Heck, the 42MT or similar non-gear reduction starter in a loaded Class 8 "semi" will move a truck a good distance in 1st or 2nd up a hill and 3rd or 4th on level ground. The gear reduction starters available are even more capable. I know this because I constantly have to repair gravel haul trucks that, due to lack of operator maintenance, eat throwout bearings in the middle of nowhere. This means that there are always a few starts in gear to get them back to the shop for transmission removal and they're not always unloaded. They're rated at 7.3kW which is just under 10HP.

 

For anybody who did not understand what I was saying in this comparison above with the paint dot on the edge of each pulley the paint dot on the 2 inch pulley on engine # 1 that only has to rotate 500 RPM to make 1 HP peak covers twice as much ground each rotation while accelerating from a dead stop so it is accelerating at twice as many feet per second as the other engine with a 1 inch pulley that has to turn twice as many RPM to do the same feat of making 1 HP.


Your torque is your ability to build and maintain your HP under a load period...


Here is another scenario which I ran into with my CR 500 which helps spell it out on what it means in the real world..


You have 2 motorbikes of same weight, # 1 makes 50 HP at 5000 RPM and the other # 2 makes 50 HP at 10,000 RPM.


# 1 makes double the torque of # 2 but the peak HP is the same maxed out. The peak HP determines your mile an hour top speed so both will do 100 MPH lets say.


You have both of them set in top gear 5th and both will max out at 100 MPH when tapped out. Then you ride both of them from a dead stop in 5th gear and see which one will drive to a 100 MPH with no shifting and do it with not much bitching and gets there first.


The engine that makes double the torque will kill the other period. I know this because I weigh 300 and a CR 500 will do it with me aboard with no problem because it has twice the ability to build and maintain it's peak HP under a load.


That's not all , lets say you are going 100 MPH on both and then you hit a hill. Guess what because engine # 1 has double the torque it has double the ability to hold the MPH and the other engine # 2 will lose MPH twice as fast.


Also I believe engine 1 would even run a higher MPH because it is just plain more powerful even though the peak work time is the same ( HP ) and would have the extra drive to pop through the air restriction better so engine # 2 would only go lets say 90 or 95 MPH wound out compared to engine # 1 that would do 100 MPH but I am unclear on this.


You cannot change this for it is what it is.


There are other factors that play a big roll in this such as REV gain when you are racing so big torque engines with slow rev gain such as diesels can and do pay a heavy price for this when racing. It's just something else engineers learn to work around.


FOR PULLING you want torque !!!!!!!

 

Let it go man, just let it go.

 

Debunk the last post I made above this one.

 

Actually this is fairly correct because the high torque engine compared to one that isn't and needs to turn way more RPM to do it's work HP for HP cannot accelerate near as much mass to speed.

 

This stuff is really easy guys.

Torque is the amount of force available at a given instance in time, RPM is a measure of time. Knowing force and RPM, you can calculate how much work can be done (horsepower).

Let's go over some basic exercises.

Engine A makes 300 ft-lbs at 2000 RPM and engine B makes 500 ft-lbs at 2000 RPM. They are both the same engine speed, one has more available force at that very moment in time. What is the horsepower of engine A vs engine B?

Engine A = 114 hp
Engine B = 190 hp

At the same RPM, engine B has more available force. Therefore it can create more work with the RPM available.

If RPM is equal and torque is not, the one with greater torque will create more horsepower.

See, it's not that hard.


Now let's take the same available force and change up the RPM.

Engine A makes 300 ft-lbs at 2000 RPM and engine B makes 300 ft-lbs at 3000 RPM. They both have the same available force, but now at different engine speeds. What is the horsepower of engine A vs engine B?

Engine A = 114 hp
Engine B = 171 hp

At the same available force but with more engine speed available, engine B creates more horsepower and can get more work done.

If Torque is equal and RPM is not, the one with greater RPM will create more horsepower.

Still not that hard.



Now lets change both the amount of available force and the RPM.

Engine A makes 350 ft-lbs at 3000 RPM and engine B makes 525 ft-lbs at 2000 RPM. Both have differing force and RPM. What is the horsepower of engine A vs engine B?

