Gran Turismo Scientist symposium

Discussion in 'Gran Turismo 1' started by gtmaster08, Mar 12, 2009.

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  1. gtmaster08

    gtmaster08

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    Welcome fellow scientists of gtplanet! My name is Professor gtmaster08, the website's top leading scientist on redlining, FF, and FR cars in Gran Turismo 1! If you have any discoveries, problems, and/or cures for said problems then feel free to share them here!:gtpflag:
     
  2. Famine

    Famine Administrator

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    Who died and made you...

    ... anything?
     
  3. Parnelli Bone

    Parnelli Bone Premium

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    :lol: Can i be a scientist? :O I be real good at it!
     
  4. gtmaster08

    gtmaster08

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    2 things come to mind;

    to Famine: What's the matter? Jealous?:sly: And after all, I meant it!

    to Parnelli Bone: Well, what exactly do you specialize in for your "Top Leading Scientist" position?
     
  5. Parnelli Bone

    Parnelli Bone Premium

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    I specialize in many things related to virtual automotive technology, sir. However, like most scientists, i am a bit absent-minded. Perhaps you can open the floor to a bit of discussion? I am currently drawing a blank.
     
  6. zed300

    zed300

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    I "discovered" that redlining any FF or FR, in any games, means a number of things.

    (a) change gear ..............CURE
    (b) change gear ratio.............CURE
    (c) change final(diff) ratio..........CURE


    I really don't know if that is a qualification for being a scientist though.
     
  7. daan

    daan Moderator

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    If you're the "leading scientist", why are you asking for cures?

    Are you going to show us the light, or do we just have to believe what you say?
     
  8. Famine

    Famine Administrator

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    You shock me.

    I'm just wondering exactly where the mantle of "website's top scientist" came from. I mean, I don't recall any discussion in the Moderator's forum to bestow this title upon you - and at least two of the moderators have "more than one" science degree.

    Someone who actually represents this site must have given you clearance to present yourself as GTPlanet's top anything. Surely?
     
  9. gtmaster08

    gtmaster08

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    Science degree? What?:confused: I just meant in terms of being a great Gran Turismo 1 mechanic. After all, I've seen many ideas (and discussions) in some of Gran Turismo 1's threads about different problems each Gran Turismo 1 player is having with his/her car(s), or even about different viewpoints about the cures to each of the said problems. Or even just discussing some things about the players' cars in general in the game, that's all I meant. And when I said "Website's top leading scientist", I was trying to come up with a cooler sounding name than just plain old "Great Gran Turismo 1 Mechanic". I mean, doesn't my first name sound a WHOLE lot cooler than my second name? Plus, I tried to come up with that name for my new avatar of Vexen. How about this then; what if I called myself a "GT1 Mechanical expert"? That okay?:)

    Oh, and a few more things;

    to Parnelli Bone: I was going to start the symposium with a light subject, which of course was redlining.

    to zed300: Actually, the term now is "GT1 Mechanical Expert". And yes, as long as you have 1 specialty in the game you are ALWAYS welcome as a "GT1 Mechanical Expert"!:gtpflag:

    to daan: I meant share their cures with everyone else. And no, you don't have to believe in what I say. Just listen, that's all this thread is about.:)

    to Famine: I hope that my explanation has cleared up this confusion. And... I'm sorry about calling myself a "Leading Scientist". After all, I'm not THAT great.:dunce::drool: And by the way, what does "Senior Member" mean?

    to all in this thread: I guess you must think I'm pretty uncool huh? Well, I don't blame you. After what I did, I don't even know if I can say that I'm cool with a straight face anymore...
     
    Last edited: Mar 13, 2009
  10. Famine

    Famine Administrator

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    "Has made 200 posts"

    We're all posting on an internet forum about a car driving game on a console.

    Cool doesn't enter the equation.
     
  11. nk4e

    nk4e

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    Can't you consider yourself a technician?
     
