Re: Cosworth V8 may be the most powerful in the pitlane?

Da Frank wrote:
On Thu, 09 Mar 2006 22:41:32 +0000, Phil Newnham <pnewnham@xxxxxxxxx>
wrote:

The heat comes from the amount of work done. The V8 produces less power, so it will do less work. IOW, the cars will go slower, in a straight line, than they used to. Except they won't, because the aerodynamics have improved - the vehicle weight might be the same, but the dominating load is the aerodynamic drag, not rolling resistance. So the V8 will be asked to do less work than the V10 because of the improved rear

I don't think aerodynamics could have improved so much, that 150KW of
power would not be missed. If they could have, they would've done that
before.

The aerodynamics will be better than last year, because the engine is smaller and consequently they can get the wake of the rear of the car smaller. But also, they have stickier tyres, so the cornering speeds will go up, and the maths for best lap time will tend to go towards keeping the speed up on the straights, so they will use less downforce than last year in order to go fast.

engine. The heat equation is simple:

Energy from fuel = useful work + heat rejected through the exhaust + heat rejected through the radiator

But that is just an "energy" equasion. It has not much to do with how
and where heat occurs, how it travels and how it is dismissed.

No, true. But it is the fundamental equation governing the source of the energy. What I'm trying to get across is that the load doesn't do work on the engine - the engine does work on the load, and the energy for that has to all come from the fuel.

So if they simply underestimated the pressures on the components with
the new configuration, then it will nicely explain exactly why the V8s
are complaining about being 'uncomfortable'. Basically this is what i'm trying ot say with this whole thing, that
it's not all "power = heat". Although, i certainly agree with you
that power does determine the amount of friction right through the
engine. So in a way you're right, it's just that i think you are
thinking of it too simplistically.

I'm not saying that power equals heat. I did say that as a first guess approach, with a brand new engine you know nothing about, you would assume that power = heat in order to spec a test radiator. But that's a rule of thumb for a car engine, not an absolute thermodynamic rule. The equation is

energy from fuel = useful work + heat down exhaust + heat through radiator

The balance of heat down exhaust and heat through radiator depends on the engine in use. I can't answer for why your engine seemed to need less radiator when you tuned it up but the heat had to go somewhere, so it must've gone down the exhaust. But the V8 is down on power, not up. If it uses less fuel overall than the V10, then the total heat output must also be lower, because energy cannot be created or destroyed - it all has to come from the fuel. Maybe it will generate more heat in the oil and put less down the exhaust, but the total will still be less, so unless the balance is substantially different it should be easier to cool.

Your example of the trailer is flawed, because an F1 engine is always asked to work at maximum load, as opposed to my car, which is only asked to work at maximum load when I'm feeling rich ;). If the drag coefficient is reduced for a particular setup, then the car runs at a higher speed on the straights, and the engine is once again at max load.

No it is not. Maximum throttle or speed is not maximum load. "Maximum load" is at the time when you floor the pedal, provided
you're on the torque curve. This load will depend on the resistance
your engine has to deal with.

The load is what makes the engine do work, but the amount of work the engine can do is still limited by its energy supply. The maximum load for an F1 engine will be at the highest speed, because that's when the drag (aerodynamic + mechanical) is at the maximum value. That's why it stops going any faster.

When they switch to V8s they will still run the engine at max load all the time, but it will be less capable. The load isn't capable of generating heat (beyond skin friction heating of the car, but they're not going *that* fast) - all the heat has to come from the fuel. Unless you're suggesting that the engine's useful power output itself is reduced by running a higher drag setup, then the specific fuel consumption will be the same at max load as it always is, so the heat rejected will be the same.

Um.. no. As i've said, drive up a long hill at a nice steady throttle.
Note temperature readings of oil and coolant. Now hook on the trailer and using the same throttle setting, do the
same. You'll notice a higher temperature both in oil and water.
Is the engine using more fuel ? No. How could it, when it's getting
the same amount of fuel. So where does the heat come from ?

But if I drive up the hill as fast as I can go, in both cases, the temperatures should be the same, but the speeds will be different.

--
Phil

http://www.usefilm.com/photographer/31307.html
.

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