Top speed…never ever!

[eriegz]

I've never really understood horsepower as a measurement... "Something, something, it's a measure of power and RPM". So then why not just say the torque at which RPM it occurs? "Something, something, horsepower allows you to express both concepts as a single number". So then why do we still give the horsepower at a specific RPM?

 

[KAR120C]

I've never really understood horsepower as a measurement... "Something, something, it's a measure of power and RPM". So then why not just say the torque at which RPM it occurs? "Something, something, horsepower allows you to express both concepts as a single number". So then why do we still give the horsepower at a specific RPM?

That’s to show where peak HP occurs. I think it’s too simplistic but allows some easy comparison. I’d rather see the torque and hp curves to understand how the car will really operate.

Is the power all down low then peters out? Or do you have to wring it out to redline to make it scoot? The graphs really help give you that info.

 

[eriegz]

That’s to show where peak HP occurs. I think it’s too simplistic but allows some easy comparison. I’d rather see the torque and hp curves to understand how the car will really operate.

Is the power all down low then peters out? Or do you have to wring it out to redline to make it scoot? The graphs really help give you that info.

Right, and that's why the dyno charts are super useful. But why do we need horsepower as a measurement, when we can give the torque vs. RPM? Doesn't torque vs. RPM give the entire story?

 

[KAR120C]

Exactly, and that's why the dyno charts are super useful. But why do we need horsepower as a measurement, when we can give the torque vs. RPM? Doesn't torque vs. RPM give the entire story?

It’s easier to have the Hp as well so you don’t have to do the math. HP exists to bring time into the power curve. Torque gives the instantaneous power and therefore acceleration. HP brings time into the equation which is useful when looking at top speed and ability to maintain that speed.

They are both useful to look at, even though HP IS derived.

 

[eriegz]

It’s easier to have the Hp as well so you don’t have to do the math. HP exists to bring time into the power curve. Torque gives the instantaneous power and therefore acceleration. HP brings time into the equation which is useful when looking at top speed and ability to maintain that speed.

They are both useful to look at, even though HP IS derived.

First of all, thank you for taking the time to try getting these concepts through my thick skull. I really am trying to understand here.

I guess what I'm still struggling with is, what can we do with horsepower that we couldn't do with just torque & RPM? (Or, how does horsepower make the task easier?) Also, how exactly does horsepower tell us how long an engine can sustain a given power output @ a given RPM (if I understand you and various internet articles correctly)? Can't any engine sustain whatever instantaneous torque it can produce at a given RPM, indefinitely? (provided that it doesn't overheat, run out of fuel, etc.)

 

[Eagle7]

Torque is what gets something moving. Horsepower determines how heavy a load can be pulled, and how easily. For example, one horse can jump start rather quickly, but if you hook it up to a wagon with a heavy load, it can't pull it very easily or very fast. If you use a 4-horse team, they can not only start, but they can pull that wagon a lot easier and faster.

So torque is what you feel that gets you moving, and horsepower is what enables you to keep moving and how fast.

 

[FederGigant]

To get back to topic, I only tried it once and managed 286 km/h on the display, and could have reached 290 as well, if there wouldn‘t have been traffic in my way.
The car behaves great at that speeds, however the steering gets pointier and you have to steer more carfully. My thought was that this happens due to the downforce.
And regarding the not so impressive 100-200 times: As said above, the car is not made for that. If you look at the torque curve, you will find a very linear and steadily rising graph. The BMW B58 engine for example has peak torque (which is a good 100 Nm higher than the Emiras peak torque) from 1.500-5.500 rpm. Of course this gives you better acceleration times, even if (and that‘s a big if in case of real world measurements of the 2GR and the B58) the peak hp number is lower.

 

[MaybeNeedEmira]

How about average hp over a 2k rev range as a measure?
That should cover drivability, and it's up to the manufacturer to get the gearing sorted.
Better than peak torque (think diesel) and peak power (max-speed - aero factors)