  12. niky

    niky Moderator

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    It actually ought to be 1000 or more. :D
     
  13. SportWagon

    SportWagon Premium

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    [​IMG]
    (A Supercar expert)
     
  14. Blitz187

    Blitz187 Premium

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    :lol:

    :lol:
     
  15. LeGeNd-1

    LeGeNd-1 Premium

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    This thread is epic, one of the funniest I ever saw on GTP :lol:.

    And can I specialize as a test driver please :D? That's the only thing I'm really good at.
     
  16. Simplex 4100U

    Simplex 4100U (Banned)

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    yes it does.
     
  17. Famine

    Famine Administrator

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    Eloquently put by a guy who claims his hobby is collecting antique fire alarms.


    It's like getting graphics card advice from St. Francis of Assisi.
     
  18. Boffin

    Boffin

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    with a emoticon like this - :sly: - ANYONE can be cool
     
  19. gtmaster08

    gtmaster08

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    Of course you can, I have no problem with that!:) And anyway, to start off this part of the symposium, aside from the gear settings and the drivetrain of the cars what do you think causes redlining? And by "you", I mean all who are in this thread so far. And don't worry, there are no wrong answers here; just suggested ideas.:)
     
  20. SportWagon

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    So is this a science symposium, or a situation-ethics therapy session?
     
  21. Parnelli Bone

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    First of all, what do you mean by the term "redlining?" Are you referring specifically to reving till your tach needle is in the redline area? Or are you referring to that point where the engine reaches its absolute max of revs and starts bouncing off the RPM limiter?

    I feel a little sillly discussing this since everyone here is tech-savvy. :guilty: As far as i know, there are no technical newbs present who haven't got a clue about engine revving, so far as i know. But there could always be some folks out there lurking, so here goes.

    If it's simply revving into the red area, this depends on which car we're talking about. Not all cars in GT1 need to be driven to this point. I mean, if it's a Civic, which has high peak horsepower RPMs that show up just before the redline area, then it's safe (assuming you've got a manual transmission) to occasionally keep the car in gear till its tach needle goes deep into the redline area. By doing so, you're actually getting maximum performance because there is a swell of speed that shows up just before the peak horsepwoer area, and doesn't die till the Civic's RPM needle is somewhat into the redline area.

    A Viper in GT1, on the other hand, has got an unrealistically high redline at 6,500 rpms. The RPM limit is at 7,000 or 7,500 but i could be wrong. Peak power for a Viper in GT1 shows up at 5,000 while the car is stock. This means if you keep it in gear as long as you can, you're actually missing out on the Viper's true best power/torque-area (which resides between @3,000 and 6,000 rpms). Vipers in GT1 should be shifted early to garner best engine-performance, assuming the driver is good with manual trannys.


    Now the actual question here: "What causes redlining?" I think you're talking about the RPM limiter, as in, what causes an engine's revs to be limited to a certain range of revolutions per minute.

    In real-life, RPM limiters are used for all sorts of reasons. Usually, cars have limiters to keep over-zealous racing drivers from blowing up their engines with too many RPMs. But there are other reasons they are used. Matter of fact, we just had a Subie WRX in our shop a few weeks ago (no joke) for a Maryland State Inspection, and it had a limiter in place to keep the engine from going any higher than 3,000 rpms!!! The driver that brought the car in wasn't the actual owner, and he couldn't give us an accurate reason why this awesome car had such a low limiter. Who knows.

    Now in the game, of course, there is no fear of blowing up engines. Why are limiters used then? Why would PD even program them? To keep things within a certain realm of realism, of course. If we could just rev any engine to infinity, there goes any credibility PD has with tech-knowlegable folks. So PD puts limits in each car's engine programming.

    Going a bit off-topic. This is a bit interesting to me, because occasionally there are cars in GT with what seems to be incredibly short redline areas, and it seems (in my opinion) PD has goofed, perhaps.

