Torque, Horsepower, and speed, A technical discussion

[CKwik240]

You are measuring engine output and not wheel torque on ice and wheel torque on the m3p. That is not how it works. You need to calculate wheel values to compare. If you do then they are very similar

See the graphs below. I took the M3P line from the graph on the previous page and eyeballed the values. I created data to simulate the M3P power if there was a flat power curve once it reached peak. I am assuming it reaches peak power sooner as I removed the effects of back-EMF. The torque curves are at the wheels. Clearly, there is a bit more torque when power is flat before and after where peak power aligns. Disclaimer: I linearized a lot of the datapoints for simplicity.

Also added in an engine I found a dyno for online that had similar HP output and mocked up some gear ratios. It's not really optimized, but it illustrates how HP is somewhat flat. The torque curve tends to somewhat follow the M3P motor with a flat power curve. Clearly more gears and better spacing would be more ideal. What's important id the the area under the curves. The last set of curves are for a CVT version of the same gas engine. With a similar peak HP output as the flat M3P, the torque at the wheels are virtually identical at all vehicle speeds after about 55 mph.

If you take engine torque and calculate wheel torque, then take the wheel torque and apply HP=(Tq * Wheel RPM)/5252 to the wheel torque, I guarantee it will match Engine/Motor HP. The fact that the respective curves converge and diverge in proportion to the differences in power/torque illustrate this quite well.

Data points are below.

I would share the excel file, but it seems I can't attach it here. Feel free to PM me for a copy if you want to see my data. Questions? Ask.

 

[oreobbq]

I took a break from looking at excel sheets at work. What do you know? More charts here

 

[Sweed269]

See the graphs below. I took the M3P line from the graph on the previous page and eyeballed the values. I created data to simulate the M3P power if there was a flat power curve once it reached peak. I am assuming it reaches peak power sooner as I removed the effects of back-EMF. The torque curves are at the wheels. Clearly, there is a bit more torque when power is flat before and after where peak power aligns. Disclaimer: I linearized a lot of the datapoints for simplicity.

Also added in an engine I found a dyno for online that had similar HP output and mocked up some gear ratios. It's not really optimized, but it illustrates how HP is somewhat flat. The torque curve tends to somewhat follow the M3P motor with a flat power curve. Clearly more gears and better spacing would be more ideal. What's important id the the area under the curves. The last set of curves are for a CVT version of the same gas engine. With a similar peak HP output as the flat M3P, the torque at the wheels are virtually identical at all vehicle speeds after about 55 mph.

If you take engine torque and calculate wheel torque, then take the wheel torque and apply HP=(Tq * Wheel RPM)/5252 to the wheel torque, I guarantee it will match Engine/Motor HP. The fact that the respective curves converge and diverge in proportion to the differences in power/torque illustrate this quite well.

Data points are below.

View attachment 1030560
View attachment 1030561
View attachment 1030562
I would share the excel file, but it seems I can't attach it here. Feel free to PM me for a copy if you want to see my data. Questions? Ask.

Looks good.
M3P has an advantage until 60mph, then even to 100mph, after that it starts to lose out to a 520 wheel HP car.
Does not fall on it's face and is incredibly impressive for the price point and overall daily capability's.

All it really needs for an upgrade is a more sophisticated suspension, super light wheels and to hold it's power a little longer. Of course if it's a better daily driver that's icing on the cake.

 

[CKwik240]

Looks good.
M3P has an advantage until 60mph, then even to 100mph, after that it starts to lose out to a 520 wheel HP car.
Does not fall on it's face and is incredibly impressive for the price point and overall daily capability's.

All it really needs for an upgrade is a more sophisticated suspension, super light wheels and to hold it's power a little longer. Of course if it's a better daily driver that's icing on the cake.

To be clear, it wasn't for a projection on what the new M3 Ludicrous/Plaid/Performance will bring. It was merely to illustrate the point I was making earlier.

 

[CKwik240]

I took a break from looking at excel sheets at work. What do you know? More charts here

Pretty much my life. Except I did this at home and didn't have the screen real estate I get on my 4K monitors.

 

[Sellout]

Looks good.
M3P has an advantage until 60mph, then even to 100mph, after that it starts to lose out to a 520 wheel HP car.
Does not fall on it's face and is incredibly impressive for the price point and overall daily capability's.

