The CB1100 Community Forum

And some of what Chip mentioned about exhaust flow plays in to the discussion on Helmholtz resonators we talked about last year.

Great post Chip!!

Read it once, need to read it again. Lol

Want to thank Chip for taking the time to type all that out, and try and make it understandable to a fellow who sometimes has trouble grasping things that others understand easily. Simple math I'm good at ( been balancing our checkbook for twenty years) ... algebra not so much. Something about letters and numbers in the same equation just sends my brain all helter skelter
Same with mechanical principals.

Thing is, I'm not afraid to ask questions. How else are you going to learn?

(03-09-2015, 10:47 AM)metallyguitarded_imp Wrote: [ -> ]

(03-09-2015, 10:29 AM)JustJohn_imp Wrote: [ -> ]No comprende. As a life-long fan of stationary engines, huge diesels, ship engines, etc I'm seeing a few holes in this story. Ok, for example: I lose whats left of my mind and install a 2500 H.P. Funny Car engine in an overseas vessel. I fully expect it to perform as well as a giant Volvo inline 6 diesel. A slow turning, torque laden engine. I wouldn't even get out of the port of call. Not looking for an fight at all. But not seeing it.

I know this isn't a fight but I just got a text message from my bookie that simply reads: "ChipBeck (-320), JustJohn (+210)". Gotta go with the smart money.

I know this isn't a fight but I just got a text message from my bookie that simply reads: "ChipBeck (-320), JustJohn (+210)". Gotta go with the smart money.
Well go with who you like, but in my brief 55 years experience with engines I will take torque EVERY time. Something as simple as an old 300 HP Cummins will take a 300 HP small block Chevy to school and OWN it every time. And I'm not saying I'm smart enough to know every single variable,but Torque wins in power. Always does. Gotta turn them RPM's up? More heat, more fuel, more wear.

(03-09-2015, 10:29 AM)JustJohn_imp Wrote: [ -> ]No comprende. As a life-long fan of stationary engines, huge diesels, ship engines, etc I'm seeing a few holes in this story. Ok, for example: I lose whats left of my mind and install a 2500 H.P. Funny Car engine in an overseas vessel. I fully expect it to perform as well as a giant Volvo inline 6 diesel. A slow turning, torque laden engine. I wouldn't even get out of the port of call. Not looking for an fight at all. But not seeing it.

John,

Modern funny car engines produce substantially more than 2500 hp, they're probably approaching double that figure and they are so highly stressed that they must be completely rebuilt after every four second quarter-mile run. So you probably wouldn't get out of port unless you could do it in about four seconds. And the frictional losses involved in transmission gearing to use a 10,000 RPM funny car engine to turn a massive ships propeller 100 RPM would be astronomical. That funny car engine is highly stressed and wears out extreemly fast. The massive diesel engine in a ship is designed to run near it's rated power for weeks on end without stopping and because they turn at very low RPM the frictional losses gearing them down to turn the slow-moving propellers of modern ships would be far more modest. So the funny car engine is not suitable to drive a slow turning ships propeller but it would be a poor choice for reasons other than power. For the same reason, that big 2500 HP inline six Volvo diesel would be a poor choice for a funny car but again, for reasons other than power.

But for the sake of argument, if the gearing horsepower losses were equal to get to a final prop speed of 100 RPM (or whatever RPM that ships propeller requires), it doesn't matter a whit whether the 2500 hp required to move that ship is generated by a massive Volvo diesel, a funny car engine, or wound up rubber bands. Horsepower is a measure of work, it has a finite value that is as absolute as 1 pound of weight.

What you are attempting to argue is that 100 pounds of feathers would have to weigh less than 100 pounds of lead. Even if it's hard to grasp, they both weigh 100 pounds. Believe it or not, understand it or not, a 2500 hp gasoline engine in a top fuel dragster, a 2500 hp Rolls-Royce Merlin engine in Reno air race plane, and a 2500 hp Volvo diesel in an oil tanker all have the exact same amount of peak horsepower which is their ability to do work.

Let me turn your example around. Do you think your massive Volvo in-line six diesel would ever be able to propel a car through the quarter-mile in under four seconds? In this case even if that big diesel didn't weigh any more than the funny car engine, it's slow RPM would require overdrive transmission gearing so steep that again, frictional losses would be astronomical. But assuming that gearing horsepower losses were equal, and assuming that your big diesel and that funny car engine were the same weight, and assuming they had the same horsepower, they would both propel both that ship and that funny car at the same velocities. 100 pounds of weight is 100 pounds whether it's feathers or lead. 2500 hp is 2500 hp regardless of what type of engine we are talking about.

Again, horsepower is an absolute measurement of energy, no different than a calorie, or a watt, or a volt. 100 W of electricity produced by a windmill will light a bulb precisely as bright as 100 W of electricity produced by a hydroelectric dam.

All the best.

Chip

So what are the "Frictional losses" called? And "weeks" without end? How about years? Whats that called? Balls? Its not hard for me to grasp...but your theory of it is. I totally appreciate your insite and time to post. However you will not convince me. Nor will simple physics lessons. NOT for motorcycle engines per se...but put a few locomotives or ships out there and tell me about torque and HP.