    The BMW M3 of GT4 is a great example. Its peak power is at 7,900 rpms, yet the redline area starts at 8,000. And the RPM limiter at 8,500! This means any serious driver (with a manual transmission) is gonna be forced to shift before it's truely necessary. In order to try to get peak performance from this otherwise awesome straight-6, you'll constantly need to be forced to take the engine into its redline area, risking lost speed due to the RPM limiter bopping the tach back.

    ....anyways, that's all from me for now.
     
    Last edited: Mar 16, 2009
  22. T-Squared

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    This thread will never be taken seriously, yet you still try...
     
  23. Parnelli Bone

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    Well, i'll try to take it seriously. :idea: If nobody else does, so be it. Personally, i hope some newbs show up to this thread tho. This kinda talk always starts to get more interesting when there are folks present who are learning.
     
  24. gtmaster08

    gtmaster08

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    to t-squared: well I say forget you about your 2 cents worth of input! If you're just going to say bad things about this thread then you're not welcome to this thread!:grumpy:

    to Parnelli Bone: thank you for your kind words. At least someone here has some sense of decency! And as to your reply here, my question was kind of open-ended...

    to sportswagon: Definitely a symposium, only thing is the fact that I'm not the only one sharing his ideas!
     
  25. LeGeNd-1

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    Well the problem with this thread is, as I said before, almost everything in GT1 has been covered in its 10+ years of existence. If this thread is in the GT5 forum, it'll make much more sense.

    Anyway back to topic. From my experiences, gear tuning aside, there's only two things that can cause redlining: shift down too early and shift up too late. Of course if you use AT then this will never happen, but even if you use MT you can (with lots of practice) avoid redlining altogether. Personally I never redline on purpose because engine braking doesn't work that well in GT1, so redlining would be useless. And the sound is quite annoying as well. If I do redline though, it's because I'm braking super late (and I mean really really late) or I'm trying to squeeze out every HP possible from an NA racing car (usually NSX). In GT5P though, it's a different story. I almost always redline when braking into a tight corner from a long straight (T1 Fuji, Chicane @ Suzuka, etc) because engine braking helps a lot in slowing down the car.
     
  26. SportWagon

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    I'm assuming here we're talking about the fully-adjustable "Racing Transmission" option.

    Each numbered gear ratio has a decimal value shown beside it. There is a slider which allows you to adjust that between values of about 0.500 and 4.400, with additional constraints for each gear, varying by car.
    And there is a similar number for the final drive, which can be varied from something like 2.700 to 5.000. (Those now appear to be the precise values).

    The value of the gear ratio is the number of times the engine crankshaft must turn in order to turn the output shaft of the gear box, that is, the driveshaft, once. The value of the final drive is the number of times the driveshaft must turn in order to turn the driven wheels once. (FF and MR may not have a long drive shaft, but there will always be some equivalent input to the differential which connects the driven wheels).

    If you multiply those two together, you get the number of times the engine crankshaft must turn in order to turn the wheels once. Larger numbers are called "lower gears" because the wheels turn less often (or less far) for each engine revolution. This allows better acceleration, but limits your top speed. (In fact, we use the number as a denominator in later calculations, which also means that smaller is higher and bigger is lower).

    Let's call the product of those two numbers the "effective gear ratio". We can see that if you pick any particular "effective gear ratio", then, if you select different final drives, there will be for each a corresponding different transmission "gear value" which will give the same "effective gear ratio". Actually that's not quite true, since you may run into the constraints which limit the minimum and maximum values for a particular gear.

    We have already said that "effective gear ratio" is the number of times the engine will turn to turn the wheels once. If you knew the diameter of the wheels, you could calculate the speed for a given RPM in a given gear.

