I know that you're smart and that certain engine builders have dynos that lie.
That's why I only trust smart people, like you and butt-dynos. Butt-dynos always tell the truth.
angela
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I know that you're smart and that certain engine builders have dynos that lie.
That's why I only trust smart people, like you and butt-dynos. Butt-dynos always tell the truth.
angela
That's why I only trust smart people, like you and butt-dynos. Butt-dynos always tell the truth.
angela
and the rest:
Apparently, the unit of one horsepower was part of a marketing gimmick by James Watt, inventor of the steam engine, which he was very keen to have replace the use of horses to get work done. According to Wikipedia, Watt needed a way of comparing what a horse could do (something most folks were very aware of) with what his engine could do. Steam engines were replacing horses, the usual source of industrial power of the day. The typical horse, attached to a mill that ground corn or cut wood, walked a 24 foot diameter (about 75.4 feet circumference) circle. Watt calculated that the horse pulled with a force of 180 pounds, although how he came up with the figure is not known. Watt observed that a horse typically made 144 trips around the circle in an hour, or about 2.4 per minute. This meant that the horse traveled at a speed of 180.96 feet per minute. Watt rounded off the speed to 181 feet per minute and multiplied that by the 180 pounds of force the horse pulled (181 x 180) and came up with 32,580 ft.-lbs./minute. That was rounded off to 33,000 ft-pounds/minute, the figure we use today. Put into perspective, a healthy human can sustain about 0.1 horsepower. Most observers familiar with horses and their capabilities estimate that Watt was overly optimistic; few horses could maintain that effort for long.
OK, so the dynamometer measures two things: power (the rate of doing work) in HP and torque (the twisting force on the shaft) in ft-pounds. Obviously, these two measurements have the same numerical value when nothing is happening, i.e., at zero speed, but that is not very interesting
Apparently, the unit of one horsepower was part of a marketing gimmick by James Watt, inventor of the steam engine, which he was very keen to have replace the use of horses to get work done. According to Wikipedia, Watt needed a way of comparing what a horse could do (something most folks were very aware of) with what his engine could do. Steam engines were replacing horses, the usual source of industrial power of the day. The typical horse, attached to a mill that ground corn or cut wood, walked a 24 foot diameter (about 75.4 feet circumference) circle. Watt calculated that the horse pulled with a force of 180 pounds, although how he came up with the figure is not known. Watt observed that a horse typically made 144 trips around the circle in an hour, or about 2.4 per minute. This meant that the horse traveled at a speed of 180.96 feet per minute. Watt rounded off the speed to 181 feet per minute and multiplied that by the 180 pounds of force the horse pulled (181 x 180) and came up with 32,580 ft.-lbs./minute. That was rounded off to 33,000 ft-pounds/minute, the figure we use today. Put into perspective, a healthy human can sustain about 0.1 horsepower. Most observers familiar with horses and their capabilities estimate that Watt was overly optimistic; few horses could maintain that effort for long.
OK, so the dynamometer measures two things: power (the rate of doing work) in HP and torque (the twisting force on the shaft) in ft-pounds. Obviously, these two measurements have the same numerical value when nothing is happening, i.e., at zero speed, but that is not very interesting
Good post. I went for "Carrera hp" but not "Carrera powerband",lol.
I have much more torque down low and my powerband is about 2k shy of the Carrera 8k powerband.
It is a fun as hell car now,but nothing like my 500+ bhp (445whp on the dyno)VW 2.0l 16V turbo Corrado I built for myself years ago,tha was scary...
I decided I wanted "fun" and not "scared"....I guess I am maturing a little,that's right,just a little.;)
I have much more torque down low and my powerband is about 2k shy of the Carrera 8k powerband.
It is a fun as hell car now,but nothing like my 500+ bhp (445whp on the dyno)VW 2.0l 16V turbo Corrado I built for myself years ago,tha was scary...
I decided I wanted "fun" and not "scared"....I guess I am maturing a little,that's right,just a little.;)
Sorry, angela, but I just had to do it.
And I had to work a little bit to figure out what a butt-dyno is, but finally it dawned on me. What I find, and what others have rightly noted, is that my butt-dyno really cannot measure horsepower, it is really only sensitive to the torque. And the output of my butt-dyno is in the units of inches. So a new question emerges: how many foot-pounds of torque are there per inch of SEG?
