Turbo charger improvement

[andyeier]

Hi i noticed some mistake in the game, it is a bit unrealistic.

The problem is that the turbocharger just works in neutral gear when im on full throttle and not starts working at for example 2500 rpm, in real it starts to work at a special rpm.

i hope you may improve this problem.

Andy

[BigB]

I would like to have it more realistic, too.

BigB

[Luke.S]

It comes on when the car is at the limiter. The turbo's on the cars are set to high revs.

[MijnWraak]

its a known bug / deficiency with the turbo.

[wheel4hummer]

The turbo's on the cars are set to high revs.

What on earth are you talking about? Turbo chargers aren't simply "set" at a specific RPM. The flow rate, or amount of exhaust is what causes boost to build up. How this is calculated in LFS, I have no idea. But I do know that in the last patch, I think the turbocharger physics were improved by adding engine vacuum that the turbocharger has to over come. In the previous patches, you would get boost by just tapping the throttle a little, whereas now you have to wait for the turbocharger to overcome the vacuum.

[tristancliffe]

What on earth are you talking about w4h?

[wheel4hummer]

What on earth are you talking about w4h?

First, of all, nice job spamming. Secondly, in patch Z, and the later Y test patches, the turbocharger starts out at negative boost. This doesn't happen in earlier patches, because when you would rev the engine at all in the earlier patches, you would immediately create boost. This is not the case in patch Z. :thumb:

[tristancliffe]

I was on about the flow rate stuff you posted.

[wheel4hummer]

I was on about the flow rate stuff you posted.

Ahh... well that would make sense then. Because admittedly I probably have no idea what I was talking about when I typed that. :nod: But what I was thinking when I was writing that is that the higher the flow rate of the exhaust, the faster the turbocharger spools up. Probably incorrect, but more at least I'm more knowledgeable about turbochargers then the person who created this thread.

[Don]

First, of all, nice job spamming. Secondly, in patch Z, and the later Y test patches, the turbocharger starts out at negative boost. This doesn't happen in earlier patches, because when you would rev the engine at all in the earlier patches, you would immediately create boost. This is not the case in patch Z. :thumb:
it was always (or for a long time) like this, there was just never a digital gauge of turbo pressure

[wheel4hummer]

it was always (or for a long time) like this, there was just never a digital gauge of turbo pressure

Well if it was like this for a long time, then I guess the turbochargers are more difficult to spool in patch Z. Because when you would rev the engine with no load in patch Y, you would make ~2psi. But in patch Z, you don't make any boost unless there is load on the engine.

[morpha]

Well if it was like this for a long time, then I guess the turbochargers are more difficult to spool in patch Z. Because when you would rev the engine with no load in patch Y, you would make ~2psi. But in patch Z, you don't make any boost unless there is load on the engine.

That can't be, the turbo is driven by the exhaust gas which should be solely rpm-dependend. However, I think the turbo inlet valve is now somehow connected to the throttle, I don't get any turbo pressure at all if I don't floor it :shrug:

[deggis]

it was always (or for a long time) like this, there was just never a digital gauge of turbo pressure
just for reference: http://www.lfsforum.net/showthread.php?p=843860&highlight=analogue+gauge+simply+stops#post843860

[wheel4hummer]

That can't be, the turbo is driven by the exhaust gas which should be solely rpm-dependend.

Then how come in the XRR, I get 16psi at full throttle at 6000rpm in 2nd gear, while I only get about 8psi or so at 6000rpm, full throttle in 1st gear? And in 3rd gear at 6000rpm at full throttle, you hit about full boost?

However, I think the turbo inlet valve is now somehow connected to the throttle

Well, the throttle valve comes after the turbocharger, first of all. There is no "turbo inlet valve", as it would be quite redundant to have two throttle valves. Also, the more you open the throttle, the more air is going into the engine, and therefore more exhaust is entering the turbine side of the turbocharger.

http://www.youtube.com/watch?v=Xp-EVOPBhIo (After 4:12 it's just about troubleshooting turbocharged engines)

[morpha]

No idea...
XRR, no gear, full throttle, 7492 rpm -> 1.7599 bar
XRR, first gear, full throttle, 7492 rpm -> 1.7599 bar
XRR, second gear, full throttle, 7492 rpm -> 1.7599 bar

Well, the throttle valve comes after the turbocharger, first of all. There is no "turbo inlet valve", as it would be quite redundant to have two throttle valves.Right, sorry, that was pretty much my point, it is as if there was such a valve in LFS.
€: To clarify, as if there was a valve between the turbo's inlet and the exhaust system. Such valves exist in RL btw. but they're not supposed to be closed on single-turbo systems :scratchch

[wheel4hummer]

No idea...
XRR, no gear, full throttle, 7492 rpm -> 1.7599 bar
XRR, first gear, full throttle, 7492 rpm -> 1.7599 bar
XRR, second gear, full throttle, 7492 rpm -> 1.7599 bar


That's because you're bouncing off the rev limiter, silly! :tilt:

Such valves exist in RL btw. but they're not supposed to be closed on single-turbo systems

On sequential twin-turbo systems, there is a valve that stops exhaust gasses from going into the secondary turbo charger.

Right, sorry, that was pretty much my point, it is as if there was such a valve in LFS.
Well, there is a throttle valve in LFS... <- Unnecessary smart-ass comment, btw

[morpha]

That's because you're bouncing off the rev limiter, silly! :tilt:
For me, the turbo pressure increases completely linearly, any gear, as long as I'm flooring it. However, I have to floor it, pedal to the metal, completely flat or I won't get any pressure at all.

Unnecessary smart-ass comment, btw
Absolutely :razz:

[wheel4hummer]

However, I have to floor it, pedal to the metal, completely flat or I won't get any pressure at all.

When I'm bouncing off the rev limiter, I get about 10psi of boost at 3/4 throttle in neutral... :shrug:

Also, look at the following replay. If the boost in LFS is solely affected by RPM, then how come when I hit the brakes while in 2nd gear, and floor it, the RPM slowly drops to 4000rpm, but my boost stays at around 16psi (please excuse the spiking, by the way, my pedals suck :P). Clearly, morpha, you are wrong. :nod:

[DragonCommando]

Vaccum will not slow down a turbo and more than likely would assist it in spooling since you are drawing air through it in the direction it is designed to push air.

If there is little or no load on the engine then vacuum will still be too high to close the blowoff valve completely and you will lose boost. Atleast untill you get near the maximum speed the engine can rev with the intake size it has. which would be a bad idea since thats usualy well above redline.

When a Turbo equiped car is idleing the blow-off valve is sitting open, when the vaccum drops off as the engine speeds up the blow off valve closses. The blow off valve and turbo spooling rate/time are completely seperate from eachother, and as soon as you get vacuum again the blow off valve will open regardless of boost or not.

When Demo had a turbo the only thing wrong that I noticed was the lag.

[morpha]

When I'm bouncing off the rev limiter, I get about 10psi of boost at 3/4 throttle in neutral... :shrug:

Also, look at the following replay. If the boost in LFS is solely affected by RPM, then how come when I hit the brakes while in 2nd gear, and floor it, the RPM slowly drops to 4000rpm, but my boost stays at around 16psi (please excuse the spiking, by the way, my pedals suck :P). Clearly, morpha, you are wrong. :nod:

Well I was wrong about the full throttle thing, there actually is some pressure starting from 50% throttle. However, the XRR's turbo boosts up to 1.7 bar at about 5k rpm, any gear, full throttle.