Chip,

Thanks for taking time to put HP vs. torque into tangible context for us laymen!

JustJohn-
Different engines are designed for different purposes in mind. Locomotive or commercial freight ship motors are optimized for low-end torque because maximum "twist" is required to get that much mass moving from a standstill; likewise, as was demonstrated in the CBR vs Chopper video, massive amounts of low-end torque can help you get off the line faster, however, if that race allowed for the CBR to reach near the high-end of 2nd gear (or even 1st), it would be lights-out. The CBR is optimized for maximum HP, which takes place near redline, whereas the V-twin chopper (undersquare, long-stroke) is optimized for low-end torque. Massive amounts of low-end torque may be perceived as "responsiveness", particularly off the line; whereas engines optimized for maximum power typically experience peak torque and peak power near the upper end of the RPM range.


Sent from my iPhone using Tapatalk

My interest and curiosity piqued, I decided to watch videos on horsepower vs. torque during my treadmill run. Talk about making an already painful experience worse. A few things I've come away with:

First, there are an immeasurable number of people who understand this stuff much better than I do or ever will.

Second, the theories explained by Chip are not ones he made up. Instead, they are grounded in physics and mathematics and shared by many who, by all appearances, know what they're talking about. I think Chip's explanations are among the best I've read/seen so far.

Third, there's more to acceleration than horsepower or torque at a certain rpm. There are a whole host of factors that figure in, only a small fraction of which I have some idea about. That includes gearing, weight, traction, wind resistance and I'm sure scores more.

Finally, as much as I'd like to pretend I don't care about this stuff, I find it fascinating. I don't have aspirations to become a mechanical engineer or engine designer but the fact that we can build a machine that propels us forward at the twist of the wrist is mind boggling. Something I take for granted. Getting a peek backstage and seeing how the magician performs his tricks is pretty exciting.

(03-09-2015, 12:00 PM)JustJohn_imp Wrote: [ -> ]So what are the "Frictional losses" called? And "weeks" without end? How about years? Whats that called? Balls? Its not hard for me to grasp...but your theory of it is. I totally appreciate your insite and time to post. However you will not convince me. Nor will simple physics lessons. NOT for motorcycle engines per se...but put a few locomotives or ships out there and tell me about torque and HP.

Frictional losses are called frictional losses. If we are measuring horsepower at the crank of an engine that power is what is generated post all engine frictional losses so it is irrelevant to an engines rated horsepower although it would probably have bearing upon fuel consumption. Modern ships can reach any port on earth in less than three weeks. I am assuming that most ships are used to transport goods so they do need to stop to offload cargo. Military diesel powered ships on patrol do stay out for months if necessary but most of them go to port every month or so as well where they are shut down to be serviced. I am not aware of any diesel powered ships, locomotives, or even stationary engines used to pump water on farms that run for years without being shut down for maintenance. But that isn't really relevant here either. You are giving examples of specific applications where low RPM and long term operation is beneficial and you are clearly a fan of such engines. That's great. But extrapolating from those specific applications that turning force in an engine is a measure of that engines power regardless of how many times per minute that turning force is applied is incorrect. What I have described here is not a "theory of mine". These are not original thoughts that I am cooking up. They are established facts you can verify with some study in engineering or elementary science. That the earth is round is not a theory no matter how many people don't believe it. And writing that a pound of feathers will push down upon a scale with exactly the same amount of force as a pound of lead is not a theory, it just is.

One horsepower equals 33,000 foot-pounds of work per minute—that is, the power necessary to lift a total mass of 33,000 pounds one foot in one minute. This value was adopted by the Scottish engineer James Watt in the late 18th century, after experiments with strong dray horses. The electrical equivalent of one horsepower is 746 watts in the International System of Units (SI), and the heat equivalent is 2,545 BTU (British Thermal Units) per hour. This measure of power is not a theory of mine, it's been an established and accepted fact for over 200 years.

You are arguing that the force of an individual hammer blow is a measure of how much work a carpenter can do and you wish to ignore how many hammer blows per minute he strikes. Then you argue that because nobody uses high RPM motors in ships, low RPM motors that produce lots of torque at low RPM must be better. Your final sentence would be the equivalent of me proclaiming, "Show me a winning funny car with a huge Volvo inline 6 diesel and then talk to me about torque and HP". That big Volvo diesel would get owned in every race.

If you want an example of a very heavy vehicle that has been successfully powered by a high RPM, low torque motor in hard use for decades then I'll give you one. It's the M-1 Abrams battle tank. It weighs 68 tons, the heaviest main battle tank in use today yet it is the fastest (capable of 60 mph ungoverned) as well as the fastest accelerating tank that has ever seen service. It has a very high RPM, low torque turbine engine with 1500 HP and about 2700 FT/LBS of torque. A 1500 HP diesel would have over 6000 FT/LBS of torque (over twice as much torque as the turbine). During development diesel engines were considered and tried but the low torque turbine smoked them in performance tests. The battle tanks of almost all other countries are high torque diesel powered and they are no match for the M-1.

