turbo boost fluctuation normal?

So I don't think I've seen this before this much before the 0.12 update...

So if you pick the ETK I-Series Street Tune... You can see the boost fluctuate from 11 to high 12s under consistent full throttle. I've noticed this isn't the only original beam vehicle that does this. Saw some other higher turbo boost level vehicles doing it too.

I disabled my mods just in case it was some mod bug but nothing changed.

Is this normal? I'm sure a little fluctuation is normal but this seems like a little much... thoughts?

 

yes, as far as i know, its a completely normal turbo-thing

 

I would disagree that this behavior is realistic or normal. I have owned a twin turbo car myself and this was never a thing unless there was an actual mechanical or engine computer issue. Like when my wastegates went bad causing hesitation and surging.
In real life this would be from a very bad boost controller/wastegate/blow off valve.
In beam I have mostly seen this behavior from a bad setup of the turborpm/psi list in the turbo jbeam. More so with adjustable turbos because they are hard to tune in such a way that you get normal behavior at all psi settings.

 

hmm
I never knew that.
Thanks for the clarification

 

Kind of like bad day of this, I guess:

 

Yikes, thats a great way to blow your engine or melt a piston or in this case a rotor... Never skimp on boost control.

 

Lowering backpressure coef and compensating exhaust power seems to do somewhat good for this spiking issue. Maybe there is bit of overload or something, maybe @Diamondback knows already why such high level of overboosting is happening with current tune of vehicles.

When I moved from 0.0005 to 0.00005 backpressure coef and around 10 000 exhaust power (only 6psi boost), issue was a lot less, but I have GT28R compressor map for this 200hp 6psi boost engine, which might not be quite optimal either. Anyway maybe information gives some ideas.

 

Yeah getting the numbers right I find is quite important otherwise you can get huge boost spikes or not hitting max boost, etc.
I think there is also some aspect of a floating point/resolution issue with the turborpm/psi list if there is too little or too much psi change per rpm level.
Especially noticeable with adjustable turbos as you have to tune it just right for it to work at least similarly at 8psi as it does at 38. But more than likely there will still be certain psi settings that will show odd behavior, while settings outside of that work fine.

 

it's a limitation with the game, increase the turbo inertia.
What kind of FPS are you getting? I get issues when i drop below 60 on the most responsive turbos (low inertia)

 

It is relative. Inertia, friction, exhaust power, and backpressure all have to be balanced correctly. Low inertia only requires lower numbers elsewhere to work.

 

For me it appears that something does not quite catch up the turbo rpm increase and pressure increase coming from that, but as it has not affected much of my own tuning, I haven't bothered to investigate. Could be that it is already fixed in developer's version, usually it is so.

 

I found that limiting the PSI under the pressurePSI category helps the turbo get to its higher PSI faster and likely doesn't fluctuate or bounce off the wastegateLimit. Still other factors have to be in balance.. else you won't have enough boost or your get fluctuation. So maxExhaustPower, backPressureCoef, frictionCoef and inertia still play a roll in this balance.

This below gave me very good results. I noticed if I moved the max PSI much above 22, it would bounce off the wastegate limit and fluctuate.

"turbocharger": {
"wastegateStart":12.1,
"wastegateLimit":12.7,
"maxExhaustPower": 44000,
"backPressureCoef": 0.0001,
"frictionCoef": 35.0,
"inertia":5,
"pressureRatePSI": 60,
"bovSoundVolumeCoef": 0.1,
"bovEnabled":false,
"damageThresholdTemperature": 750,
"pressurePSI":[
//turbineRPM, pressure(PSI)
[0, -1.5],
[30000, 0],
[60000, 5],
[90000, 10],
[150000, 14],
[200000, 18],
[250000, 22],
],

I'm trying to improve my turbos for my diesel d-series mod. Hope to have an update out soon. Not sure if dev's plan to change how turbos work to reduce this fluctuation on their current vehicles or if they will just tune them more in the future to avoid this... like I am.