[wheel4hummer]

However, the XRR's turbo boosts up to 1.7 bar at about 5k rpm, any gear, full throttle.

No it doesn't!
Each time I slowed down to 2000RPM and then went full throttle until the rev limiter
1st gear, at 5000rpm - 0.36 bar
2nd gear, at 5000rpm - 0.73 bar
3rd gear, at 5000rpm - 1.2 bar

I have no idea how you get up to 1.7 bar at 5000rpm in every gear. Do you have some sort of ill3gal nawzzz mod or something? :razz:

[morpha]

No it doesn't!
Each time I slowed down to 2000RPM and then went full throttle until the rev limiter
1st gear, at 5000rpm - 0.36 bar
2nd gear, at 5000rpm - 0.73 bar
3rd gear, at 5000rpm - 1.2 bar

I have no idea how you get up to 1.7 bar at 5000rpm in every gear. Do you have some sort of ill3gal nawzzz mod or something? :razz:

I think we're talking about different ways of testing here.
You're trying normal, linear acceleration, basically building up speed rather than turbo pressure. I go for turbo pressure rather than speed :D

To get 1.7 bar in 1st @ 5000, I actually have to left-foot brake to keep the revs @ 5000 while still applying full throttle. If I just go for it and accelerate like I normally would, my results pretty much match yours.

Click me, I'm a video! (http://rapidshare.com/files/127709715/turbo_rpm_relation.avi.html) ... showing how I drive when I'm concentrating on a little read-out instead of the tarmac I'm meant to stay on :D

[wheel4hummer]

To get 1.7 bar in 1st @ 5000, I actually have to left-foot brake to keep the revs @ 5000 while still applying full throttle.

Yes, that is what happens. That proves your previous statement to be incorrect.

That can't be, the turbo is driven by the exhaust gas which should be solely rpm-dependend.

[DragonCommando]

I think we're talking about different ways of testing here.
You're trying normal, linear acceleration, basically building up speed rather than turbo pressure. I go for turbo pressure rather than speed :D

To get 1.7 bar in 1st @ 5000, I actually have to left-foot brake to keep the revs @ 5000 while still applying full throttle. If I just go for it and accelerate like I normally would, my results pretty much match yours.

Click me, I'm a video! (http://rapidshare.com/files/127709715/turbo_rpm_relation.avi.html) ... showing how I drive when I'm concentrating on a little read-out instead of the tarmac I'm meant to stay on :D

And this is because you are putting a high load on the engine (by braking and accelerating at the same time)
The high load keeps the engine from accelerating and maintaining vacuum, because the throttle is open, the blow off valve closess and you get higher boost.

[morpha]

In your eagerness to prove me wrong, you both seem to have missed the point. The turbo pressure increases linearly, if there was a way to keep the throttle completely open in first gear without accelerating, the turbo pressure would increase in exactly the same time at the same engine RPM as it would in 6th. The difference is that the acceleration in 6th is way slower, giving the turbo more time to rev up.

Get my point?

[Ricerguy]

Why are you all arguing on a point, which is directly affected by each of your cars gearing? In LFS the turbo is only RPM related, when it comes to the speed at which it spools up ( e.g. @redline with no throttle > full throttle the turbo will spool faster than it will from 2k RPM ). Also, I shall use the XRT for this next explanation. the turbo in the XRT can not attain full boost untill 4k RPMs, the exhaust below 4k rpms is simply not enough to fully spool the turbo. This makes me remember also that new in patch Z there is also a lag between the time you accelerate and the turbo kicking in, is this the time it takes the exhaust to overcome the rotational inertia of the turbine? :D

EDIT: from wikipedia
Boost Threshold
Turbochargers start producing boost only above a certain exhaust mass flow rate (depending on the size of the turbo) which is determined by the engine displacement, rpm, and throttle opening. Without an appropriate exhaust gas flow, they logically cannot force air into the engine. The point at full throttle in which the mass flow in the exhaust is strong enough to force air into the engine is known as the boost threshold rpm...

[wheel4hummer]

In LFS the turbo is only RPM related, when it comes to the speed at which it spools up

I agree with you completely. It seems that the speed at which the turbo spools is related to the RPM in LFS.

The turbo pressure increases linearly
No, it doesn't! Obviously, if you think about it, Ricerguy is quite correct. The rate at which boost increases is directly related to the RPM. So, the faster the engine spins, the faster the boost increases. Therefore the boost does not increase linearly. To try to prove this I am going to use outgauge and attempt making a chart of boost and RPM vs time.

EDIT:FFS I cannot seem to get the struct correct in python...FAIL!!!!!!!!

[morpha]

No, it doesn't! Obviously, if you think about it, Ricerguy is quite correct. The rate at which boost increases is directly related to the RPM. So, the faster the engine spins, the faster the boost increases. Therefore the boost does not increase linearly. To try to prove this I am going to use outgauge and attempt making a chart of boost and RPM vs time.

EDIT:FFS I cannot seem to get the struct correct in python...FAIL!!!!!!!!

And once again you missed my point, I clearly stated it will increase linearly in any gear, full throttle at the same engine RPMAnd if you scroll back up you'll see I was the first one to say that it depends solely on the RPM :shrug:

At 5000 rpm with the throttle fully opened, the turbo pressure will increase EXACTLY IN THE SAME WAY in ALL GEARS, that is what I said the whole time.
The only reason why it doesn't produce as much boost in lower gears as in the higher ones is that the gears are to short to give the turbo enough time to spool up.

[wheel4hummer]

And once again you missed my point, I clearly stated it will increase linearly in any gear
Boost doesn't increase linearly! The rate at which the boost increases, however, increases with RPM.

And if you scroll back up you'll see I was the first one to say that it depends solely on the RPM :shrug:

You said that boost depends solely on the RPM, and that is not true.

EDIT: As you can see in my chart, the higher the RPM is, the faster the boost builds.

[morpha]

Ok either get your facts straight or count me out!
What I said it that the amount of exhaust gas is solely rpm-dependent, which is what powers the turbo. Therefor, the turbo pressure is rpm-dependent.
The turbo's air compression / output in terms of volume is rpm-dependent, which is in fact the boost. That you can't see that boost in-game is because the BOV is open but that doesn't change the turbo's output, apart from letting the turbine spin a little faster due to the reduced resistance which is counteracted for by the fact that the throttle is closed, which then reduces the overall amout of exhaust gas.

Once again, at FULL THROTTLE ( = throttle 100% open, all of the compressed air is delievered to the intake manifold), the turbo pressure increases linearly in any gear while keeping the same engine rpm.

That this is not the case if you're accelerating should be obvious, simply because a shorter gearing will accelerate a lot faster than the higher gears, 3rd or 4th, depending on if it's a 5 speed or 6 speed gearbox.

€: Great, once again we're talking about completely different things even though I made my point as clear as it can be.
Your chart makes perfect sense but it has nothing to do with what I'm talking about.

[wheel4hummer]

the turbo pressure increases linearly in any gear while keeping the same engine rpm.

Yes, if the RPM stays the same then the rate of boost increase is staying the same, so the increase is linear. But you didn't say "at the same RPM" earlier, you only said "boost increases linearly" but you DID NOT say "at the same RPM" afterwards earlier! If you would have said "at the same rpm" in your previous posts, then I would have not disagreed with you!!!!! I made a chart of bars/second vs RPM. If the XRR is held at ~4000rpm, the boost increases linearly at 0.3Bar per second. (I messed up my chart a little, so just multiply the bar/s values in my chart by 10). At the rev limiter, the boost increases linearly at 0.7Bar/s.

