Unrealistic Turbo Characteristics

[Mike_grpA]

I don't know if this topic has been done before, and I did use the search function, and didn't see one, so if it has I apologise.

The characteristics of turbo charged cars in gt6 is waaayyyy off realistic, and it seems odd, as it can't be hard to get at least similar to real life, yet pd has made it ridiculously unrealistic.

For example, I've noticed more times than I can remember, whilst driving a turbo charged car, not getting any lag whatsoever. I don't actually remembering ever getting turbo lag. The power band changes with each stage of turbo, but you don't get any real turbo "lag" as such.

Before the custom gauges update, it was hard to see what the turbo was doing, as the hud boost gauge has no numbers, and seems to work more like a throttle percentage gauge than a boost gauge. Once the custom gauges were available, I put one, configured for psi and in/hg in a small engined turbo car(nissan march), fully modified, with a stage 3 turbo (Tiny engine/big turbo should produce tons of lag).

You would expect the gauge to sit at 0 if you did a standing start in top gear, and then it would rise as the revs rose, sharply hitting full boost once the revs were high enough, then going sub zero when you lifted off and let the car slow back down. Well that is just about the opposite of what it does in the game.

First of all, it sat at 5psi at idle... Taking off in top gear, it went straight to around 15psi at slightly higher than idle speed, and slowly went from there to around 25 psi by mid rpm, then once the car got into it's stride, and felt like it was getting into it's power band, the boost dropped off to 20 psi. Then when I lifted, it went to about 3psi until the car stopped, and then it sat at idle pumping out 5psi again lol. Apparently the car produced no vacuum at all, always being on boost.

I then tried revving in neutral. In my real car, which is turbocharged, this wouldn't do much to the boost gauge, as the engine's under no load, and especially a so called "stage 3" turbo (presumably meaning to be the biggest turbo you would strap to any given engine), revving the engine in neutral wouldn't make boost. In gt6, doing this will make it go from 5psi to around 25psi.

So based on this, no turbocharged car would have even remotely realistic characteristics in gt6 for this reason alone, let alone any other problems with the simulation.

 

[rixtar]

I don't know if this topic has been done before, and I did use the search function, and didn't see one, so if it has I apologise.

The characteristics of turbo charged cars in gt6 is waaayyyy off realistic, and it seems odd, as it can't be hard to get at least similar to real life, yet pd has made it ridiculously unrealistic.

For example, I've noticed more times than I can remember, whilst driving a turbo charged car, not getting any lag whatsoever. I don't actually remembering ever getting turbo lag. The power band changes with each stage of turbo, but you don't get any real turbo "lag" as such.

Before the custom gauges update, it was hard to see what the turbo was doing, as the hud boost gauge has no numbers, and seems to work more like a throttle percentage gauge than a boost gauge. Once the custom gauges were available, I put one, configured for psi and in/hg in a small engined turbo car(nissan march), fully modified, with a stage 3 turbo (Tiny engine/big turbo should produce tons of lag).

You would expect the gauge to sit at 0 if you did a standing start in top gear, and then it would rise as the revs rose, sharply hitting full boost once the revs were high enough, then going sub zero when you lifted off and let the car slow back down. Well that is just about the opposite of what it does in the game.

First of all, it sat at 5psi at idle... Taking off in top gear, it went straight to around 15psi at slightly higher than idle speed, and slowly went from there to around 25 psi by mid rpm, then once the car got into it's stride, and felt like it was getting into it's power band, the boost dropped off to 20 psi. Then when I lifted, it went to about 3psi until the car stopped, and then it sat at idle pumping out 5psi again lol. Apparently the car produced no vacuum at all, always being on boost.

I then tried revving in neutral. In my real car, which is turbocharged, this wouldn't do much to the boost gauge, as the engine's under no load, and especially a so called "stage 3" turbo (presumably meaning to be the biggest turbo you would strap to any given engine), revving the engine in neutral wouldn't make boost. In gt6, doing this will make it go from 5psi to around 25psi.

So based on this, no turbocharged car would have even remotely realistic characteristics in gt6 for this reason alone, let alone any other problems with the simulation.

I remember turbo lag happening in a rally car in a seasonsal or two. You had to keep the revs up or it would bog down when you hit the accelerator. But there is never any in higher power motors that I can remember.

 

[Mike_grpA]

If it was a modern rally car that is too funny for words, since they all have very sophisticated anti-lag systems. I only have group b rally cars, and none of those have lag.

Also, there's a difference between a car dropping out of it's power band, and turbo lag. They feel very very different to one another, and a car of any aspiration will bog down if the revs drop out of it's power band.

The best way I can explain it is to compare two cars I've owned: An '87 corolla twin cam, and my current celica grp a.

