Brazilian GP 2010 - Interlagos

[Tim.Wright]

It's harder on the engines becuase the engine has to deal with the same load with less power.
Imagine going up a hill with less power. That's more strain for the engine, since the throttle has to opened up more to get the same result as if the altitude was lower.

I'm not convinced high altitude is worse for the motor. My logic is;
high altitude = less pressure = less air pulled into the cylinder = less cylinder pressures = less force on the conrod = less force on the bearings

I Brazil is hard on engines, sureley it must be for some other reason (long straights)

[ringo]

well first you have to look on what 800m of elevation does to the atmospheric pressure. Such a small change in pressure is not enough to relieve the stress on parts considerably.
800m of elevation is about 7.3% drop in the value of pressure at sea level.
instead of 101325 kPa it's 93955kPa
It isn't really much of a reduction in stress if we take into account the compression ratio is what 13.5? that along with a 8% power loss.

The real stress comes with the work the engine has to do.
I would imagine it's like lifting a weight in a room with constantly decreasing oxygen. Less oxygen the harder the work gets, since your arms have less power to do the same work.

I think the pikes peak hill climb is a good example.

[spinmastermic]

Less Oxygen = Less Power = Less stress

[ringo]

What about the load? That has to be considered.

You are saying that if i block the throttles, basically stifling the engine of oxygen, and put the same load on it, it is less stressed.

[alelanza]

I'm not convinced high altitude is worse for the motor. My logic is;
high altitude = less pressure = less air pulled into the cylinder = less cylinder pressures = less force on the conrod = less force on the bearings

I Brazil is hard on engines, sureley it must be for some other reason (long straights)

That's exactly right

What about the load? That has to be considered.

Load will not vary due to altitude. If anything drag is reduced, assuming same aero package. Unless i misunderstand what you mean by load.

You are saying that if i block the throttles, basically stifling the engine of oxygen, and put the same load on it, it is less stressed.

Yes it would be less stressed as long as it can still run within a reasonable rev range (before knock appears). Look at it the other way, if more pressure and oxygen were beneficial to engine life, we would all be running extremely cheap and fragile yet infinitely boosted turbo engines.

[ell66]

can anybody explain to me how jenson thinks he has a chance? iv jut read on the bbc that he wont give up.
even if it were a stright 2 horse race between himself and alonso, he;d have little to no chance. but theres another 3 guys inbetween all a lot closer, theres NO chance of them all screwing up the last 2 races, even if they did id fancy kubica over jenson to be perfectly honest.

why cant he suck up his pride and help the team/lewis?

[raymondu999]

I think what Jenson said was more along the lines of "Probably won't win it, but until I'm mathematically out, I'm fighting"

[omar2726]

It's kinda hard to accept that you lost to your teammate, especially if you're the defending champ, especially if your teammate is Lewis.

[forty-two]

theres NO chance of them all screwing up the last 2 races

While I think that the likelihood of them all screwing up is low, to say that there's NO chance is a little unfair. I can think of a number of ways that all other drivers in contention for the title could have problems.

How about these for possibilities:
- 1st corner incident could easily take out 3 or 4 of the drivers at the front. It's happened plenty of times in the past. In this situation, a "poor" qualifying for JB could well mean that he's far enough behind to avoid the crash and then able to capitalise.

- Ferrari are marginal on engines, Red bull are not in quite as bad a position there, but Vettel's engine blowup in Korea could be a sign of things to come for the next two races

- What if SV and MW are fighting toward the end of a race, we've seen them take each other out before this season, it would not be beyond the realms of possibility for a similar thing to happen again, especially now the pressure is piling on. Who's to say that such an incident might also knock one of the other title contenders out for one race?

I'm not saying that Jenson is a dead-cert for the title, not by any means. But to say that there's NO chance of the others having a problem is certainly incorrect.

[GTO]

Less Oxygen = Less Power = Less stress

All you guys that belive this should run 5k at sea level & then at high altiture & compare your findings.

