Hi all

Like probably many other racers, I would like to get the LFS cars dyno charts. They would be used for precise gear setup creation. I personally started a custom program which could calculate gear spacings with my own criterion, but without these damn torque curves :gnasher: .. frustration.

I havn't succeeded to estimate them or extrapolate them from .raf files because of the turbo lag, so I imagined a (crazy?) method:

• We already know two points of the torque curve: max torque and max power.
  
• Is there another accurate parameter? the red shift light. It is switched on every time the current engine torque is lower than the one that would be generated on the next gear at the same gearbox output shaft rotation velocity. And since it's calculated by LFS it is always right, no estimation (I think).
  
• So, when the red light switches on, we can deduce from the gear ratios the equivalent lower rotation velocity with same engine torque.
  
• But until then on the dyno chart we only have rpm coordinates, not torque ones. So we need as much "mirrored" rpm values as possible to get the curve shape, probably hundred or thousand equally spaced on the torque axis, that makes the idea crazy...
  

It's quite hopeless, but I want these charts. So I ask what do you think about it. Can it be a community work? Would it be easier and successful to ask the curves from the dev?

get replay analyzer

Torque curves are available, I've asked for them myself a long time ago and it wasn't new back then. Keep on searching. I think that Bob Smith has made some, ask him. But I'm not 100% if it was him or some other mod. But ask Bob anyway

Hello,

Have you checked Bob Smith's VHPA?

It contains torque/hp graphs for all cars, and more.
Press CTRL+G to see the graph bigger, and then guesstimate..

The grid lines, as far as i can tell, horizontally represent steps of 1000rpm, vertically steps of 50. Colors are Nm, Hp.

I did originally extract the curves from RAF data, but I haven't done it recently, and the torque curves got tweaked with patch Y, IIRC. Also, you don't get smooth data, and the low revs for turbocharged cars end up way off until the boost peaks. It was this old data I roughly shaped the curves in VHPA too - I have also been meaning to re-extract the curves and tweak them as necessary. The spacings and units in VHPA are customisable btw.

The curves I need must be processed by my program, VHPA's ones are estimations and I don't want to recreate the curve generation algorithm. I've also noticed a deviation between LFS and VHPA results, so I would like something more accurate.

BTW any replay analyzer can't generate torque curves...

PS: Breadfan, are you talking about this?

Quote from Bob Smith :

Also, you don't get smooth data, and the low revs for turbocharged cars end up way off until the boost peaks.

Isn't that the point of how turbos work? As they spool they create torque. I would just powerbrake to be honest, if you're not at the minimum RPM for the turbo to be spooled 100% that's not really that close to shift points. Though I have started to think that in the FZR power falls off at upper RPMs and a lower shift point might be better.

Anyway... Best of luck. I'll be interested to see how it all works.

Quote from jaxx751 :

Isn't that the point of how turbos work? As they spool they create torque.

Turbochargers don't create torque.

Quote from wheel4hummer :

Turbochargers don't create torque.

... you wanna be stupid about it I'll even say that turbos create vacuum.

Quote from jaxx751 :

Isn't that the point of how turbos work? As they spool they create torque.

Quote from wheel4hummer :

Turbochargers don't create torque.

Are you a member of the pedantic society? Or should that be society of pedants.

Quote from jaxx751 for the pedantic amongst us should have written :

Isn't that the point of how turbos work? As they spool they indirectly create extra torque.

Quote from jaxx751 :

Isn't that the point of how turbos work? As they spool they create torque. I would just powerbrake to be honest, if you're not at the minimum RPM for the turbo to be spooled 100% that's not really that close to shift points.

I think Bob is talking about turbo lag. Of course the turbo will not spool to it's 100% at low rpms but with the lag LFS turbos have, it will not be able to spool fast enough to produce the power it was supposed to in e.g. 2500rpm, when accelerating even with a single tall gear at the dragstrip.
You need a constant load in constant rpm to do this, which can't be achieved by just accelerating the car.

Anyway even if low rpm power is not that accurate at the graph, I think this doesn't matter that much because no one is using below 4000rpm when racing. So why bother?

Quote from jaxx751 :

Though I have started to think that in the FZR power falls off at upper RPMs and a lower shift point might be better.