    Let
    RPM = revolutions per minute (engine speed)
    ER = effective ratio (no units) (that is, gear value * final drive value)
    pi = ratio of wheel circumference to diameter (constant, no units)
    WD = wheel diameter (in some units)


    speed = (RPM / ER) * pi * WD

    That will give you speed in units per minute, where "units" is the unit you use for wheel diameter.

    Assume WD is in inches.

    speed in mph = (RPM / ER) * pi * WD * 60 / ( 5280 * 12)

    to convert from inches-per-minute to miles-per-hour.

    Also involved in a precise calculation would be wheel slippage, but that's generally negligible.

    Now, in [size=+1]GT1[/size], one approach would be to infer a working wheel diameter by taking observations of speed at rpm, and working backwards through the equation. (Solving for WD).

    I.e.
    WD in inches = (speed in mph) * (5280 * 12) * ER / ( RPM * 60 * pi )
    (It might be difficult to make precise enough observations to solve this accurately enough. Wheel slippage does enter into things here, but, except where slippage varies greatly in the same setup, you can actually work with an "effective diameter" which includes the effect of wheel slippage. I.e. the diameter you might get from your calculations might be smaller than the true wheel diameter for the particular car, but that's probably the value you want to use to calculate speeds at differing RPM and ER).
    Edit: Actually, I was forgetting the wonderful calibrated gear charts that [size=+1]GT1[/size] gives. You should be able to read RPM and speed off that chart, and would know the ER for a particular gear. You should be able to use such a point from the graph to solve the above accurately. And, in practice, what you do is move the graph lines so that the attainable speeds in each gear are appropriate for the conditions--bypassing the need for much calculation.

    In practice, an educated guess often works well to give adequately precise calculations.

    In any case, each effective ratio ER will have a speed which corresponds to the redline of the particular car. To increase the speed at which the redline is reached, you must reduce ER (since it is a denominator). You can do that by reducing the value for the final drive (which is termed "using a higher final drive", since it is a denominator), or by decreasing the value for the gear being used. (Or both). (If you want to prevent hitting the redline in top gear, then use the slider to reduce the value of the top gear).


    Summary: If you slide the final drive all the way to the left, and the top gear all the way to left, I guarantee that you will not hit the redline in top gear. In fact, you may not even be able to get in to top gear.

    Someone please proof-read this, i.e. especially the equations. Someone who relates to starvation, perhaps. :D

    What you actually want to do is determine the ER you should use to achieve desired conditions.

    speed in mph = (RPM / ER) * pi * WD * 60 / ( 5280 * 12)
    MPH = (RPM / ER) * pi * WD * 60 / ( 5280 * 12)

    ER = (RPM / MPH) * pi * WD * 60 / ( 5280 * 12)

    With that you could plug in a desired RPM and MPH, and get back the required ER. Depending upon other constraints, you could adjust gear value, or final drive, or both, to give that ER. A case study would be good, but for that I need my PlayStation available.

    And again, in [size=+1]GT1[/size], the calibrated gear charts actually let you do precisely this without calculations. (Move the slider to achieve the desired speed at the desired RPM).

    Case Study: Concept Car LM (USvsUK prize)

    Take the Concept Car LM and restore its default settings. (Go to change parts, click the part, click the grey alternatives, then reclick the valid part).

    You should get gears of

    3.178
    2.182
    1.643
    1.241
    1.010
    0.929
    -----
    4.292

    There's a table showing

    2nd 49
    3rd 72
    4th 95
    5th 126
    6th 155mph
    8200rpm

    Experimentation suggests that is the speed when the previous
    gear reaches 8200rpm.

    I.e. 3rd gear will achieve 95mph@8200rpm.
    Eyeballing the chart suggests 3rd gear is 100mph@8200rpm, or maybe even 100mph@8000rpm.

