Spec differences between RPS Hawk 250 and Xpro Hawk 250

[Thumper]

Originally Posted by ProDigit

Wrong. While engine hp output increases ever so slightly with a heavier load, HP output to the wheels definitely increases, especially if a too small gearing does not make use of the full engine potential.

For instance, stock gearing 65mph at 8.5k rpm will output a lower engine HP, than at 6-7k rpm through modified gears, if the HP curve clearly shows that that's engine peak HP.

Interesting perspective. It's like you think the engine perceives load and gets stronger (heavier load).

Maybe you mean that the two main things that affect hp output (rpm and throttle opening) result in less than, or peak hp for the engine. Well, YES. Peak horsepower on an rpm curve is the standard output of the DYNO.

But peak hp for the engine actually does not change.

For instance, you can obtain higher torque to climb a steep hill by shifting to a low gear. Seems like higher hp, but the same amount of work is being done...I mean, The overall kWatts of power is the same as pushing the bike through the air at 75mph. That's horse power.

Torque is a MECHANICAL ADVANTAGE, but you expend the same amount of kW (hp).

Got to admit, your argument sounds like AI generated. No real intuition.

[ProDigit]

Originally Posted by Thumper

Interesting perspective. It's like you think the engine perceives load and gets stronger (heavier load).

Maybe you mean that the two main things that affect hp output (rpm and throttle opening) result in less than, or peak hp for the engine. Well, YES. Peak horsepower on an rpm curve is the standard output of the DYNO.

But peak hp for the engine actually does not change.

For instance, you can obtain higher torque to climb a steep hill by shifting to a low gear. Seems like higher hp, but the same amount of work is being done...I mean, The overall kWatts of power is the same as pushing the bike through the air at 75mph. That's horse power.

Torque is a MECHANICAL ADVANTAGE, but you expend the same amount of kW (hp).

Got to admit, your argument sounds like AI generated. No real intuition.

All the math concerning this works on a fixed load. Which a dyno is.
There is a point where gearing is optimized, and you can't get past.
In most cases, ho to the wheel is lower than in that optimized state.

It's when the engine peak output and the load balances one another out where the engine does no longer accelerate, or rpm no longer increases.
On a dyno, rpm increases past peak HP, because the load isn't realistic.
Hence you'll get different HP ratings from dynos with heavier or lighter rollers.

All the math on this forum doesn't take that into consideration. It only takes into consideration when engine output is measured on a single load (single dyno). Not on a variable load, which is what happens when you accelerate, and wind resistance becomes higher at higher speeds, and prevents the bike to go faster.

[Thumper]

Can't interpret your post. You really seem to think that the optimum output of an engine in kW or hp changes. Bottom line is in fact that the engine can't make more.

As I stated,
"Torque is a MECHANICAL ADVANTAGE, but you expend the same amount of kW (hp)".

Just because a geared down engine can lift a 3 ton pallette doesn't mean that the 20hp engine in the forklift makes more than 20hp. You are just not thinking. It is still 20 hp. Work includes a distance meaurement and time factor. Maybe you are missing this? 70mph pushing through the wind (more than a mile per minute, where wind provides constant friction), or lifting a truck at 3 inches per minute, against gravity. It is still 20 hp (14.914 kW).

[ProDigit]

Originally Posted by Thumper

Can't interpret your post. You really seem to think that the optimum output of an engine in kW or hp changes. Bottom line is in fact that the engine can't make more.

As I stated,
"Torque is a MECHANICAL ADVANTAGE, but you expend the same amount of kW (hp)".

Just because a geared down engine can lift a 3 ton pallette doesn't mean that the 20hp engine in the forklift makes more than 20hp. You are just not thinking. It is still 20 hp. Work includes a distance meaurement and time factor. Maybe you are missing this? 70mph pushing through the wind (more than a mile per minute, where wind provides constant friction), or lifting a truck at 3 inches per minute, against gravity. It is still 20 hp (14.914 kW).

Cant make more than what?
The rated output or the actual output?

And your example shows lifting a pallet at a fixed speed (thus fixed load), vs wind resistance, which can be both variable and fixed.
The point I'm trying to make is in one example, the engine is easily overcoming the load lifting, but lifts at a fixed speed. In the other, the wind resistance and engine output will balance to a point where the engine won't be able to overcome the wind anymore.
It would make sense if the same engine can lift the weight at different speeds.
The work performed with low gears, will put out a low power output; say 10HP; despite the engine being rated at 20hp,because the engine load is 50%.

You take that engine to the calibrated factory dyno, and it'll still show 20hp.
You change the load on that dyno, is the same as advancing the timing a bit, and the engine's efficiency rating goes up. If the engine runs more efficiently, it's HP output can exceed it's factory rated output.
And there are lots of reasons why an engine can exceed it's rated output, one of them is increasing the load to match maximum load with maximum engine output, where both forces balance one another out.

The factory never tests and rates engines like this, but if you load an engine like that, the output can most certainly exceed it's rated output.
You have no difficulty understanding that nos, or forced induction can increase HP, no?
Well, in a way, increasing the load can increase the efficiency; resulting in a higher than rated performing engine.

[Megadan]

How an engine brake dyno works. A high load is applied to an engine that it must overcome, giving maximum effort. This is known as brake horsepower, and that is an industry standard. Horsepower ratings are stated, at the engine, as the maximum output the engine can deliver, AKA - it doesn't go any higher.

Horsepower at the engine doesn't increase when put through gears. Ever. It will decrease from driveline loss, but the engine will never ever make more horsepower than it's brake horsepower rating. Ever. I proved that the last time you wouldn't let this go. I can prove it again. Math doesn't lie.

So, you're wrong, and you have always been wrong. If you keep thinking the way you do you will always be wrong. Want to prove me wrong, post an actual credible source that proves your claims. I can post endless articles from physicists and engineers on this proving me right. Give me an actual source that isn't you, and I will listen. Othewise...

Just because I am a jerk, and it's fitting.


I am saying nothing more on the subject. Good luck.

[Megadan]

Originally Posted by Thumper

Just because a geared down engine can lift a 3 ton pallette doesn't mean that the 20hp engine in the forklift makes more than 20hp. You are just not thinking. It is still 20 hp. Work includes a distance meaurement and time factor. Maybe you are missing this? 70mph pushing through the wind (more than a mile per minute, where wind provides constant friction), or lifting a truck at 3 inches per minute, against gravity. It is still 20 hp (14.914 kW).

You mean...

HP = Fd/T

aka, Force x distance / Time.

Or Ft-lbs, Newton-Meters, or other measure of force multiplied over a distance, divided over a period of time. Aka, Energy in terms of Kilowatts, Horsepower, Water Chicken power, etc.

You won't get through to him on this. He has too much ego to admit he is wrong, and no actual facts to back it up, just his beliefs. You may as well work on blood from a rock.