Might be, that LFS engine modelling not yet allows different turbo-boost-patterns in different gears, and they might just have taken a middle of none boost-restraints, and IRL boost restraint?
Hey there's been some decent footage posted in this thread since I last check it out!
A few more thoughts:
I've been researching turbo's a bit more and I'm still not sure I understand them all to well, but there's a few things I've been reading about. I'm sure some of this will be novice material to some reading this thread, so to bring it down to my level:
First is the efficiency range. A turbo can often put out more boost pressure than is being asked, but this can actually be counter-productive! Adding more pressure is not the answer. For instance, when running my little K24 @ 1.0bar, and then flooring it to 1.5bar, there isn't much increase in power. (Despite the increase in pressure, the turbo is now working at poor efficiency to produce this, therefore heating the air - so, due to the extra heat produced, all it's done is increase pressure and not really increase the airmass!)
Which leads me onto ECU control of the turbocharger - the turbo definitely is limited by the ECU, at least in any newer car. Boost characteristics are quite different for various setups though as they work differently... some are purely mechanical WG's, some entirely ECU controlled WG, others kinda use both. Whilst my turbo settles at 1.5bar, I know of some who've seen the exact same setup settle at 1.8bar. Difference is, that extra 0.3bar is giving very inefficient power (compressor wheel gives optimum efficiency about 1-1.2bar) and spinning the turbo to far higher RPMs than it was designed to - dramatically shortening it's life! It's all down to how the car is mapped, not the natural restrictions of the turbocharger.
The reason the pressure builds to a crescendo that seems quite natural is because the wastegate doesn't suddenly kick in when max boost is achieved, it starts bleeding off right from the start. So even though it's limited, you wouldn't expect it to hit violently.
I think there's so many variables now with different turbo designs, that it'd be more a case of matching which setup could theoretically cause the behaviour seen in a sim, than actually trying to model the behaviour of a specific turbocharger... I think, as long as the model gives an accurate representation of some 'generic features' of any turbocharged engine, it's all good. I haven't raced on LFS:S2 so I probably should to see how it compares...
One point, if the turbo won't spool right up when free-revving the engine (ie in neutral or on your roof!) then that's a good sign; you won't see max boost unless the engine is under load IRL. I guess ideally a sim would model a turbo from a compressor map, a virtual ECU map and real-time exhaust temps + flow etc..
Cheers
Ross
A few more thoughts:
I've been researching turbo's a bit more and I'm still not sure I understand them all to well, but there's a few things I've been reading about. I'm sure some of this will be novice material to some reading this thread, so to bring it down to my level:
First is the efficiency range. A turbo can often put out more boost pressure than is being asked, but this can actually be counter-productive! Adding more pressure is not the answer. For instance, when running my little K24 @ 1.0bar, and then flooring it to 1.5bar, there isn't much increase in power. (Despite the increase in pressure, the turbo is now working at poor efficiency to produce this, therefore heating the air - so, due to the extra heat produced, all it's done is increase pressure and not really increase the airmass!)
Which leads me onto ECU control of the turbocharger - the turbo definitely is limited by the ECU, at least in any newer car. Boost characteristics are quite different for various setups though as they work differently... some are purely mechanical WG's, some entirely ECU controlled WG, others kinda use both. Whilst my turbo settles at 1.5bar, I know of some who've seen the exact same setup settle at 1.8bar. Difference is, that extra 0.3bar is giving very inefficient power (compressor wheel gives optimum efficiency about 1-1.2bar) and spinning the turbo to far higher RPMs than it was designed to - dramatically shortening it's life! It's all down to how the car is mapped, not the natural restrictions of the turbocharger.
The reason the pressure builds to a crescendo that seems quite natural is because the wastegate doesn't suddenly kick in when max boost is achieved, it starts bleeding off right from the start. So even though it's limited, you wouldn't expect it to hit violently.
I think there's so many variables now with different turbo designs, that it'd be more a case of matching which setup could theoretically cause the behaviour seen in a sim, than actually trying to model the behaviour of a specific turbocharger... I think, as long as the model gives an accurate representation of some 'generic features' of any turbocharged engine, it's all good. I haven't raced on LFS:S2 so I probably should to see how it compares...