    3rd gear is ER 1.643*4.292

    Plugging into
    WD in inches = (speed in mph) * (5280 * 12) * ER / ( RPM * 60 * pi )
    gives

    95mph 8200rpm => 27.5"
    100mph 8200rpm => 28.9"
    100mph 8000rpm => 29.6"

    A fairly substantial variation. But we can work with 27.5". (Checking an online wheel diameter calculator, all these sizes seem a bit large for reality).

    For max speed tests, you always set the downforce figures to the minimum. But, even after doing that, the initial Max Speed test, using these settings, does not seem to go beyond 192 or 193mph.

    In the Engine:NA Tuning "Change Parts" screen,
    max torque is shown as 439.7lb-ft@6000rpm
    max power is shown as 568hp@7000rpm

    It seems like the car should be easily capable of 200mph. Let's try to achieve that in 5th gear, to leave room in 6th gear.

    And let's try to achieve it at 6500rpm.

    ER = (RPM / MPH) * pi * WD * 60 / ( 5280 * 12)

    ER = (6500/200) * pi * 27.5 * 60 / ( 5280 * 12)
    = 2.6589

    Based on that, let's simply keep the default gearing, but slide the final drive all the way down to 2.700, changing nothing else. (Giving ER for 5th gear of 1.010 * 2.700 = 2.727).

    Without changing anything else, the car now easily does 227mph, (that's if you have minimum downforce, remember) and that's before suspension tuning, which will help too.

    Such a low final drive value is probably good for the Maximum Speed test. Perhaps raise the number for road racing, unless you see yourself running out of revs on the really long straights, like Grand Valley and SSR5.

    Also note how close 6th gear is to 5th. Sliding it to a slightly lower number might be an easy way to get a bit more top speed, although you've got to watch the gap between 5th and 6th; at high speeds it's easy to get stuck in a bad spot on the power curve.

    And, in general, if you tweak both gears and final drive, you can leave yourself more flexibility for future tuning.
     
    Last edited: Apr 1, 2009
  27. Parnelli Bone

    Parnelli Bone Premium

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    ^^thank you SW, i think that just about covers it. +Rep

    Yup.


    Cars in GT5P sound more realisitic when over-revving, i've noticed.




    Hey i wanted to open up the next topic....something i've thought about since GT1 days but never brought up here before: the carbon driveshaft.

    It occured to me 4 years ago that if you replace a car's normal driveshaft with a lighter one, that (in theory) it will throw off that car's front/rear weight balance. This would be especially so with a light, front engine/rear-drive like a Mazda Miata, for instance. So i was tuning for some race one day, and didn't install the carbon drive on my MX5, just in case PD took weight distribution into account in GT1. The Miata, in real-life, has near-perfect weight distribution after all. Why screw with this in the game?

    In GT4, we all know the weight can be changed in small increments via ballast, and weight distribution can also be switched front to rear as well. Greycap and others have commented that they believe when you buy weight reductions for a car in GT4, this also affects its weight distribution, sometimes in a negative way by throwing off a car's balance. I also believe that when we do endurances in GT4, as fuel is used, this definately changes a car's weight (i can prove this via lap times and small additions of speed down straightaways in long endurance races), and perhaps its balance as well.


    So my question: does anybody think a carbon driveshaft in GT1 can throw off a car's balance? Did PD account for this in GT1?

    Personally, i don't think they could have, but i could be wrong.
     
    Last edited: Mar 18, 2009
  28. nk4e

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    I wonder if we could apply this to Gran Turismo in general, as a series though.
     
  29. viperin

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    I also doubt they took this into account as the effect would have to be marginal at best.
    More likely, they focused on engine response and power delivery factors following the addition of a carbon shaft.

    The adding and placement of ballast in GT4, was a very handy tool, and I hope they incorporate it into future versions.
     
  30. LeGeNd-1

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    I don't think it does. The carbon drivehsaft is supposed to help with acceleration. And I think it makes minimal effect to weight balance even if it's the case. But then again I never drove a car stock and compare it to a car with carbon driveshaft part only, so I might be wrong.
     
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