And I had to work a little bit to figure out what a butt-dyno is, but finally it dawned on me. What I find, and what others have rightly noted, is that my butt-dyno really cannot measure horsepower, it is really only sensitive to the torque. And the output of my butt-dyno is in the units of inches. So a new question emerges: how many foot-pounds of torque are there per inch of SEG?
Gents,
In the similarly named thread, lots of cool stuff reported, and more than a little misinformation about torque and horsepower. I was gonna let it slide, but then decided: naw, let's get this right. So at the risk of great personal embarassment, and in the spirit of: the truth will set you free, here goes: Does HP equal torque?
Well first of all, it does not, just like how fast you are going now does not tell you how far you have already come. The question is to tell why the value of horsepower (HP) shown on a dynamometer matches the value of torque measured in ft-pounds at 5252 RPM. There is nothing magical about this, by the way, just like there is no magic involved by noting that there are always 12 inches in a foot. It is a matter of units, and just a little physics. The issue of units is one of the most amusing and confusing aspects of science and engineering. A foot, after all, is nothing more profound than the length of the King
In the similarly named thread, lots of cool stuff reported, and more than a little misinformation about torque and horsepower. I was gonna let it slide, but then decided: naw, let's get this right. So at the risk of great personal embarassment, and in the spirit of: the truth will set you free, here goes: Does HP equal torque?
Well first of all, it does not, just like how fast you are going now does not tell you how far you have already come. The question is to tell why the value of horsepower (HP) shown on a dynamometer matches the value of torque measured in ft-pounds at 5252 RPM. There is nothing magical about this, by the way, just like there is no magic involved by noting that there are always 12 inches in a foot. It is a matter of units, and just a little physics. The issue of units is one of the most amusing and confusing aspects of science and engineering. A foot, after all, is nothing more profound than the length of the King
My head hurts!
" In Kelly We Trust " I actually understood a majority of this ...Thanks buddy !
HEY VINCE
NOW I KNOW WHY U AND I USE PAID MECHANICS
NOW I KNOW WHY U AND I USE PAID MECHANICS
Sorry, I too old and stupid to have figured out "butt dyno"- if you are alluding to a "pucker factor", then I guess my filament has a slight glow to it. At any rate, if I'm on the right track, then, why are we NOT expressing the units in pinch-pounds?...
Scott, think seat-of-the-pants power measurement.
As in "That kinda feels like about 300 hp."
As in "That kinda feels like about 300 hp."
Kelly, this is the first discussion of H/P that has painted a picture in my noggin! EUREKA! Thanks for the History/Physics/Algebra lesson. And I'm employing that Butt Dyno in the Roadster now that I have the 2110 under the lid. I believe that my findings can be expressed as SEG=DxA where D=Displacement, A= angle of accelerator pedal from vertical.
I move that Will's equation be adopted as the official SOC math. Who'll second it?
It DOES take a rocket scientist to figure all this out!
I enjoyed the explanation --and we have a new scientific term from Angela; "butt dyno". Gotta love it!
I always heard about the difference between power and torque was that power determines how fast you are going when you hit a wall and torque is how far you move the wall when you hit it!
Thanks, Kelly---I'll print and save that explanation.
I enjoyed the explanation --and we have a new scientific term from Angela; "butt dyno". Gotta love it!
I always heard about the difference between power and torque was that power determines how fast you are going when you hit a wall and torque is how far you move the wall when you hit it!
Thanks, Kelly---I'll print and save that explanation.
Two things, Kelly: Thanks for helping those of us who would like to know but don't and secondly for providing those using the term (torque) frequently, the opportunity to examine prior statements surrounding it. Ya, I think so.