One point, if the turbo won't spool right up when free-revving the engine (ie in neutral or on your roof!) then that's a good sign; you won't see max boost unless the engine is under load IRL. I guess ideally a sim would model a turbo from a compressor map, a virtual ECU map and real-time exhaust temps + flow etc..
Cheers
Ross
What you posted is mostly good I think, and provides a good background for this thread... However this last statement requires reproof... Given all the variables that you stated it's not necesarily true. All the required to build boost is heat - which one COULD argue that load helps create I suppose... But load in the engine isn't inherantly required! In fact, I can pull up a video of a car reaching over 10lbs just by revving. That SRT-4 I rode in could almost do this as well.
I'll be back shortly to post that video.
Also, could you clarify what you meant by crescendo in terms of the building up of boost pressure, cause that could go either way (< or >), but only one way is true in my mind.... The biggest point I've been TRYING to make is the fact that boost creates heat which creates more boost which creates more heat etc etc etc, thus there IS a crescendo which increases the speed at which boost builds, the more boost there is the faster it builds! That is exactly WHY we need a wastegate in the first place, boost does not taper itself off!
Here is the afforementioned video.
It speaks for itself!
It speaks for itself!
I think the turbo lag is part of the strategy. Just as ABS is banned, it may just be a big lonesome turbo with simple wastegate, due to any form of anti-lag not being allowed. This makes it more competitive as you have to try and keep it on boost as much as possible. Sometimes left foot braking while holding the boost up etc.
It doesn't quite feel right in LFS though. Redlining and engine in neutral would see close to full boost in no time. None of this slow building up like you get on the start line. It also feels too tied in to RPM. Rather than being on a truely independant RPM of it's own.
Anyway, what you want is a supercharger
http://www.zen97015.zen.co.uk/BoostGauge.mpg
http://www.zen97015.zen.co.uk/revups.avi Zero lag (Nearly)
It doesn't quite feel right in LFS though. Redlining and engine in neutral would see close to full boost in no time. None of this slow building up like you get on the start line. It also feels too tied in to RPM. Rather than being on a truely independant RPM of it's own.
Anyway, what you want is a supercharger
http://www.zen97015.zen.co.uk/BoostGauge.mpg
http://www.zen97015.zen.co.uk/revups.avi Zero lag (Nearly)
Hi! Yeah, I meant crescendo in terms of building boost not diminishing boost. 100% agree that a wastegate is needed
I'm not sure what you mean when you say that all you need is heat to run a turbocharger.... it's the exhaust gases turning the turbine that cause spooling, and this effect is gonna happen regardless of their temperature. Of course, more heat = higher pressure = faster spooling is that's what your getting at. And yes, you're gonna generate alot more heat with all that extra fuel burning in the engine.
As per the car giving boost when free-revving, the SR4 has a diddy little turbo I imagine; of course a small turbo will build more boost free-revving as it takes less to spin it. My K24 isn't exactly large, and it's old-skool (ie, no ball-bearing job) which doesn't help
. To spool the turbo to max. pressure the engine needs to be under load, or else you simply can't burn enough fuel in it to create enough exhaust gases to spin the turbo fast enough. And you'd really quickly get shedloads of heatsoak if you could...Cheers
Ross
This is a common misconception. The kinetic energy of the exhaust gases impacting the turbine side is almost negligable compared to the main principle by which turbochargers operate.... It's primarily the expansion of high heat, high pressure gases that drive the turbine. It's not like blowing on my sons shiny air fan thingy that you wave in the wind. Turbine housings are specially engineered to harness the energy of expanding gases. The greater the differential in pressure between the inlet and outlet side of the turbine, the more energy is dumped into the turbine itself. You can spool up a turbocharger bigtime on a bench with a blowtorch, due to the heat.... far more than you can with a hairdryer, even though the hairdryer "moves" more air. This is why with a turbocharged car wants a very large free flowing exhaust system, whereas a NA car benfits most from a properly tuned system, not necessarily a larger diameter system. The larger diameter on the exit side of a turbocharger's turbine makes the pressure differential between the inlet and outlet side larger, and spool times are quicker etc. There is plenty of information available on this topic if you dig, and it's a REALLY common misconception of the the fundamental physics of turbochargers.Did you check the video I posted? hehehe
I do however agree that of couse the dynamics of the system can change dramatically with different turbos / sizes / engines etc, however things just are off in LFS. I can't imagine for the life of me a car behaving like the RA, speaking in terms of the boost delivery... it's unreal, can you imagine trying to pass someone on the highway in that thing? By the time you've got boost you're finished your pass!