The corolla had a 4age engine, which was an extremely peaky little engine. It red lined at 7,500rpm, and made no usable power below 3,500rpm. It only got into it's power band over 4,200rpm. Once over that magic number, it went like stink, and felt so lively. Under 4k it had very little to give. The throttle response at low revs was still good, although it mostly produced a louder noise, and didn't give the impression of power at low revs lol. It had very little torque.

By contrast, the celica, which has a 3sgte engine, is very torquey, but also has a great top end. It too needs the higher end of the rpm range to get into it's stride, but below that, it's got good torque, as long as it's high enough to make usable boost. Under 2,500rpm it doesn't, so it feels very sluggish. Once it hits about 2,600-2,700rpm the turbo comes on quite strong, and there is a massive surge, which isn't power, it's torque. You then ride that wave up to over 4,500rpm, where it gets into it's power band, and keeps going from strength to strength until 7000rpm.

Both cars had peaky engines, but where the corolla just lacked torque, and had a very linear power curve, the celica has torque in spades, but only once the turbo spools up. If the rolla dropped down below 2,500rpm mid corner, it would be bogged down on exit, but it's acceleration would increase as the revs rose. If the celica dropped below 2,500rpm mid corner, it would feel like a huge hole in the torque, and it would struggle for a couple of seconds, before suddenly lurching into life with explosive power.

It's hard for me to explain, but I hope that helps lol.

 

[Streeto]

@Mike_grpA

I think the power delivery in most cars is fine, but I think the calculations involved with boost are a little rushed.

It would make sense if we could adjust the PSI, but we can't.

I think they were lazy on that because of the fact it isn't adjustable so they figured nobody would care.

I do find it funny how every single car, no matter what turbo (not sure about stock) seems to peak at 25psi.

We need a dyno simulator and working boost controllers.

But then people would just boost the 🤬 out of their cars without repercussions;

Unless PD implemented a system that caused your engine to detonate if you ran too high PSI, causing you to change car or go pay for an engine rebuild.

That would be hard to make realistic though, because every engine is obviously different and there are too many factors involved.

The system needs changing in some way though, that's for sure.

 

[Vegard]

The amount of research and modeling required in order to accurately represent 3-4 different lag characteristics for the
huge number of engines and configurations would probably have taken 10 years (we're talking about PD here).

I agree that it's pathetic to have instaboost on all cars though.

 

[CSLACR]

GT2 modeled turbo lag very well imo. Certainly for it's time, and since then,(GT2) GT has actually been modelling it less well.
It's one of those "1 step forward 2 steps back" deals I think. This thread just caused the removal of gauges for GT7 (thanks bro, you don't think they'll leave tools like this that show physics holes do you? ;p )
Kind of like SSRX. It came with time measuring, and accelerative g-force readings, but since that exposed some physics flaws, it's gone. Now we can just cruise stock Corvettes to 230+ on SSRX

 

[alexnipi]

I then tried revving in neutral. In my real car, which is turbocharged, this wouldn't do much to the boost gauge, as the engine's under no load, and especially a so called "stage 3" turbo (presumably meaning to be the biggest turbo you would strap to any given engine), revving the engine in neutral wouldn't make boost. In gt6, doing this will make it go from 5psi to around 25psi.

Boost gauge under speedometer

I think that depends on the engine and turbo setup

 

[Mike_grpA]

Boost gauge under speedometer

I think that depends on the engine and turbo setup

If you were using that video to somehow argue with what I said, I don't think you paid attention to the video yourself. The middle of that gauge is 0, which is no boost, and is where the gauge went to when the engine was revved. Below 0 is vacuum, which is what your engine produces in the inlet manifold when the throttle is closed, because the engine is sucking everything out of it, but the throttle is closed, not allowing more air in (bar idle air).

I also wouldn't trust a stock boost gauge on any old Japanese car anyway, as the stock gauge in my car is ridiculously inaccurate, as they pretty much all are. I have an aftermarket gauge in my car, and I have owned a few turbo cars in my time, and have plenty of experience working on them too, so I do know how a turbocharged car should behave. Gt is completely backwards for turbos. I also don't accept that it would take too long so they didn't bother to make it different to any other aspiration, they shouldn't call their game a sim if they work like that. Even Grid and Dirt games have better boost characteristics, and they don't pretend to be sims. Hell, even Test drive ferrari has half decent boost characteristics, and that game is so badly broken that it's got a half second input lag lmao.

