eu decat sa ma incurc in explicatii mai bine va pun un link, cel putin pt mine, edificator.

 

http://www.netscape.com/viewstory/2006/09/...ower&frame=true

 

edificator si in cazul ideii de motoare cu aceeasi putere si cuplu diferit.

159735[/snapback]

 

interesant... l-am citit... as pune aici doar:

 

* Gearing is extremely important because it controls RPMs (and therefore horsepower).

* Low gears magnify torque -- hence the acceleration available in first gear.

* Racecars have high horsepower due to high RPMs, not due to high torque (see gearing).

* "Below 5252 RPMs any engine's torque will always be higher than its horsepower, and above 5252 RPMs any engine's horsepower will always be higher than its torque. At 5252 RPMs the horsepower and torque will be exactly the same." -- revsearch.com deci variaza hosepower si torque...

* "It is better to make torque at high rpm than at low rpm, because you can take advantage of gearing." -- vettenet.org

acumam dat click pe link, deci nu l-am citit inca, dar Paul are dreptate 100%. Masina accelereaza si ajunge la viteza maxima, tot prin accelerare, datorita puterii, putere care este obtinuta prin cuplu si turatie.

159738[/snapback]

 

 

Vrei sa spui ca accelereaza datorita cuplului si atinge viteza maxima datorita puterii.

Am citit si eu tot, foarte misto realizat, si foarte bune explicatii, as mai pune un citat bun care mi-a placut mult.

 

"We actually have a similar relationship with horsepower, torque, and RPMs. In case you haven't already seen the similarities:

 

Horsepower = power

Torque = work

RPMs = time (not strictly, but it's a component)

Torque is how much work you can do, or, how much weight you can lift by twisting, but it doesn't say anything about how fast, or how often, you can do it. Try and think of something that can pull a ton of weight, but not very quickly. Yes, a tractor. A tractor has extremely high torque, but very low horsepower. Why? Because the RPMs are so low."

 

@crisjohn acum ii dai dreptate lui paul? puterea conteaza, nu cuplul. si tine minte ca sunt dieselist. :blink:

eu voiam sa mai bat moneda pe treaba cu aceeasi putere dar cuplu diferit insa acum am net pe PDA nenorocit asa ca aman :blink:

si uite ca umbland prin Internet am dat si de chestia asta (tot de la linkul lui Mihai plecand)...

 

Apropos, eu nu sustin nimic anume ci incerc sa clarific situatia pana si pentru mine... Deci nu am opinii contrare lui Paul sau altcuiva ci doar vreau sa ajung la ceva concret logic si pe intelesul tuturor in aceasta explicatie... si uite care e explicatia data de: http://www.netscape.com/viewstory/2006/09/...ower&frame=true

 

Horsepower and Torque "At the Wheels"

 

Now when we're talking about automobiles, the amount of horsepower or torque generated at the flywheel is not very useful when determining acceleration. What is useful, however, is horsepower and torque "at the wheels". The problem here is that drivetrains cannot be perfectly efficient and pass 100% of the power of the engine through its components to the wheels. Some of the power is lost for several reasons. Generally 15-25% of engine power never makes it to the wheels. Different types of drivetrains will have different levels of efficiency. Generally, drivetrains with more weight and those with more components will be less efficient.

 

Let's use my own car for some sample calculations. In stock form, it has 165 hp @ 5600 RPM and 166 lb-ft @ 4000 RPM.

 

Dyno results have shown that the car has around 127 peak hp at the wheels. That's a 23.03% loss. Note that this is higher than most cars because of the heavy and sophisticated all-wheel-drive system.

 

Here's a chart to show how the power and torque change before they reach the wheels. Although, the efficiency loss is difference for each gear, we'll assume that 127 peak hp is attainable in every gear. At 5600 RPM, the flywheel torque calculates as 154.7 lb-ft. Calculating the same efficiency loss (23.03%) as horsepower, this would come out to 119.1 lb-ft.

