Net horsepower

[Hungfan]

Do you guys have any guess how much net horsepower is delivered for F1 engines?? We've been arguing and just could not rest the case. So what actual juice might get down to the tires from those official "above 700" horses?? Thanks!

[yelowca]

I only have a few so here it is:

BMW 760Hp
Honda 730Hp
Cosworth 750Hp
Mercedes 710Hp

Sorry, I can't find the rest

[Hungfan]

thanks, but I assume these figures represent the "pure" power of the engines not the actual-net hp that gets down to the tires, I guess I should ask how much is lost. Thanks anyway!

[West]

If you use the typical "15% lost in drivetrain" in road cars (RWD), just take 85% of said numbers.

[pyry]

yelowcas numbers are old, the new mercedes is said to have 770hp. also a typical rwd roadcar would have a 4 meter cardal and the overall weight, including the unspurg mass is probably over 60kg lighter in an f1, so id argue that the powerloss would be somewhat under 10%

[DaveKillens]

Some engine manufacturers use every trick to inflate the numbers. Engines are run at ideal conditions, with all auxiliarys run by external power. Water pump, alternator, oil pump, things like that are disconnected so as not to draw power. They even put in an unrealistic deep oil pan to reduce windage. So an advertised power level is nowhere realistic.
In Formula One, everything is designed for minimal power loss. But the oil pump system still takes a lot of power. Straight cut gears are more efficient than others, so the end result is a much reduced power loss in the drivetrain. But the hard part is that in F1, engines are in an eternal cycle of inprovement, they change on an almost weekly basis. And no one is frank and honest about giving out accurate power figures, they reveal nothing to their competition.

[jgredline]

If a Nextel Cup (NASCAR) looses only about 5-8% of its power to the rear wheels going through a gear box, drive shaft and axles, then my guess is that an F1 car would loose be no more than 2-3% of its power from the crankshaft to the wheels. Dave is right in that straight cut gears loose very little. They also run very trick slippery lubricants in the gear boxes.
As far as power output, those numbers are all rounded to the next highest even number. I would have to say that Ferrari has the most power with Renault and cosworth right there. Honda and BWW are close as well, but Mercedez is at the bottom. Like Kimi said, Barcellona is a place where you can't hide your flaws.

[DaveKillens]

AS jgredline pointed out, using low friction lubricant is one trick to reduce power loss. They also treat the gear surfaces with a low friction treatment like teflon. The gears run in an oil mist, more like a dry sump system to eliminate windage. Shafts are kept as small a diamater as can be without breaking, because a small diamater bearing has less frictional losses than a larger one. Same with the gears, they are as thin as possible.

[Ciro Pabón]

This should be easy and long.

Let's say, 2.5 seconds for 0-100 kph. We shall assume negligible drag with air, or, if you have figures for 0-50 kph or 0-20 kph, the better. I don't. I swear I won't change this value (2.5) as I write, value I haven't checked but took from the top of my head. Let's see where it takes us:

Acceleration = (100 / 3.6) / 2.5 m/s2 = 11.1 m/s2
Distance = (100 / 3.6)^2 / (2 * 11.1) m = 69.4 m
Mass = 600 kg
Force = 600 * 11.1 newtons = 6667 newtons
Work = 6667 * 69.4/1000 Kjoules = 463 Kjoules
Power = 463 / 2.5 Kwatts = 185.2 Kwatts
Power (hp) = 185.2 / 0.746 = 248 hp

First number: the power delivered to your a** is 250 hp.

To answer your question, we should sum the power dissipated on friction with air. From the 2.5 seconds I gave, we should discount the time the engine is idle because the pilot is changing gears. Can an F1 car reach 100 kph in first gear? I don't know. I assume you can.

Then, with:

Coefficient of drag = 1.0
Density of air = 12 kg/m3
Frontal area = 0.9 m2 (my guess)
Coefficient of rolling resistance = 0.012 (another, this time educated guess)

So:

Drag force = 1.0 * 12 * 0.9 / 2 * v^2 = 5.4 v^2 newtons
Drag power = 5.4 * (100/3.6)^3 / 2 joules = 57.8 Kwatts
Drag power hp = 57.8 / 0.746 = 78 hp

Rolling power = 0.012 * 600 * 9.8 * 69.4 = 4.9 Kwatts
Rolling power hp = 7 hp

Finally, second number:

Power to the wheels: 248 + 78 + 7 = 332.4 hp

Percentage of power to the wheels = 770/332 = 43 %

I think I have something wrong integrating the force over distance (maybe I did it over time?) to get the drag power, but you get the idea.

