2014 engine power from onboard videos

[PhilS13]

See lower right corner purple arrow

[Blanchimont]

Thanks for wind info, let's see if the data shows the same wind conditions.

The first picture shows the DRS sections, the blue line from the back straight shows a slightly faster increase in speed than the red line at the start finish straight, but the difference is not that big. If Rosberg had the same power available for these two sections, then i would say the wind was pretty much the same for these two parts.




Here are the speed curves of the Non DRS parts of the track, the lowest acceleration can be found from T2 to T4, the fastest from T13 to T14 towards the end of the lap. The yellow and the green one are close to each other, so are the red line (slightly uphill) and the blue one. The difference between the yellow and the blue line could indicate that the wind was blowing from T13 to T14 and Rosberg had a headwind during driving from T2 to T4.



And finally, all sections together in one graph for a comparison of DRS and Non DRS straights. The difference is clearly visible. Unfortunately the beginning of Rosbergs pole lap wasn't part of the youtube video, the part were DRS is used from 280km/h to 326km/h.



I'll erase the T8 to T9 line because it was recorded in an uphill section and delete the first second of the T2 to T4 line, where it seems there occured some wheel spin from after T3. Let's see if the results change or stay the same.

Any other interpretations?

[Artur Craft]

As the drag is a function of v^3, the power that is available for accelerating above the traction limit is also a function of v^3 and becomes a line when plotting P against v^3. The point where the blue line of P_acc crosses the vertical axis shows the engine power, even if we would only plot P_acc. The point where it crosses the horizontal axis is the maximum speed.

Any errors in my assumptions?

Drag and downforce/lift acting on the vehicle are a function of v^2

[Lycoming]

As the drag is a function of v^3, the power that is available for accelerating above the traction limit is also a function of v^3 and becomes a line when plotting P against v^3. The point where the blue line of P_acc crosses the vertical axis shows the engine power, even if we would only plot P_acc. The point where it crosses the horizontal axis is the maximum speed.

Any errors in my assumptions?

Drag and downforce/lift acting on the vehicle are a function of v^2

Drag force is proportional to v^2, but drag power is proportional v^3.

[Pumaracing]

Hi Blanchimont,

I have full computerised vehicle performance simulation available to me (self written over many years) and I can calculate bhp from acceleration or vice versa taking into account all factors such as gearing, drag, mass, rotational inertia of wheels, tyres and engine components, headwinds, tailwinds, up and down slopes. I use this program to optimise gearing for my engine customers. My field is race engine building. I've been looking for data such as yours for a while now and have even posted a request for someone to do this from onboard footage but have only just found this website.

I can work with you on this but need the data in tabular format rather than trying to interpolate it from graphs. Speed versus time in 1 second increments would be fine and then I can get the computer to vary power and drag until it matches your curves at both low and high speeds. Obviously slopes and wind speed are a big factor but maybe we can find a way to either find those out or eliminate them. I can certainly pin down wheel bhp very accurately, within 1 percent, if the acceleration data I have is accurate. Then maybe we can get back to crankshaft bhp with further work. Looking forward to hearing back from you.

regards

Dave Baker
Puma Race Engines

[Blanchimont]

Hi Puma,

it would be cool if you could check the speed data with your simulation. I think I'm working on something similar right now with the help of Freemat, an opensource Matlab software. Thanks to hollus for the thoughts on this.

So, here's he data with t in seconds and v in km/h, now also with the acceleration from the beginning of the lap. The maximum speed was 326km/h in 7th gear at ~11500rpm with DRS activated.

Have fun!

