Reply With QuoteThis must be why my junk is so slow. You see, I am a genius. :boxed:
My junk is so low because it is 120 degrees in my garage.
This must be why my junk is so slow. You see, I am a genius. :boxed:
WOW! It looks like LVJetboy is just like, or is my brother (not Buzzz a.k.a. Wannaberacing). He has an in depth understanding of quantum physics, and the relationship that math plays within it, but would never race in fear that his theories would prove to be wrong. I can't count the times we have been instructed how stupid we are for making a change on the car, just before it performs better than before the change. I guess that is why we don't see many engineers and physics professors racing. Oh well, back to the topic. Sorry for the side track.
Paul
This must be why my junk is so slow. You see, I am a genius. :boxed:
My junk is so low because it is 120 degrees in my garage.
Hey Boys! The math goes like this.... #1 cubic dollars #2 cubic inches #3 cubic power #4 cubic balls "That is all you need to know". I ordered extra butter large popcorn, with the captain and coke!
Hey Boys! The math goes like this.... #1 cubic dollars #2 cubic inches #3 cubic power #4 cubic balls "That is all you need to know". I ordered extra butter large popcorn, with the captain and coke!
Torque is the power that is actually measured by a dyno, etc. and is the working force that you have. Horsepower is derived from the mathematical equation of:
TORQUE X RPM / 5252 At 5252 RPM TORQUE and HP are the same. An engine that can maintain Torque at higher RPM's will have higher Horsepower.
And then there is uncorrected and corrected horsepower...... Uncorrected or raw power is what you have on a given day on the dyno. Corrected is the uncorrected numbers adjusted by weather factors, such as humidity and barometric pressure. There are two generally used correction factors.... STP and SAE. These factors are good to use when correlating and comparing one engine to another or a given engine to itself on different days.... Also considered to me as the bragging numbers....the numbers everyone wants to see as big as possible. But all you actually have on any given day is the power measured at that time.... which is the uncorrected power. On a typical or bad weather day the corrected will correct the power numbers up. Now on an extremely good atmospheric weather day the correction factors may correct down. There is no substitute for good air.
When comparing dyno sheets with performance predictions, I use both the uncorrected and corrected data. These numbers can give you an actual range of performance that you may see. Using the uncorrected data as your baseline will help you not to be disappointed in the real world use. Same thing with properly calibrated dynos versus hot ones...... In the prediction software, weather factors need to be considered in your predicted ranges of performance.
Hey Any more popcorn left??
No, but here's a littel history lesson. Too much to type out, so I just cut and pasted it.
Torque vs Horsepower
The word horsepower was introduced by James Watt, the inventor of the steam engine in about 1775. Watt learned that "a strong horse could lift 150 pounds a height of 220 feet in 1 minute." One horsepower is also commonly expressed as 550 pounds one foot in one second or 33,000 pounds one foot in one minute. These are just different ways of saying the same thing. Notice these definitions includes force (pounds), distance (feet), and time, (minute, second). A horse could hold weight in a static position but this would not be considered horsepower, it would be similar to what we call torque. Adding time and distance to a static force (or to torque) results in horsepower. RPM, revolutions (distance) per minute (time), is today's equivalent of time and distance. Back to horses, imagine a horse raising coal out of a coal mine. A horse exerting one horsepower could raise 550 pounds of coal one foot every second.
Here is an example of another way horsepower could be directly measured. Say you have a horse hitched to a plow. In the hitch is a spring scale (like a fish scale). The horse pulls the plow one foot every second and you see 550 pounds on the scale. That horse would be generating one horsepower.