I would love for someone to correct this, as a mere 78 hp expendend on drag seem little at first sight. If you wish you can download these quick calculations here and try with different 0-100 kph times, or, if you have the time, correct the suspicious drag power part.

If you a) have live data and b) analyze the sound of the engine, you can even get a curve of engine performace vs rpm. So I do not know how they keep these things secret... You could do a little spying on the performance of F1 engines from the comfort of your own living room.

[Apex]

I feel that the assumption that the acceleation is constant is not correct.

Also during a 0-100kmph accel the traction control system is working overtime... The engine is not delivering all it can...

[Jason]

BMW - 760Hp
Honda - 730Hp
Cosworth - 7445Hp
Mercedes - 770Hp
Ferrari - probaly around 735-9Hp
Renault - probal around 736-8Hp

These are just my estimation, not correct I tihnk.

[Ciro Pabón]

I feel that the assumption that the acceleation is constant is not correct. Also during a 0-100kmph accel the traction control system is working overtime... The engine is not delivering all it can...

You could check the distance I gave versus reality to check the acceleration rate, or, if you are really into it , take a movie and analyze it by steps.

This is the power you need to move 600 kg from 0 to 100 in 70 meters in 2.5 seconds. If you wish, you can substitute the 70 meters for another figure to correct for uneven acceleration.

But this is irrelevant: the question is not about how much could it deliver, but how much it delivers to the wheels.

You are limited by "what the rubber can give you" all the time, not only at start, if you see what I mean. I guess you could "burn rubber" around the whole circuit if you put the pedal to the metal, except on the straights. In that sense, most of the power of an F1 engine (or a Corvette's! ) is "hidden forever" from the pilot: he can not use it to accelerate the car without spinning the wheels.

Actually, the less traction control you have, the less effective power you can deliver... in a Corvette, for sure, you have to "squeeeeeeze" the gas pedal, a gesture not always visible on F1 telemetry (but don't worry, old pilots never die, they just race away).

You have a really good point: most of the power is there to overcome drag, but I let the power calculation based on trap speed to other forum members. That, I would love to see.

[Mikey_s]

Ciro,

I am far outside my field of expertise here, but a few comments on the calculations that you did;

up to 100kph probably the drag is not too significant - so probably you are not too far out on your estimations - as I understand it the drag squares with speed, so it becomes increasingly significant as the speed climbs.

As has also been pointed out (and you have also understood) the cars are traction limited at lower speeds, therefore they are unable to use the power the engine actually has.

Finally, the car must have some fuel in it, so the weight should be more than 600kg.

The main point where the cars will be using every ounce of power the engine can deliver is probably at the end of the start/finish straight - max revs, max speed, max d/f (except for Ferrari with their bendy wings!!), no wheel spin/TC - by I guess that makes the calculations more difficult ( I wouldn't know because I was always useless at maths!!)

[johny]

Jason you've a dyno at home?

[Ciro Pabón]

The main point where the cars will be using every ounce of power the engine can deliver is probably at the end of the start/finish straight

Exactly. But if we take the "equation" I presented for drag and I remember well that Massa was doing somewhere around 318 kph in the speed trap...

Drag Power = 5.4 * (318/3.6)^3 / (2 * 746 ) = 2.500 hp

It would be nice for someone to correct this.

BTW, look what I read on FIA's site (F1's racing April 2004 interview), that explains your point in detail:

Stéphane Samson: I was in Barcelona the other day and watched a few drivers making practice starts. I was amazed to see there was absolutely no sign of rear-wheel spinning. Is that something you were expecting?

Charlie Whiting: Absolutely. There’s a big difference between traction control and traction optimisation. This brings us back to pre-launch-control days, when there were rumours about some teams using illegal traction control. You can do things based on known grip levels. Teams can say: “We know exactly how much grip we’re going to have with these types of tyres on this surface, so let’s modulate the power through fuel and ignition in order to optimise grip. So however much the driver puts his foot on the throttle, we won’t give him any more than this much power.” They can do that. Traction control is measuring the grip and altering the power as a consequence. That’s very different. Now, as far as we’re concerned, as long as the throttle and clutch are under the direct control of the driver during the launch period – from the moment at which the car comes to a stop on the grid to the time it reaches 100km/h – everything is fine. After that, traction control can take over.

Interesting. So the launch up to 100 kph (at least back in 2004) was under total control of the driver, if I read it well.