A work of pure genius! - Brilliant "Revetec" Engine

[revetec]

No you aren't reading it literally and I'm not modifying it at all.

Maybe you should ask other people to read it for you, and explain it.

Remember that Heat =/= Temperature. Heat content is everything when it comes to energy. If you know that a system contains 100 Joules of heat energy then it is largely irrelevant what the volume, pressure, or temperature is as you can manipulate those 3 variables however you wish in accordance with gas laws.

You are talking about heat energy, fine! But temperature does not define heat energy, as you need to include into the equation, volume and pressure.

But I don't need clarification from BMW. My interpretation of their quote fits perfectly well with conventional laws of physics and the laws of logic. Your interpretation doesn't.

With your way of logic, it would have been impossible to achieve what I have. So my testing proves otherwise. It's not my arrogance, it's yours not to accept my acheivements from my in-house development and testing and in independent testing performed.

So what? The mechanical advantage doesn't change from varying forces, only by lever arm length. The varying forces change the composite torque curve.

This inturn provides more torque from a defined amount of heat energy.

But once you know the power, why would you need to know the torque? All performance parameters can be calculated from power...

Because with higher torque at lower RPM you produce higher power at that given RPM. This provides a lower RPM operational point. Lower RPM means less swept volume per minute, and saves fuel.

The point is to change gears to match speed not RPM. Your scenario took accelerating from two different starting speeds to be a fair comparison. This is blatantly false.

I guess you must have misread or misinterpreted my statement... Read it carefully again.

So what? Once you know the power curve the torque is irrelevant.

You needed to know the torque before you calculate power. Hahaha.. A dynamometer takes torque and RPM measurements, then calculates power, not the other way around. When you calibrate a dyno, what do you do? You place weights on a lever arm and correct the torque value. No torque, no power.

BTW: I have been looking at my own equations for composite torque that we have been talking about. Do you happen to have a pressure over crank angle graph that can be made public? The few that I have from testing aren't allowed to be made public unfortunately. I am trying to find a generic one to use in comparison with you. To see if we can figure out the relationship with thermal efficiency. Failing that I will construct a simple one.

Just google image seach; cylinder pressure graph and you'll find one.

[revetec]

We know the relationship with torque and power so let's show how they effect an engine in real life application....

We have two engines exactly the same. One we increase power without increasing torque by providing better breathing at higher RPMs. The other engine we will provide more torque down low by increasing the torque lever while not increasing the power at high RPM.

Now put the engines into two vehicles. How do they drive. The first engine providing more power performs better at higher RPMs and when driven at higher RPMs can do more work that the higher torque engine.

The higher torque engine accelerates more effortlessly from a standing start because the resulting power is higher at lower RPMs.

I hope we agree at this point?

Now for a race car, the ultimate importance is power and speed. So power is everything. For the average driver, good acceleration and economy is all important as we tend not to drive majorly at peak power RPMs.

Most of our driving is either stop start in traffic (city) or cruising (highway). Most of us drive at part throttle. In the city we majorly drive between 2,000RPM and 4,000 RPM. On the highway we majorly drive between 1,500RPM and 2,500RPM.

Power at higher RPM has more power strokes per minute, and this uses more fuel and emits more pollutants. If we look at a BMEP chart we see that the peak efficiency is usually around 2,000RPM.



When looking at cruising on the highway for ultimate economy, cars are usually geared to drive at 100kph and around 2,000RPM for this reason.

So the arguement is, for racing, peak power at high RPM is the ultimate performance, but is not the ultimate fuel economy for mainstream applications such as the normal motorist who is looking for economy.

This is why performance cars state a maximum speed rather than the fuel efficiency, and normal cars like to quote MPG highway and city cycles.

While we look for fuel economy, higher power provides us with higher top end speed and performance so both are important, but in a world of high fuel prices and trying to lower emissions, fuel economy is now at the highest of importance.

Also note that younger people who don't care about running costs prefer to say power is everything. Businesses, families and the world's environment have more importance towards fuel economy and emissions.

I met with the Development Managing Director of a major automotive company. He made this statement to me which was translated from Japanese to english through his interpreter was: "Torque is all important in the automotive industry, except for marketing."

So in summary, In vehicles: Power is most important to racing, people driving fast (mainly younger), and people going maximum speed on autobahns. Torque down low is most important to fuel economy, emissions and mainsteam drivers. Because of this we have different views of importance.

The world enviroment and resorces has only one view, at it isn't outright power.

Cheers

[hightower99]

Maybe you should ask other people to read it for you, and explain it.

