You need to stop thinking in old fashioned petrol head terms such as horse power and think about torque. It is torque that causes a wheel to rotate and hence a car to accelerate. Power is simply torque multiplied by speed.

Power = torque x speed

Watts = Nm x radians per second (rotational speed)

Depending on the design of the motor, the torque can be fairly constant from zero to high speed, hence acceleration can be much greater than the nominal power figure suggests in a petrol engined context.

 

This makes a lot of sense although I wonder why they don't mention Torque in there specs, like most car manufacturers do now, Torque has seemed to be the buzz word over the last 5 years or so which I can understand.

It's the amount of current that the battery can provide that is restricting the power available, not the motors.

Yep can understand that, I believe 1300 amps or 1500amps with new fuse for Ludicrous mode.

I think it was the 463hp moving a 2.2t car to 60 in 3.1s, when up to 762hp could potentially be available and have seen this written down in articles, this would make much more sense for a car weighing this much, if you thought in the 'old way' and not considered torque as Mark B has suggested.

I guess this came around as my Porsche has more power 500bhp weighs 3/4t less but will hit 60 .1s slower...

#1st world problems.

 

As I read it P90D has 503 hp rear, 259 hp front - Motor, this bit's pretty clear.
This is the bit that's confusing:-
532 hp (Ludicrous) *
463 hp *
* Battery limited maximum motor shaft power.

It's the amount of current that the battery can provide that is restricting the power available, not the motors.

 

What was interesting for me when I was deciding whether to go for a P model, is that the quoted HP for a P90D (463) is with Insane mode switched on. When in Sport mode, the power output is the same as the 90D. I had this confirmed by the Sales Manager at the time. I ended up going for the 90D.

 

As far as I am aware, the 90D wiring can supply 1000 Amps, a P90D 1200 Amps and a P90DL 1500 Amps. Maximum power occurs only at high rpm and is a totally irrelevant for an electric car with no gear change. A petrol powered car can operate around the maximum power peak by changing gear, but this is irrelevant for an electric car with one gear ratio.

Obviously to get maximum performance from your car you need a well charged and warm battery and warm tyres and asphalt

 

That makes very interesting reading, Simon, thanks.

The dyno on the Tesla was not what I was expecting to see but does explain that initial punch in the back feeling that is different from the Porsche, with so much Torque available instantly.

And I have no doubt either that the Porsche would be far quicker to 120mph, but I'm purely guessing of course as have not taken it on a track to find out and anyway I can't test it, as since getting the Tesla 2 weeks ago, the Porsche has been in Porsche getting more work done luckerly under warranty (even German cars break down )
Also the 40-70 feels slower in the Tesla, I know this would be different if it had the Ludicrous option. (I'm not excepting either to be similar as they are 2 completely different beasts, it's just a nice comparison between 2 totally different cars, that happen to have almost identical 0-60's)

Is the other dyno graph from one of your own cars? Just under 470bhp at the wheels! Is that after a remap?

 

Is the other dyno graph from one of your own cars? Just under 470bhp at the wheels! Is that after a remap?

Not one of mine unfortunately... I have to make do with "only" 350bhp (at the crank) but then it weighs the same as a crisp packet, so goes well enough

There is a German firm (Komotec) that will take mine up to 500bhp, but it's still in warranty, and frankly even on track it's plenty fast enough for me.

I know what you mean about different beasts, headline numbers really don't tell the whole story.

 

As a pedant may I point out that the curves only cross at 5252 rpm if you are plotting power in bhp and torque in lb.ft on the same scale? Those of us who were brought up using SI might do things a little differently.

 

Those of us who were brought up using SI might do things a little differently.

Theoretically I was brought up on SI too (I'm not that old.)

Probably more important is where you grew up. I was brought up here in the UK , so we are stuck being half metric / half imperial.

What's the speed limit?
What size container is beer normally sold in?

But the single critical test as to when we finally go full on metric, is when McDonalds UK start selling a "Royale with Cheese"

 

An electric motor supplies constant torque up to it's base speed and then constant power up to it's maximum speed. It can usually operate above the stated maximum but at much lower efficiency. To move a vehicle the highest true demand is at zero speed and this demand drop as the vehicle accelerates (at least in the normal range for a road vehicle).

an antique ICE has zero torque at zero speed and bugger all at idle usually which is why you need a clutch. An ICE will also deliver maximum torque a good way towards it maximum speed, and maximum power a bit higher up the speed range. Because it's os peaky it need several gears so the optimum one for the desired speed can be selected. Without a gearbox cars would either be very slow to accelerate or have very low maximum speeds. It's all rather quaint

Conventional dynos have real difficulty in getting any sort of reading from EVs because of the high torque at low speed characteristic. On most of the plots I've seen you can see the traction control system is going nuts and the dyno controller is all over the place until you get to quite high speed. Makes for some really interesting (but useless plots)

 

Also the 40-70 feels slower in the Tesla, I know this would be different if it had the Ludicrous option.

When I test drove a P85D a while back I really wasn't that impressed by the 50mph+ pulling powered compared to my 335i running a remap with 380bhp at the wheels.

But one thing to remember, you can only get peak performance from the combustion engine if your in the right gear, add in the need to wait for oil to get up to temp, and than the chance of something breaking if you use full throttle all the time, oh and buring fuel at <10mpg, in the real world EVs offer you much more chance to use the performance.

 

I was brought up using rigorous SI, but then I started working with Americans. So I had to teach myself Imperialist ways and now get to ask questions like 1) Which pint (16 or 20 fluid ounces)? 2) Which barrel (oil, dry mass or chemical drum) 3) Which gallon etc etc.

As for UK beer glasses, they may be a pint but I typically only get served 500ml in one.

But consider the following, car wheels and tyres are in inches despite MIchelin's attempt to metricate some years ago.

Hydraulic and air conditioning fittings tend to be Imperial even on German cars. Mercedes sump plugs need a half inch socket as it is considered a hydraulic item.

German domestic heating uses imperial pipe sizes with British Standard Pipe threads, whereas ours are metric.

And when Volvo patented the three point seat belt (and allowed everyone else to use it without charge) they specified a 7/16" UNF bolt, which is what all seat belt fittings use to this day. Unfortunately the metric Nazis in the ISO can't tolerate this so they have redefined it as M11.1 (an 11.1mm bolt!!??), but I don't know how they have defined the thread pitch (UNF being threads per inch and metric being pitch length in mm).

But the one that still gets me is American tape measures in the oil industry being in decimal feet (an item measures 10.25 feet rather than 10ft 3 inches) as it is much easier to add up pipe lengths correctly.

I could go on but I can see your eyes glazing over again.

P.S. The speed limits on UK roads might be in mph, but inland waterways are in km/h as the civil servants forgot about those during the negotiations. So all the locks on the Thames, for example, changed the "5 in a red ring" sign to "8 in a red ring" and so all the boats went at 8mph. They had to get new signs made saying 8km/h. I don't want to think about the cost.

 

@Mark B Tyres, the most crazy mismatch of "standards". A hotch potch of imperial/metric AND non-dimensional numbers