Overdrive Gears?

Discussion in 'Gran Turismo PSP' started by Lancia stratos, Mar 26, 2010.

  1. Lancia stratos

    Lancia stratos

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    O wow I never thought the mustang was a 5 gear. I thought it was just stuck. Like the viper concept, it cant touch gear 6 even if it depended on its life.
     
  2. PAPPACLART

    PAPPACLART

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    Please you are arguing with the wrong person:sly: I am very aware that HP is a product of torque and RPM. After torque has fallen off bhp does not always continue to rise, as this is still very dependent on how sharply the torque falls away as revs continue to rise. I have a catalogue of BHP graphs where you will find many instances where also at some point power will tail off.



    Wrong wrong wrong.

    A 500 bhp car producing it's peak BHP @ 5500rpm does indeed make 477 ft/lb of torque @ 5500rpm. I never for one second said that both engines also make 625bhp at 7000rpm in which case yes both would be making 477t/lb also. I clearly stated that both imaginary engines produced 500 (peak) bhp @ 5500rpm. both engines continued to rev after making peak power both with different results. engine 1 produced 350bhp @ 7000rpm while engine 2 produced 450bhp @ 7000rpm.

    Engine 1 := 500bhp @ 5500rpm and 477ft/lb @ 5500rpm - and 350bhp @ 7000rpm would be producing 262ft/lb at 7000rpm.

    Engine 2:= 500bhp @ 5500rpm and 477ft/lb @ 5500rpm - and 450bhp @7000rpm would be producing 337 ft/lb @ 7000rpm.


    In my original post I did not want to get too technical, but still my original example of a power/torque curve is mathamatically correct as you can work out BHP from torque and torque from Power

    (Torque x Engine speed) / 5,252 = Horsepower
    (Power / Engine speed) x 5,252 = Torque

    You are getting confused, you simply can't take the peak torque figure of an engine and use this figure wherever you like in the rev range. All engines have a peak torque output but all produce varying amounts of torque spread over an entire rpm range which is lower than the peak. My bike has a peak of 78ft/lb @ 8000 rpm and 60ft/lb @ 4000rpm and 65 ft/lb at 10000rpm. A good engine would be one that prodcues an average figure close to it's peak spread right accross the entire rev range.

    Because an engine has 500bhp @ 5500rpm and 477ft/lb @ 5500rpm does not mean if we could magically make it rev to 7000rpm it would make 635bhp. It would only make 635 bhp at 7000rpm if the motor produced 477ft/lb at 7000rpm but my imaginary engines did not produce this torque figure @ 7000rpm! The engines in my example made 262 ft/lb and 350bhp @ 7000rpm and 337ft/lb and 450bhp @ 7000rpm and both still had 500bhp @ 5500rpm.

    Do the math. :)

    Notice how both engines power tails off - one at 8750rpm and the other at 10000rpm

    [​IMG]



    You also forgot to mention the bore and stroke which is quite important. Slow reving engines with big pistons often have a long stroke giving better leverage and thus more torque for every given stroke. Longer stroking pistons travel a greater distance in any one stroke of the engine vs a piston of the same size with a shorter stroke. Having a big piston does not always limit how fast it can spin. My motorcycle pistons are 500cc each, not exactly small but my motor can still spin @ 10750rpm. The reason for this is that the pistons travel a very short stroke as the motor is a 'short stoke motor'.



    The above is nothing to do with the potential of the design. The whole reason why we have different engine configs is that is gives us flexibility/balance. In a perfect world we may have a 6000cc single, but 1: it would not be able to rev high, and 2: it would be very tall or long depending on how it was mounted, both making it impractical. 4 pots are generally 2000cc or less with pistons 500cc or less each. V8 generally are 4000cc and above although there are exceptions. Pistons in most road cars above 2000cc range from 500cc to 750cc in size but there are of course exceptions either side more so in performance or with little eco cars.


    Wrong again, if the stang could produce 319ft/lb @ 7000rpm then it would have 425bhp @ 7000rpm.

    Simply being able to rev to a certain rpm does not magically procude power. You first need to be able to produce torque @ any specific rpm before you can have BHP. The Stang would need to simply continue making torque as it revs to 7000rpm.



    What you really should be looking at are thrust curves. This takes the power and torque graphs that many obsess over and actually shows the force in each gear at any given speed measured in lbs. This is the actual force created at the wheels once the torque of the engine has been multiplpied by the vehicles gear ratios.

    In every example of a thrust curve I have ever looked at or created myself from BHP/Torque curves...where torque tails off, so does thrust in every gear.

    So back to the original point, many big american V8's have a dramatic fall in torque after the peak has been rached. if you could see the thrust curve you would see this represented in the thrust curve. this no doubt hurts a vehicles top speed.

    I am at work now but will post up some thrust curves later.

    This is a thrust curve of my bike. Each thrust curve in each gear follows the same shape as my torque curve. And as you can see, regardless of if a motor continues to make power while the torque curve tails off, as long as torque tails off so will thrust at the wheels.

    [​IMG][/url][/IMG]

    Torque curve
    [​IMG][/url][/IMG]
     
    Last edited: Mar 31, 2010
  3. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    This is rich, Yeah I know the Torque level falls after peek (lol, that's why its called peek, highest point, lol) As peek is when the air is filling the chambers at its most efficient rate. once the engine spin faster, and the air doesn't have enough time to fill the chambers as it did at the peek point, torque falls, however the HP will still climb with the RPM until the rpm's become too fast to fill the cylinders. So the engine will be still making torque until it get to the rev limit, if the 2 engines have the same limit, then OBVIOUSLY they both will be making torque until that point, doesn't that go without saying? lol The rev limit wont be after the engine STOPS producing torque completely now would it...