I have asked several other people. They have all come to the same interpretation as me. Of course this has little value on an internet forum, but honestly no-one I have talked to about the turbosteamer has made the same interpretation as you...
Have you asked anyone else about their interpretation? Has it always been the same as yours?

With your way of logic, it would have been impossible to achieve what I have.

I assume you are talking about your engine? I don't think your engine breaks the laws of thermodynamics or stretches the barriers of logic at all. Remember I don't believe in the magic 37% rule. Why would you say this???

Because with higher torque at lower RPM you produce higher power at that given RPM. This provides a lower RPM operational point. Lower RPM means less swept volume per minute, and saves fuel.

Agreed but why does one need to even mention torque? Higher power at low RPM = good <- not a difficult concept to understand.

You needed to know the torque before you calculate power. Hahaha.. A dynamometer takes torque and RPM measurements, then calculates power, not the other way around.

Most dynamometers work this way, however inertia dynamometers measure power directly. Most hydraulic dynamometers also measure power directly as well (measuring oil flow). Even so I agree that you can use torque and RPM to calculate power. I see no other use for torque values once you have used them to calculate power. I am not arguing the concept of torque, simply it's usage as a performance parameter.

I can see from your last post that you might have misunderstood my point about power vs. torque. I was not talking about engine tuning. I would just rather people talked about low RPM Power as opposed to low RPM Torque if talking about economy engines. Instead of getting excited that an engine makes 300lbs/ft of torque by 1500RPM I would rather they got excited about 86hp at 1500RPM. I hope you understand my point now.
I always cringe when people trip themselves up when comparing engines by saying something like "Yeah it is 50hp down but it should still give a better kick because it is 50lbs/ft up on engine X".
Peak torque values are completely irrelevant as they could be replaced by a power figure.
Another huge misconception that I dislike is the whole "Peak torque RPM is the most efficient place for any engine" It is very rare that peak torque is even fairly close to peak efficiency. Look at the picture in your post. Peak efficiency is roughly at 30% power at 2000RPM whereas peak torque is at 70% power at >3000RPM.

[revetec]

Most dynamometers work this way, however inertia dynamometers measure power directly. Most hydraulic dynamometers also measure power directly as well (measuring oil flow). Even so I agree that you can use torque and RPM to calculate power. I see no other use for torque values once you have used them to calculate power. I am not arguing the concept of torque, simply it's usage as a performance parameter.

Measuring oil flow? OMG!

From your reference: eHow.com How Does a Dyno Work? | eHow.com

The dynamometer mechanism then uses either hydraulic fluid or water to create resistance to the engine's spinning force. This resistance is continued until the engine's maximum turning force is measured at every RPM, giving the tester an accurate reading of the engine's torque. A computer or the tester can then use the same equations to derive a horsepower number for the engine.

They don't measure oil or water flow, they are used as a brake. The brake creates a twisting motion which acts on a torque sensor. I used an electric brake dyno in house. This dyno also used the same type of system, braking the engine and using a torque sensor (Dyno Dynamics brand).

I can see from your previous post that you might have misunderstood my point about power vs. torque. I was not talking about engine tuning. I would just rather people talked about low RPM Power as opposed to low RPM Torque if talking about economy engines.

You would prefer to talk power? Ok!
But you state that torque is an illusion, which is just plain wrong.
Torque is the force that moves your vehicle, how far you move it, is work done which is power. No torque, no work done and no power.

Instead of getting excited that an engine makes 300lbs/ft of torque by 1500RPM I would rather they got excited about 86hp at 1500RPM. I hope you understand my point now.

If you would rather think of it that way, then that's your preference.

But I will tell you from experience, for an engine developer working on fuel efficiency it is easier to look at how flat a torque curve is, when it comes in and fades away, rather to try and interpret the changes in angles of a power curve. I'm sure that when you look at a power curve, you look straight towards the peak of the curve to see the engine's peak power. This is not what people look for when looking at fuel economy, we look at how early the torque comes in, and how long it is sustained for. A simple preference for the task at hand.

I always cringe when people trip themselves up when comparing engines by saying something like "Yeah it is 50hp down but it should still give a better kick because it is 50lbs/ft up on engine X".
Peak torque values are completely irrelevant when they could be replaced by a power figure.

You are correct in your way of thinking. the higher torque provides higher power at a lower RPM which creates more "kick" You like to know the power at this point because you can relate to it better. The people you talk to that make you cringe find it easier to relate to the torque curve. It's as simple as that in this case. No one is right or wrong. This doesn't make torque irrelevant at all, just you like to relate to power, and that is your preference.

Another huge misconception that I dislike is the whole "Peak torque RPM is the most efficient place for any engine" It is very rare that peak torque is even fairly close to peak efficiency. Look at the picture in your post. Peak efficiency is roughly at 30% power at 2000RPM whereas peak torque is at 70% power at >3000RPM.