Well, I'm not too sure about running in to walls, and hope to avoid that for all time. And I think how far you move the wall after you hit it would require a discussion about momentum, the product of speed and weight. We can take that up another time. But I do know that torque is what you feel, and some say is what wins races -- getting out of the turn quickly, in other words, or maybe zipping around that semi at 75 mph on the interstate. Maximum horsepower is only seen when the engine is running very fast under load with throttle wide open, like at max speed in top gear -- flying down the straight, as it were. Here the energy required to overcome drag and friction is what the motor is putting out. How often does that happen? When red lined in second gear, you are not developing max HP. A nice flat (and high) torque curve vs. RPM is what makes a car "driveable" and fun. In recent times, much technology has gone into automotive engines to help achieve this, most notably fuel injection and the really cool thing: variable valve timing. For us old Type 1 foggies, w/ regular old carburation and old fashioned ignition and valves, we just have to keep the revs up and working the gears to stay on the the torque curve. Still plenty of fun in that.
Cars have taken huge leaps & bounds in efficiency. How about factory turbo cars with 10:1 compression ratio?
These new fangled POS's run high pressure fuel injection. The fuel injection "of old" ran 45-60 psi pump pressure,the new cars running direct injection run 1500-1800 psi fuel pressure via cam driven mechanical pumps like a diesel,yet it is a gas engine.
The cars don't detonate because there is nothing to cause pre-ignition since the fuel is injected directly in the cylinder right when the piston is close to TDC,that is whythe pressures are so high,to counteract the combustion/cylinder pressure.
There is a actual fuel injector right next to the sparkplug in the head!!
These systems are great however thay have a lot of issues since they are new technology.
This is why I own 3 aircooled/VW powered cars,since I workon this modern crap all day long,and the simplicity of the old cars remind me of a time when the world was sane.
Either way,these direct injection engines are very efficient.
I had a Audi TT (now sold) that was 9:1 compression and took 30psi boost to make 414whp (aprox 470hp at the engine) this is a 1.8l,with 5 valve cylinder heads/1.8T. With the 2.0l direct injection engine in the newer 2007 VW GTI,it made 397whp(approx 458) atonly 20 psi boost pressure ,both with similar sized turbos.
These new cars are very efficient,yet I still think they are pieces of shit.
These new fangled POS's run high pressure fuel injection. The fuel injection "of old" ran 45-60 psi pump pressure,the new cars running direct injection run 1500-1800 psi fuel pressure via cam driven mechanical pumps like a diesel,yet it is a gas engine.
The cars don't detonate because there is nothing to cause pre-ignition since the fuel is injected directly in the cylinder right when the piston is close to TDC,that is whythe pressures are so high,to counteract the combustion/cylinder pressure.
There is a actual fuel injector right next to the sparkplug in the head!!
These systems are great however thay have a lot of issues since they are new technology.
This is why I own 3 aircooled/VW powered cars,since I workon this modern crap all day long,and the simplicity of the old cars remind me of a time when the world was sane.
Either way,these direct injection engines are very efficient.
I had a Audi TT (now sold) that was 9:1 compression and took 30psi boost to make 414whp (aprox 470hp at the engine) this is a 1.8l,with 5 valve cylinder heads/1.8T. With the 2.0l direct injection engine in the newer 2007 VW GTI,it made 397whp(approx 458) atonly 20 psi boost pressure ,both with similar sized turbos.
These new cars are very efficient,yet I still think they are pieces of shit.
Jetman agrees, keep it simple
http://www.youtube.com/watch?v=h4arnATc04U
http://www.youtube.com/watch?v=h4arnATc04U
Oh, Gordon, cut the crap -- you understand all of this better than most.
Yeah, but I try not to let on. My neighbors might get suspicious.
Besides, I always had to hire other people to do all that heavy thinkin. Why strain your brain when you could hire the top 2%?
Besides, I always had to hire other people to do all that heavy thinkin. Why strain your brain when you could hire the top 2%?
Some of us who've known Kelly for a couple years know he sometimes wears a neck brace to support his 15-lb. brain. He could probably figure out away to convert 186,000 mph into rods per furlong -- using the Pakistani Hand Abacus Method, naturally -- but is being nice to us 'seven-pounders.'
Dude's a genius. Right before this photo was taken, Kelly was asked how much torque Tom's engine produced, roughly. Kelly's answer?
"At the moment, none. The object is at rest, so that would be zero times two pi ... well, anyway, zero times anything is ... did somebody say 'pie'?"
Fact. Observe:
Dude's a genius. Right before this photo was taken, Kelly was asked how much torque Tom's engine produced, roughly. Kelly's answer?