T14 to DRS_line prestart

t	v
3,52	202
3,72	208
3,92	215
4,22	222
4,42	228
4,62	233
4,92	239
5,12	244
5,42	250
5,72	255
6,02	260
6,52	268
6,82	273
7,22	278


DRSline to T1 (DRS)

t	v
7,62	282
8,12	288
8,62	293
9,22	298
9,82	304
10,49	309
11,29	314
12,22	319
13,49	324


T2 to T4

t	v

11,31	215
11,58	221
11,98	229
12,31	235
12,54	241
12,88	247
13,18	252
13,48	257
13,88	263
14,18	268
14,58	273
14,98	278
15,48	283
15,88	287
16,48	291
17,11	295


T8 to T9 (uphill)

t	v
37,84	160
38,07	169
38,14	174
38,34	182
38,54	189
38,7	195
38,9	202
39,14	208
39,47	217
39,64	222
39,84	227
40,07	232
40,34	239
40,64	244
40,94	249
41,24	255


T10 to T11 (DRS)

t	v
48,07	168
48,24	178
48,47	186
48,67	194
48,84	202
49,07	209
49,24	215
49,47	222
49,67	228
49,87	234
50,07	239
50,47	249
50,87	258
51,24	267
51,54	272
51,87	278
52,24	283
52,54	288
52,94	293
53,47	298
53,94	303
54,47	308


T13 to 14

t	v
10,76	175
10,96	183
11,09	188
11,26	195
11,46	202
11,66	208
11,86	214
12,06	219
12,26	225
12,46	230
12,66	236
12,96	242
13,26	248
13,56	254
13,89	260
14,13	265
14,56	271
14,96	277
15,36	282
15,76	287
16,23	292
16,86	297
17,66	302
18,33	307


T14 to DRS_line

t	v
23,48	173
23,54	177
23,74	185
23,94	191
24,14	197
24,24	202
24,48	208
24,68	213
24,88	219
25,08	224
25,24	230
25,54	235
25,74	241
26,11	247
26,34	253
26,64	258
26,91	263
27,14	267
27,51	272
27,91	277
28,24	280



DRS_line over Finish Line (DRS)

t	v
28,24	280
28,64	285
29,14	291
29,64	296
30,11	300
30,68	306
31,14	310
31,64	314
32,28	318

[Pumaracing]

Well it seemed like an excellent idea but there is really too much variation in the acceleration rates at different parts of the track. Even taking just one curve I can see strange things happening at different parts of the speed range. For example I can get the bhp right at the low speed parts where drag is not a big factor and then at the top end by adjusting the drag but it goes wonky in the middle almost like power is cutting in and out which of course it could be with this new engine system.

However I get a reasonable approximation at about 690 wheel bhp which would indicate around 770 flywheel bhp after factoring in transmission and tyre losses. With really good data such as a car magazine test on a dead flat test track and either no wind or a known wind speed I can dial in an entire acceleration curve from zero to top speed to within a tenth of a second all the way through but we just don't have good enough data here. Too many unknowns of slope, windspeed and possibly power actually varying down a single straight.

[Tommy Cookers]

anyway your transmission and tyre losses seem to be vastly greater than Blanchimont's

[Pumaracing]

Transmission and tyre losses are very well known for road vehicles but obviously there is not going to be much data for F1 cars. However the basics of gear tooth and bearings losses are fairly standard. For normal 2wd road cars in the sub 200 bhp category total losses are about 15% of flywheel bhp. Hub dyno data from such places as the Rototest Institute indicate that average transmission losses between crankshaft and wheel hub are about 7%. The balance is lost in the tyres themselves.

As bhp goes up to F1 levels the percentage losses do fall but I would be very surprised if they are less than 10% total.

[Pumaracing]

Ok I've got some more info for you. I found the actual gear ratios in another thread which helped quite a bit. By averaging the DRS and non DRS plot lines I've got a reasonable estimation of the difference in drag. I assume a frontal area of 15 sq ft and the drag coefficients come out as approx 0.82 without DRS and 0.66 with it so a 20% reduction with the flaps open. Top speed comes out at about 320 kph without DRS and 340 kph with it.