True, this is due to at 2,000RPM and around 85-95% load the engine losses have the least amount of influence. Over 2,000RPM the influences from piston inertia are counteracted by the changes of point of maximum pressure on the piston cause by less timeframe of the stroke (with a not so variable burn time), induction pulses, exhaust pulses and flow etc. Notice the drop in fuel efficiency over 4,000RPM at heavier loads. Refering to the torque curve it is easier to relate the drop in torque to the drop in efficiency. Maybe you don't see this as easily as you like to relate to power. But again, it's someones preference to what you are looking for and understand more easily.

[revetec]

Here is a link: Here

Getting back to the BMW turbosteamer. Note that the exhaust temperature is 50degC at the tailpipe in the thermal image photo, and I would assume the temp of the air going into the engine may be around 25degC. So the increase in expelled gas temerature is around 25degC gain from ambient?

The system uses 80% of the exhaust's thermal heat energy from the exhaust.

And let's say that the turbosteamer system has 50% losses.

Calculate it for me considering their exhaust temp at the manifold is 800deg. I would like your view please.

I calculated it out and it has interesting results. I also noticed in the photo that it is a bit of a composite image, as I can see insulation around the system up to the second heat exchanger which I think has been removed for the image.

[hightower99]

They don't measure oil or water flow, they are used as a brake. The brake creates a twisting motion which acts on a torque sensor. I used an electric brake dyno in house. This dyno also used the same type of system, braking the engine and using a torque sensor (Dyno Dynamics brand).

Note that I was talking about inertial dynamometers.

You would prefer to talk power? Ok!
But you state that torque is an illusion, which is just plain wrong.
Torque is the force that moves your vehicle, how far you move it, is work done which is power. No torque, no work done and no power.

Torque isn't the force that moves the vehicle. Torque can't move anything, its static. As soon as movement is involved torque becomes power... Hence engine torque is an illusion (the concept is true and real but only for static systems). Measured torque from a running engine is also an illusion because in order to measure the true amount of torque you would have to stop the engine completely (not just brake its acceleration). The reason you measure torque is because the engine dissipates power into a static system. Once power loses its motion it turns back to torque. BTW Power =/= work done, Power = Rate of Work! Can you finally see my point? It isn't just my preference, Torque doesn't exist in dynamic systems...

If you would rather think of it that way, then that's your preference.

Its also technically more accurate.

But I will tell you from experience, for an engine developer working on fuel efficiency it is easier to look at how flat a torque curve is, when it comes in and fades away, rather to try and interpret the changes in angles of a power curve. I'm sure that when you look at a power curve, you look straight towards the peak of the curve to see the engine's peak power. This is not what people look for when looking at fuel economy, we look at how early the torque comes in, and how long it is sustained for. A simple preference for the task at hand.

Well I have no problems interpreting power curves. I don't look straight to the peak I am much more interested in the overall shape of the powercurve. Also do you think that the most efficient torque curve is a flat one?

You are correct in your way of thinking. the higher torque provides higher power at a lower RPM which creates more "kick"

Look closely at my quote again. Only differences in peak power and torque are mentioned. The higher peak torque could happen at only a single RPM point with the rest of the curve being down exactly enough to be 50hp less than the more powerful engine. You cannot tell anything about performance solely from torque values.

True, this is due to at 2,000RPM and around 85-95% load the engine losses have the least amount of influence. Over 2,000RPM the influences from piston inertia are counteracted by the changes of point of maximum pressure on the piston cause by less timeframe of the stroke (with a not so variable burn time), induction pulses, exhaust pulses and flow etc. Notice the drop in fuel efficiency over 4,000RPM at heavier loads. Refering to the torque curve it is easier to relate the drop in torque to the drop in efficiency. Maybe you don't see this as easily as you like to relate to power. But again, it's someones preference to what you are looking for and understand more easily.

I understand and "relate" to power and torque equally well. The people who make me cringe just don't understand what torque and power are.
I think you will find that it is difficult to find a relationship between torque and thermal efficiency. According to the graph you showed between 1000RPM and 3000RPM torque increased by 16% and the BSFC went from roughly 0.45 to 0.50 (11% increase) but from 4000RPM to 6000RPM the torque fell roughly 30% but BSFC only increased from 0.55 to 0.59 (7% increase).

[revetec]

[ame="http://en.wikipedia.org/wiki/Torque"]http://en.wikipedia.org/wiki/Torque[/ame]

Just read the link!

