Can't seem to find this suggested anywhere, so here goes...

The LFS engines seem to be too "heavy". As in, taking off in any car requires almost full throttle to avoid stalling, using a clutch pedal. IRL just a touch on the throttle provides plenty of revs. I know that the GTRs have race engines and whatnot, but there's no excuse for the road cars.

I know it's a race simulator, so takeoff RPMs don't really matter, but it's still quite unrealistic...so I propose that the engines be made somehow "lighter"...

Does anybody else agree with this?

These engines all have high rev powerbands, so you have to give it much gas to get going. Think Honda Civic 1.5

Quote from Impreza WRX :

These engines all have high rev powerbands, so you have to give it much gas to get going. Think Honda Civic 1.5

Ah lol I was thinking more Toyota Yaris

Two points to consider:

a) the torque curves in LFS are (or at least, were) not as broad as your typical road car, i.e. less torque at low revs
b) we typcially use very tall first gears (say 45mph at rev limiter), whereas 25mph is much more typical for your japense shopping trolley

I agree, but the stock XFG for instance would be similar to say, a VW Golf. I know next to nothing about torque curves or anything like that (I'm used to measuring an engine in good 'ol BHP :tilt, but shouldn't they be similar?

Maybe I should just use a low geared set for cruising

Bob, do your road sets have gearing similar to IRL?

BHP and torque are very different, you can't really compare the 2 directly.

But it's like someone said, 1st gear is very, very tall (and so difficult to set off) in nearly all LFS sets, 1st gear in a road car is normally around walking/jogging pace.

In real life I think I change into 2nd before I even hit 10mph or 15mph, then upto around 30mph for the change into 3rd (that is normal driving tho).

I did a road going car as similar as a 1.1i Saxo.
1st gear in idle should make the car move @ 11kph
5th gear in idle should make the car move @ 51kph.
Spread them in the middle - and youll find it much easier to take off.

Some setups do have a very long 1st gear indeed.
However, the default setup on the GTI looks pretty accurate. The top speed in 1st gear is just above 60KM/h, about the same as a Honda Civic type R.
I think the problem lies in the fact that you can't really feel the clutch grabbing and compared to a real road car, the clutch in LFS is more "sticky" (more like a racing clutch).

If it was a road clutch it would be toast off the line. :P

Is it possible to see the torque/power curves somewhere? I would like to see them to know when to shift etc.

There are some in this thread: http://www.lfsforum.net/showthread.php?t=18710

They are outdated though as we are told the torque curves got changed with patch Y for the new clutch model. I've not got around to re-measuring them.

Quote from breadfan :

Is it possible to see the torque/power curves somewhere? I would like to see them to know when to shift etc.

actually the shift light tells you when to shift, because it know everything about your POWER-curve and gear-ratios.

to assign shift-points by looking at torque-curves alone is not really possible.


@dougie: golf?? although the golf might be the mother of all hatchbacks, it's probably the one the XFG is least related to. Just take a look at the weight, engine size, bhp/litre, torque- and power-peaks... really NOTHING golf there.

the way an engine responds to the throttle is mostly a matter of adjustment IRL.

by the way, talking about 1st gear ratios, clutch and taking off: I don't have a clutch-pedal so I use autoclutch, and I did a test: with a road-like 1st gear, the clutch-indicator gets red after about 17 "city-" or "trafficjam-take-offs"... hmmm... I don't have problems with the clutch in races (unless I want to pull away in 2nd after a spin), but realistic??? nah, c'mon.

Quote from Bandit77 :

to assign shift-points by looking at torque-curves alone is not really possible.

Yes it is. If you know the torque curve (even just the top half of it) and the gearing then you can EASILY calculate the gear change points.

Quote from Bandit77 :

to assign shift-points by looking at torque-curves alone is not really possible.

and even if you have the POWER-curve or the WHEEL-TORQUE-curve, it's not THAT easy, becuse this curve is no math. function.

I remember you saying in another thread that in your racing class, shiftpoints always assigned using the torque-curve... I really hope you were talking about wheel-torque and not engine-torque.