 

[alexnipi]

If you were using that video to somehow argue with what I said, I don't think you paid attention to the video yourself. The middle of that gauge is 0, which is no boost, and is where the gauge went to when the engine was revved. Below 0 is vacuum, which is what your engine produces in the inlet manifold when the throttle is closed, because the engine is sucking everything out of it, but the throttle is closed, not allowing more air in (bar idle air).

if you see it right the gauge pass the 0 i can't find a better video but i know what is possible get pressure in neutral
Another video, can't recognize the car but is what i want to show

 

[eran0004]

For example, I've noticed more times than I can remember, whilst driving a turbo charged car, not getting any lag whatsoever. I don't actually remembering ever getting turbo lag. The power band changes with each stage of turbo, but you don't get any real turbo "lag" as such.

Did you try the Lotus F1?

 

[Vegard]

Did you try the Lotus F1?

Even that car hits peak boost on throttle blips during downshifts.

 

[alexnipi]

Even that car hits peak boost on throttle blips during downshifts.

I see what you say on the hud gauge but the car gauge works well

 

[Vegard]

I see what you say on the hud gauge but the car gauge works well

Wow, that means they actually modeled some lag characteristics for the 97t, visually.

Have a look at this pCARS clip with actual turbo lag modeled in the physics engine and compare it to GT6:


That is proper turbo lag, not just a high boost threshold.

 

[Johnnypenso]

@Mike_grpA

Unless PD implemented a system that caused your engine to detonate if you ran too high PSI, causing you to change car or go pay for an engine rebuild.

That would be hard to make realistic though, because every engine is obviously different and there are too many factors involved.

The system needs changing in some way though, that's for sure.

Funny how that keeps coming up in relation to the GT series. Can't make boost realistic because there are so many engines and factors involved. Can't make all cars premium because too many cars. Can't make realistic tire models for various eras because too many cars. Can't get new sound samples for every car because too many cars.

I'm sensing a common thread in those excuses.

 

[eran0004]

Even that car hits peak boost on throttle blips during downshifts.

According to the HUD it does. According to the cockpit instrument it doesn't. What the car actually does we don't know.

Edit: Actually, the HUD instrument could just be a valve indicator, rather than a boost pressure indicator. So what you see isn't necessarily peak boost, it could be peak valve position.

 

[Vegard]

Actually, the HUD instrument could just be a valve indicator, rather than a boost pressure indicator. So what you see isn't necessarily peak boost, it could be peak valve position.

What valve would that be?

Funny how that keeps coming up in relation to the GT series. Can't make boost realistic because there are so many engines and factors involved. Can't make all cars premium because too many cars. Can't make realistic tire models for various eras because too many cars. Can't get new sound samples for every car because too many cars.

I'm sensing a common thread in those excuses.

You forgot all premium cars and realistic engine tuning.

We can't even keep half the in-game cars in our garage

 

[eran0004]

What valve would that be?

Blow off valve? I have no idea. It doesn't look like boost pressure however, because the Lotus have a lot more lag than that.

 

[Vegard]

Blow off valve? I have no idea. It doesn't look like boost pressure however, because the Lotus have a lot more lag than that.

It's a boost gauge.

- It's marked -/+
- Neutral position is in the middle
- There's a picture of a turbo on it
- Shut throttle gives manifold vacuum, open throttle gives positive pressure

I'll give the 97t a run a little later and analyze the data logger for concrete evidence of zero turbo lag (it's the only way to be absolutely sure, looking at the thrust curves).

 

[eran0004]

It's a boost gauge.

- It's marked -/+
- Neutral position is in the middle
- There's a picture of a turbo on it
- Shut throttle gives manifold vacuum, open throttle gives positive pressure

I'll give the 97t a run a little later and analyze the data logger for concrete evidence of zero turbo lag (it's the only way to be absolutely sure, looking at the thrust curves).

Yep, I just tested and you're right, it indicates boost pressure.

It could be that it just shows pressure up to a certain limit and that the Lotus goes "off the chart".

Edit: The Lotus boost gauge starts at 2 bar, and it seems like the HUD gauge max value is less than 2 bar.

 

[Mike_grpA]

I'll concede that some stock turbos are capable of producing a tiny amount of boost pressure in neutral, but in that video, if you look, the needle moves so slowly in that boost gauge (it's a rubbish stock gauge in what looks like a lancer), it slowly goes down to 0 when there's no throttle applied. That gauge isn't working properly, as no engine sits at 0 when off throttle. It should be showing vacuum, but it never does. When you lift off, the needle should move instantly into vacuum. Accurate boost gauge needles move very very fast when you lift off. Also, my whole point about gt6 was that in a fully modified engine, running the biggest turbo you could, you'd never get boost in neutral, and you certainly wouldn't be getting full boost so quickly or so early in the rev range. Remember, the car I used as an example IDLES at 5 psi boost lol.