Hmm, thanks for the info - expected a reply along those lines
I wasn't trying to imply it's the kinetic energy in the exhaust gases, but in all honesty I wasn't sure; my understanding is very basic and I understand it to be rather like an aerofoil - it is the difference in pressure that causes the movement; makes sense that this is not just an effect of gases flowing over the compressor wheel like an airplane wing, but caused by a massive pressure increase on the exhaust side due to the mahoosive temps reached. Also explains how the wheel can "stall" (not fun). I almost wish I'd studied fluid mechanics now. I can't watch that vid but will post when I can later. Don't seem to have access @ work... without watching, sure the car isnt fitted with an anti-lag system? There is simply no way idle can give large amounts of boost without some assistance or a very small turbo.. just not enough energy avaliable. Could try flooring it and keeping the throttle buried of course, but I doubt the engine would last too long like that! there's a reason dyno's are braked 
A very informative post though, in fact you've answered a puzzling question to me - I recently had a 3" decatted exhaust fitted with a removed centre box and vent-to-atmosphere WG pipe, it made a HUGE difference to low-end performance and reduced turbo lag. Now it makes complete sense
G2G, work to do before the shift ends-
Cheers
Ross
PS any links for reading on this topic much appreciated
All this turbo-talk gets me excited 
illepallMakes sense, but why do manufacturers bother with split pulse tubines. Why bother with different A/R ratios if it's only the pressure/heat difference that affects spooling. A turbo spools up quicker when it has distinct pulses of flow, rather than a smooth continuous one. You can reduce turbo lag on a V6 by running two turbos, and sending 3 cylinders worth into each turbo. Even though there would be less heat energy going in. (Assuming the two turbos are just a scaled down version of a bigger alternative that would provide the same boost)
Variable-vane technology would also be useless if it was only down to heat.
ALL of these things drastically affect spool up times.
Heat has an effect because the gas is higher pressure, and this higher pressure will try an equalise past the turbine. Which creates flow. Heat alone wont make it spool. The kinetic flow of the gas is what turns the turbine. Heat of course is what causes the flow. Just as heat expansion is what causes the piston to move down. As the mass of the exhaust is the same as the fuel and air that went in. Nothing extra was created to increase volume.
So on reflection no-one is really wrong, but a turbo is spooled ultimately through kinetic energy, and not thermal. As if you were to seal off the turbine inlet, and put a heat source in it, it wouldn't continue to spin.
OK had a quick look at the vid. That turbo seems to have minimal lag, and seems like a rather small car, so I'd assume it's a small ball-bearing job that spools very quickly at low rpms (ie, with little flow). And 10psi isn't a huge amount of pressure. I haven't really paid attention yet, but I'm sure my turbo spools to about 5 or so psi on free-revving. Point I'm getting at is that's much less than peak boost, which for me is 22psi.
After some thinking, this is the conclusion I've come to now.. feel free to add comments, rip my comments apart etc or tell me where I'm wrong
It's the difference in pressure, that is the primary reason for the turbo to be spooling. The flow has to make a difference, or else porting a turbo or changing A/R ratio's wouldn't make a difference (it quite obviously does). I think it's kinda like holding a vacuum cleaner hose in front of your little desk fan, it starts spinning wildly - the pressure difference on either side of the blades causes them to turn. Of course, in the engine, a bunch of gases at the same temp wouldn't do much. Heat these to 1000degs and there's a huge increase in pressure; of course the faster the turbine spins the quicker pressure is trying to equillise, so you need lots of gases to replace those that are 'escaping' - hence the need for higher revs (and more burnt fuel) to sustain higher boost levels.. you can double the flow without increasing the pressure. it's all inter-related. I'm clueless about pulsing so can't comment, but physics is really wierd so it doen't surprise me!
