Turbo Behaviour

[tronicson]

the turbo behaviour is only correct with the bugatti veyron where you see the boost-pressure indicated on the lower left of the dash...

if you accelerate, the pressure slightly rises until the engine produces enough under-pressure (around 3500 - 4000rpm) to open the valve where the turbo starts to spin up (you hear it) and finally builds up the boost-pressure, and the power increases...

this behaviour is wrong with the other cars! if you per example lift your foot from the acceleration pedal, the boost-pressure stays up (how is that possible?!) - only if you shift it goes down a bit... (compare once with the veyron, there it reacts real - pressure drops instantly as you lift - the wastegate opens to bypass the air to the turbo)

so far so good (with the veyron) or bad (with the others) - somebody has a glue where this behaviour is steered? i found turbo files, but they have not really to do somethings with the indicators, only the engine power...

i would really like to react all cars with a turbo charger correctly like the veyron - has somebody an idea?

[KingAntikrist]

i think its correct on Koenigsegg CCX

[tronicson]

the Koenigsegg CCX has no Boost Gauge where you can see the pressure... it's all about the correct indications on the Gauges - and the Koenigsegg CCX has also no turbo but two Twin Rotrex superchargers - a supercharger is not powered by exhaust gases.. so therefore you cannot judge if turbobehavior is right or wrong with the CCX! superchargers build up boost-pressure continously with RPM

probably i have too exotic findings and too realistic demands to that game...

it's frustrating, i spent now about 2 hours to find something that steers the turbo behaviour and sound - and works really in the game... no success

i hope the next patch corrects turbo behaviour, incl. turbolag and boost etc. :-(

[Sensekhmet]

I've noticed that straight away but I thought the gauges were buggy as I think the sounds are quite correct: judging by the sounds turbo is modeled as an independent device, not just a canned bump in the torque curve like in Simbin titles and rfactor. I was also expecting the boost pressure to fall slightly as the engine passes it's optimal rpm as it seems to happen in real life: some turbo race cars don't even have a tach, just a big boost gauge (rallycross car for example). Actually, my dad's common rail diesel minivan could use such a mod too: it really moves only when the 'fan' is spinning: the tacho is of not much use.

[tronicson]

yes there are separate turbo files: ...Need for Speed SHIFT\vehicles\physics\turbo

//Generic model for LowRPM - all in by 3500 rpms
Turbo1 Size=50.0 // size of turbo influences eventual power delivered
Turbo1 Turbine Optimum RPM=140000.0 // optimum rpm where turbo produces max power
Turbo1 Engine RPM=500.0 // engine rpm that the turbine begins to spin up from
Turbo1 Inertia=10000.0 // turbo inertia/spin up speed
Turbo1 Friction=2000.0 // turbo friction/spin down speed
Turbo1 Fuel Percentage=10.0 // extra percentage of fuel burned at optimum RPM (0 = no change)
WasteGate Opening=0.5 // minimum time taken in seconds for the wastegate to open
WasteGate Closing=0.3 // minimum time taken in seconds for the wastegate to close

this adds power to the engine seperately...

but - the underpressure steering from the engine to the turbo is not in there - if you know from practice how to drive a turbo (have mine with a cossie escort) once the pressure is there, you handle the gas the way to steer actually and primarily the boost-pressure, not the same direct manner like a normal aspirated engine... therefore it would be useful in the corners and out of the corners to have full control via visibility (you mention that some race-cars have the boost gauge only) :thumbup:

well - i did not found until now the mechanism in the game that steers it, not sure if it's in the .exe / the bugatti-veyron do not reveal how its working, or at least i do not find it... :crying:

[KingAntikrist]

the Koenigsegg CCX has no Boost Gauge where you can see the pressure... it's all about the correct indications on the Gauges - and the Koenigsegg CCX has also no turbo but two Twin Rotrex superchargers - a supercharger is not powered by exhaust gases.. so therefore you cannot judge if turbobehavior is right or wrong with the CCX! superchargers build up boost-pressure continously with RPM

probably i have too exotic findings and too realistic demands to that game...

it's frustrating, i spent now about 2 hours to find something that steers the turbo behaviour and sound - and works really in the game... no success

i hope the next patch corrects turbo behaviour, incl. turbolag and boost etc. :-(

So you're worried that the turbo gauge might not be accurate? lawl... the turbo is THERE and works... why do u care so much about the gauge lol...

U feel the superchargers kick in at ~5000 RPMs on the koenigsegg

[pez2k]

The point of working gauges is that they show that the turbo implementation itself actually works. If it's not a proper simulation, with boost threshold, turbo lag, and so forth, then what's the advancement over gMotor2 where you simply add some power to the engine file?

