thus, the bore would have to be 1.3 cm (13 mm) (about 1/2 inch for those who prefer inches).

I don't think OP is suggesting using the same design as a piston engine, he is, I think, trying to show why that design is not very efficient. Yes, the big marine diesels do use a much longer crank throw, which they achieve through using a box at the end of the connecting rod, consequently they are much more efficient. The down side is that they work very slow.

... he is, I think, trying to show why that design is not very efficient.

Perhaps that is what he is trying to do, but his argument and math are completely wrong. As we all know, internal combustion engines are not less than 1% efficient. Leverage always represents a trade-off, and does not, by itself, change power output or efficiency.

Rather than constructing nonsense to which rational people will react negatively, he might better present the details of his new engine design (in a new thread). If he is pedaling his old design, which he presented here several years ago, then there is little to be said about it that has not already been said, unless he can present actual data from testing a simple, inexpensive, proof-of-concept prototype.

This in reply to #277

This is not a fact. Exhaust valves open at various times (from one engine design to another) and now, even at different times (for a particular engine) according to operating conditions. and again at 15 degrees BDC pressure is negligible.

This is not correct although the timing of the opening of the exhaust valve does vary slightly from engine to engine, it has to open before BDC, as otherwise the strain on the crank shaft might prove too great and it might crack or shatter.

Hi Blink,

With that one, all seeing eye, you remind me more than ever of that "Moody' character from Harry Potter !

Before we start off again about the speed of the piston down the cylinder and about how work = force x distance and power = work/time etc., etc., the basic fact that is being ignored is that the amount of torque generated IS a function of the hp generated. Therefore none of the facts such as piston speed etc., negate this basic fact. It follows that if you could generate say 1000 ft lbs of torque instead of the 40 ft lbs or so torque being generated (in this particular engine) , you would, provided you were able to maintain a decent rotational speed, also generate a similarly large amount of hp. Ergo, the IC piston engine is not all it is made out to be.

DDjames,

It has become blatantly obvious that not only do you not understand the fundamentals required to do accurate mechanical engineering analysis, you refuse to learn when you are corrected. You mix units nearly at random that shows that you have no understanding of the meaning of the units at all. You still think that you can equate torque to horse power. Both of these response curves do have a common basis of engine speed, but just because they both happen at the same time does not mean that they have a direct cause and effect. Farah Fawcett's death did not cause Michael Jackson's death.

You have repeatedly demonstrated here your complete incompetence in fundamental algebra and simple kinematics. Compounding this insult to this forum you refuse to consider anything but your hallucinations.

I tolerate many erroneous ideas born from ignorance. But you clearly need help that cannot be found at this forum. Until you get this....

OK, just do the prescribed thing to throw a spanner in the works !! Say the units are wrong!!! BUT you have to be a MORON not to see the basic sense of what I am saying. Repeat MORON !!

P.S It has already been obvious for some time, that you don't really know what you are talking about !! So just ..... up!! OK!

It has become blatantly obvious that not only do you not understand the fundamentals required to do accurate mechanical engineering analysis, you refuse to learn when you are corrected.

A lot of strong language but is it really justified.

Torque is not being equated with horsepower . Take it from the beginning, force applied at the cylinder head results in the piston moving down the cylinder moving the connecting rod which is attached to the crankshaft resulting in torque being generated and the rotation of the crankshaft. The speed at which the crankshaft rotates depends on the amount and frequency of the torque being developed, this in turn (i.e., velocity of crankshaft) determines how much horsepower is generated. So torque and horsepower are more closely related than you seem to imply . They are not separate disparate functions as you seem to believe.

Yes this strong language is justified. DDJames and you mystery guest refuse to accept cited and linked references that clearly show that you do not know basic kinematics. I did not come to a perpetual motion, free energy blog and laugh at your foolish ideas. Instead you came to an Engineering blog and insisted that pathetic attempts at simple algebra proved that an IC engine was grossly inefficient.

If I could get my hands on you, I would take your meditations and you preparations and ram them up your snout!

GO AWAY!

redfred you have been aggressive and have shown only too well how incompetent you are! Time and again in fact but the fact is that those mistakes are just not worth going into. They are too transparent.

Ditto to redfred's response!