"At the moment, none. The object is at rest, so that would be zero times two pi ... well, anyway, zero times anything is ... did somebody say 'pie'?"
Fact. Observe:
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I could offer up a slew of Engineer jokes (when you've been surrounded by them for decades, it tends to rub off),
but I'm resisting.
I'm resisting......
Oh, Hell....I know Kelly's seen all of these:
You might be an engineer if..
...you've tried to repair a $5 radio. (Tried? I've fixed it TWICE! I even fixed the PCB on my GPS!)
...at an air show you know how fast the skydivers are falling. (Oh, c'mon....That's EASY.)
...you spent more on your calculator than you did on your wedding ring. (uh....yup. And for my wife's calculator, too.)
...the sales people at the local computer store can't answer any of your questions (they're FAR worse than going to Autozone - except for the Apple store - They're AWESOME!)
...you bought your wife a new CD-ROM drive for her birthday. (That was a while back. Now it's a 32 GB Thumb drive.)
...you have saved every power cord from all your broken appliances. (You never know when you'll need one for a project - got a box of different lengths)
...you look forward to Christmas so you can put the kids' toys together. (Mattel is the BEST! NOTHING comes pre-assembled)
...you see a good design and still have to change it. (That's because I didn't design it.)
...you still own a slide rule and know how to use it. (Yup, a K&E. Faster than a calculator, too.)
...you window shop at Radio Shack (for as long as your wife is in JC Penny's - They used to be a lot better (and it took more browsing time) when that had oodles of electronic PCB parts displayed.)
...your laptop computer costs more than your car. (and your tower PC is a house down payment, not to mention your internal networking components and whole house control system.)
...your spouse hasn't the foggiest idea of what you do at work. (well, mine does, but that's another story.)
...you've already calculated how much you make per second. (constantly, since it changes with salary and minutes worked)
...you can't write unless the paper has both horizontal and vertical lines (What's wrong with that? Doesn't everyone? You always need to sketch something...)
but I'm resisting.
I'm resisting......
Oh, Hell....I know Kelly's seen all of these:
You might be an engineer if..
...you've tried to repair a $5 radio. (Tried? I've fixed it TWICE! I even fixed the PCB on my GPS!)
...at an air show you know how fast the skydivers are falling. (Oh, c'mon....That's EASY.)
...you spent more on your calculator than you did on your wedding ring. (uh....yup. And for my wife's calculator, too.)
...the sales people at the local computer store can't answer any of your questions (they're FAR worse than going to Autozone - except for the Apple store - They're AWESOME!)
...you bought your wife a new CD-ROM drive for her birthday. (That was a while back. Now it's a 32 GB Thumb drive.)
...you have saved every power cord from all your broken appliances. (You never know when you'll need one for a project - got a box of different lengths)
...you look forward to Christmas so you can put the kids' toys together. (Mattel is the BEST! NOTHING comes pre-assembled)
...you see a good design and still have to change it. (That's because I didn't design it.)
...you still own a slide rule and know how to use it. (Yup, a K&E. Faster than a calculator, too.)
...you window shop at Radio Shack (for as long as your wife is in JC Penny's - They used to be a lot better (and it took more browsing time) when that had oodles of electronic PCB parts displayed.)
...your laptop computer costs more than your car. (and your tower PC is a house down payment, not to mention your internal networking components and whole house control system.)
...your spouse hasn't the foggiest idea of what you do at work. (well, mine does, but that's another story.)
...you've already calculated how much you make per second. (constantly, since it changes with salary and minutes worked)
...you can't write unless the paper has both horizontal and vertical lines (What's wrong with that? Doesn't everyone? You always need to sketch something...)
Don't always believe the butt dyno; mine says the Caravan is faster after I wash it...
And Jack, the wall can tell you more:
understeer is when you hit the wall with the front of the car
oversteer is when you hit the car with the back of the car.
And Jack, the wall can tell you more:
understeer is when you hit the wall with the front of the car
oversteer is when you hit the car with the back of the car.
Allen--that's a good one---pretty easy to grasp! Thanks!