EDIT: I am going to redo this, except do it in neutral and start off with the engine off, and turn on the ignition while full throttle. That way there won't be the spike in the beginning, I don't think.

[morpha]

....the turbo pressure would increase in exactly the same time at the same engine RPM as it would in 6th....

And once again you missed my point, I clearly stated it will increase linearly in any gear, full throttle And if you scroll back up you'll see I was the first one to say that it depends solely on the RPM :shrug:

At 5000 rpm with the throttle fully opened, the turbo pressure will increase EXACTLY IN THE SAME WAY in ALL GEARS, that is what I said the whole time.

Where did I not say "at the same RPM"? :really:

[wheel4hummer]

Where did I not say "at the same RPM"? :really:

Right here is what caused me to disagree with you:

For me, the turbo pressure increases completely linearly, any gear, as long as I'm flooring it.

You did NOT say "at the same RPM" after that! :schwitz:

By the way, let me use this post to upload a better chart of boost increase vs rpm...

[morpha]

Well that post was followed by the following one: Well I was wrong about the full throttle thing, there actually is some pressure starting from 50% throttle. However, the XRR's turbo boosts up to 1.7 bar at about 5k rpm, any gear, full throttle.

Anyway, enough useless text and charts proving facts we already knew for me, I'm out :tilt:

[wheel4hummer]

Well that post was followed by the following one:

Anyway, enough useless text and charts proving facts we already knew for me, I'm out :tilt:

Well the only thing you said that I disagreed with is the linear part. :tilt:

[tristancliffe]

Let's throw a spanner in the works - a turbo's ability to generate boost has more to do with exhaust gas temperature than flow rate.

[wheel4hummer]

Let's throw a spanner in the works - a turbo's ability to generate boost has more to do with exhaust gas temperature than flow rate.

Well after realizing that I have no idea about how real turbochargers generate boost, I decided to just try to see how the turbochargers in LFS do so. :D

[Zen321]

Let's throw a spanner in the works - a turbo's ability to generate boost has more to do with exhaust gas temperature than flow rate.

Let's throw a second one - a turbo's ability to generate boost has more to do with the revs and size of the exhaust turbine than flow rate :razz:

[wheel4hummer]

Let's throw a second one - a turbo's ability to generate boost has more to do with the revs and size of the exhaust turbine than flow rate :razz:

Well the displacement of the engine also matters as much as the revs do.

[Ball Bearing Turbo]

Judas Preist.

Wow.

[tristancliffe]

Leave it Jeff, it's not worth it!

[Ball Bearing Turbo]

Ok Tristan I'm not going there overall, but I have to point out that:

A) When you go WoT, last time I checked you should be at or near 0 vacuum very quickly (almost instantly at idle, not quite so at higher RPM) due to equalization when you slam the throttle open.

B) Why the hell would a blowoff valve always be open under vacuum; you would be taking in unfiltered ambient air almost all the time, which would be silly. The turbocharger would also never be able to pressurize the manifold if it didn't close until it was under pressure - quite the conundrum! :doh:

[DragonCommando]

For the most part, stock turbos don't have blow off valves, they have recirculating valves, so it doesn't matter if its open or not, it's always filtered.

But a performance turbo usualy has a blow off valve, which in most cases has it's own filter to prevent dust from being sucked in at idle. But some people like to hear that noise made popular by a particular movie, and run a blow off valve with no filter without realizing what they are risking.

When you go WOT from a stand still in gear the vacuum will drop almost instantly and boost can then build as soon as the turbo spools, because the engine has a load on it and will not just rev up as fast as it can.

If you go WOT with the car out of gear, the engine has no load and will then wind up as fast as it can, usualy keeping up vacuum. This causes the valve to either only close partialy, or not at all. Which means that even though the turbo is spooling up, the boost is lost through the valve.


So the turbos in LFS behave quite realisticaly in that sence, if you just WOT out of gear the engine will keep up with the vacuum drop, and it won't drop enough to close the valve.

I could provide a diagram of the system, but it would take some time to make. It would more than likey need to be animated to show without load, and with load.

[Ball Bearing Turbo]

Ok, well everyone has to look stupid sometimes. For years I always assumed the BoV/Recirc was soley pressure activated. Turns out after some quick research that it's a combination of post-throttle vac and pre-throttle pressure that activates it, not just one or the other.

There's plenty of cars BTW that can get to good amounts of positive manifold pressure in neutral. There's a video floating around here that I uploaded a few years ago where 12lbs or so is acheived just by reving the engine; it just depends on the system in question. That phenomenon is just about efficiency range / compressor map on the turbocharger vs engine characterisitics.

This also means I can almost gaurantee that there are other problems with the modelling in LFS based on something Scawen said to me about it in December. Pardon me while I dig it up.

[DragonCommando]

Well, it realy depends on how quickly the engine responds to throttle position, if it responds slower than you can get positive manifold pressure in nutral. but on a car that responds very quickly the engine will keep up and you will only get a small drop in vacuum.

If you put a turbo on a formula 1 engine or an engine with similar responce time I'm positive you won't get boost in nutral. The turbo will spool, theres no question about that, but the valve won't close bacause of vacuum.

[wheel4hummer]

Ok, well everyone has to look stupid sometimes.

Some people more often then others. :(
>/me feels stupid most of the time<
Technically, everyone in this thread is spamming, because this thread is about "Turbo chergers". Everyone is discussing turbochargers, when they should be discussing Turbo chergers!!!! :razz:

[Ricerguy]

Meh. I'm just excited that BBT is back doin what he does best. :D
I'm going to learn alot from this thread.

P.S. so im not the onlyone who realises the sluggishness(?) of the XRT's motor? Thought it was just me. :)

[MAD3.0LT]

this is a extreamly dumb thread if u guys dont know how a turbo works corectly dont argue that ur right.

i dont fully understand turbo's but they dont all work the same due to differnt boost controlers wastegates and even the way it dumps the gass's can cause differnt boost curve's

shit AR ratio's of the exhaust wheel and compresser wheel alter the lienairty of the turbo's boost curve allso

yes the turbo's in LFS are WRONG!

i drive a car that can hit full boost 17psi at 2600 RPM in 3rd and 4th if u floor it from 1000 RPM and in 2nd it gets to 15PSI at 2500 RMP befor the wheels spin and it Drops down to 12 PSI when spinning

BTW it holds the boost untill 5000 RPM then drops off 2 psi befor hiting the 6500 LIMITER!

and i can go from -20 vacume to -2 vacume free reving the engine

[wheel4hummer]

this is a extreamly dumb thread if u guys dont know how a turbo works corectly dont argue that ur right.

But isn't that what you are doing by making that post? Seems a little hypocritical to me...

[MAD3.0LT]

But isn't that what you are doing by making that post? Seems a little hypocritical to me...
no if u read correctly im not argueing im stating what i have seen and im not saying i understand how they work i merly stated that i have seen ALOT of differnt things. but yer a little hyporcritical from ur point of view.

[wheel4hummer]

but yer a little hyporcritical from ur point of view.

Could you point out where I have been hypocritical?

[Mako.]

google: how turbocharging works

[Ball Bearing Turbo]

Could you point out where I have been hypocritical?

Actually he stated that you were being "hyporcritical", get it straight!

:really:

To the guy above, since you have the literacy of a baboon (you know who you are) I can't be bothered to read much of what you ... "write", much less put any manner of confidence in your observations.

