I'm not any expert on this subject, but I think there is something really wrong with the turbo simulation of LFS...

for example, look at the graphic of power and torque of the original XRT:



now compare to a NA XRT, with power raised to the same that it had when was turbo:



as you can see, the only thing the turbo does, is "cut" the power while it's "charging" (is this the right word for this?)

i'm almost sure that one turbo engine and one NA engine should have totally diferent graphic of power and torque

You used a tweak program to remove the turbo and magically increase the engine power to the same level, what did you expect to see? And yes, the turbo (and engine in general) model is simplistic and could use a bit of work.

I expected two graphics totally different, I always heard that turbo add lots of torque, and it appears to be true, for example:

Chevrolet Cruze 1.8 16v has 144hp and 18,9kgfm of torque...

Mercedes C180 1.6 16v Turbo has 156hp and 23,5kgfm of torque...


as you can see, even with lower displacement, and just 12hp more, it has much more torque

Quote from Specht77 :

I expected two graphics totally different, I always heard that turbo add lots of torque, and it appears to be true, for example:

Chevrolet Cruze 1.8 16v has 144hp and 18,9kgfm of torque...

Mercedes C180 1.6 16v Turbo has 156hp and 23,5kgfm of torque...


as you can see, even with lower displacement, and just 12hp more, it has much more torque

And at what RPM are those peak values?

It could very well be the turbo version operates at lower RPM's, which would explain the higher torque value. For a given HP value, the torque will increase as RPM decreases. This makes torque alone essentially meaningless when comparing engines that operate in different RPM ranges. Tractive force is a much more effective tool for comparison, because it takes into account the gear reduction necessary to reach a particular speed, in addition to torque. High RPM's require high gear reduction, which means more torque multiplication.

HP is torque/time so raising torque and/or rpm gives more hp. How a turbo engine behaves compared to a normally aspirated is entirely down to design, damn great turbo's that only start working at high rpm give monster HP but poor low rpm performance while most turbo trucks use small turbo's (relative to engine capacity) to boost power from low rpm. As to the graphs, they're f***ed up.

Even bigger problem is spool times, which are nowhere compared to real ones.
Overall, turbo 'simulation' is quite basic, and could use some love by devs

With LFS-tweak you can have pretty much any turbo response you want. It can take a little tweaking, but you can have anything from tiny insta-spool turbos to massive spools-in-a-week compressors.

the major problem with turbos as I see it is that they never run out of flow, so no matter how fast the turbo is, it won't be restrictive.

Quote from atledreier :

With LFS-tweak you can have pretty much any turbo response you want. It can take a little tweaking, but you can have anything from tiny insta-spool turbos to massive spools-in-a-week compressors.

the major problem with turbos as I see it is that they never run out of flow, so no matter how fast the turbo is, it won't be restrictive.

you can have a slow or fast turbo lag, but if you turn of turbo, and just add more "Power (per cilinder)" till you get the same power of the turbo, you'll get the same power graphic, but without the turbo lag, and it should't be like this

It should, because the parameters that generate the torque curve is completely arbitrary and not based on any physical attribute of the engine. There are three parameters that affect the torquecurve, regardless of turbo and other settings. The turbo settings are then added to the curve.

Play around with LFS-tweak, you'll see how the values work.

This was discussed many times:
ie.: http://www.lfsforum.net/showthread.php?t=23581

Quote from atledreier :

It should, because the parameters that generate the torque curve is completely arbitrary and not based on any physical attribute of the engine. There are three parameters that affect the torquecurve, regardless of turbo and other settings. The turbo settings are then added to the curve.

Play around with LFS-tweak, you'll see how the values work.

I play with tweak since S1, I know what you can change, and I know that the turbo just add power, just like if you add power with NA, the only difference is that with turbo it make less power while it's charging, as I alreadly said, and this is not realistic

sorry for it being alrealdy discussed, but nobody had put graphics i think... Moderator can merge topics?

Specht77, you figured out the big "tchan" of the turbocharger. If you have two identic cars, one turbocharged (with a considerable turbo lag) and one NA, with the same power, the NA can respond faster to throttle command because there's no lag in the power delivery.

BUT (and a big but... rs) is that you generally can't have the same power of a turbocharged engine on a NA engine, unless you tweak the engine to generate the torque on a higher rpm level, sacrificing the bottom end.

I'll try to summarize: Turbocharger will give engine more torque, and so you have more power. (HP = RPM x TORQUE).
NA tuning can only move the peak where the maximum torque happens. If you move to the high RPM part, you have more power too, but in a tighter rpm band.

What you did on tweak is not too feasible on reality.

I think maybe turbo modelling can be improved, but it's already a good advantage of LFS over GTR, for example.