The lotus f1 car on gt6 is just a joke in this department. There is no noticeable lag. It is the same as every other car, it has a power delivery like any n/a car on the game. Look at the gauge in that video, as soon as he gets on full throttle its right on max boost through most of the rev range. Those f1 cars did not behave like that. The pcars video is much more accurate. F1 drivers at the time complained about having literally SECONDS of lag. I remember Alain Prost speaking about needing to have the balls to mash the throttle before apexing a corner, to build the pressure, so you had some drive out of the corner a second or two later, and then needing to be able to predict when the boost was going to hit, so you could feather the throttle to avoid the car spinning the wheels on exit.

The power delivery on those cars was brutal. A tiny 1.5 litre engine, coupled to massive turbos, will do that.

Check this video out for an example. Listen carefully to the engine, you'll notice how big the lag is, and just how strong the power comes on once the turbo spools up (this guy isn't employing the prost method of hitting the throttle early to compensate for lag, so he has pretty poor drive out of slow corners)

 

[CSLACR]

I'm agreed that turbos don't reach full boost in neutral, but to continue to insist it isn't possible or is really hard to reach a small amount of boost seems fairly ignorant. Predicted accuracy of a gauge based on an internet guys opinion of said video...
Let's leave it at "GT6's turbo system sucks, and boost in GT6 doesn't work worth crap. Maybe some boost could be reached in neutral, but not much and only towards the rev limiter most likely."

 

[Mike_grpA]

I'm agreed that turbos don't reach full boost in neutral, but to continue to insist it isn't possible or is really hard to reach a small amount of boost seems fairly ignorant. Predicted accuracy of a gauge based on an internet guys opinion of said video...
Let's leave it at "GT6's turbo system sucks, and boost in GT6 doesn't work worth crap. Maybe some boost could be reached in neutral, but not much and only towards the rev limiter most likely."

I said it's possible to get a tiny amount of boost in neutral, but if you think I'm wrong about that boost gauge, please explain to me how you think a turbo works, or how a boost gauge which is working correctly should behave when revving an engine.

 

[CSLACR]

I said it's possible to get a tiny amount of boost in neutral, but if you think I'm wrong about that boost gauge, please explain to me how you think a turbo works, or how a boost gauge which is working correctly should behave when revving an engine.

Looks perfectly fine. The vaccum doesn't go to minimum(maximum, I should say*) until the engine slows down,(all the way) it responds quickly, predictably, and equally to itself, meaning it doesn't spike in reading.

Looks frickin dandy tbh.

But that's not the point, is it?

 

[Mike_grpA]

Which video are you watching? The gauge never shows vacuum at all, and the needle's sweep is quite slow. I'm not sure how you think that is how a boost gauge should work...

Edit* I think you might be referring to the 300zx video, where I was responding to the second video he posted, which as I said, looks like a lancer. In that video, the gauge goes no lower than 0, showing no vacuum, and hits 1 bar when free revving (which is almost 15psi) lol. Clearly the gauge isn't working properly.

 

[CSLACR]

It was a 300ZX yes. 👍

But GT6 still doesn't act right, so, :/

 

[Mike_grpA]

Yeah for sure. I also don't understand people who say it would be too difficult to do because of how many cars are in the game. Most other parts of the simulation seem to be generic, not specific to every car, so why couldn't they do a generic boost simulation? maybe three different levels of lag, one for each stage of turbo.

 

[Vegard]

@Mike_grpA Because they'd have to model some sort of real time dynamic torque output algorithm.
And they'd have to model that for individual stock engines.

I also didn't say that it would be too difficult, more like too time consuming.

 

[Mike_grpA]

They could just half arse it like they do with everything else in the physics simulation, then it wouldn't be time consuming at all lol

I don't see why it's this part they'd have to spend tons of time on to make it perfect, when the rest is anything but. You can't say it has to be done perfect, or not at all. Especially on gt6, which has a seriously flawed physics model anyway. My point is, it seems they didn't even try to simulate realistic boost characteristics, so they just made turbocharged cars drive the same as n/a cars.

 

[Vegard]

Even a half baked lag simulation would take time and resources (system and human) to model/implement.

System resources and human resources for GT6 are scarce (they're working full time on GT7 for PS4).

Turbo lag comes far down a long list of features that will never be implemented IMO.

 

[Mike_grpA]

I think you're missing my point. I'm not suggesting they add it in an update. The game is severely lacking in a lot more departments than just this, so I couldn't care less if it would be too hard for them to add it now. I'm saying they should have made an effort to do in when they were making the game.

System resources wouldn't be so scarce if they didn't stuff around with things like tesselation and gimmicks in the game that are completely useless to 99% of players. There is far too much dead weight in the game bogging the system down, that doesn't need to be there in a ps3 game.

I've said it before, and I'll say it again. They should have made the actual game a priority over the gimmicks and updated graphics, which weren't a problem on gt5. As it is, the core game is half arsed, broken, and feels mostly unfinished. But hey! At least we've got a gps data visualiser!! Thanks pd!!!!!!