I can't believe people like this will be running the world one day. Can you imagine the company emails? "i wont 2 hav a meetin 2day in ur ofise get teh teem 2gethur 4 sum brane stormin or yer fyrd lolz11" :rolleyes:


Idiocracy is actually happening, isn't it.

...no, sadly I won't be taking any technical advice from this guy. :shrug:

[wheel4hummer]

Idiocracy is actually happening, isn't it.

Yes, there are people who are even stupider then me. Surprising, isn't it? :D

[MAD3.0LT]

Could you point out where I have been hypocritical?


lol i said
A little hyprocital from ur point of view means= that from ur side i can see how its a little hyprocital but thats besides the point my statement was ment to give you guys the realization that not everything works the same way as you have been tould or read!

and to Ball Bearing Turbo im guessing ur post was directed at me? if so who really gives a shit about trying to be professional on a public racing forums??:"?

[wheel4hummer]

my statement was ment to give you guys the realization that not everything works the same way as you have been tould or read!

:chairfallI lol'd!

I'm going to stop make senseless posts in this thread now. :thumb:

[MAD3.0LT]

:chairfallI lol'd!

I'm going to stop make senseless posts in this thread now. :thumb:


awww why not ur on a role :D:D

and im enjoying this thus far :D

[DragonCommando]

and i can go from -20 vacume to -2 vacume free reving the engine


This is because the engine doesn't respond as fast as one with more than a fue performance bolt ons, if the whole inside of the engine has been replaced with stronger but lighter parts, the vacuum will not drop as much. It will still drop, but not as much, sometimes not enough to close the BOV.

This doesn't hurt anything since you don't need boost if you are just reving for kicks n' giggles.

However, from what I'm getting from what you people are saying about the turbos in LFS. There apears to be two problems, one is that the turbo lags alot, and the other is that they all act as if the car can maintain enough vacuum to prevent the boost from being used.

[Ball Bearing Turbo]

I'm not sure if the lag is just due to rotational inertia or what the deal is there. Vacuum disappears very quickly as illustrated by the digital boost gauge in the XRR, that part seems pretty correct. There doesn't appear to be any of the positive feedback aspect of turbocharging. As cylinder pressure increases so does the EGT (drastically) which creates a larger pressure differential between the inlet and outlet side of the turbine - which is the primary ingredient for spooling by a large factor.

In any event, I'm certain that the current model is just a very simplistic approximation of turbocharging, as is the engine simulation overall (per a different conversation with Scawen). It'll be improved one day.

[Crashgate3]

I can't believe people like this will be running the world one day. Can you imagine the company emails? "i wont 2 hav a meetin 2day in ur ofise get teh teem 2gethur 4 sum brane stormin or yer fyrd lolz11" :rolleyes:


You laugh, but a fair amount of the emails I get at work are like this.... it's enough to make you want to weep.

[DragonCommando]

You laugh, but a fair amount of the emails I get at work are like this.... it's enough to make you want to weep.

The sad part is, some schools are starting to allow the use of this for tests and assignments. One girl wrote a whole short story like that.

It's just getting mental now.

[Ball Bearing Turbo]

You can't be serious....

[Homeless_Drunk]

The sad part is, some schools are starting to allow the use of this for tests and assignments. One girl wrote a whole short story like that.

It's just getting mental now.

Do you have a link to any information on that? I find that very hard to believe...

Yes, this generation is pretty poor when it comes to grammar but to allow such mistakes and not punish those who take shortcuts and ultimately 'un-educate' themselves is just plain silly. Ever seen the movie Idiocracy? (http://www.imdb.com/title/tt0387808/)

Anyways, I think this, like 99% of the other suggestions, is something that will be addressed later. In my opinion this section of the forum is almost comical at this stage of LFS development. Sure, it is great to see what people want and what the community still wants to be fixed/added but after 4+ years I think the devs have a pretty good idea of what everyone would like, or atleast what the general concensus is.

[mitza4rally]

This is a racing car, U don`t need turbo to work at low rpm, U need max boost at full throtle but it would be nice if they make somme kind of ALS for the FXR and XRR bcz they rely need the turbo to work.

[TurboLag]

1st of all, a turbocharger is an exponential chain reaction (more air in = more exhaust => even more air in), which in turn means that the "fade" in boost gain in the higher revs is totally wrong. Exhaust temperature has NOTHING to do with it! It's all about the dynamic exhaust manifold pressure vs exhaust turbine blade area. The wastegate is connected either electronically or mechanically to a pressurized area in the intake and is opened whenever the vacuum or pressure force overcomes a spring in an actuator.

I'll try to post a tranfer function for a turbocharged engine when I get home..

[tristancliffe]

hahahahahahahahahahahahahahahahahahahahahahahahaha hahahahahahahahahahahahahahahahahahahahahahahahaha hahahahahahahahahahahahahahahahahahahahahahahahaha haha



No, there's more:

hahahahahahahahahahahahahahahahahahahahahahahahaha hahahahahahahahahahahahahahahahahahahahahahahahaha hahahahahahahahahahahahahahahahahahahahahahahahaha hahahahahahahahahahahahaha

[lalathegreat]

Which post are you laughing at?

[Gills4life]

I wasted 10 minutes of my life reading all of this :nerd: i'm pissed off now :irked:

lol

[Ball Bearing Turbo]

Exhaust temperature has NOTHING to do with it!

Actually, you are dead wrong.

The turbine does not work like a pinwheel from the fair. Influent exhaust gas velocity has comparitively little to do with how much energy is dumped into the turbine, the larger component is the pressure differential across the turbine. The turbine is mainly driven by the expansion of gases inside the turbine. This is precisely why turbocharged vehicles benfit from larger exhaust systems since the pressure drop is greater and therefore spool times are shorter. This is also why the positive feed back effect you correctly mentioned happens - but not directly because of the increased flow as cylinder pressure rises; what rises with cylinder pressure? OH right, the EGT skyrockets - often causing the turbine housing to actually glow.

I don't care what any moron tells you, that is the truth.

If you don't think so... get ahold of a turbocharger, and try to spin it up with just air. Then try it with a blowtorch and see what happens ;)

[tristancliffe]

Which post are you laughing at?

The stupid one above my previous post. And yours now. Hahahahahahahaha

[mitza4rally]

1st of all, a turbocharger is an exponential chain reaction (more air in = more exhaust => even more air in), which in turn means that the "fade" in boost gain in the higher revs is totally wrong. Exhaust temperature has NOTHING to do with it! It's all about the dynamic exhaust manifold pressure vs exhaust turbine blade area. The wastegate is connected either electronically or mechanically to a pressurized area in the intake and is opened whenever the vacuum or pressure force overcomes a spring in an actuator.

I'll try to post a tranfer function for a turbocharged engine when I get home..
Dude U just made-it catastrophicly boring, and wrong........no very wrong.

[TurboLag]

To the people who think explanation is boring, mark this thread as read and move along..
...If you don't think so... get ahold of a turbocharger, and try to spin it up with just air. Then try it with a blowtorch and see what happens ;)...
Then put bare piping between the compressor wheel and the exhaust turbine inlet, mount a fuel injector and a flare, spool up the turbo, start the fuel supply and ignite.. it WILL run by itself simply because of it's generating pressure by raising the temperature. It's exactly how a jet engine works.. So it's the pressure rise, not the temperature rise that drives the exhaust turbine. If there were some other way to increase the pressure (well, you could use another pressure supply but that would just ruin the whole idea), it would work aswell!
The reason a larger exhaust pipe system would improve spool-up is because it generates less backpressure on the exhaust turbine, thereby increase the difference in dynamic pressure between the manifold and the downpipe..