Now show us this marvelous new engine that you have developed, or take your snake oil somewhere else!

Are you nuts Redfred !!! Look at the responses I have been getting for putting forward a perfectly reasonable hypotheses!! Do you want me to be flayed alive or what? Still the fact does exist that the IC piston engine is not what it is made out to be!!! In fact it sucks!!!!

You truly are delusional DDjames. In the middle of hundreds of responses that point out the many inaccuracies in what you propose you still claim that you have a reasonable hypothesis.

I do not want you to be flayed alive. I only want you to get some help. I originally thought that the help would be some formal mechanics training. I'm now afraid that you need psychiatric help.

Please, take care of your self.

You say "Still the fact does exist that the IC piston engine is not what it is made out to be!!! "

What exactly is the ICE being made out to be? What I see is that the ICE has been a rugged, time proven robust design. Perfect? Hardly...but automobiles are used for a variety of purposes and many times what is perfect for one use (highly fuel efficient) is not good for another (adequate power for climbing the side of a hill). The ICE in all it's variations has helped to mobilize millions.

I don't think anyone here is claiming it's an efficient machine or perfect either. Several have shown that the efficiency is in the range of what most technically educated think it is. What was being argued is that it's quite a bit higher than your original claim of less than 1%.

The ICE has been around long enough and had very bright talented folks study, experiment, theorize and modify it time and time again over the years. Perhaps it's design is matured to the point where it's close to as good (efficiency-wise) as it's every going to get. Perhaps some technological breakthrough will come along and revolutionize the ICE. If you have an improvement, great....build it, market it. I can't imagine any car maker out there who wouldn't love being able to advertise they have a car that gets twice the gas mileage as their competitors. And if you can't get the auto manufacturers to buy your idea/design, then find you some venture capitalist and start your own auto company.

Without this engine (piston engine) the world would collapse !! Literally, everything would fall apart. The IC piston engine is the glue that holds everything together. IF there is even a CHANCE that this engine is less than 1% efficient as OP seems to claim, what a disaster it would be, we would have to get rid of it, even though it has made possible the present stage in our evolution, as soon as possible. What impresses me about this post, is not the efficiency or not of the piston engine but of the wonderful properties of the fuel that drives it. Let's not waste fuel, here's to a green future.

Listen up. Horsepower is a function of torque, not the other way around. Horsepower depends on torque and engine speed. That's how someone can make huge amounts of horsepower at smaller magnitudes of torque; if the engine speed's high enough.

You've consistently gotten your information incorrect. The pseudoscience you're trying to sell doesn't work.

I suspect CrimeCrusher's right. You're trying to peddle a scheme like 200 mile per gallon carburetors and perpetual motion.

You are right , either way. What it sums up to is that if torque is greater so is the hp. What are you cribbing about???

Horsepower is a function of torque, not the other way around. Can't have it both ways.

I'm not cribbing about anything. I am pointing out a fundamental flaw in the argument, that an incorrect assumption is being made.

Incorrect assumptions can lead to a proof a lack of fundamental knowledge.

And, sign your name. It is easy to throw stones hiding behind the moniker of "Guest". It takes courage to stand in the open and do it.

A mere correction, but that does not support the other guest though.

Horsepower is a function of torque, not the also other way around. Can't have it both ways.

However the function has another critical variable, ω .

P = f(τ,ω)

A GT @9000 RPM with only about 6500 N-m produces 6MW power

But for a hydro-turbine @250 RPM, 36 times torque will produce that MW.

So the guest's statement HP and torque are same does not hold petrol water.

After all my vehicle has a nice Engine RPM detector , and I see the reading (RPM) varying as I stress the engine.

But more and more threads are adding up to confusion. I am still not sure from where the torque et all has come up.

Long long back we have learn't the calculation of efficiency from Energy ratio or power ratio

Now we have to unlearn it and make it a torque ratio?

And that case a reducer gear box is a torque multiplier so it is an overunity device? say a 100:1 multi-reduction gearbox will have an 10000% efficiency ?

Op & Guest , I am impressed.

My post 249 covers engine speed reference.