All it really needs for an upgrade is a more sophisticated suspension, super light wheels and to hold it's power a little longer. Of course if it's a better daily driver that's icing on the cake.

People seem to have such an issue with “falls on its face.” That is so strange to me.

As if the opinions of others are things you can invalidate by insisting that yours is clearly the correct one or that the language those people use is offensive. Why are we afraid of offending the inanimate objects in our garages? Clearly it’s not about offending each other. None of us has our entire sense of self-worth tied to how fast our EVs are, right? I really don’t get it.

I’m curious. In what way would most of you be ok with us describing the dramatic drop in acceleration with speed? Forget that it can happen in ICE cars too. There’s no place for “whataboutism” when we’re just describing something that we experience that we wish was better. (Kind of amazing to me that I even need to state that, tbh)

 

[jjrandorin]

People seem to have such an issue with “falls on its face.” That is so strange to me.

As if the opinions of others are things you can invalidate by insisting that yours is clearly the correct one or that the language those people use is offensive. Why are we afraid of offending the inanimate objects in our garages? Clearly it’s not about offending each other. None of us has our entire sense of self-worth tied to how fast our EVs are, right? I really don’t get it.

I’m curious. In what way would most of you be ok with us describing the dramatic drop in acceleration with speed? Forget that it can happen in ICE cars too. There’s no place for “whataboutism” when we’re just describing something that we experience that we wish was better. (Kind of amazing to me that I even need to state that, tbh)

Since this appears to be a serious question, I will take a stab at it even though I dont care at all about the discussion at hand.

"Falls on its face" isnt much different than someone looking at a bunch of models and saying "that one though? They are uuuuggglly!". "Falls on its face" implies the car stops, which it clearly doesnt do. Its a term that seems ment to denigrate, and it seems to be purposefully so.

"Doesnt pull as hard as XXX / YYY" is whats actually happening, but "falls on its face" is a term designed to instigate an argument, either accidently, or accidently on purpose, and it doesnt have anything to do with insulting inanimate objects, it has to do with going out of the way with hyperbole to make a point.

 

[rayrevolver]

CKwik240, not an attack on you, but on the first page you posted this below. Yes the engine at a certain RPM will make the same HP/TQ for each gear, but its connected to a transmission. So the graph below doesn't really say anything useful, does it?

As you figured out on the second page, when you apply gear ratios to the engine output, and show actual torque to where the rubber that meets the road, things are different. And guess what? Your ICE revved out in 1st gear shows torque at 7668 and 5th gear is 1768 (assuming these are ft*lb). So an ICE with a transmission will NOT accelerate as hard in 5th as it does in 1st... right?

So isn't this the argument Lindenwood made on the first page?

Didn't Porsche address this with a 2-speed transmission? I didn't even know this was a thing (2-speed trans for an EV) until I read this:

2023 Porsche Taycan 4S review

After reading @Struja post regarding his Taycan, I had to test drive the Taycan and this is my review. For context, I currently own a 2016 Model S75D and I have done my best to not compare the Taycan to it as my car is almost 8 years old now and is not really a comparable car to a new Porsche...

teslamotorsclub.com

EDIT: FWIW, I club raced for 3 years and learned a lot. In that time, my 2000 era engine was surpassed by a 2006 model, peak HP/TQ was similar, but it revved to ~2,000rpm more. So what??? It meant those guys could run shorter gearing. You can make Torque with shorter gearing but HP is HP. When the flag dropped they accelerated harder and then carried 1st longer. I lost even more ground when I grabbed 2nd gear and they were still in 1st. If this was a drag race I would never catch up.

 

[Sellout]

Since this appears to be a serious question, I will take a stab at it even though I dont care at all about the discussion at hand.

"Falls on its face" isnt much different than someone looking at a bunch of models and saying "that one though? They are uuuuggglly!". "Falls on its face" implies the car stops, which it clearly doesnt do. Its a term that seems ment to denigrate, and it seems to be purposefully so.

"Doesnt pull as hard as XXX / YYY" is whats actually happening, but "falls on its face" is a term designed to instigate an argument, either accidently, or accidently on purpose, and it doesnt have anything to do with insulting inanimate objects, it has to do with going out of the way with hyperbole to make a point.