[davehenrie]

That snippet of turbo code looks like both an improvement and not an improvement over the previous turbo implementation. I am guessing the lag can be adjusted by increasing the spin up resistance via these two lines:

Turbo1 Engine RPM=500.0 // engine rpm that the turbine begins to spin up from
Turbo1 Inertia=10000.0 // turbo inertia/spin up speed

The minimum spin-up rpm level could be raised to delay the beginning of the spin up. And the inertia could be raised to increase resistance of the spool to spinning and thereby introduce the 'feel' of lag.

A problem, at least for modders, is the first line which defines the size of the turbo. Presumably the larger this number, the more power produced. The old method had a calculation involved so the modder could specify a percentage of extra power. Now it looks like someone would have to spend a good deal of time trying different sized turbos to deduce how much more power a turbo sized 53 makes over a turbo sized 50

[pez2k]

I would think the turbo size would also increase spoolup time, as the turbo upgrades only change its size. It's especially vexing to fiddle with because nowhere does the game actually display how much power each car is making.

[tronicson]

@KingAntikrist: hmm.. you probably have no technical background.. but no problem we all have different demands to a racing-game - but shift is a hybrid between arcade and simulation - therfore we probably just must be careful to demand too much reality from it... i was just wondering that everything is correct and fine with the veyron ;-) (regarding the other cars: when you lift your foot from the gas completely, and the boost pressure and torque stays up - thats just bullshit - when talking of turbos, not superchargers)

for some tier 1 and 2 cars, are huge turbo and engine upgrades available that offers twice or three times more power then... you can imagine that you will then have a significant bigger turbo built in then, with a good remarkable turbo-lag - well, it's just not there

The point of working gauges is that they show that the turbo implementation itself actually works. If it's not a proper simulation, with boost threshold, turbo lag, and so forth, then what's the advancement over gMotor2 where you simply add some power to the engine file?

completely agree.. ;-) i did manage it so far now, that i modified the engine file to have suddenly between 3500 and 4000RPM a jump in torque (what actually is the case in reality too)
but this way the torque will stick to rpm - not boost-pressure, thats not real

a correct working gauge would be helpful to see if the turbo is still with you, and you can expect some power when you fully accelerate out a corner - if you had once the chance to drive a car with one big turbo - like an old "911 turbo" you will know what i'm talking about - you lift your gas foot in front of the bend and out the corner you will have to wait for the pressure if you did wrong, if you did not keep the turbo spinning up (proper control of this has significant effect to the time-result of a track)

in the turbo-era of F1, ayrton senna once explained how he managed to keep boost-pressure through the corners to accelerate at 100% available power out of the bends.. he did really a smooth/careful staccato with his foot on the accelerator to just keep the turbo spin at useful RPM's - this you could perfectly control then on a proper working gauge :-D

i did also fiddle around with these parameters - with lack of expected effect in the game when driving, but i don't give up completely, i just always keep in mind that i forgot something or did something wrong ;-)

Turbo1 Engine RPM=500.0 // engine rpm that the turbine begins to spin up from
Turbo1 Inertia=10000.0 // turbo inertia/spin up speed

.. i wrote once to "slightlymadstudios" to point to this (perhapps they did not realize yet) - honestly i do not think that they will engage on this.. but at least we tried to get it corrected by a future patch where they transfer the bugatti turbo characteristics to the other tuned turbos ;-)

[tronicson]

oh wow! slightlymadstudios did write me an answer back :-D

Hi Mike.

Answer below from Doug. It's simply a visual gauge thing. We put a lot of
effort into recreating the gauges accurately but some simpler visual
implementations are essential when making games.

Very well spotted :)

Cheers,

Ian Bell.

Sent: 09 November 2009 11:06 AM
To: Ian Bell
Subject: Re: FW: NFS Shift / Turbo modification

The Turbo "lag" is there for all turbo's and they're all similar
depending on turbo size.. What this guy is looking at it the guage
reaction which I believe is scaled somehow in the car art files. A
question for Jan maybe.
There's 10 or so Turbo files btw, not just this one.

Doug Arnao
Car Physics & AI
Slightly Mad Studio's

makes me looking forward that this is fixed soon :-)

[pez2k]

I really appreciate when games companies take the time not only to read their support emails, but actually go and find out the root cause of your issue. It's honestly the sort of thing that would make me buy a future SMS game on faith alone. Also a great contrast to the classic EA stereotype, and to a certain other PC sim developer.