JustJohn_imp
Running like a top
Actually Chip Beck is 100% on the money. 1 hp is 1 hp, 1 ft lb of torque is 1 ft lb of torque, no matter how you slice it. My view of things is a little skewed. Facts are facts.
Chip Beck Explains HP vs. Torque for Mr. Ferret
- Thread starter ChipBeck_imp
- Start date
metallyguitarded_imp
Road warrior
I find myself waiting for the, "Ha! Just kidding!"JustJohn_imp said:
Taking you at your word, it shows strength of character to admit your view of things was off. Hats off to you John.
DGShannon_imp
Been there
Excellent write up, hitting the main points of a complex mechanical relationship. So many variables come into play.
Now, lets have some real fun, and bring two strokes and expansion chamber design into the mix! Or, the effects of bore and stroke on piston side loading friction! I always enjoy reading Kevin Cameron's stuff, such as THIS, on engine design.
Now, lets have some real fun, and bring two strokes and expansion chamber design into the mix! Or, the effects of bore and stroke on piston side loading friction! I always enjoy reading Kevin Cameron's stuff, such as THIS, on engine design.
the Ferret
Road warrior
I have been a Cycle World subscriber for many many years. Read it cover to cover including all ads except for Kevin Cameron's articles. Lord knows I've tried. Two paragraphs in and my eyes glaze over, my mind drifts off, and I might as well flip the page because there is no way I'm getting through the rest of the article. I miss Egan. Him..I could understand lol.
ChipBeck_imp
Road warrior
Thread starter
Gentlemen,The ferret_imp said:
Certainly different strokes for different folks here. If I could spend one afternoon having a discussion with anybody in the motorcycle industry, it would be Kevin Cameron. Top Dead Center is the first thing I read when I get Cycle World each month. I have read and reread both of Kevin's books. I know I'm strange but one of the most enlightening and surprising series of articles I've ever read was Kevin's history on the development of the pneumatic tire from it's first beginnings on the new "safety bicycle" in the 1800's to the car and motorcycle tires of today.
Kevin ranges effortlessly from steam locomotives to WW2 aircraft radials to space shuttle booster rocket engines. Reading his explanations of the properties of different metals, how they endure stress and transfer heat, and what makes them crack and fail is fascinating to me. As someone said earlier in this thread, his ability to take a complex subject and make it understandable makes his writing special. But he's not just a tech guy. Kevin writes a lot about personality characteristics and how they effect an individuals performance and behavior both on and off motorcycles. I love the guy and can't get enough of his writing.
That said, I have read every one of Egan's books as well. Cheers.
Chip
the Ferret
Road warrior
You are a well rounded man Mr Beck!
cbdtran_imp
Been there
torque + horse = energy released by the engine.
assume no energy lost due to heat released due to speed - in 10 min on 3th gear then 10 min on 6th gear you have more torque in the first and more horses on the second. during this time on 3th and 6th gear, the gasoline consumption are the same. on the first, you can climb stiffer road, one the second you gain more speed on straight road reflected on MPG
cbdtran_imp
Been there
torque + horse = energy released by the engine.cbdtran_imp said:
assume no energy lost due to heat released due to speed - in 10 min on 3th gear then 10 min on 6th gear you have more torque in the first and more horses on the second. during this time on 3th and 6th gear, the gasoline consumption are the same. on the first, you can climb stiffer road, one the second you gain more speed on straight road reflected on MPG
wikipedia
1 HP = 745.6998 Watt
1 hp ≡ 33,000 ft-lbf/min by definition
horse and torque are energy
JustJohn_imp
Running like a top
What I find interesting may not mean a hill of beans to others, but here it is: The perfect overlap of HP to torque on dyno graphs. The difference between brake HP and HP. The difference between diesel engines, naturally aspirated and turbo'd. Same with gas jobs. C.I. vs C.C. RPM vs ability to attain RPM's. Throw in engine braking, stall speed, "feel in the seat", absolute sustainable torque, quickness vs. being fast, and its alot to take in. Then there's 2 stroke vs 4 stroke, Rotary's, Jet propulsion, turbine's, valves per cylinder, scavenging, yeah I got a headache now. But Chip is on the money. My little view of unique situations doesn't change mechanical facts. I'm gonna read all I can of Kevin Cameron and report back at some point. But I apologize for clouding this thread with my limited experience with engines, large or small. And before anyone jumps any conclusions, this is not tongue in cheek. But further research is called for. I'm only going by experience, so I have to do the research. And I will. But so far the numbers are the numbers.
rboe
Road warrior
John; you forgot steam engines...... then there are steam piston and steam turbines. Also; electric drives (diesel electrics, stepper, universal and induction motors.
In general; efficiencies rule the day when the customer and engineer are deciding what power plant to use. But other considerations can hold sway depending on the job and where the machine will be used. The military is less interested in efficiencies and more interested in winning the battle. Costs can take secondary importance to winning also. In general, efficiencies will reduce costs for a customer but high maintenance or difficulties in obtaining cheap fuel will guide power plant choices too. Large radial engines lost out to jets and turbines because they were more efficient to operate at high altitude, became much more reliable (cheaper to operate!) and longer times between major overhauls (cheaper to operate!) even though they are bloody more expensive to buy.