I don't think it's as much a case of who's correct with what hypothesis, as it is to them all being linked - without the heat, there wouldn't be the extreme pressure difference. This causes the airflow through the turbine which causes it to spin, much like airflow through a prop makes it spin (or like puting a cd on a table and blowing across it makes it lift, just to confuse things ). Which is why variable trim turbines are effective; they are angled for optimum spool-up time (ie, by changing the angle they require less flow to turn) and then once spinning change trim level in order to be more effective at higher RPMS. I think Porsche play with that stuff.
Disclaimer - this is just a bunch of my crazy thoughts and I could be entirely wrong.
So, to bring this to LFS relevance - it's all very complex, nobody would ever quite agree so it's best to make a simpler turbo model. However, it does need some improvement as LFS turbo's behave really wierd.
Cheers
Ross
After some thinking, this is the conclusion I've come to now.. feel free to add comments, rip my comments apart etc or tell me where I'm wrong
It's the difference in pressure, that is the primary reason for the turbo to be spooling. The flow has to make a difference, or else porting a turbo or changing A/R ratio's wouldn't make a difference (it quite obviously does). I think it's kinda like holding a vacuum cleaner hose in front of your little desk fan, it starts spinning wildly - the pressure difference on either side of the blades causes them to turn. Of course, in the engine, a bunch of gases at the same temp wouldn't do much. Heat these to 1000degs and there's a huge increase in pressure; of course the faster the turbine spins the quicker pressure is trying to equillise, so you need lots of gases to replace those that are 'escaping' - hence the need for higher revs (and more burnt fuel) to sustain higher boost levels.. you can double the flow without increasing the pressure. it's all inter-related. I'm clueless about pulsing so can't comment, but physics is really wierd so it doen't surprise me!
I don't think it's as much a case of who's correct with what hypothesis, as it is to them all being linked - without the heat, there wouldn't be the extreme pressure difference. This causes the airflow through the turbine which causes it to spin, much like airflow through a prop makes it spin (or like puting a cd on a table and blowing across it makes it lift, just to confuse things
). Which is why variable trim turbines are effective; they are angled for optimum spool-up time (ie, by changing the angle they require less flow to turn) and then once spinning change trim level in order to be more effective at higher RPMS. I think Porsche play with that stuff.Disclaimer - this is just a bunch of my crazy thoughts and I could be entirely wrong.
So, to bring this to LFS relevance - it's all very complex, nobody would ever quite agree so it's best to make a simpler turbo model. However, it does need some improvement as LFS turbo's behave really wierd.
Cheers
Ross
Whoa, I never said it's the ONLY thing that affects spool times!
Twin turbo systems benfit primarily from reduced rotational intertia. You'll have to provide some info about this "pulsing" business, I don't see it making sense. At least I've never heard of what you're describing. More consistent flow produces more consistent work, I can't forsee splitting flow more than necessary creating a positive effect at all
The amount of heat energy dumped would still be proportional to the size of the turbine, however the mass is less and therefore two small turbochargers react much quicker than one larger one. This is just for twin designs; mating one large and one smaller turbo is a whole different ballgame.The difference is that the "flow" (read: the dumping of energy into the turbine) happens inside the turbocharger housing, rather than before it. Without high pressure/heat, that cannot happen. I realize that the heat energy is transferred mechanically but it still originates in the form of heat rather than kinetic form. That might be where it ends up, but the fundamental principle is still different from common belief, and this is what I was pointing out. Obviously it takes kinetic energy to apply force to the turbine - but there's a transfer that takes place, hence turbochargers by nature use the wasted thermal energy in exhaust for our benefit. They wouldn't be described as using the velocity of exhaust in the manifold, because that's not really how it works....
Likewise, without heat, putting airflow through the turbine won't do much either. Therefore thermal energy is a fundamental requirement. Thermal energy is still the "fuel" for the turbine.
edited for clarity
Interesting thread. We should get the terminology right, though. Boost LAG and the engine speed by which the turbo is producing full boost are two different things.
Boost lag depends on the inertia of the spinning parts...how much is the boost pressure lagging behind compared to a 100% load/constant engine speed scenario. Take the RA up to 220km/h, let off, then floor it at 200km/h. You'll notice it'll take some time to get back up to full boost. That's lag. It's also the reason engines with big turbos often don't reach full boost in the lower gears, even though the engine speed/load would be sufficient.
