Mid range turbo giver more power and PP than High range
- Thread starter xSNAKEx
- 48 comments
- 18,503 views
- 239
- Houston, TX
- walterjoe
- IAS EAGLE 5
Does it work like that in GT6 or is it always better to go Stage 3?
I don't really see the point in Stage 1 and 2 turbos in GranTurismo, we aren't using the cars as daily runabouts we are racing so we are only ever in the high rev range.
It actually does so you really have to consider what track and what car you will be running. Long straights and fast sweepers you may want to go all out. Technical courses and heavier machines benefit from mid range power.
Your theory is wrong because T3 outputs less (peak) power than T2. If the engine design would be a limiting factor, you would get at least the same amount of (peak) power from T3 as from T2
And ofcourse it's a very deep thinking about this whole 'engine design' thing anyway. ~95% of all cars in the game produce more power with T3 than with T2, the way it's supposed to be. I haven't heard or read anywhere about this sophisticated tuning modeling from PD that you are trying to impose
- 28,470
- Windsor, Ontario, Canada
- Johnnypenso
Not necessarily. You're maybe thinking real life vs. GT. In GT everything happens the way they program it to happen and how turbos affect HP/Torque/PeakHP/PeakTorque is simply mathematical calculations based on the power curve and the programmed effect of the turbo. One might call that a bug or just flawed programming but everything I've seen seems to fit with what I am guessing is the underlying program.
- 422
- Eastern MA
- Odin_Wednesday
This speaks to one of my biggest annoyances with GT6. They didn't make the power curves usable. You can't tell where the redline is, and you can't tell what RPM any of the gridlines are. I have to guess at my shift points, and I don't have a sense from looking at the plot of what section of the graph I need to care about optimizing (because it's the RPM range I'm living in on the track).
- 8,725
Whilst I appreciate the whole "kit" thing, there is the small issue of PD allowing the engine tune up as well as the turbo kits. Before GT5, if you did turbo tuning, it was in place of "engine" tuning (it was called NA tune up or something back then) - you couldn't have both.
Now, with these engine stage 1, 2 and 3 "kits" (as they are), what you should be getting is a progressively more high-rpm biased torque curve? Maybe not, as you can in reality keep the same shape and just increase torque everywhere, but such modifications can still be "stage 3 expensive".
What's interesting is that the engine tuning kits don't really affect the shape of the torque curve, but the hidden stage 4 and 5 in GT5 do - massively so. In fact, putting a stage 3 turbo on a car with a stage 4 or 5 engine tuning was usually optimal in terms of peak power - and there was at least another turbo kit above stage 3 as well, also hidden.
Something tells me the tuning isn't what it should be at this stage (I think it's waiting for the sound update). However, it's obvious that what PD mean by "High RPM Turbo" is just that - it is sized to produce boost at higher turbine throughputs, i.e. higher rpm. It is perfectly possible to have a turbo that is "too big" for a given engine (tuning), such that it doesn't even come on boost (because the exhaust can't drive the turbine, effectively).
- 239
- CT
- Z3R0OneOneSe7en
some cars only have a redline of 6k,so the stage three is useless. stage 2 is a good all round turbo for those kind of cars. while I found stage one great for drifting as it spools up quickly.Does it work like that in GT6 or is it always better to go Stage 3?
I don't really see the point in Stage 1 and 2 turbos in GranTurismo, we aren't using the cars as daily runabouts we are racing so we are only ever in the high rev range.
to be honest I figured out the stage 3 issue while trying to do the IA final championship. I realize I was barely getting any power,so I restarted the championship and threw a stage 2 turbo on. the car became a lot more responsive.
- 132
- lavosim
People are mistaken because they compare turbo stages to engine upgrades. It was more apparent in gt5 where you could not detune engine, while you could swap turbos at will. Engine is always better with better upgrade, while turbos upgrades mean three different things. Most of the time high rpm turbo is the best option, but medium and low range turbos can be superior in some cases.
- 6,100
- Finland
Increasing torque throughout the rev range is only possible to a point though, if a two litre NA engine is giving 200 Nm at 4000 rpm and 200 bhp at 8000 rpm (figures right out of my head) it can't be made to give much more than 250 Nm at the said 4000 rpm because the limits of natural aspiration come to play. It just isn't possible, 125 Nm per litre out of a naturally aspirated engine is one hell of an achievement already. Such an engine would then produce around 250 bhp at 8000 rpm if the torque curve remained the original shape. However, if the torque can be retained until the rpm of the maximum power the relatively measly 250 Nm is good for much more, resulting in well over 300 bhp.
It's certainly one of the weak sides of GT6 tuning, higher engine stages should always change the torque curve and/or increase the rev limit instead of giving more power everywhere. After all those two things are the ones which enable getting more peak power out of an NA engine because torque is inherently limited, the magical thing is shifting it higher in the rev range.
