I was going to stay out of this thread, but I could not resist any longer...

 

Ok, I am no engine guru and I don't play one on tv. I know just enough to do the basic stuff, and some things I have learned here. But one thing I do have is common sense. Now you might not agree with me and I'm ok with that, but I see no way you can have two same size engines with no modifications in two same size and weight vehicles, and expect there to be a major difference as you keep pointing out. Common sense tells me they will produce almost the same result. Possibly minor differences that would be mostly unnoticeable. Now if you are changing the gear ratio to make one turn faster than the other then so be it, then I can understand a different rating. But as an ignorant to the internal workings of an engine person, I don't see this to be a highly guarded secret. I mean I believe I could take two identical engines, change the output ratio by changing a gear or pulley, and modify the output as you are suggesting. Then I could modify one engine itself to produce more power. That would alter my output too. This wouldn't be a highly guarded secret either.

 

@OP- Ask your question. How much torque and how much HP do you want to make at particular RPMs?

What engine and mods do you have? Post up your current dyno runs so we can see where you are now.

Then we can work with some real numbers and get you the answers you seek

Like the old saying goes:

How fast do you want to go? Depends on how much money you want to spend.

I am very curious about the values you wish to achieve and how close you are already.

 

I will have to jump into this. I will be out at my dads tonight to help him get his scanner setup. I'll ask him to get out his horsepower explanation sheet and scan it along with some horsepower test sheets we have done over the years.

We need to try not getting hung up on a peak hp or torque value. I would rather have more power across the entire engine rpm range with a nice broad curve in my truck than a spike at a specific rpm. AND the ability to hold and continue producing that power like needed when pulling a load up a hill.

We run a Prony Brake at several antique tractor shows (invented by Gaspard Clair François Marie Riche de Prony in 1821). Ours was built in 1995 and the pto attachment added a few years later. We have run 1/4 scale model steam engines at 7hp and numerous small tractors running poorly up to a few steam engines and turbo tractors around 145hp. At that point belt alignment, grip and smooth operation become extremely important. Pto clutches start having trouble not slipping.

You connect it to a tractor or steam engine with a flat belt. You can also use a short belt to a jackshaft and connect that to a tractor pto. The jackshaft has a pulley about half the size as the main belt pulley keeping the main shaft speed at a reasonable level. We have ran a few tractors on the pto that we had get a load on at part throttle then have them open it up at a higher load to limit the rpm as they were spinning much faster than the standard 540 rpm pto shaft speed mostly hopped up antique tractor pullers.

On the main shaft between the framework is the brake pulley. Around it is a band with wooden blocks that is split so it can be tightened. You tighten the brake band with the steering wheel.

As the brake band tries to slow the shaft force is applied to the scale. The distance from the centerline of the shaft to the centerline of the pivot point on the foot that pushes on the scale is 5.25 feet. This has to do with the formula for calculating horsepower and simplifying the math.

The smallest pulleys and belt is to run a tach that the person running the brake can see and use as a reference.

Rpm readings are taken from a digital tach held against the end of the main shaft.

Due to the length of the lever arm pushing on the scale you take the scale reading in pounds multiplied by the main shaft rpm and divide by 1000 to get horsepower.

Water is used to cool the brake wheel. It is just gravity fed in and another pipe will scoop it out once it reaches a certain level.

One thing that is rarely discussed is how long can "xx" HP or "yy" torque at "zz" rpm be held. Get a tractor or steam engine warmed up and pulled down measuring 102 hp maintaining rpm and will do it as long as you ask.

Tighten up the brake a little more and hp is 110 woohoo but 15 seconds later rpm is falling off at the same load and if you recalculate hp you get 90.

Now back the load off and remember what at what force on the scale your peak reading was at. Bring the load back on very quickly but smooth and take 1 reading at the peak. Wow look at that the rpm is a little higher (for a few seconds) and you have a fraction of a horse to a few more horsepower. Make sure you take the load back off before you watch the rpm plummet.

 

I wasn't going to reply again, but this is like a train wreck that I can't stop watching.

I thought I made it crystal clear in post #36:

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

But you've blatantly ignored it, and still claim that this is some "guarded secret" and engine builders are "tight lipped", as if RPM and horsepower is some sort of conspiracy against torque. Then you continue with these extreme comparisons that don't have any real-world application.

I'm going to ask a real world question based on a real world application. My father had his 2001 7.3L stolen last week, and just a few days ago bought a 2013 F-150 3.5L Ecoboost. The 7.3L produces more torque, the Ecoboost more horsepower. Which truck will out-pull the other?

I know the answer. Do you?

 

subscribe.....

 

 

The "end of days" is near. You may as well have divided by zero!

 

Really? Even with having a drive wheel twice as tall as the other car? Acceleration is proportional to force. The taller wheel reduces the force. That is why a lot of us install lower gears with taller tires. It increases the force which is felt as acceleration.

And since the claim is for two motors with the same horsepower (calculated from torque at RPM), do these two motors have identical torque curves across the power band other than the scalar difference? If not, then one can not directly compare acceleration from a stop to max power using information at only one RPM.

Just subscribing to see how this ends...

 

Man, That's 4 forum pages of existence I'm never getting back.......I'm out!

 

Depends on the type of pulling
If you are talking short-chain pulling(truck against truck), I'd count on the '01... Not because it has more torque, but simply because it has more weight! (Yes, I know this is a totally useless metric by any means).

Otherwise, generally speaking, the 3.5L ecoboost will totally out-accelerate and out-power the 7.3L... but we all knew that.

The only question is whether the ecoboost would be able to maintain that power over time(without overheating or blowing up), something that dyno tests(hp and torque numbers) never show. The 7.3l is so 'under stressed' that it'll do it's rated power all day long, as long as the cooling system is in good shape.

 

So if you had to explain the difference between horsepower and torque to a twelve year old kid who was interested in trucks, how would you do it and what would you say?

 

Tell the kid to give you his hand.

Take a ruler to his hand. Press it there and hold.

Ask the kid if he can feel the ruler on his hand, the answer will be yes. Ask him if it hurts. The answer will be no. The ruler isn't moving, but the kid can feel it. That's torque.

Now raise the ruler up, then bring it down quick and smack him on the hand with it.

Ask the kid if that hurt, the answer will be yes. The ruler hit him with the same force, but this time it was moving. That's horsepower.

Now tell the kid to get back to work and not to call child services on you.

 

Torque is the amount of force you apply to get a job done. For example, lets say you are trying to remove a bolt from something, doesn't matter what it is, maybe the water pump, washer - dryer, etc. Lets say all you have is a 3/8 8" socket set. As hard as you try the bolt won't break loose. So you go with a longer extension on the handle and with the same force, or less, the bolt breaks loose. That's torque.

 

All those years ago, I thought I was being punished. It turns out, my mom was just teaching me physics.