That'll be the issue. I'm used to a higher level of hyperbole being completely normal in general conversation centered around cars, and most of us naturally avoiding getting our feelings involved because we're used to a comedic/aggressive banter. (and forum threads being used as general conversation between like-minded individuals rather than reading it like a debate)
Maybe I got too old for the Model 3 crowd. Heh.

We have a bit of an interesting mix of people here that normally wouldn't be intermingling IRL as anything other than strangers, so there's bound to be some issues discussing things, I suppose.

CKwik240, not an attack on you, but on the first page you posted this below. Yes the engine at a certain RPM will make the same HP/TQ for each gear, but its connected to a transmission. So the graph below doesn't really say anything useful, does it?

As you figured out on the second page, when you apply gear ratios to the engine output, and show actual torque to where the rubber that meets the road, things are different. And guess what? Your ICE revved out in 1st gear shows torque at 7668 and 5th gear is 1768 (assuming these are ft*lb). So an ICE with a transmission will NOT accelerate as hard in 5th as it does in 1st... right?

So isn't this the argument Lindenwood made on the first page?

Didn't Porsche address this with a 2-speed transmission? I didn't even know this was a thing (2-speed trans for an EV) until I read this:

2023 Porsche Taycan 4S review

After reading @Struja post regarding his Taycan, I had to test drive the Taycan and this is my review. For context, I currently own a 2016 Model S75D and I have done my best to not compare the Taycan to it as my car is almost 8 years old now and is not really a comparable car to a new Porsche...

teslamotorsclub.com

EDIT: FWIW, I club raced for 3 years and learned a lot. In that time, my 2000 era engine was surpassed by a 2006 model, peak HP/TQ was similar, but it revved to ~2,000rpm more. So what??? It meant those guys could run shorter gearing. You can make Torque with shorter gearing but HP is HP. When the flag dropped they accelerated harder and then carried 1st longer. I lost even more ground when I grabbed 2nd gear and they were still in 1st. If this was a drag race I would never catch up.

I think our whole problem with this particular conversation is that it's being investigated all the way to the most minute detail to score points for an imaginary team. Nobody is going to learn anything new because you can clearly graph out anything and make it fit whatever minute detail you find to score a point.

 

[CKwik240]

CKwik240, not an attack on you, but on the first page you posted this below. Yes the engine at a certain RPM will make the same HP/TQ for each gear, but its connected to a transmission. So the graph below doesn't really say anything useful, does it?

It does. Not it wasn't as clear as I'd hoped. My second graph was more clear.

So isn't this the argument Lindenwood made on the first page?

The context of the discussion was drop off in power above certain speeds. I was ultimately commenting on how power at any given speed relates to the amount of torque at that given speed. The implication is that more power at any speed means more torque at the wheels. The argument originally made was that power drops of anyways so it's irrelevant, but the examples I have later prove otherwise.

Didn't Porsche address this with a 2-speed transmission?

Sure. But to a large degree, so did Tesla with the Plaid motor. Transmissions help acceleration by keeping the engine at or near full power. More gears and shorter spacing keeps three vehicle running where there is more HP. Through the transmission, peak HP always results in the most torque at the wheels at a given speed. Consider if more and more gears are added. If you're a math geek, it's basically an integration as the number of gears goes to infinity. A CVT does essentially just that and that's why you see the 5-sp curves in my second graph start to converge with the CVT curves (the gearing is spaced shorter in the higher gears). If it were possible to have engines run at peak power through a CVT from 0 through to speed, two engines with different HP curves would accelerate identically if the peak HP was the same as the HP and torque output at the wheels would be identical. The same is true if you had an engine or motor put out the same HP at all RPMs.

 

[Izzyz28]

If you've ever driven a M3P, you know full-well it falls on its face. If you ask a random internet stranger on a car forum about the M3P, the responses will be "it's a one-trick pony", "LOL, worthless from a roll", "0-60 is all it has", and of course "it's fun up to 60 but then falls on its face, got bored with it after a month".

 

[mpgxsvcd]

If you've ever driven a M3P, you know full-well it falls on its face. If you ask a random internet stranger on a car forum about the M3P, the responses will be "it's a one-trick pony", "LOL, worthless from a roll", "0-60 is all it has", and of course "it's fun up to 60 but then falls on its face, got bored with it after a month".