Boost response on the other hand depends on the geometry of the turbo (turbo vs. engine size, A/R ratio, etc.) and the boost control mechanism and refers to the boost vs. rpm curve you get in a 100% load/costant engine speed scenario barring any lag.
As far as I can tell there are 2 problems with the boost modelling in LFS.
1. Too much lag - After letting off, it simply takes too long to get back full boost.
2. Unrealistic boost response curves - The RA for instance starts making boost at 1000rpm but doesn't reach full boost until 5000 rpm. It should climb steeper and peak sooner. Additionally the boost usually tapers off slightly towards the redline. Manufacturers tend to pick small turbos to improve boost response and low-end torque, and these usually start to choke at high revs.
For reference, here's a small video:
http://www.blinkerfluid.net/0auf290mittel.wmv
The engine is a 2.0L with about 330hp. The turbo is either a KKK K26 or K29, so a good bit bigger than what you would find on the 250hp-ish 2.0L engines in LFS.
A dyno graph along with the boost curve can be found here:
http://www.eds-motorsport.de/D ... /Calibra_C20LET_PH-35.jpg
(not the same engine, but an identical one)
The video does a good job of showcasing turbo lag (or lack thereof), boost spike ("overshooting" the target boost level) and the slight drop in boost at higher revs.
Boost lag depends on the inertia of the spinning parts...how much is the boost pressure lagging behind compared to a 100% load/constant engine speed scenario. Take the RA up to 220km/h, let off, then floor it at 200km/h. You'll notice it'll take some time to get back up to full boost. That's lag. It's also the reason engines with big turbos often don't reach full boost in the lower gears, even though the engine speed/load would be sufficient.
Boost response on the other hand depends on the geometry of the turbo (turbo vs. engine size, A/R ratio, etc.) and the boost control mechanism and refers to the boost vs. rpm curve you get in a 100% load/costant engine speed scenario barring any lag.
As far as I can tell there are 2 problems with the boost modelling in LFS.
1. Too much lag - After letting off, it simply takes too long to get back full boost.
2. Unrealistic boost response curves - The RA for instance starts making boost at 1000rpm but doesn't reach full boost until 5000 rpm. It should climb steeper and peak sooner. Additionally the boost usually tapers off slightly towards the redline. Manufacturers tend to pick small turbos to improve boost response and low-end torque, and these usually start to choke at high revs.
For reference, here's a small video:
http://www.blinkerfluid.net/0auf290mittel.wmv
The engine is a 2.0L with about 330hp. The turbo is either a KKK K26 or K29, so a good bit bigger than what you would find on the 250hp-ish 2.0L engines in LFS.
A dyno graph along with the boost curve can be found here:
http://www.eds-motorsport.de/D ... /Calibra_C20LET_PH-35.jpg
(not the same engine, but an identical one)
The video does a good job of showcasing turbo lag (or lack thereof), boost spike ("overshooting" the target boost level) and the slight drop in boost at higher revs.
THAT, is an awesome video!!! Is that your car?
And it shows everything I've been trying to say this whole thread very very well.
Excellent post, and excellent video. I 100% agree with your post.
330HP from 1 bar on a 2 litre... That's not too shabby either (for a road car)
Noticed the peak at 1.25Bar in 3rd, what are you supposed to be limited at?
And it shows everything I've been trying to say this whole thread very very well.
Excellent post, and excellent video. I 100% agree with your post.
330HP from 1 bar on a 2 litre... That's not too shabby either (for a road car)
Noticed the peak at 1.25Bar in 3rd, what are you supposed to be limited at?
If it was my car, I'd know for sure what kind of turbo is on there.
It's supposed to run 1 bar. The spike is due to the manifold being held completely shut for as long as possible. When it actually hits target boost, it takes a bit of time to fully open and bleed off the excess exhaust. This is also why the spike is less pronounced in the upper gears.
Small correction to my post above, which was worded a bit poorly. The actual boost pressure tapering off is more commonly found on modded cars having a stock turbo spinning at the top of its lungs. Completely stock cars usually just see a decrease in efficiency in the upper rev range (hotter air, less density).
Efficiency is also why 1 bar of boost can be either 230hp or 330hp on the same engine, depending on what kind of turbo is used.
It's supposed to run 1 bar. The spike is due to the manifold being held completely shut for as long as possible. When it actually hits target boost, it takes a bit of time to fully open and bleed off the excess exhaust. This is also why the spike is less pronounced in the upper gears.