Gas engines work well in environments where speed is always changing (commuter cars) where diesel works best where speed is a steady state (boating, transports); mainly because of their efficiencies and the way they put power to final drive.
So when it comes to power plant choice there are many criterion that are taken into account; the order they are taken will depend upon the job and who is paying the bills.
In general; efficiencies rule the day when the customer and engineer are deciding what power plant to use. But other considerations can hold sway depending on the job and where the machine will be used. The military is less interested in efficiencies and more interested in winning the battle. Costs can take secondary importance to winning also. In general, efficiencies will reduce costs for a customer but high maintenance or difficulties in obtaining cheap fuel will guide power plant choices too. Large radial engines lost out to jets and turbines because they were more efficient to operate at high altitude, became much more reliable (cheaper to operate!) and longer times between major overhauls (cheaper to operate!) even though they are bloody more expensive to buy.
Gas engines work well in environments where speed is always changing (commuter cars) where diesel works best where speed is a steady state (boating, transports); mainly because of their efficiencies and the way they put power to final drive.
So when it comes to power plant choice there are many criterion that are taken into account; the order they are taken will depend upon the job and who is paying the bills.
thessler3_imp
Running like a top
As a retired scientist, let me add my two cents:
Dyno's do not directly measure horsepower, they measure torque in foot pounds. Horsepower is then CALCULATED and displayed by the century old formula below:
Horsepower = torque * RPM / 5252
On any dyno chart, horsepower will ALWAYS equal torque at 5252 RPM and the two curves will cross, with horsepower usually exceeding torque beyond 5252 RPM. Bad news for Harleys and other cruisers that top out at 5200 RPM. Their horsepower can never exceed their torque numbers.
If you see any dyno charts that do not cross at 5252 RPM, they are bogus. You can look up where the 5252 number comes from on the web. It is a "units" conversion factor.
Looking at the formula again, you can make bigger horsepower numbers by increasing either torque or RPM above 5252 RPM. That is why GP racers are turning close to 20,000 RPM. Friction losses reduce torque, so there are limits in practicality.
One final point - gearing: Gearing multiplies torque. The "lower" the overall gear ratio, the more torque applied to the rear wheel. Engines that can turn high RPM can be geared lower and apply monstrous torque at the rear wheel. That is why small displacement, high-revving motorcycles can out accelerate big-block low revving bikes. Soichiro Honda figured this out in the 1950's. He obviously got an A in physics class.
BTW - Kevin Cameron is a class act. As busy as he is, he always responds to my emails.
Dyno's do not directly measure horsepower, they measure torque in foot pounds. Horsepower is then CALCULATED and displayed by the century old formula below:
Horsepower = torque * RPM / 5252
On any dyno chart, horsepower will ALWAYS equal torque at 5252 RPM and the two curves will cross, with horsepower usually exceeding torque beyond 5252 RPM. Bad news for Harleys and other cruisers that top out at 5200 RPM. Their horsepower can never exceed their torque numbers.
If you see any dyno charts that do not cross at 5252 RPM, they are bogus. You can look up where the 5252 number comes from on the web. It is a "units" conversion factor.
Looking at the formula again, you can make bigger horsepower numbers by increasing either torque or RPM above 5252 RPM. That is why GP racers are turning close to 20,000 RPM. Friction losses reduce torque, so there are limits in practicality.
One final point - gearing: Gearing multiplies torque. The "lower" the overall gear ratio, the more torque applied to the rear wheel. Engines that can turn high RPM can be geared lower and apply monstrous torque at the rear wheel. That is why small displacement, high-revving motorcycles can out accelerate big-block low revving bikes. Soichiro Honda figured this out in the 1950's. He obviously got an A in physics class.
BTW - Kevin Cameron is a class act. As busy as he is, he always responds to my emails.
Lord Popgun
Road warrior
Here is a link that shows where the 5252 comes from: Power vs Torque Explained in Engine Performance | EPI Inc.
Also, I am not a scientist and don't play one on TV, just posting the link
Also, I am not a scientist and don't play one on TV, just posting the link
cbdtran_imp
Been there
no - go google HP and torque chart, it very much depend how engine is designed, they don't always crossed at 5252thessler3_imp said:
Lord Popgun
Road warrior
CB,
You're going to have to explain that one as every scientist and physics expert on Earth says it does. Look at the formula again and tell us how it cannot cross there. Look at the link I provided for more info, or read the post by the SCIENTIST above.
You're going to have to explain that one as every scientist and physics expert on Earth says it does. Look at the formula again and tell us how it cannot cross there. Look at the link I provided for more info, or read the post by the SCIENTIST above.
DGShannon_imp
Been there
no - go google HP and torque chart, it very much depend how engine is designed, they don't always crossed at 5252cbdtran_imp said:
As he said, you may find charts that don't but they are bogus. The 5,252 comes from a mathematical formula. The two lines absolutely must cross there. It would be like saying that Pi isn't always equal to 3.14159
the Ferret
Road warrior
Mmmm pie. I like warm peach the best with vanilla ice cream.
thessler3_imp
Running like a top
Somebody mentioned Pi R squared
Pie are round, cake are square
Thought that should be cleared up.
Pie are round, cake are square
Thought that should be cleared up.