I have found out long time ago and it is still the same way. That FZR's powercurve is quite flat up there... there is not much power variation between 7500 and 8500rpm. And this is logical considering the enormous powerband for a NA motor... (peac torque @ 5250rpm - peak power @ 8100)
Exactly the opposite from what you expect also happens to the turbocharged GTR cars where the powerband is much narrower. (peak torque @ 4800rpm - peak power @ 6300rpm)
It's not realy that unexpected for the power to drop off sustansialy after peak power for a turbocharged car, but this happens to be so profound at LFS turbocharged GTRs that makes them have a great disadvantage compared to FZR especially on fast tracks.
(I am speaking from experience being a member of the only team that didn't use the FZR in MoE GT2 class οf the last season. We where struggling to keep up in straights using the barely minimum downforce settings while FZRs drove with plenty of it despite having 9HP less due to the GT2 class restrictions. (!) )

My old method for dynochart generation with raf file, maybe it would inspire some peoples:



The rear tires don't touch the ground.
Engage a gear, apply handbrake and just press the long pedal.
Extract engine rpm vs time from the raf file, derivate it and voilà.

But the results for the XRT is very disappointing:



The max torque is not at 38xx rpm. I think the wheels acceleration is a lot too fast to erase the turbo lag on this chart...


Attached the layout I made for the operation.

I'll have stab tonight at a revised version the method I used to use, see how it comes out.

Quote from kaynd :

I think Bob is talking about turbo lag. Of course the turbo will not spool to it's 100% at low rpms but with the lag LFS turbos have, it will not be able to spool fast enough to produce the power it was supposed to in e.g. 2500rpm, when accelerating even with a single tall gear at the dragstrip.
You need a constant load in constant rpm to do this, which can't be achieved by just accelerating the car.

Anyway even if low rpm power is not that accurate at the graph, I think this doesn't matter that much because no one is using below 4000rpm when racing. So why bother?

What I was saying is even at full throttle and holding the brake at 3k RPM you often don't see full boost. in LFS there are limits to boost depending on RPM.

Quote from kaynd :

Of course the turbo will not spool to it's 100%

And I don't disagree with that. I just justified why you get even less than that low pressure the turbo is supposed to produce in low rpm when accelerating - without a constant load.
(All the dyno methods I have seen mentioned here do not introduce the use of brakes, hence the inaccuracy that Bob is referring to, in low rpm)

Anyway this is meaningless because no one cares about what the engine does in those lazy rpm in a race sim.

Quote from kaynd :

no one cares about what the engine does in those lazy rpm in a race sim.

Even when the race starts?

Do you ever start with less than 3000rpm in a race? Anyway this depends on the engine's powercurve, if you are talking about a diesel, 3K is considered high rpm but we are talking about most LFS cars here.

Seeing as I wanted to re-do all mine again anyway, I've started from the beginning, just did the UF1 again tonight to remember how it all works.

I added some smoothing, and got data on engine brake torque too:

Wonderful !
This seems to be very accurate

Do those numbers include some arbitrary drivetrain loss or is that at the wheels?

That is at the engine. In that case, I took drivetrain efficiency into account (85%), and then 'invented' an extra loss (presumably rolling resistance), and tweaked that until the peaks on the graph came out correct (I ended up using 3%).

One silly request: Any way to get metric/SI units on this chart?
My brain smokes when I have to think about bhp/lbft...
Thanks!

I'll release graphs in both sets of units once I've redone them all.

I've just learned in 5 minutes how to read an application's process memory, and found the actual engine output torque value, expressed in a float value in N.m. The value depends of clutch state and temp, and engine damage. When applying full throttle it is really the max torque@rpm specified at garage. The value is negative while engine braking.
Tracing the charts with memory reading would be the most accurate method (except getting the engine algorithm from the devs...).

1. Problem: this value's address is always different each time you start the race, so a search is needed each time.
   
2. Problem: the common memory hacking softwares can't log the desired values continuously, so a specific tool must be developed. For my case, I want to do it but I have skills with the Python language only, and I don't think it is memory reading capable.
   
3. I always thought that looking for such game values was a matter for geeks only. I realized it is very simple and I'm now frustrated that I could do that long time ago :doh:
   

Quote from Bob Smith :

Seeing as I wanted to re-do all mine again anyway, I've started from the beginning, just did the UF1 again tonight to remember how it all works.

I added some smoothing, and got data on engine brake torque too:

It looks like you had some problems at start So how much longitunal force curve from replay analyser is different than torque curve?