[henk4]

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

Just read the link!

quite a number of substantial formulas, dealing with an "illusion"
Apparently these are all wrong, starting with the use of Nm as the measurement unit for torque. That could never be used if the unit was static, as m would be equal to zero....

[hightower99]

quite a number of substantial formulas, dealing with an "illusion"

Please note that I have maintained that the concept of torque is real and that I understand it. The illusion is specifically engine torque values and their connection to movement.

Apparently these are all wrong, starting with the use of Nm as the measurement unit for torque. That could never be used if the unit was static, as m would be equal to zero....

Ummm you do know that the m in Nm is for the length of the lever arm and not a distance travelled right???

Revetec: What part did you want me to read specifically? What exactly do you disagree with?

Do you not agree that torque is static?
Do you not agree that when movement is involved then it is work?
Do you not agree that work/time = Power?

[henk4]

To conclude this as far as I am concerned we just have to quote Carroll Shelby:

Horsepower sells car, torque wins races...

I think races do have to do with movement.

[Alastor]

To conclude this as far as I am concerned we just have to quote Carroll Shelby:

Horsepower sells car, torque wins races...

I think races do have to do with movement.

Did he even really say this? Is there some kind of legitimate citation that confirms this is an accurate quote?

Not that it matters, it is not like he pioneered the concepts of torque and power so I don't know why he is always quoted as though he did.

You needed to know the torque before you calculate power. Hahaha.. A dynamometer takes torque and RPM measurements, then calculates power, not the other way around.

This argument has been used before on UCP before and it is BS. What difference does it make how power or torque are measured? The concepts are and their relative importance are unchanged.

If it is really so important to measure something directly can you prove that what you call a ‘torque sensor’ really measures torque directly. I doubt it does since torque is no more a real quantity than power. I would guess it is actually measuring some physical quantity like strain and converts that back into some equivalent torque.

[hightower99]

Thank you Alastor.

Henk4: It turns out that when the vast majority of people talk about "torque" they either mean low rpm power (that causes that low down kick) or a wide power band (which helps win races). They are not normally talking directly about the concept of torque. Which is still static.

Revetec: I believe that Alastor has adequately pointed out one of the major faults in your reasoning. Have you ever really thought about how a brake dynamometer really works? The brake is static when you actually take a torque measurement.

It seems that this thread has gotten quite off topic. This thread is not for arguing the concepts of torque and power but the technical aspects of the revetec concept.

Honestly I am still more interested in Brad's interpretation of how the BMW turbosteamer works. I would ask how Henk4 and Alastor interpret the quote and the overall article???

Henk4: Do you think that the turbosteamer article proves (or even implies) a total thermal loss through the exhaust around 18%?

Alastor: ----ditto----?

The article in question is: Here.

[Alastor]

Alastor: ----ditto----?

First off both you and Revetec know way more about IC Engines then I ever will. However, if I put my ‘thinking hat’ on I would read it as follows:

The heat in the exhaust gas heats up some through a heat exchanger fluid and this fluid becomes steam. This steam is used to power the engine. More than 80 percent of heat in the exhaust gases can be converted back into usable energy this way.

I read that 80% of the total exhaust energy is extracted by the BMW system. However, the last few words are confusing.

…converted back into usable energy…

What does useable mean? Does that mean it is available to do work but when it used it will undergo additional losses. Or does that mean that after all the additional losses in the recovery system there is 80% of the exhaust energy available to do work?


For the information on the system output:

This results in reducing fuel consumption by 15 percent, and an additional 14 horsepower and 15 lb-ft of torque for BMW’s inline-4 1.8 liter engine.

I don’t know enough about IC engines to know how a reduction in fuel consumption really impacts efficiency. In other words does a 15% reduction in fuel consumption automatically mean a 15% improvement in efficiency?

Nevertheless, couldn’t you use the 14 HP to determine the system performance? Isn’t that a direct measure of the usable power recovered by the system from the exhaust?

[henk4]

Henk4: Do you think that the turbosteamer article proves (or even implies) a total thermal loss through the exhaust around 18%?

look, I graduated more than 30 years ago as an economist....I just drop in here for every once a while to enjoy your crusade against the use of torque figures. If they are that irrelevant, why would manufacturers quote them in the first place? Just to pamper what you call illusions?
And I agree that this thread should be about the Revetec concept (which is too difficult for me also), and we could reopen the old thread on the torque discussion from way back when. (some though might see the last ten days of this thread as a welcome change in the bickering of the Revetec finances...)

[revetec]

Honestly I am still more interested in Brad's interpretation of how the BMW turbosteamer works. I would ask how Henk4 and Alastor interpret the quote and the overall article???

Well start a topic on the BMW Turbosteamer then and I will be active in it.