We see horsepower can be directly measured. However there is a problem directly measuring horsepower of modern day internal combustion engines because they produce rotary motion not linear motion, and unless the engine is geared down, the speed at which they do work (time and distance or RPM) is too great for practical direct measurement of horsepower. It seems logical then that the solution was to directly measure torque (rotational force eventually expressed in pounds at one foot radius) and RPM (time and distance, i.e. distance in circumference at the one foot radius) and from these calculate horsepower. Torque and RPM are easily measured directly. Early dynamometers used a brake device to load the engine. A torque arm was attached to this brake's stator. The brake's rotor was coupled to the engine's crankshaft. A spring scale or other measuring device connected the torque arm to the stationary fixture holding the engine and brake. During a test the brake's application loaded the engine. Torque and engine rpm were observed and recorded. Click here for a description of how this happens on our dyno.
On modern day dynamometers horsepower is a calculated value. It's important to remember the dyno measures torque and rpm and then from these calculates horsepower. On the dyno it takes more water flow to the water brake to increase the load on the engine being tested. As the test engine's torque rises more water flow is needed. As the test engine's torque drops less water flow is needed. The dyno's water brake does not respond to Horsepower. Major adjustments to water flow are needed as an engine crosses its torque peak but none are needed as it crosses its horsepower peak. In other words the water flow to the brake during a dyno test follows the engines torque curve and not its horsepower curve. Torque is what twists the tire, prop, or pump. Horsepower helps us understand an amount or quantity of torque. (Torque + time and distance)
Now if we are measuring torque and RPM how can we calculate horsepower? Where does the equation HP=TORQUE * RPM / 5252 come from? We will use Watts observation of one horsepower as 150 pounds, 220 feet in one minute. First we need express 150 pounds of force as foot pounds torque.
Pretend the force of 150 pounds is "applied" tangentially to a one foot radius circle. This would be 150 foot pounds torque.
Next we need to express 220 feet in one minute as RPM.
The circumference of a one foot radius circle is 6.283186 feet. ft. (Pi x diameter 3.141593 * 2 feet)
The distance of 220 feet, divided by 6.283185 feet, gives us a RPM of 35.014.
We are then talking about 150 pounds of force (150 foot pounds torque), 35 RPM, and one horsepower.
Constant (X) = 150 ft.lbs. * 35.014 RPM / 1hp
35.014 * 150 / 1 = 5252.1
5252 is the constant.
So then hp = torque * RPM / 5252
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Here is another way; Remember we know 150 foot pounds and 35.014 RPM = one horsepower
1hp is to 150 ft.lbs. * 35.014 RPM as X hp is to observed ft.lbs.torque * observed RPM
Example; We dyno test and observe 400 ft.lbs. torque at 5000 RPM
1 hp is to 150 ft.lbs. * 35.014 RPM as X hp is to 400 ft.lbs. * 5000 RPM
When we cross multiply X hp * (150 ft.lbs. * 35.014 RPM) = 1hp * (400 ft.lbs. * 5000 RPM)
X hp * (5252 ft.lbs. RPM) = 1 hp * (2,000,000 ft.lbs. RPM)
Divide both sides by 5252 ft.lbs. RPM
X hp = 1 hp * 380.80
X hp = 380.80 hp
Horsepower = torque x rpm / 5252
Here's an interesting bit of trivia; below 5252 rpm any engine's torque number will always be higher than its horsepower number, and above 5252 rpm any engine's horsepower number will always be higher than its torque number. At 5252 rpm the horsepower and torque numbers will be exactly the same.
You might see my screen name in a few of those older discussions.
And as our buddy LVJetboy explained. Torque is not necessairily measured it is calculated as well. If the dyno uses hydraulic pressure to read torque.
You might see my screen name in a few of those older discussions.
And as our buddy LVJetboy explained. Torque is not necessairily measured it is calculated as well. If the dyno uses hydraulic pressure to read torque.
Exactly...Torque by itself, is just a word to describe a force. It's when we give it a value that the calc's come into play. As mentioned above, HP is also "measurable", and dosen't necessarily have to be calculated using "torque"...it's just an easier way of giving a force a name, mostly for comparison...and argument's sake.
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