BBT: I agree with you, but the chain reaction IS there and it's why we have wastegates to route exhaust pressure outside the exhaust turbine.. And as you say, it's the expansion of gases (yes, we do use temperature to achieve that) that drive the turbo, not the temperature itself.

[wheel4hummer]

So it's the pressure rise, not the temperature rise that drives the exhaust turbine.

P1T1 = P2T2

:nod:

[Ball Bearing Turbo]

Hotter gas is inherantly under more pressure in the same volume, hence it's symantecally correct to state that heat is the primary factor. Effluent velocity is higher than influent velocity because the turbine is not perfectly efficient. Ideally it would be the same and all the energy from the expansion would go into the turbine. What makes this all possible? Heat!

[DragonCommando]

I'm realy considering making an animated diagram of the system, so people will stop mentioning wastegates and BOVs and trying to explain the function of each, and failing horribly at it.:x

A wastegate is on the exhaust side, a blow off valve is on the intake side.

The wastegate is used to contol boost. It is run by a pressure line going from the charge side of the turbo to the wastegate. Boost controlers just change the pressure on the wastegate, so you can obtain a higher boost before it opens, or limit boost by running a weaker spring in the wastegate and compensating for it with the controler when you need more boost.
Wastegates also prevent the turbo from overspeeding, which can cause damage or even failure. If you've ever seen a turbo explode, I can garantee it was because it was spinning faster than it was designed to.

Generaly high performance race cars won't need boost controlers, unless they are bracket racing drag cars. If you have a boost controler on a road car, it's simply for show and serves no function other than to say "I have a boost controler, I'm cool":rolleyes:

The blow off valve serves a completely different function and controls boost during throttle off, there are no servos or switches of any kind on the bov, just a single vacuum line going to the intake after the throttle plate.

[1303s_vortech]

Here is a pic:
http://home.comcast.net/~phantoms/vacuum/turbo_system.jpg (http://home.comcast.net/%7Ephantoms/vacuum/turbo_system.jpg)

[AjRose]

Generaly high performance race cars won't need boost controlers, unless they are bracket racing drag cars. If you have a boost controler on a road car, it's simply for show and serves no function other than to say "I have a boost controler, I'm cool":rolleyes:

What the hell are you talking about?! Why would a race car/road car not need a boost controller? Do you think they just magically stop building boost?

Every turbocharged vehicle needs some type of boost controller. Whether it be electronic, manual or just the wastegate spring.

The blow off valve serves a completely different function and controls boost during throttle off, there are no servos or switches of any kind on the bov, just a single vacuum line going to the intake after the throttle plate.

So what exactly are you saying here? Is controlling boost a different function than controlling boost?

But seriously the Bov does not technically control boost it just releases the positive pressure from the charge pipes to prevent surge. And provides that wicked sound everyone loves so much.:riceboy:

[tristancliffe]

I think by boost controller he meant the electronic version, and wasn't referring to the obligatory wastegate.

I don't love the sound of atmospheric blow off valves. They generate the sound known to me as 'pure moron'. Only an idiot would fit one on a road car in place of a recirculating valve.

[AjRose]

I don't love the sound of atmospheric blow off valves. They generate the sound known to me as 'pure moron'. Only an idiot would fit one on a road car in place of a recirculating valve.

I know what you mean, Mine is recirculated before the compressor. I was looking for a sarcasm/ rolls eyes smiley to put after that.

Maybe this one will work ---->:riceboy:

Back on topic though I'm sure just about every race car is using a 3 way electronic boost control valve that is controlled by the engine management. Wastegates generally do not provide accurate boost control when using just the spring.

[1303s_vortech]

Wastegates generally do not provide accurate boost control when using just the spring.

It do the job for reasonably boosted engine (like most regular road cars).

[AjRose]

It do the job for reasonably boosted engine (like most regular road cars).


It does indeed for low exhaust output road cars.

[DK_USA]

Car without turbo go Vroom....Car With turbo go VOOOOOOOOOOOOOOOOOM.......

Srry Couldnt help Myself..

[DragonCommando]

I think by boost controller he meant the electronic version, and wasn't referring to the obligatory wastegate.

I don't love the sound of atmospheric blow off valves. They generate the sound known to me as 'pure moron'. Only an idiot would fit one on a road car in place of a recirculating valve.


Thats exactly what I meant, and I agree about the blow off valves as well. I hate that sound almost as much as I hate the sound of a car without any valve. Compressor surge/stall is bad, period. If your car makes a funny fluttering sound when you let off the throttle, there is something wrong.

[Rotareneg]

The most obvious way to show that the turbo isn't modeled realistically is to take a car like the XRR up to 100 mph in 6th and, while leaving the throttle open, toggle the ignition on and off. This will roughly simulating a diesel engine which doesn't have a throttle, just variable amounts of fuel injection. In real life the turbo will vary in speed significantly when the fuel is toggled on and off, however in LFS it's only affected by RPM and throttle.

[MAD3.0LT]

hahahahahahahahhahahahaahahah

jajajajajajajajajajajjajajajaja

fuk this is amusing to read
i thought i was dumb (maybe i still am )

their is many ways to controle boost and vary intake pressures but personaly id prefer a externaly wastegate or even 2 on a 4 inch dump with a 2 and a half inch wastegate pipe :D but thats costly and ilegal here

[DragonCommando]

hahahahahahahahhahahahaahahah

jajajajajajajajajajajjajajajaja

fuk this is amusing to read
i thought i was dumb (maybe i still am )

their is many ways to controle boost and vary intake pressures but personaly id prefer a externaly wastegate or even 2 on a 4 inch dump with a 2 and a half inch wastegate pipe :D but thats costly and ilegal here


2 wastegates? You can't mean on the same turbo, that would be completely pointless. One wastegate, controlled by the management computer, is all you need. And all I've ever seen on turbo charged race cars. That means no fancy crap that lets you change boost from inside the car either, boost controlers are useless if the engine management can do it already.

[lalathegreat]

2 wastegates? You can't mean on the same turbo, that would be completely pointless. One wastegate, controlled by the management computer, is all you need. And all I've ever seen on turbo charged race cars. That means no fancy crap that lets you change boost from inside the car either, boost controlers are useless if the engine management can do it already.
Dual waste gates are common when you have a highly modified car running a lot of boost.You would normally use two waste gates when one cannot flow enough to maintain a specific boost preasure; What tends to happen is the boost pressure starts to creep until it goes kaBoooM boOOm.

[Mikkel Petersen]

hahahahahahahahhahahahaahahah

jajajajajajajajajajajjajajajaja

fuk this is amusing to read
i thought i was dumb (maybe i still am )

their is many ways to controle boost and vary intake pressures but personaly id prefer a externaly wastegate or even 2 on a 4 inch dump with a 2 and a half inch wastegate pipe :D but thats costly and ilegal here
Everything I hear from you is blablabla.

[wheel4hummer]

What tends to happen is the boost pressure starts to creep until it goes kaBoooM boOOm.

That's what overboost protection is for. I believe that Subaru has a system on their turbocharged vehicles where the fuel is cut if the boost gets to high, in case the wastegate somehow fails. :nod:

Example: http://www.youtube.com/watch?v=jk8em2rhmRk

[DragonCommando]

If you can fit 2 wastegates, you can fit one big one. This is even more true on high boost applications where the turbo and exhaust will be much bigger.