Your estimate of the additional effective mass for rotating components is a bit low at 5% of the base mass. My program splits wheel and tyre inertia into one segment and engine component inertia into another which varies in each gear and is most important in low gears. However in the higher gears and for your purposes if you take 8.5% total it will cover both. I've taken 700 kg as the base mass to allow for a bit of fuel so effective total mass is 760 kg.

Tyre rolling resistance I have as 0.013.

My program uses a full power curve obviously rather than just a single bhp number and I come up with 700 bhp wheel figure at the maximum fuel flow point of 10,500 rpm and approx 690 bhp average over the full rpm range used which is from about 10k to 12k. Anyway if you rework your calculations with these new assumptions hopefully you'll get a better fit to your speed data.

[Foyle]

Great work. A suggestion:

Use 3 consecutive frames from the overhead shot of the start at Bahrain to give you position=>velocity=>acceleration=>power at just above the traction limit speed (guessing about 2.5s after start). before drag is significant. Allows you to compare multiple cars and multiple engines against each other under known conditions of weight (790kg with possible +/-10kg), with guaranteed max power being used.

Could finally end the speculation about engine power with some actual numbers for different cars and engines under equal conditions.

[sectionate]

May i introduce to you a method to estimate the power output of the 2014 PUs.

At first i calculated a generic F1 car with:

Power = 750 hp = 552000 W (at every single rpm, the 2014 cars should come close to this)
rho/2*cd*A = 0,655 (= power / (340km/h / 3,6)^3 )
rho/2*cl*A = 3*0,655 = 1,965 ( this car has an efficiency of 3=cl/cd )
mass = 695 kg
friction_coefficient = 0,015 (it better should read rolling_resistance_coefficient)

From that i could calculate P_drag(v), P_roll(v) and P_acc = P - P_drag - P_roll. P_acc is the power that can be used to accelerate the car, in reality this is only valid above the traction limit.

The following plots were the result, the first showing P [W] as a function of v [km/h], the second one P as a function of v^3.
As the drag is a function of v^3, the power that is available for accelerating above the traction limit is also a function of v^3 and becomes a line when plotting P against v^3. The point where the blue line of P_acc crosses the vertical axis shows the engine power, even if we would only plot P_acc. The point where it crosses the horizontal axis is the maximum speed.

http://i.imgur.com/8R8w180.png

Any errors in my assumptions?

You do realise that power is a function of RPM?

[Lycoming]

You do realise that power is a function of RPM?

Not if your fuel flow is restricted above a certain RPM.

[hollus]

...My program uses a full power curve obviously rather than just a single bhp number and I come up with 700 bhp wheel figure at the maximum fuel flow point of 10,500 rpm and approx 690 bhp average over the full rpm range used which is from about 10k to 12k...

That is very interesting. How clean is the fit to model you are getting? Even better, can you show the engine power curve in your model? From the Cosworth V6turbo thread and some logic involving upshifts it was assumed that engine builders were aiming for maximum power somewhere around 11000-11500rpm.
If Mercedes really peaks at 10500 (either the team or the engine), maybe that would be one things they are doing differently to the rest.

[Pumaracing]

The shape of the power curve in my simulation is what I've calculated from the fuel flow limits. There is not enough data here to try and fit the power curve to the car acceleration. They accelerate too quick and the graphs are too variable. However I can certainly deduce an entire power curve with perfect acceleration data in a single gear from a road car i.e. from a well conducted magazine test on a flat track. I can even see quite clearly the lower transmission losses in a direct 4th gear in the old rwd cars with a 5 speed box like capris, escorts etc.

I remember running a simulation of I think it was a Rover V8 about 25 or so years ago from an old Autocar Magazine track test. The in-gear times matched perfectly for all the gears except 4th where the actual car was a bit faster than the simulation. I scratched my head until finally I realised 4th is a direct gear of 1:1 ratio in a rwd car and I dropped the transmission losses by 2% in that gear and it all matched up again. Ah the things we fritter our time away on eh? Still, it's all good fun and usually instructive.

Which thread is that exactly you refer to? I'll have a look.