 

Engine RPM = 5600

Gear Gear Ratio Axle Ratio Total Ratio Flywheel Horsepower Wheel Horsepower Flywheel Torque Wheel Torque after loss

1 3.545 4.11 14.57 165 127 154.7 1735

2 2.110 4.11 8.67 165 127 154.7 1033

3 1.448 4.11 5.95 165 127 154.7 707

4 1.088 4.11 4.47 165 127 154.7 532

5 0.780 4.11 3.21 165 127 154.7 382

 

To prove the accuracy of the wheel torque numbers, let's look at the example of 1st gear. Using the Speed/RPM Calculator, we can determine that the vehicle will be traveling at approximately 27.5 mph in 1st gear at 5600 RPM. Using the Tire Size Calculator, we can determine that the circumference of the tire is approximately 78.16 inches. Let's calculate the RPM of the tire:

 

27.5 mph = 145,200 ft/hour

145,200 ft/hour = 1,742,400 in/hour

1,742,400 in/hour = 22,294 revs/hour

22,294 revs/hour = 372 RPM

 

Now we know that there is 127 hp generated at the wheels. If we use the horsepower formula above:

 

127 HP = (Torque * 372 RPM) / 5252

667,004 = Torque * 372

Torque = 1793 lb-ft

cred ca era bine sa fi spus pe romaneste ce am priceput fiecare din linkurile respective caci vad ca o dam in tractoare si alte chestii caz in care se schimba lucrurile :blink:

pai ce teorie sti tu ma?

159733[/snapback]

tocmai a fost expusa o explicatie...citeste cu atentie... :blink:

Deci pana la urma la roti ajunge mereu aceeasi putere, dar cuplu mai mare, deci doar cuplul se multiplica? cred ca am inceput sa -mi pierd ideile. prea mult!! :) :blink:

Intradevar, la roti ajunge aceeasi putere, dar variaza raportul cuplu / turatie. In viteza 1 poti avea la roata 4000 Nm la 200 rpm iar in viteza 5-a 200 Nm la 4000 rpm. Cutia de viteze face transformarea cuplu - turatie.

 

Pentru simplificare am plecat de la premiza ca pastram aceeasi turatie a motorului in ambele cazuri. Deci motorul va realiza acelasi cuplu si aceeasi putere.

:blink:

Ma rog, cred ca am prins cate ceva. Am facut acest topic deoarece am ramas surprins cand am aflat ca un 325, 192 HP a luat bataie la fundulet la semafor de la un mercedes 2000 sau 2200 cmc diesel... care sincer nu cred ca are mai mult de 150 HP... Si "infrantul" zice: "Ala are cuplul mai bun..."

Edited December 2, 200619 yr by 320i_24valve

Eu cred ca avea ala mertzanul preparat. :blink:

"horsepower sells cars, torque wins races"

:blink:

Ma rog, cred ca am prins cate ceva. Am facut acest topic deoarece am ramas surprins cand am aflat ca un 325, 192 HP  a luat bataie la fundulet la semafor de la un mercedes 2000 sau 2200 cmc diesel... care sincer nu cred ca are mai mult de 150 HP... Si "infrantul" zice: "Ala are cuplul mai bun..."

159857[/snapback]

 

"INFRANTUL" nu stia sa conduca...

"INFRANTUL" nu stia sa conduca...

159870[/snapback]

 

si eu cred asta mai degraba...

ori masina era preparata..prost..adica defecta, ori baiatul nu mai avea benzina si s-a gandit sa nu-si forteze norocul sa pape benzina pentru o saptamana pentru o liniutza :blink:)

P = C x rpm /7023

 

159676[/snapback]

 

 

btw: se imparte la 5252 nu la 7023 din cate stiam eu :blink:

btw: se imparte la 5252 nu la 7023 din cate stiam eu :blink:

159998[/snapback]

Daca citeai atent ai fi vazut ca am specificat ce e cu acel 7023.

 

Acea constanta 7023 provine de la transformarea unitatilor de masura din SI in alte unitati convenabile noua, si anume : cp, Nm, rpm.

 

Daca exprimam cuplul in unitati de masura anglo saxone : lbf x ft atunci constanta devine 5250.

intr-adevar n-am citit atent, scuze