I have only ever seen dual waste gates on dual turbo systems with a small and large turbo.

Unless you are talking about dual port external wastegates, but to my knowlege, the second port serves a different function and isn't needed for proper functionality of the wastegate.

[tristancliffe]

Often two smaller valves will be easier to package than one big one, and give the same skirt area as the big one. It's the same reason multivalve cylinder heads have two or more smaller valves instead of one big one.

[DragonCommando]

Thats true, but in the case of a waste gate, its easier to manage one, so one big one will generaly be better than 2 smaller ones. All you have to do to contol boost is control pressure on one valve, and generaly, the less moving parts, the more reliable it will be.

[AjRose]

Dual wastegates are actually very common. And they are almost required for split-pulse manifolds.

[MAD3.0LT]

lol na i did mean 2 wastegates on the 1 turbo but the ones im talking about are EXTERNAL ones that mount on the side of the dump pipe from the turbo i see it done on ALOT of high HP cars cause they flow so much air that one 54mm wastegate cant release the presure quick enough


and Mikkel Petersen all i here from u is whining like a female ;)

[AjRose]

lol na i did mean 2 wastegates on the 1 turbo but the ones im talking about are EXTERNAL ones that mount on the side of the dump pipe from the turbo i see it done on ALOT of high HP cars cause they flow so much air that one 54mm wastegate cant release the presure quick enough


and Mikkel Petersen all i here from u is whining like a female ;)

There is no reason for a wastegate to mount on the dump/exhaust. Where they mount is the opposite of a dump.

Also It doesnt have very much to do with releasing pressure quickly. If a wastegate cannot flow well enough especially on a large turbo/low boost setup you will suffer from boost creep at higher rpms/engine load.

[T.J.]

It is a bit more realistic turbo-lag in Patch Z

[AjRose]

It is a bit more realistic turbo-lag in Patch Z

Yes, Back on topic ;)

I think it's very hard to feel the lag (or lack thereof) in lfs. All of the turbo cars seem to feel "ok" Most stock turbocharged cars do not have very much turbo lag. They have properly sized turbochargers for a daily driving application. It's once you start modifying that lag plays a larger role.

My only problem with the lfs turbocharger is the fact that it builds boost very linear (ly?) It doesnt really seem to grow exponentionally. Not sure how to word it correctly.

edit: I just base this off of memory which is not very good. I would have to drive the tbo cars around a bit to get a feel for the physics of the turbochargers in game before I made any real suggestions for improvements.

[MAD3.0LT]

There is no reason for a wastegate to mount on the dump/exhaust. Where they mount is the opposite of a dump.

Also It doesnt have very much to do with releasing pressure quickly. If a wastegate cannot flow well enough especially on a large turbo/low boost setup you will suffer from boost creep at higher rpms/engine load.


well i understand ur what ur saying but alot of the 9/8 sec drag cars i see run 2 wastegates on the 2nd dump pipe into the atmosphear :D

[lalathegreat]

http://www.full-race.com/catalog_images/evo8/evo%20prostreet%20div%20t4%20dual%2044.jpg

well people do use dual waste gates; here is an example of a turbo manifold for Lancer Evolution

[maoriBOII]

I own an 88 TX3 Turbo and use a T28 turbo and its characteristics are as described in the first post, boost kicks in around the 2000-2500rpm mark. My brother also has the same car but uses a BBT28 and his kicks in a bit earlier.

For lag to be useable and realistic in LFS you would have to determine what size turbo and specifically sort would be modelled on to the car(bigger turbo, longer the lag - smaller turbo not as much but top end boost is normally over). Then take into account the displacement size of the engine and so on.

Im yet to use any of the turbo cars because im only a demo user but once i purchase my s2 ill come back with my thoughts

[Daviticus]

The only reason why it doesn't produce as much boost in lower gears as in the higher ones is that the gears are to short to give the turbo enough time to spool up.


Yachtzee! :thumb:

This is why Man invented anti-lag. :D

[Riel]

Bit of an old topic, but I think the turbo is very well simulated.

Turbo spins trough energy in exhaust and depends on these factors:

Amount of exhaust gas (RPM and Throtlleposition)
Temperature of exhaust gas (hotter = more energy, hot gas expands and creates more volume to spin turbo)
Load of engine (well, more torque gives more push in exhaust)

These three combined will not get very linear turbolag.

I think the lag is very good, when off-throttle, you need about half a sec to spin back the turbo. I am experiencing it very well with the XRR on Westhill. The first lefthand corner, you need to brake a tiny bit and step on it again. When you do that with one foot, you have a turbolag. When doing a left-foot brake and applying full-throttle to keep turbo spinning, you accelerate out of the corner much quicker.

This experience is very realistic to me TBH. (Oh, i drive a Renault 5 GTT, so i know turbo LAG :p :) )

The reason you don;t get full pressure in 1st gear is that the the amount of time is too short, when hitting rev-limiter the torque drops massively, so no turbopressure there.





But, I found this topic to report a bug in the game, and don't know where to put it:

When out of fuel, applying throttle still spins the turbo (testen when rolling) :p That's impossible.

[M3THANOL]

If you are standing dead still in first with clutch engaged (XRR), the turbo will reach full boost after 3-4 seconds, then you will have full boost right through 1st gear if u dump the clutch, but if you put it in first and accelerate normally, not dumping the clutch and then accelerating hard you will reach 1.1 - 1.2 bar boost before changing to second gear, simply because there isn't a long enough duration in first to full spool the larger turbo that the XRR has. If you do the same with the XRT you will reach full boost (0.8 bar) in 1st gear because number one the boost is set lower and I am sure that the turbo is smaller. :)

[juliao]

:schwitz:

[MAD3.0LT]

That can't be, the turbo is driven by the exhaust gas which should be solely rpm-dependend. However, I think the turbo inlet valve is now somehow connected to the throttle, I don't get any turbo pressure at all if I don't floor it :shrug:


lol real turbos are NOT RPM based
a comment miss conception is that its the exhaust gas that spools the turbo but its really the Heat from the gas that makes a turbo spool harder and faster. A turbo charger has to rely on the gas being hot so it can travel extreamly fast to hit the rear housing fins more heat ='s faster expanding gas = more load on the engine = more heat and in turn ='s more boost.
allso most turbo cars u can hold them flat to the floor in nutrel and it wont go over 0psi exept on its way up to redline. allso the AR's of the intake and exhaust wheels have ALOT to do with how a turbo will react on the car allso engine displacement and ALOT of other things come into affect ie tuned lenght extractors and even the placement of a external gate can alter how the car spools.

but as this is a racing sim forum i wont go into much more depth :P
the turbo's are wrong but Not as bad as they used to be.


oh and AjRose stupid me calling it a dump :P its just what it looks like to me as thats the only pipe im going to dump into the air :P

[wheel4hummer]

I thought that the boost that a turbocharger produces is related to the RPM, displacement, volumetric efficiency, and the density of the air entering the engine. Volumetric efficiency, and air density, are altered by load and RPM, as far as I know. I have no idea if I am correct or not, but that's just what I think is the case.