Just so as not to be showing favorites here, and also to see if this thread is dead, I offer up the following. In most other parts of the world HP and ft-pounds are not the way things are done, these others preferring to use watts and newton-meters, a newton being the metric unit for force, and equal to about 0.225 pounds. So suppose the dyno were calibrated in watts and nt-m, vs. HP and ft-pounds? At what RPM point would the two values have the same numerical value? Noting that a meter is 3.28 ft, a watt is 0.0000000001341 HP, the value comes out to about 9.55 RPM. Nothing magic again, just silly units.
I'll post ya'll the engine curves of a true Porsche Carrera engine a 3.6 L fuel injected, dual distributors. a cam per bank and darn, 25.9 MPG and book speed at 160 MPH
But, least we forget...HP is a measurement of doing work! Strange, no work is accomplished unless the object has a change in elevation. He, He!
But, least we forget...HP is a measurement of doing work! Strange, no work is accomplished unless the object has a change in elevation. He, He!
I love silly units!
A looooong time ago, I worked with a Mechanical Engineer from Ireland (I think his name was Emmet Turley - sounds pretty Irish to me...). Anyway, he was working on a mechanical assembly that I would see incorporated into a larger system down the road and I stopped by to see some of his preliminary sketches. As I was looking over his shoulder I noticed on his sketches that all of the weights that I expected to see were really, really low, but when I pointed to something and asked it's expected weight his immediate reply was higher and right in the ballpark of expectations. Finally, I asked what all of the really low weights were and he said; "Oh! THOSE? I calculate everything in Irish stones and then convert in me head. It keeps me mind active!"
I found out that an Irish stone is something like 14.7 pounds.
Silly units......
A looooong time ago, I worked with a Mechanical Engineer from Ireland (I think his name was Emmet Turley - sounds pretty Irish to me...). Anyway, he was working on a mechanical assembly that I would see incorporated into a larger system down the road and I stopped by to see some of his preliminary sketches. As I was looking over his shoulder I noticed on his sketches that all of the weights that I expected to see were really, really low, but when I pointed to something and asked it's expected weight his immediate reply was higher and right in the ballpark of expectations. Finally, I asked what all of the really low weights were and he said; "Oh! THOSE? I calculate everything in Irish stones and then convert in me head. It keeps me mind active!"
I found out that an Irish stone is something like 14.7 pounds.
Silly units......
Great job Kelly. One of the more interesting posts I've read here in a long time. I doubt that you stepped on anyone's toes, especially when it all makes sense, even to this engineer wanna-be.
Velocity should always be calculated in terms of "furlongs per fortnight"
1 furlong = 201.16800 meters 1 fortnight = 14 days
1 furlongs per fortnight = 0.000166309524 m / s
1 furlong = 201.16800 meters 1 fortnight = 14 days
1 furlongs per fortnight = 0.000166309524 m / s
OK, now Wild Bill has it down. The only units that matter, 12 oz at a time. Have enough of these, and no units will matter, let alone make any sense. So how many pints per minute does it take to . . .
BTW: "Minding one's Ps and Qs" is an old English (or possibly Irish) pub admonition to be careful with your pints (Ps) and quarts (Qs).
PS to Aaron: work is force times distance, and the distanc does not have to be verical. When it is vertical, then the force (absent friction and other losses) is the weight, of course.
BTW: "Minding one's Ps and Qs" is an old English (or possibly Irish) pub admonition to be careful with your pints (Ps) and quarts (Qs).
PS to Aaron: work is force times distance, and the distanc does not have to be verical. When it is vertical, then the force (absent friction and other losses) is the weight, of course.
Burrrrrrp!
I thought Ps and Qs was related to typesetting.
Sorry Kelly, Not according to my physic prof. Gotta have a change in potential energy to kinetic. Pushing on a level surface,,,No work. Push the same weight up an incline you do work! changes from potential to kinetic energy. I believe that the law is know as the Law of the Conservation of Energy.
Rolling resistance be damned! --
Newton (or Professor Irwin Corey...hmmmm)
Newton (or Professor Irwin Corey...hmmmm)
Too much wave modulation.
Kelly, when Mars attacks I want to be on your team.
On the other hand, it might be you that they're pissed at, for flinging all that hardware at them.
On the other hand, it might be you that they're pissed at, for flinging all that hardware at them.
Barter with them: trade your Pickett slide rules for their best seller "To Serve Man"...hey, what'cha cookin' there...?