So i have been thinking this over and over, 1)does (in LFS) the red light at the HUD means you MUST shift to get the best out of the car? 2)And how can we know whats the best RPM to shift up/down? i've seen theres a line at the car specs that says "X power @6500 RPM" 3)does that means its the RPM line wich the car gets the highest torque?
X power @ 6000rpm means it has the most horsepower at that rpm, not torque (that's why there is a X Nm torque @ 4500rpm). However, the red light that flashes up signalises the ideal shift point for the current gearing, so you should always shift up as soon as you see it go on.
When to downshift depends on the situation, as the quickness of downshifting can greatly affect the brake balance, and thus what happens at corner entry. If you mean when to downshift while accelerating, well it should be quite obvious when the car has no power due to a too high gear, no?
i personally think that the rev limiter should be just after when the red dot comes on, not 2 or 3000 more revs to go... can i ask why the car has all that more way to go before the limiter please?
Because the limiter is there to keep the engine from tearing itself apart. If it were right after its peak power output, then it would leave you no time to shift and then it would hit the limiter and then it would drop power and speed, etc.
I have always understood the red shift-light coming on to mean that there is more torque available in the next gear, depending on the track and situation its sometimes better to hold a lower gear for longer, even up to the limiter (just before a brake zone for example).
OK, attached is an image from Bob Smith's latest setup analyser (thanks Bob!).
This shows a gearing chart for the XFG. Each single curve represents the engine's torque curve. They are then scaled by the gear ratio of each gear to give the family of curves shown here. The x-axis is wheel speed (not engine speed) and the y-axis is wheel torque (not engine torque).
The tall pointy gear is first, the low flat one is fifth. The point of gearing is to always keep the torque at the wheels (not the engine!) maximised across a wide range of speeds. You start off in first gear at low wheel speed, then as the car accelerates you move along the first gear torque line in the direction of increasing wheel speed. The ideal shift point occurs when more torque is available in the next gear, so when the first gear line crosses the second gear line, you should shift.
Note that, with this gearbox, the shift point from 1st to 2nd is almost at the redline, whereas the shift point from 4th to 5th is much earlier in the rev-range.
One thing to add is that this is exactly the same as shifting when more power is available in the next gear. Then you don't even need to differentiate between power at the engine and power at the wheels as power doesn't get scaled by gears.
Actually they don't rev that high at all.
The XRT has it's peak power at 6000 rpm, the XRG only at 5950 rpm and the XFG peaks at 6871 rpm. Those are ambitious, but alright figures. However the redline isn't where it should be. In most roadcars the red line is just above peak power. In LFS there is a fair margin. That has a lot to do with LFS's very very basic (and very forgiving) engine damage simulation.
So if you discount the very optimistic redline the rev-figures aren't that far off at all.
Hmmm..., thanks.
But is it correct to say (i think it is) that the best time to shift up (while accelerating, heh) is based on the peak of the torque right? i mean if the torque peaks @ 5000rpm the you will mostly shift up(in every gears) at (for example) 6500?
Nope. You shift when the next gear offers the same hp as the current gear, as explained. It is equivalent to shifting when the next gear offers just as much wheel (not engine) torque, which is stated as well.
You cannot possibly work out when to shift WITHOUT considering the whole power (torque) curve AND the two gear ratios. Not possible. So looking at only the torque peak is quite useless.
XRT and XRG figures are about in the right range. XFGs peaks are rather highish though. If you think it as a hot hatch type car (type R and the likes) it makes more sense. XRG and XRT are more like normal road cars having their peak torques at 4500rpm and peak power a bit later.
The power one works, but you can't do as much with it (imo).
Here are two, for my Reynard. The drag curve is an estimate, and is not for a particular setup (yet).
Tractive effort is the wheel force (in Newtons), which IS affected by gearing.
Tractive power is the wheel power (in horsepower), which ISN'T affected by gearing.
Edit: For reference:
Peak Power is 190hp at 6000rpm
Peak Torque is 180lbf.ft@4500rpm