Engine A = 200 hp
Engine B = 200 hp

At that point both engines intersect with the exact same amount of available work (horsepower), because the one with more force has reduced RPM, and the one with less force has increased RPM. In this instance, both engines are identical.

Still not that hard.



What complicates these threads is the silly "what-if" super specific scenarios that clearly pit one engine as winning, and thus assuming that engine is superior in all other aspects.

If that argument comes up, it's simple. Let's say in the last example I gave someone wants to accelerate a load, which one will win? Well now the RPM and available force at every step along the way changes, so now we look at the bolded statements in the first 2 examples, those are the answers.

The answers are easy. The silly what-if scenarios only serve prove how little some people actually understand the differences between horsepower and torque.

And stop with the whole going through a wall thing, it's the worst way possible to try and explain horsepower vs torque. Seriously.

 

Nice try Pocket! We all know you’re just trying to keep the conspiracy going. Next, I’ll bet you’re gonna tell me that chem trails are just water vapor.

 

Can't pull the wool over everyone's eyes

 

Nobody will debunk what I posted, it really is that simple.


This a guarded secret because this info can be the difference between being 1st or 2nd when building racing engines.


That's why I asked the ? in the first place.

 

I don't like to do this, but it's really hard to say anything other than "you are wrong". It's basic physics, easily provable.


No, it's not. You are just wrong.


I really recommend watching this video from 1936:
It's pretty explanatory about how gearing works to increase torque(or decrease it for speed), which is what you need to do if you have different engines running at different speeds.

 

Thanks for posting this video took me back to my high school autoshop days the teacher played this same video on VHS.

 

I ran out of popcorn on page 2

 

The original thread was if a motor has to turn more RPM to make it's power compared to another that turns less and they are the same HP rating is the one that turns less RPM to do it a more powerful motor and yes it is.


I had a PM in my box and was told I was wrong as usual so maybe I should make it a little easier to understand.




This time 2 RC cars each with 1 HP motors and identical weight but one motor turns twice as many RPM's and only has 1/2 the torque.


Both are direct drive and at a wheel on the rear.


The car with 1/2 the torque makes 1 HP at 1000 RPM and the other makes 1 HP at 500 RPM.


The car with 1 HP at 1000 RPM engine has a 1 inch drive wheel and the other that makes 1 HP at 500 RPM has a 2 inch drive wheel.


The torque at the wheels is the same on both cars because one is 1 inch on the 1000 RPM car and the other 2 inch on the 500 RPM car.


When you put them on the ground and turn them on what happens ? The car with the 2 inch wheel travels twice as far each revolution of the motor and only has to go to 500 RPM to reach the 1 HP mark peak output. The other car with the 1 inch wheel only goes half the distance every revolution of it's rear wheel of the other car and has to go to 1000 RPM to reach the 1 HP mark.


The car with the 500 RPM motor has twice the acceleration as the one with the 1000 RPM motor. They have the same peak MPH but the one that only turns 500 RPM has twice the ability to drive the load to that peak and accelerates at twice the rate.


There is simply no comparison, this is why a tractor trailer rated at 400 HP can do what it does. It has 4 times the ability to drive the load to peak output over a 400 HP gas car motor.


You cannot gear around this, if you put a tranny or a slipper clutch on the one with less torque to try and compensate you can do the same to the other and the results will be the same the higher torque engine will drive the load to peak faster.


A semi can accelerate 40 tons like a PU accelerates 10 because it has 4 times the ability to drive the load because it has 4 times the torque.


I don't know who came up with the " torque at the wheels " but it's total hog wash....


Yes it is a conspiracy by our overlords the reptilian space monsters......

 

What is "total hogwash" is this thread and the inane comments OP has littered it with.

 

Were sorry if you cannot see the lower torque engines have to drag the load farther up the RPM range to reach there final peak HP destination.


You see the math does not lie but they are omitting the fact because one does not make as much torque it has to drive the load further to do the work.


I found this nonsense everywhere on the net so obviously it's a guarded secret but one that is right in front of your face.


It must mean very much to engine builders to try and keep it so tight lipped......