A major benefit of that low torque turbine is that it is much lighter. A 1500 HP diesel engine weighs about 5000 lbs, that 1500 HP turbine weighs 2500 lbs. So why aren't turbines used in more heavy trucks and ships? Because they are expensive, require more maintenance, have slightly higher fuel consumption, and don't last quite as long. Again, these factors are unrelated to engine power.

All I can do is present established facts and inarguable long accepted units of measurement and if they run contrary to someones belief system, I can't help. All the best.

Chip

Chip,

Thanks for the write up, a lot of time and effort. We ride these bikes and don't realize the engineering that goes into setting up the proper strength of push rods, Pistons, lifters and valve springs to get the proper balance so motors last a very long time.

In layman's terms my 100yd dash hit the nail on the head so to speak, think of the runners feet being the hammer and the ground being the nail.

(03-09-2015, 03:48 PM)ChipBeck_imp Wrote: [ -> ]

(03-09-2015, 12:00 PM)JustJohn_imp Wrote: [ -> ]So what are the "Frictional losses" called? And "weeks" without end? How about years? Whats that called? Balls? Its not hard for me to grasp...but your theory of it is. I totally appreciate your insite and time to post. However you will not convince me. Nor will simple physics lessons. NOT for motorcycle engines per se...but put a few locomotives or ships out there and tell me about torque and HP.

Frictional losses are called frictional losses. If we are measuring horsepower at the crank of an engine that power is what is generated post all engine frictional losses so it is irrelevant to an engines rated horsepower although it would probably have bearing upon fuel consumption. Modern ships can reach any port on earth in less than three weeks. I am assuming that most ships are used to transport goods so they do need to stop to offload cargo. Military diesel powered ships on patrol do stay out for months if necessary but most of them go to port every month or so as well where they are shut down to be serviced. I am not aware of any diesel powered ships, locomotives, or even stationary engines used to pump water on farms that run for years without being shut down for maintenance. But that isn't really relevant here either. You are giving examples of specific applications where low RPM and long term operation is beneficial and you are clearly a fan of such engines. That's great. But extrapolating from those specific applications that turning force in an engine is a measure of that engines power regardless of how many times per minute that turning force is applied is incorrect. What I have described here is not a "theory of mine". These are not original thoughts that I am cooking up. They are established facts you can verify with some study in engineering or elementary science. That the earth is round is not a theory no matter how many people don't believe it. And writing that a pound of feathers will push down upon a scale with exactly the same amount of force as a pound of lead is not a theory, it just is.

One horsepower equals 33,000 foot-pounds of work per minute—that is, the power necessary to lift a total mass of 33,000 pounds one foot in one minute. This value was adopted by the Scottish engineer James Watt in the late 18th century, after experiments with strong dray horses. The electrical equivalent of one horsepower is 746 watts in the International System of Units (SI), and the heat equivalent is 2,545 BTU (British Thermal Units) per hour. This measure of power is not a theory of mine, it's been an established and accepted fact for over 200 years.

You are arguing that the force of an individual hammer blow is a measure of how much work a carpenter can do and you wish to ignore how many hammer blows per minute he strikes. Then you argue that because nobody uses high RPM motors in ships, low RPM motors that produce lots of torque at low RPM must be better. Your final sentence would be the equivalent of me proclaiming, "Show me a winning funny car with a huge Volvo inline 6 diesel and then talk to me about torque and HP". That big Volvo diesel would get owned in every race.

If you want an example of a very heavy vehicle that has been successfully powered by a high RPM, low torque motor in hard use for decades then I'll give you one. It's the M-1 Abrams battle tank. It weighs 68 tons, the heaviest main battle tank in use today yet it is the fastest (capable of 60 mph ungoverned) as well as the fastest accelerating tank that has ever seen service. It has a very high RPM, low torque turbine engine with 1500 HP and about 2700 FT/LBS of torque. A 1500 HP diesel would have over 6000 FT/LBS of torque (over twice as much torque as the turbine). During development diesel engines were considered and tried but the low torque turbine smoked them in performance tests. The battle tanks of almost all other countries are high torque diesel powered and they are no match for the M-1.

A major benefit of that low torque turbine is that it is much lighter. A 1500 HP diesel engine weighs about 5000 lbs, that 1500 HP turbine weighs 2500 lbs. So why aren't turbines used in more heavy trucks and ships? Because they are expensive, require more maintenance, have slightly higher fuel consumption, and don't last quite as long. Again, these factors are unrelated to engine power.

All I can do is present established facts and inarguable long accepted units of measurement and if they run contrary to someones belief system, I can't help. All the best.

Chip

All I can do is present established facts and inarguable long accepted units of measurement and if they run contrary to someones belief system, I can't help. All the best.

Chip
The Internet and cable news...two places where Established facts and unarguable long accepted units of measurement don't seem to matter!

Good stuff, Chip, thanks a bunch.