[Riel]

To react on MAD"s first line, more RPS is more air, for so far you were wrong :)

It IS the exhaust gas, the heat makes it expand so more volume. It all comes together. SO you are right in a way but not explaining it properly :)

[MAD3.0LT]

To react on MAD"s first line, more RPS is more air, for so far you were wrong :)

It IS the exhaust gas, the heat makes it expand so more volume. It all comes together. SO you are right in a way but not explaining it properly :)


well yer i know what you mean but their is so many things that come into play i cant explain them for the life of me :)

example
in a road car i drive if i put it foot flat from 1000 rpm it dose this
1st gear wheel spin and 11 psi at 2200 rpm and drops off at 4000 rpm to 4 psi
2nd gear 14 psi at 2400ish rpm wheel spin and drops off to 12 at about 5000rpm
3rd gear no wheel spin 15psi and drops off to 14 psi at 6000 rpm
4th same as 3rd
5th would be the same but cant get the car to 6000 rpm cause thats like 270kph :P

as u can see when rpm's are higher and load on the engine is lower it makes less boost :)

but the main reason the car lose's boost at higher RPM is the turbo ar's and size is wrong for the engine displacement

[Riel]

Yes, I wanted to mention but I read your last line :)

For my 1.4 GTT (renault 5) and hybrid turbo the boost just climbs :p
It's in there at 2000rpm (well, current turbo's are way better then they were in the 80's).

Well, it's very hard to say how a turbo would react, tbh :)

But, that bug, is it reported anywere? Think it is stupid to spin turbo while out of gas :)

[BigPeBe]

I'm not sure if this is what MAD3.0L explained, but if your boost drops off at certain rpm's without any reason, it's not working properly. Probably wastegate opening in wrong situations and not able to keep the desired boost.

When turbo works as it should, it first wakes up and then keeps to boost as where it is adjusted for, as long as you keep your foot down.

[Riel]

I'm not sure if this is what MAD3.0L explained, but if your boost drops off at certain rpm's without any reason, it's not working properly. Probably wastegate opening in wrong situations and not able to keep the desired boost.

When turbo works as it should, it first wakes up and then keeps to boost as where it is adjusted for, as long as you keep your foot down.


As big engine tend to suck in a lot of air at high RPM it is good possible the (small) turbo can't blow that amount of air. So it gets sucked a bit, dropping boost. A turbo can spin a certain amount of RPM (somewhere between 110.000 and 170.000) and for each turbo the efficiency is, just as with engines, at a certain RPM.

So when you 1) push your turbo above a certain RPM (like with old air-filters (the "i hold my hand on the vacuum cleaner hose"-effect) ) 2) Make TOO much boost, it drops performance, and another thing is that the outgoing air will be too heated by the bad performing turbo, dropping Power drastically.

( My GTT for example, will have 200nm torque at 3000rpm, and its HP will be at 140hp at 5500 RPM, running on 14psi of pressure.

When I, with my small turbo, run on 20psi, I measure 220nm torque at 3000RPM (good, increase), but 135hp at 5500 RPM! Performancedrop coz turbo got out of range.

[MAD3.0LT]

yer more or less my issue with this turbo is it cant flow enough air at higher RPM for to hold the boost at higher RPM im only talking about 3rd gear up.the issue with the lower gears is wheel spin limits load yer . i cant explain what i mean :P but if anyone wants to learn more about it go to allmost any decent car forum and you shall be enlightened :D

their is 2 ways i should go about fixing this

1 is change the exhaust wheel from a .73 ar to a .86 or 1.06 rear ar

or get a bigger turbo with both .86 ar's like a GT35/82 that i will be buying :D


:)


Riel

i dont have a hot air issue :) 600x330x90 intercooler dose the job well rated at around 700hp :P
btw im only making 290 HP at 5500 at the wheels and about 450 NM of tq at 4000 :P
got about 7k to spend to get 400+ :D

[Riel]

Ah, nice cooler :)
But when the air is cooler when it goes inside the cooler, you always win more. 3% more air at 10 degrees temperature drop (Celcius).

The wheeldiameter can be a solution for sure, but it'll take spooltime. Twin-setup maybe? :)

Anyway, it's really not easy, and maybe it even isn't theoreticcally explanable for the sake of normality :p Mostly it's a combination of knowing what you do and experience.

Good luck with your setup, got a story running somewhere on the net?

But, well, the XRR drives quite predictive in terms of boost. So not that bad.

[MAD3.0LT]

Ah, nice cooler :)
But when the air is cooler when it goes inside the cooler, you always win more. 3% more air at 10 degrees temperature drop (Celcius).

The wheeldiameter can be a solution for sure, but it'll take spooltime. Twin-setup maybe? :)

Anyway, it's really not easy, and maybe it even isn't theoreticcally explanable for the sake of normality :p Mostly it's a combination of knowing what you do and experience.

Good luck with your setup, got a story running somewhere on the net?

But, well, the XRR drives quite predictive in terms of boost. So not that bad.


na no story mate i been slowly modding the car for 2 years now owned it 8 years :) done all the work my self
list of mods

custom cold air intake
3inch mandrel bent exhaust (paid for this to be done)
boost controler set from 6psi to 15
converted from auto to 5spd manual
put lsd in live axel removed broken lsd (1 week) installed mini spool
re did the hole suspension with custom kingsprings ie the lb progressive rates
swaped out so many differnt size tyres and rims its not funny looking for traction
removed rear swaybar to help with the locker on the track

repaced the clutch twice :)

and other various things but my current step is waiting on my tyres
Falken Azenis Sport - RT-215
235x40x17's
and after that im geting a custom 35mm front swaybar ebc redstuff pad's and then on to more power :)

[BigPeBe]

As big engine tend to suck in a lot of air at high RPM it is good possible the (small) turbo can't blow that amount of air. So it gets sucked a bit, dropping boost. A turbo can spin a certain amount of RPM (somewhere between 110.000 and 170.000) and for each turbo the efficiency is, just as with engines, at a certain RPM.

So when you 1) push your turbo above a certain RPM (like with old air-filters (the "i hold my hand on the vacuum cleaner hose"-effect) ) 2) Make TOO much boost, it drops performance, and another thing is that the outgoing air will be too heated by the bad performing turbo, dropping Power drastically.

( My GTT for example, will have 200nm torque at 3000rpm, and its HP will be at 140hp at 5500 RPM, running on 14psi of pressure.

When I, with my small turbo, run on 20psi, I measure 220nm torque at 3000RPM (good, increase), but 135hp at 5500 RPM! Performancedrop coz turbo got out of range.

Yea well ok I'm actually quite aware of that, but I just didn't put into consideration that a turbo car would have a turbo what is so too tiny for the engine.
But now reading MAD3.0LT's post I notice that his car is very far from stock, so it is just a bad choose of turbo.

I would replace to better turbo immediately, because something what drops at 4000 rpm just sounds horrible to me. In my car the engine is starting to just live there!:) Not a turbo tho.

I'm also more of a "two-litre" man, so cars what are usual in my hobby, it is very rare that someone haves a turbo what actually isn't able to keep the boost, of course on bigger engines that is more likely to happen.

BTW I browse many very decent car forums.:razz:

[MAD3.0LT]

hehe i did other things to the car like the cooler and better intake piping for more air flow but the turbo is what the RB30ET came standed with :D

[BigPeBe]

That just sounds weird to me that a stock car would have a turbo what isn't able to keep the boost up. I see that's possible then too.

Tho when stock the effect might not been that high, because the stock boost was only 6psi, with the higher boost it is just not able to keep it up. But of course you already know this, so get a bigger turbo man.:razz:

[wheel4hummer]

That just sounds weird to me that a stock car would have a turbo what isn't able to keep the boost up.