Small correction to my post above, which was worded a bit poorly. The actual boost pressure tapering off is more commonly found on modded cars having a stock turbo spinning at the top of its lungs. Completely stock cars usually just see a decrease in efficiency in the upper rev range (hotter air, less density).
Efficiency is also why 1 bar of boost can be either 230hp or 330hp on the same engine, depending on what kind of turbo is used.
:doh: I suppose so. Who knows? Maybe you'd been into the sauce
As you alluded to, the whole purpose of intercooler is greater efficiency at the same boost. Which brings me to a question - when travelling on high mountain roads do turbocharged cars lose power? Assume the same air temperature (although it would be colder most likely, we'll ignore that for now) since the air is less dense at higher altitudes does this affect the output on turbo cars?
If I pressurized a bottle to 14lbs on a high mountain road... And then brought it down to sea level, what would the pressure be in the bottle? I would think that since the external pressure is greater at sea level that the relative pressure in the bottle should drop, therefore an engine running 14lbs on a high mountain road still has less oxygen available to burn than an engine running 14lbs at sea level... correct?
Yep, they do, but not as much as naturally aspirated engines. It's easier to understand when you consider the absolute air pressure, not just relative.
Say the atmospheric air pressure at sea level is 14.7 psi absloute. So a naturally aspirated engine has an intake air pressure of...well...14.7 psi absolute. A turbocharged engine at sea level running 1 bar of boost would have a manifold air pressure of 29.4 psi absolute.
At high altitude with an atmospheric pressure of say 12 psi absolute, the naturally aspirated engine would lose ~18.4% of its power cause the air is ~18.4% less dense.
A turbocharged engine would still try to achieve 14.7 psi over atmosphere (remember the wastegate is spring-loaded, and you still need the same amount of boost pressure acting on the spring to compress it), making it 26.7 psi absolute in total, so the turbocharged engine only loses ~9.2% of its power.
Now, what's relevant for the efficiency for the turbo is the pressure ratio across the compressor (boost (abs.)/ambient air pressure (abs.)). While it's 2:1 at sea level, it goes up to 2.225:1 at high altitude. That means depending on the turbos efficiency range, the drop in power may be slightly smaller or slightly bigger than 9.2%. To determine that you'd need the compressor map of the turbo, though.
By the way, modern engines with electronic boost control often have an altitude sensor. At high altitude they pull a small amount of boost in order not to overspin the turbo, despite the higher pressure ratio.
Well, depends on how you measure it. If said bottle has 14 psi over ambient at 12 psi ambient pressure, it would only have 11.3 psi over ambient at sea level, simply because the reference point changed.
If it has 14 psi absolute at 12 psi ambient, it'll have 14 psi absolute anywhere.
Ok, that makes sense. What would the boost gauge read in that situation then - because the wastegate is looking for enough pressure to activate a mechanical gate (which is constant) whereas the gauge will still be reading relative pressure won't it? So then your boost guage may not be giving you accurate info at higher altitudes? Or am I getting confused....
That makes perfect sense.
If they maintained the same ratio as sealevel then the engine should lose the same % of output as an NA then right?
So, if I capped a bottle at sealevel and took it to space there would be 14.7psi pushing on the inside of that bottle.... Wonder if it would explode; guess that would be the same as pressurizing one to 14.7psi on earth at sea level.
Depends on the gauge. An electronic gauge run off the cars MAP sensor will read absolute, since that's all that matters for the ECU. So it would read lower at high altitude.
Most mechanical gauges read relative to ambient, so they'd be accurate.
Yep. Most turbos still have some headroom at stock boost levels, though, so the ECU usually allows a slightly higher pressure ratio. As a rule of thumb you need 1% more rpm from the turbo for each 500ft of altitude.
Exactly. Btw, if you want something to ponder, what kind of absolute pressure does the air have which a scuba diver breathes at 40m?
I wonder if Scawen has read this thread and what his thoughts are?
Just wondering if boost delivery will be tweaked at all in the future (I'm not asking when... just if...)
Scawen?
Just wondering if boost delivery will be tweaked at all in the future (I'm not asking when... just if...)
Scawen?