And about quicker spooling turbos giving more power and PP, more power would be a rare occurrence in real life but my own car is a good example of one that would get a lot more "PP" with a small turbo compared to a big one if nothing else was changes. The engine in question is the bulletproof Volvo redblock which comes equipped with a Mitsubishi TD04H-13C turbo (well, it looks like a turbo but is hardly sized like one) and the spooling is quick to say the least, coming on boost at around 1700 rpm and giving 1 bar well below 3000 rpm. The engine can't take much more than the said 1 bar as it is but the -13C gives around 400 Nm at 3500 rpm and 220 bhp at 5000 rpm. Putting in a bigger turbo such as a TD04HL-19T would cause slower spooling and result in less low end torque but no more top end power because boost is limited - naturally the bigger turbo can create a much higher boost pressure but it's no good as it can't be used or something goes kaboom.
- 2,913
- UK
- phil_75
So, on which car(s) is a stage 2 faster than a stage 3?
Also when a car only revs to 6k that doesn't mean a high rpm turbo won't be any use.
The high rpm turbo will just kick in earlier, say 4500 - 6000.
Thats the way i always understood it, after all if on cars that run to 10k+ the high rpm doesn't run out at ~7k does it!?
Also when a car only revs to 6k that doesn't mean a high rpm turbo won't be any use.
The high rpm turbo will just kick in earlier, say 4500 - 6000.
Thats the way i always understood it, after all if on cars that run to 10k+ the high rpm doesn't run out at ~7k does it!?
- 1,210
- Sydney
No a high RPM turbo doesn't kick in earlier, it kicks in later. HIgh RPM is GT6s way of saying bigger turbo. Bigger turbos take longer to spool up higher in the rev range.
The problem I have with the 400R is its basically a RB26 bored and stroked to 2.8L, so its really an RB28. The trouble is these engine have no problems taking massive turbos, so I would certainly expect it to take GTs Stage 3 turbo without loosing power.
- 8,725
@phil_75
The Cappuccino is one off the top of my head. The high rpm kit adds a nice little spike to the torque at about 6000 rpm, but the "engine" isn't tuned to capitalise on that - it always has the stock torque curve shape (which is a compound of the underlying engine tuning and turbo stuff). The medium kit adds it a "torque boost" around 4000 rpm, right where the stock car peaks. The tail of that is presumably long lived enough up the rpm scale to result in a higher peak power than the high rpm kit, but not by much (10-20% I think).
Exactly, there are diminishing returns when chasing specific torque output, even F1 engines don't do much more than high performance road engines - but that's brake specific, i.e. minus friction, which is much higher at high rpm, hence all the focus on low friction coatings, tribology and electrical ancillaries on performance cars today.
The turbo sizing thing is pretty complicated, as it's recursive in nature. The size doesn't necessarily give an indication of the boost possible, because it depends on the shaft speed as well the engine capacity - you have to read the maps. If you're limiting yourself to 1 bar boost, it's obvious that that effective ~200% volumetric efficiency will beget a faster car if you "position" it higher in the rev range, so that the torque is multiplied by a larger rate of rotation, giving more power. But the engine clearly has to be tuned to take advantage of that as well (mainly cams).
Electronically controlled wastegates have made undersized turbos useful, so they spool faster, operate at high bypass ratios near their "peak", and then shut up firm for higher rpms, giving a nice broad, almost flat torque curve. Without that, the smaller turbo would almost certainly be inferior, because you have to scale the whole boost curve according to that 1 bar peak, and it would be asthmatic at high rpm.
Please also, everyone, note the distinction between lag (spool time) and operating off-map (whether the throughput is enough to initiate the chain reaction of boost building, of "spooling up"; for compressor and turbine). An excessively large turbo will never spool up; a properly sized turbo operating off-map (rpm and throttle position) will never spool either.
The Cappuccino is one off the top of my head. The high rpm kit adds a nice little spike to the torque at about 6000 rpm, but the "engine" isn't tuned to capitalise on that - it always has the stock torque curve shape (which is a compound of the underlying engine tuning and turbo stuff). The medium kit adds it a "torque boost" around 4000 rpm, right where the stock car peaks. The tail of that is presumably long lived enough up the rpm scale to result in a higher peak power than the high rpm kit, but not by much (10-20% I think).
Exactly, there are diminishing returns when chasing specific torque output, even F1 engines don't do much more than high performance road engines - but that's brake specific, i.e. minus friction, which is much higher at high rpm, hence all the focus on low friction coatings, tribology and electrical ancillaries on performance cars today.