In addressing horsepower vs. torque, torque is a physical parameter that can be measured. Horsepower was an advertising ploy invented by James Watt to sell steam engines. He artificially created a method to "equate" the amount of power generated and work done by his steam engine with horses used at the time. Horsepower is in most cases an irrelevant and artificial number to make people feel good. Torque is the real parameter to be examined. Virtually any reasonable number could have been introduced for a conversion to horsepower. After all, what kind of horse are we talking about? Shetland ponies, or race horses, or Clydesdales? Obviously, if I were Watt, I could use any "type of horse" to come up with a horsepower number. 20 Clydesdales are going to produce more "horsepower" than 20 Shetland ponies.

Horsepower is just a number that means little in many instances, and is a function of torque and engine speed.

These other issues have arisen as people have introduced additional elements to the discussion. Some of their assertions are correct, some not.

I appreciate your comments. My comments are in response to a guest attempting to imply that torque is a function of horsepower and vice versa. It doesn't work that way.

With regard to horsepower, I respectfully point out that there are many ways to report on horsepower. In the past one could see SAE, Modified SAE, DIN, taxable, etc. Often, a supplier would select a measurement parameter to imply their engines generated substantially more horsepower than they actually did.

With regard to the comment "Horsepower is in most cases an irrelevant and artificial number to make people feel good", I certainly do not dismiss horsepower as a parameter to be ignored. I simply point out that horsepower claims can be overblown to the point they have no relationship to reality.

During my days as a race engineer with a major and successful race team, our engines were consistently 25 to 45 horsepower shy of our competition, who we consistently beat (and won a major national racing championship) because our engines generated the torque needed at the engine speeds needed to win.

To close, I quote Smokey Yunick, one of the greatest mechanics and self-taught engineers who has never received the laurels his work in engineering deserves, told me one time, "Son, horsepower gets the headlines, but torque wins the race".

The said guest replies .

In addressing horsepower vs. torque, torque is a physical parameter that can be measured. Horsepower was an advertising ploy invented by James Watt to sell steam engines. He artificially created a method to "equate" the amount of power generated and work done by his steam engine with horses used at the time. Horsepower is in most cases an irrelevant and artificial number to make people feel good. Torque is the real parameter to be examined

The Horsepower word has been from the quouted post, which I didn't correct to Power, however the meaning was clear when the following lines have mentioned

A GT @9000 RPM with only about 6500 N-m produces 6MW power

With regard to the comment "Horsepower is in most cases an irrelevant and artificial number to make people feel good", I certainly do not dismiss horsepower as a parameter to be ignored. I simply point out that horsepower claims can be overblown to the point they have no relationship to reality.

The horse power unfortunately is the first differential of a fundamental parameter (Energy) and if Energy is not real .

and

torque is a function of horsepower and vice versa. It doesn't work that way.

Blink has already covered this aspect, and I agree with him on this (as with many of his posts) – the Energy and hence power is more fundamental in physics, and hence if you want it is otherway round. After all within the cylinder what is produced as a result of combustion is not torque, it is energy/power, and this Energy/power is what drives even racing cars, not the torque.

I have already mentioned , the torque, whatever value you want, I can generate simply by using a gearbox, and we do too to drive huge ball mills that we manufacture , @1000RPM, the motor torque is only 24KN-m but at the mill it is 1.2MN-m. But the power that is transmitted is 2.5MW at motor, reduced only by the gear reducers – may be 2.4MW at the mill.

In any functional (mathematical) relation, the relationship between variables are reversible, as we have long back learnt in matrix inversion. In any relationship between physical quantities this relationship inversion is valid.

From the beginning this thread is making a mess of physics by insisting on torque, which is a derived quantity from the power/energy, whatever the unit one wishes to measure/ call it by, but end of the day that is what is produced by the engine, and that is what is used to compute the efficiency.

The example one may equate it is to mass. One does not measure mass, one measures the force exerted (ie the weight) but the real physical quantity that does not change across realms is the mass and not the weight. Does it matter what is the unit of mass, how it is derived, why it is derived ?

And of course

w = mg makes

m = w/g equally valid, or in the old pendulum experiments

T = 2π√(l/g)

also makes

g = 4π²l/T²

of in spring

F = Kx is regularly used both ways

for calibration K is computed, for user it is F.