... but then again IIRC you also stressed that it's never done according to the power-curve - which would basically give the same correct results as using the wheel-torque-curve.
So either you do it with the wheel-torque-curve or you just THINK you do it with the engine-torque-curve (and then it's probably not you in person 'calculating' them). Because if you really 'calculated' them according to the engine-torque-curve, you'd be damn slow, buddy.

I use the engine torque curve, modified by the gearing (therefore wheel torques). If you know the wheel torques alone then you don't need any gearing information, you just change gear when they cross.

And yes, you can do it with power curves, but I find the solution less elegant and intuitive, and you also need to consider the losses (so you need wheel-power.

Engine figures are useless (except on engine development work on an engine dynomometer). Wheel figures FTW.

I dont think they need lighter engines, because if anything the weight raito according to where the engines are are way off (too center ballanced).

I kind of hear what your talking about with the clutchs but I use a button as a clutch and just have to use it like I'm releasing a brake(same with the GTR class). Soo I gotta rev it to 4k let out the clutch, pop the clutch again and get the momentiun going.

Quote from tristancliffe :

And yes, you can do it with power curves, but I find the solution less elegant and intuitive, and you also need to consider the losses (so you need wheel-power.

Ok, I see where you're coming from. But as far as I know the "bang" on the wheels is pretty much linear to the powercurve, i.e. if the engine delivers x bhp, you have y nm on the wheel, if it delivers 2x bhp, you have 2y nm on the wheel.

If my understanding is wrong, then I wonder what a powercurve is good for. And by the way: I think the shiftlight in LFS is working based on the powercurve.

But hey, I'd really like to know how to do this with engine-torque and gear-ratio. If it's easier/ more elegant, as you say, I'm very interested.

Quote from dougie-lampkin :

Can't seem to find this suggested anywhere, so here goes...

The LFS engines seem to be too "heavy".

It hasn't been suggested, and actually the engines were too "light" already and were made "heavier" in the last official patch..

Quote from Scawen :

Engine moment of inertia increased in all cars

http://www.lfs.net/?page=patch_y

I wasn't really, thinking torque curves, I was thinking more along the same lines as Bandit with clutch takeoffs...

I picked Golf because it goes fast

Quote from Bandit77 :

Ok, I see where you're coming from. But as far as I know the "bang" on the wheels is pretty much linear to the powercurve, i.e. if the engine delivers x bhp, you have y nm on the wheel, if it delivers 2x bhp, you have 2y nm on the wheel.

If my understanding is wrong, then I wonder what a powercurve is good for. And by the way: I think the shiftlight in LFS is working based on the powercurve.

But hey, I'd really like to know how to do this with engine-torque and gear-ratio. If it's easier/ more elegant, as you say, I'm very interested.

The basic idea is this (using a spreadsheet is easier!)

1. Plot you torque curve every 250rpm or so. Closer steps is more accurate if you have accurate data to enter, but more work. I like 250rpm. 500rpm would be fine too.

2. Work out your road speed in each gear at each rpm point.

Speed (km/h) = rpm x 120 x pi x tyre radius (m) / 1000 x gear ratio x final drive ratio

3. Calculate the tractive force (effort) at the wheels for each rpm point.

Tractive Effort (N) = Torque (Nm) x Gear Ratio x Final Drive x Drivetrain efficiency / Tyre radius.


Plot a graph of force against speed for each rpm and each gear, and you'll end up with a graph like this. Where they cross is the gear change point (in mph), which is easily converted back to an rpm (automatically if you're good with spreadsheets).

You can also easy add another curve for drag (aero + rolling resistance), both of which vary with speed and download. Where that crosses the top gear curve is the max speed of the car (and if it doesn't cross before the redline then the car is rev limited.

You could also take into account the dynamic radius of the tyre (can be very different from the static radius), ram-air effects and tyre slip (up to 20% at high accelerations iirc).

What's wrong with going by feel?

It's less accurate sometimes. Many drivers (especially the Max Power driver) think more revs are always quicker.

The way I see going-by-feel is: You might get quite a good feel for when it doesn't pull anymore in a set gear, but you just CAN'T feel what's going on in the next gear - it might be even less.