Heya, just read through the thread, when I get back from England I will give a video of me free revving in my SRT-4 then again with a load rolling and then again launching and revving and shifting (effectively a 1/4 mile =P)
(I would do this tonight but someone rear ended the front of my car and it's in the body shop, they tore my bumper, grill and bent my intercooler.... not fun, they drove away too, a new stock intercooler is 600 bucks...)
(I would do this tonight but someone rear ended the front of my car and it's in the body shop, they tore my bumper, grill and bent my intercooler.... not fun, they drove away too, a new stock intercooler is 600 bucks...)
Oh sure, rub it in
LOLSounds like a good plan thanks for that. Sorry to hear about the "rear ending of the front of your car"... That's a bummer
OT: I might be purchasing a certain car with that same mill
Ok I am ressurecting this thread, just to give an update... my sticky pod camera mount was sent to the wrong address delaying it for two weeks, I should have it this weekend :banana:
I will show boost in neutral revving, boost in 4th gear from 1800 or so until I deem it becomes not safe anymore(will hit over 120 or so in 4th), and then from a dead stop through 4th gear.
Things to note about SRT-4
Boost is controlled by the stock ECU to keep horsepower constant below like 90-95 degrees air temp depending on how dense the air charge is. During the winter I was running about 4-5 pounds of boost, I should be able to run max boost this time of year though, some days I do some I don't. Anyone feel that this would not model boost properly?
I will show boost in neutral revving, boost in 4th gear from 1800 or so until I deem it becomes not safe anymore(will hit over 120 or so in 4th), and then from a dead stop through 4th gear.
Things to note about SRT-4
Boost is controlled by the stock ECU to keep horsepower constant below like 90-95 degrees air temp depending on how dense the air charge is. During the winter I was running about 4-5 pounds of boost, I should be able to run max boost this time of year though, some days I do some I don't. Anyone feel that this would not model boost properly?
NO I think it will do wonders
Thank you! Is it also not limited in 1st to 12lbs?
Thank you! Is it also not limited in 1st to 12lbs?
Donno it goes by so fast I never had time to look
it's possible, first gear just doesn't last long enough for me to look down there while concentrating on keeping strait, sliding the clutch, and making sure I don't get too much wheel-spinNice video.
You can notice in that how just before the car shifts into top gear (5th or 6th? couldnt work out because of the crazy start) that the boost drops off a bit. Then when shifted into top gear, boost actually sits a bit higher then the other gears.
My RX7 comes onto boost fairly quickly with the stock turbo, even though i think they're quite large for a stock unit (Hitachi HT-18S). I would be well into the full 10 pounds of boost by the time 2500rpm came along. I haven't even noticed the speed increase of boost from 0-2500rpm though. It just seems to jump up to boost, not a long enough period to notice different speeds.
As the video above shows, boost generally (depending on turbo) comes on 10x quicker then it does in LFS. I would also agree with the point BallBearingTurbo made about them increasing boost faster as they increase boost, which seems to be the opposite in LFS. But as i said above, the time between 0 and full boost for a small to medium sized turbo is a short one, indeed. I also agree with what someone said earlier in regards to the turbo cars feeling like they're N/A. They just seem to lack that punch in the guts.
One of the reasons i was all for engine/parts changing in LFS was because i'd like to fit larger turbos to the cars. I'm a bit of a boost nut and just love the feeling of a truck load of boost building up and getting thrown out the exhaust with the tyres leaving darkies all over the place. Over here i'm labelled as a "rev head" :hyper: lol
I made a quick video of what i think hitting boost should be more like in LFS:
http://files.filefront.com/LFS ... /;5179991;;/fileinfo.html
I think the boost noise isn't in sync with the engine RPM/load because as you can see on the 3rd gear launch just after the hairpin coming onto finish straight, it's pretty nicely simulated. But not so nicely simulated coming onto the main straight in 4th previous to this.
This may start evolving into a "this is a racing sim, not NFS boost your car up shite" argument, but please, don't take my post in that direction. That's not what i'm trying to get at. I'm trying to suggest different ways of simulating/recreating boost for LFS, i'm not talking about neons and chrome wiper blades.
For what it's worth, i think the car in that demo had about 300kw + 500nm of torque. Not a rediculous power figure by any means.
Boost modelling questions...
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