How many "random internet strangers" do 130 mph down the highway on a regular basis? How do you all not get tickets all the time driving like that? The cops are everywhere around here. All of our open highways where you can achieve those speeds have cameras and cops waiting up ahead.

 

[golfcart]

I think what I would say is that the P3D, when compared to other cars that can go 0-60mph in 3 seconds, is not particularly quick from 60 - 120mph. So a lot of cars that you'll absolutely smoke from a stoplight will pull on you over 80mph. "Falls on its face" is a bit hyperbolic, but the torque curve clearly shows that it falls off quite a bit after 70mph so I understand the feeling.

I think Lindenwood nailed the gearing discussion right from the get go in this thread. You can use gears to stay in the fat part of the torque curve but they are not magic. At higher speeds you have to use a less advantageous gear ratio so torque to the wheels does drop off and acceleration with it.

 

[CKwik240]

I think Lindenwood nailed the gearing discussion right from the get go in this thread. You can use gears to stay in the fat part of the torque curve but they are not magic. At higher speeds you have to use a less advantageous gear ratio so torque to the wheels does drop off and acceleration with it.

Typically, most engines have peak HP somewhere in the meat of the torque curve, but usually after the torque peak. But it's actually keeping HP as high as possible gives you the most torque at the wheels. HP essentially tells you where the given torque in an engine will provide the greatest mechanical advantage.

 

[mpgxsvcd]

Typically, most engines have peak HP somewhere in the meat of the torque curve, but usually after the torque peak.

It would be impossible to have the HP peak occur before the torque peak. By definition peak torque must occur at or below the peak HP rpm.

A line of constant torque has constantly increasing HP. Even in that case Peak torque happens at Peak HP rpm only because torque is constant.

 

[scalbert03]

"Doesnt pull as hard as XXX / YYY" is whats actually happening, but "falls on its face" is a term designed to instigate an argument, either accidently, or accidently on purpose, and it doesnt have anything to do with insulting inanimate objects, it has to do with going out of the way with hyperbole to make a point.

I am curious where 'falls on it's face' is a term designed to instigate an argument? The term has been used since vehicles started racing. It is meant to state that the acceleration rate tapers quicker than other vehicles the individual has experienced. Yes, it is a hyperbole in that it isn't meant to be taken at face value. But is a common term in racing.

 

[scalbert03]

That'll be the issue. I'm used to a higher level of hyperbole being completely normal in general conversation centered around cars, and most of us naturally avoiding getting our feelings involved because we're used to a comedic/aggressive banter. (and forum threads being used as general conversation between like-minded individuals rather than reading it like a debate)
Maybe I got too old for the Model 3 crowd. Heh.

We have a bit of an interesting mix of people here that normally wouldn't be intermingling IRL as anything other than strangers, so there's bound to be some issues discussing things, I suppose.

The natural progression of internet discussions on vehicles. No different than in the mid-90's with email Listserv's and no forums.

 

[Black306]

The natural progression of internet discussions on vehicles. No different than in the mid-90's with email Listserv's and no forums.

Just talk to Jesse. M3Ps have an issue with the induction map, it’s got a nasty hole. That’s why they unload at 100mph. Gotta length the magnetic pulse another millisecond and tune the timing, they’ll run 9s.

 

[golfcart]

Typically, most engines have peak HP somewhere in the meat of the torque curve, but usually after the torque peak. But it's actually keeping HP as high as possible gives you the most torque at the wheels. HP essentially tells you where the given torque in an engine will provide the greatest mechanical advantage.

I don't disagree with anything you said here (aside from removing the "usually") but I am not sure how it applies to my comment. HP = (Torque x RPM)/5252 so you can easily calculate HP given a torque curve. Yes, you want to shift in such a way that maximizes your use of HP... I just said gears aren't magic meaning that you won't accelerate just as hard in 5th gear as you would in first gear even if you are at near your peak HP rpm in both instances because your mechanical advantage from gearing is much less in 5th.

 

[CKwik240]

It would be impossible to have the HP peak occur before the torque peak. By definition peak torque must occur at or below the peak HP rpm.

A line of constant torque has constantly increasing HP. Even in that case Peak torque happens at Peak HP rpm only because torque is constant.

Correct. I had to kind of prove it to myself again but I was between meetings when I posted this and the next one was about to start. Didn't want to misspeak.