The turbo sizing thing is pretty complicated, as it's recursive in nature. The size doesn't necessarily give an indication of the boost possible, because it depends on the shaft speed as well the engine capacity - you have to read the maps. If you're limiting yourself to 1 bar boost, it's obvious that that effective ~200% volumetric efficiency will beget a faster car if you "position" it higher in the rev range, so that the torque is multiplied by a larger rate of rotation, giving more power. But the engine clearly has to be tuned to take advantage of that as well (mainly cams).
Electronically controlled wastegates have made undersized turbos useful, so they spool faster, operate at high bypass ratios near their "peak", and then shut up firm for higher rpms, giving a nice broad, almost flat torque curve. Without that, the smaller turbo would almost certainly be inferior, because you have to scale the whole boost curve according to that 1 bar peak, and it would be asthmatic at high rpm.
Please also, everyone, note the distinction between lag (spool time) and operating off-map (whether the throughput is enough to initiate the chain reaction of boost building, of "spooling up"; for compressor and turbine). An excessively large turbo will never spool up; a properly sized turbo operating off-map (rpm and throttle position) will never spool either.
- 2,913
- UK
- phil_75
Yes i know mate, i think you misunderstood or i just didn't explain properly.
What i meant was, the turbos don't have a fixed rpm when they kick in.
For example a stage 3/high rpm Turbo on a car with a 6k redline will work between say 4.5k - 6k.
On a car with 10k redline it will work between 7.5k - 10k
Thats how i think it works anyway.
- 8,725
(I think you have it right, but I'll rather rudely use this as an excuse to further the points being made)
The issue is with how you define "work".
You have to know the underlying engine torque curve without the turbo to know what the effect is, and only by comparing with the torque curve with the turbo fitted. Mostly, without that information, you'll be talking about the intake manifold pressure: when it exceeds atmospheric pressure, i.e. you're "on boost", is when the turbo is deemed to be "working".
The problem with that is, the engine operates under a varying amount of vacuum in the manifold when NA, so the turbo is actually "working" long before "boost" is indicated. Then there's part-throttle, engine and turbo-compressor shaft speed changes and other dynamic considerations.
So either you dumb it right down, or you try to account for these things somehow - preferably without cheating or inventing silly rules that you have to constantly tighten up in the name of "balance" ("hand made" tunings fall into this category - there are lots of cars in GT games these days).
That basically means using simulation* as a starting point, and balancing with real world data. But how many players will actually care about that?
* there are extra benefits to this, I think I mentioned sound earlier...
- 41,043
It's a combination of the stock motor being properly modelled, and the tuning in Gran Turismo being flawed.
All power parts in Gran Turismo, except turbo/superchargers, function as torque multipliers across the rev range.
That means that a car like the 400R will keep its curve profiles even when fully built with stage 3 engine, exhaust, intake, re-map etc etc.
When you then stick a high rpm turbo on it, most of the power gain will come after the engine has started to choke.
That means you improve the overall performance compared to the stock turbos, but peak power gain is relatively moderate.
The mid rpm turbo will boost power in the mid range where the engine peaks, leading to this result.
If the engine tuning were to improve to a more realistic model, this problem would be resolved.
The particularly odd part about this is that this wasn't the case in GT1 and GT2. Granted, in those two all of the performance parts seemed to be hard coded to get specific horsepower numbers after specific parts were applied (which is why you could "revert" hybrids in GT2 by installing performance parts), and those cars still tended to get unrealistically high torque numbers simply with engine tuning; but you could still get fairly (or at least comparatively) realistic results from highly tuning whatever car you were using. I remember the Camaro Z28 in GT2 would shift the power peak and redline a couple thousand horsepower higher than stock when the engine was fully modified; and with the torque increase being much smaller than the increase in horsepower (my limited experience with GT1 makes me think that it was even more free with how much it moved torque curves, coupled with the ability to adjust boost pressure with turbocharged cars). Then with GT3 they moved over to the odd power multiplier system that they've continued to use (largely unaltered, as shown by GT5 hybriding) since, with the only improvements on it being that now you can attempt to adjust the meat of the power band with turbochargers.
There's actually a really good way to compare to two tuning systems between the first two games and every game since. Almost all of the games in the series have had the Spoon Civic Type R (which acts as the baseline for how such a car would respond to the required modifications in real life) and the regular EK9 Civic Type R it was based on. In GT2, if you went all out with tuning a stock Civic to match the power of the Spoon, the torque curves wouldn't really match up (mostly because GT2 didn't shift the power curves or redlines that high for it to match the 12,000 RPM motor the Spoon had), but the torque number would be fairly close between the two cars (you'd add nearly 40 horsepower to the car, and the torque would only rise 15 or so). If you tuned a stock Civic to the horsepower of the Spoon in any game since GT3, not only would the the torque curve and RPM range be largely identical to the stock car before you tuned it, but the torque number would be probably at least 30 lb-ft higher than the Spoon was.
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