[spinmastermic]

Any decrease in stress would be tiny.

Why we gotta run? A 5k shuffle sounds better.

[Tim.Wright]

...
I would imagine it's like lifting a weight in a room with constantly decreasing oxygen. Less oxygen the harder the work gets, since your arms have less power to do the same work...

All you guys that belive this should run 5k at sea level & then at high altiture & compare your findings.

All you guys making analogies between the human body and an engine at altitude need to think a bit more logical.

The only load an engine sees is the inertial reaction to the torque it produces itself. E.g. if the engine produces 500Nm, then the internals are stressed to 500Nm. If the engine can only produce 450Nm at altitude, then the internals are only stressed to 450Nm.

The simple fact that the engine produces less power at altitude means there is less stress on the engine internals. Nothing to discuss.

Like I said, if brazil is hard on engines, its not a primary effect of the altitude. There might be some secondary effects (eg to do with thermal dynamics, oil viscousity etc etc) which come into play at low atm pressure but I'm not an engine guy so I can't say.

Tim

[ringo]

Look on it this way Tim. The engine is almost like the human body or living thing if you want. They all take chemical energy and turn it to mechanical energy.
If you are short of breath while doing a job, you have the breath faster to compensate.

If there is roughly a 7% decline in atmospheric pressure and a subsequent reduction in power, you engine will be making less power over the whole rev range.
This means that even though the engine is limited to 18,000rpm, it will still be down on power at 5000, 12000, 14000 rpm etc.
At certain points on the track the engine will have to run at a higher speed to deal with the same loads it would deal with at any other track; the load being moving the mass of the car, which does not change with altitude, up and down inclines, accelerating out of corners etc.
It follows that if the engine is spinning at 15,000 to produce a certain amount of power, it would need to be spinning at 16,180 rpm to produce the same power in 7.2% lower atmospheric conditions.
So the average kinematic stress through the rev range is increased, even though the engine only goes to 18,000rpm. And well all know that the kinematic stress in an engine is much more critical to the parts than the compressive stress.
That little savings on compression afforded by lower pressure, doesn't change much for the adiabatic combustion pressure either; which is what forces the pistons down.

If a team is satisfied with making lower power at 15,000rpm to accelerate out of the corner or to have a lower top speed, when another team keeps up performance by going to 16,180 it's easy to see who wins here.

So It's always a balancing act with saving engines. In a sense, the altitude does not stress the engine anymore if you chose to accept the reduced performance to do reduced work. But if you want to do the same work you would do in denser air, you would need the same performance but at a cost of increased stress.

edit: I guess this sounds like a gear ratios game; it's one way of controlling which parts of the track match with which rpm.

[omar2726]

Less air density means less molecules to cool the engine right?

[alelanza]

The engine is almost like the human body or living thing if you want.

Really? so a 150000 km engine is probably better than a new one, i mean, it has exercised and increased its capacity, just like training athletes do.

If a team is satisfied with making lower power at 15,000rpm to accelerate out of the corner or to have a lower top speed, when another team keeps up performance by going to 16,180 it's easy to see who wins here.

A team satisfied with making lower power? This is motor racing.
What you're saying is only true if you had a set goal in terms of power levels, and it would have to be a goal that is less than your max power. But if you are in a scenario where you basically just give it all you've got, provided traction is there, then it won't make a difference. You'll still be at WOT, and if you reduce gearing to compensate you'll either be hitting the limiter on 7th gear going into turn 1 or you'll have some nasty gap between your gears.

Again, do you really think you can increase an engine's life by increasing boost?

Mario Theissen, BMW Motorsport Director

... Interlagos is about 800 metres above sea level. Due to the thinner air, all engines lose around eight per cent of their output. This makes the engine wear a little less as the loading on the crank assembly is slightly reduced. That will not only suit our team. Nick will keep running his ninth race engine which was fitted in Singapore, and Robert his eighth also from Singapore. Naturally we want to avoid fitting another new unit, which would mean being relegated ten places on the grid."