It's because they use a turbocharger that is most efficient at that specific boost level with no modifications whatsoever to the engine. So when you "tune" a stock turbocharged car (or any car for that matter), it is likely that you will make it less reliable then it was from the factory.

[BigPeBe]

It's because they use a turbocharger that is most efficient at that specific boost level with no modifications whatsoever to the engine. So when you "tune" a stock turbocharged car (or any car for that matter), it is likely that you will make it less reliable then it was from the factory.

Yes. But as like I said, that's not usual with the cars I'm interested about, of course with these bigger engines the "boost drop" is easier to produce.
But ie. with Cossie engines with the original turbo it is possible to get even +100bhp extra out of the engine without even opening it, quite reliable too, without having problems with keeping up the boost.

Tho this "boost drop" doesn't have a much to do with reliability. But raising boost can lower the reliability, depends of the engine and how much.

The thing what I actually meant with that what you quoted, was that it sounds weird that a stock engine would have a "boost drop". When I originally started about the boost drop thing I assumed the engine was running with stock boost.
As a stock it runs 6psi and it may have a little drop to 4psi, but that isn't that noticeable I think.

When it comes to turbos with me, for my budget now it is more something like "get all-stock in decent condition Ford Pinto 2.0i engine + some turbo and a manifold and downpipe + few k-jet injectors for extra fuel supply + maybe a intercooler + do some piping from the turbo to the intake and then just launch the engine, have some boost and give right foot to the engine, it's ready! :razz: There's no many turbos what would have problems keeping the boost up in build like this.:D

[wheel4hummer]

As a stock it runs 6psi and it may have a little drop to 4psi, but that isn't that noticeable I think.

Maybe that is some sort of exhaust leak? The exhaust pressure gets higher with more load on the engine, and then a leaky gasket ends up blowing apart because of the pressure? :scratchch

[MAD3.0LT]

lol the boost drop im talking about in 1st and 2nd gears isent cause the turbo is to small it cause their is no load on the engine cause the wheels spin so easly and thats in the dry :P in the wet the most boost i can make is 12psi in 5th gear at 110 kph befor it spins :P

and yer im going o up grade my turbo :) but injectors ECU and exhast manafold and new plenum will be needed befor the turbo :)

allso got a 255L PH fuel pump and sard reg siting here to go in :)

but in stock form no car should lose boost at higher rpm :)

[Osco]

To react on MAD"s first line, more RPS is more air, for so far you were wrong :)

It IS the exhaust gas, the heat makes it expand so more volume. It all comes together. SO you are right in a way but not explaining it properly :)

ever taken a look at a compressor map?
considered pressure ratios?

[erfrag]

This is precisely why turbocharged vehicles benfit from larger exhaust systems since the pressure drop is greater and therefore spool times are shorter. This is also why the positive feed back effect you correctly mentioned happens - but not directly because of the increased flow as cylinder pressure rises; what rises with cylinder pressure? OH right, the EGT skyrockets - often causing the turbine housing to actually glow.
;)

i know this thread is a couple months old but i thought i'd add my obervations since i have been daily driving, and tracking turbocharged cars since i got my driving license.

i wanted to add that the first sentence in the above post is not always true. it is true for probably 90% of all turbo applications since most people aim for larger power over stock or n/a. for many factory turbo setups where a car is equipped with a fairly small turbo, i have found that the exhaust size can be used to shift the power band around. the larger the exhaust, the higher the power band till you maximize the pressure differential.

for example i have a fairly small turbo on my car. it was designed to be a very livable-daily around town setup. the turbo spikes at 18-20 psi early and tapers to 12-14psi around optimal shift points for best acceleration.

from a 2" to 2.5" spool was much quicker, mid range was strongest of the exhaust systems i have tried. 2500-4000 was quite a bit stronger than the 2" exhaust. 235ft-lbs and 195hp to 250ft-lbs and 205hp at the wheels was obtained. boost pressure seemed to taper off quicker than the 3"

from a 2.5" to 3" spool was slightly slower than the 2.5", but i had more top end. with the 3" on the motor in my car some people have experienced over spinning and damaging their turbine. when the turbo sppols, it spools quicker, but slighty later compared to the 2.5" or 2". 2000-3500 was slightly weaker than the 2.5" as the turbo didn't spool quite as fast, but 3500-6000 was a lot stronger. 240 ft-lbs and 215hp at the wheels. it makes pretty much the same amount of torque past 4000 rpm's, but is shift up in the powerband, netting slightly higher HP figures.

i attribute this to the way the exhaust gasses flow through the turbine at faster velocities where the flow may not be as efficient as if there was some back pressure on the turbo form the 2.5" vs the 3".

i have always used engine load to explain how boost is built, and how fast from my observations. with a 24 pound flywheel my car generates more boost in neutral than a 12 pound. but the 12 pound accelerates quicker as there is less rotational mass.

EGT's reach in the low thousands of degrees C. without going into positive pressure my EGT's are around 300-400C depending on around town cruising or highway cruising. which is the efficiency range of a catalytic converter for emmissions purposes. when i really get on it over and over again they are in upwards of 1000-1200C, and my turbo starts to glow orange. this is why some people install turbo timers on street cars. the engine must run to allow the oil and/or water to cool the turbo so coking does not occur in the oil lines and houseing of the turbo where the oil flows. so if you have a turbo charged car, don't beat on it, then shut it off without idleing the engine for a few seconds (15-60 depending on how hot your EGT's are), or driving a short, low-load distance.

[Ball Bearing Turbo]

Very nice post, glad to have you here!

Indeed, that wasn't the whole story as you very nicely expanded on, generalities are not invaribale truths :)

[MAD3.0LT]

lol many months later and this thread is still a intresting read :D

nice post erfrag though i dont fully agree with some of ur post most of it would make sense depending on the setup/conditions/ lots of things

one question erfrag what kind of boost controler are you useing on this car or is it actuator controled?

if its controled is whats the setings of the controler

[Riel]

I wanted to point out this bug back then:

When out of fuel, applying throttle still spins the turbo (tested when rolling) That's impossible.

Is there taken knowledge of this?

[wheel4hummer]

Well, if the engine is still turning, it is still pumping air.

[Riel]

Well, that's some thinking, but it sucks air from that turbo too. Since there is no new source of energy (like, burning fuel), the turbo will not spin faster. But, you are partly right: the turbo can be spinning. I really mean it different :p

So I will state it otherwise:

When out of fuel, applying throttle still generates boost (tested when rolling) That's impossible.

[flymike91]

thats probably a result of another more basic problem. when out of fuel, pressing the accelerator raises rpms.

[Rotareneg]

thats probably a result of another more basic problem. when out of fuel, pressing the accelerator raises rpms.

I tried and couldn't get that to happen.

The turbo issue is easiest to see by simply toggling the ignition on and off while moving in gear (so the engine doesn't stop right away.) In real life, even with the throttle wide open, the turbo will spool down rapidly without the extra exhaust energy from combustion. It won't completely stop since there's still air being pumped through the engine, but it sure won't be generating full boost like it can in LFS.

[Riel]

Pressing the accelerator does not raise RPM's.

The turbo-spooling simulation is not taking into account whether engine is running, it looks like it is just a RPM * THROTTLEPOSITION simulation, instead of RPM * DELIVERED TORQUE simulation (which would come a bit closer to real ;))

[Not Sure]

Good informative posts!

I am anxiously waiting for the day the devs have time to correct these issues. I _think_ they are not that hard to fix, as the turbo model is "almost there".

The new car has a turbo.. :scratchch