    However in your example the only specs given were RPM & hp, getting the same peek at the same rpm, with the same rev limit, but a different end result, so naturally if there were to be any serious difference in the engines beyond the end result, those differences would HAVE to be mentioned or we have to take the 2 as the same..... But yeah, your saying they make different hp at 7000rpm, just because you imagine them like that, lol....

    How about Show me 2 REAL engines that, have the same amount of torque, reach the peek torque level at the same rpm, on top of rev'ing to the same max, but produce 100hp difference.

    Your imaginary engines are quite that, imaginary.... lol


    What a joke, lol.

    They are both making 477 ft-lb if they both make 500hp @ 5500rpm, its as simple as that....

    (hp)500 X 5252 / 5500 = 477ft-lb

    No matter how you want to argue, the 2 engines (even though they may be imaginary) BOTH make 477ft-lb.


    Now your just being ridiculous neglecting important details about these 2 imaginary engines..

    I did, lol (hp)500 X 5252 / 5500 = 477ft-lb

    How do they make the same peek torque at the EXACT same point, Then both imaginary engines differ after that, BUT rev to the same limit? HYPOTHETICALLY speaking the fact they are making the same HP at the exact same peek point & rev'ing to the same limit IMPLIES that they are VERY similar (you could even say identical) Neglecting to mention the pertinent details that would make them perform so different after being so identical.... If you don't mention that on your imaginary engines, they they are looked at as Identical, you simply put different max hp at the same max rpm to suit your argument, yawn...

    "How about Show me 2 REAL engines that, have the same amount of torque, reach the peek torque level at the same rpm, on top of rev'ing to the same max, but produce 100hp difference."


    Just look at your example, lol EVERYTHING is identical. Peek torque point, same torque, & they both rev to the same limit, yet different results, no pertinent details, lol you imagined the engines btw, so this is a pathetic argument, you simply imagine it to suit your argument, lol.


    Yeah, neither did I, was more trying to generalize as your imaginary engines example was ridiculous, and still is... Missing details completely...

    Ohh yeah, (hp)500 X 5252 / 5500 = 477ft-lb ROFL!!!!!!!!!!

    Again...

    "How about Show me 2 REAL engines that, have the same amount of torque, reach the peek torque level at the same rpm, on top of rev'ing to the same max, but produce 100hp difference."

    But that's only in your imagination, rofl.

    No your right (wasn't trying to get to technical on 2 imaginary engines, that have the pertinent info to make those correct calculations missing....) but I can assume that the 2 imaginary engines in your example are the same unless stated other wise (not result, but why the result is different, what is different about the 2 engines that until peek torque are completely identical, then rev'ing to the same limit, that would have them producing 100hp difference as your imaginary end result lol) SO I can use the info at hand & generalize when you fail to produce the pertinent info to make the FULL calculations, & make you point. Again I'll say....

    "How about Show me 2 REAL engines that, have the same amount of torque, reach the peek torque level at the same rpm, on top of rev'ing to the same max, but produce 100hp difference.."

    Dude the only one confused, is you. Your confusing reality, and your imaginary engines....

    The bold is defiantly true, But when your leaving out sooo many required details to make those calculations, I can be a lil lose with the calculation, until the nessesary details are provided (oh yeah you cant, you can only imagine them) how about include some details about the difference in engines that are so similar EXCEPT for your imaginary 100hp difference at the top end ;) OR the power graph, this would be used to see exactly how much torque is produced at any given point in the RPMs so a more accurate calculation can be made, but don't forget they 2 engines are imaginary, and critically flawed (My original point) So your example is lacking the details it requires to illustrate your point, instead its just in your imagination.

    Yeah more like YOU forgot to mention bore and stroke, or any pertinant info to make your imaginary engines more realistic, lol

    Simply because it's what you fail to see in your exaggerated example, again I have to say....

    "How about Show me 2 REAL engines that, have the same amount of torque, reach the peek torque level at the same rpm, on top of rev'ing to the same max, but produce 100hp difference."

    If you can do that, Then you have an argument....

    WOW isn't that exactly what I posted, wait, lets check

    Hmm it is...

    Yes we are assuming it could keep its 319ft-lb up that high (It cant) That's why its hypothetical, lol

    You would have to understand Being able to rev to that point, it goes without saying it can produce torque to that engine speed, or it wouldn't be able to rev to that engine speed. lol remember HYPOTHETICAL, ohh boy...

    The grafs you pointed out are useless in this argument, #1 because they Don't reach their Peek torque levels at the exact same rpm or even rev to the same limit, in fact everything about them is different, when your 2 imaginary engines are completely identical, EXCEPT for the hp level at 7000rpm..... #2 I also like how you went from talking V8 muscle car engines to Bikes, lol Being as bikes are tiny displacement going to very high revs, & American V8's are the opposite, big displacement rev'ing low (thought it wouldn't be noticed? lol)

    However the final torque graph is quite nice showing that the torque level doesn't plummet after reaching peak, and pulls until the rev limit (or the rev limit would be lower, lol) rofl

    Anyways after all this, what the biggest issue, using imaginary engines to give an example, its all in your head and not real, lol Ill say this one last time...

    "How about Show me 2 REAL engines that, have the same amount of torque, reach the peek torque level at the same rpm, on top of rev'ing to the same max, but produce 100hp difference."

    You could of gave a better example with 2 identical engines, that make the same peek torque, but one has a variable valve timing system on it when the other doesn't (Man, those imaginary engines make horrible examples) That would have it making more HP after peek torque, but not 100hp from 477ft-lb inside 1500rpm (gap from peak torque at 5500rpm to 7000rpm) That just makes your example ridiculously exaggerated and WRONG, had you imagined the hp difference being much less, and included some pertinent details, it might of made an okay example, but nothing beats the real thing..

    Never mind it takes the imaginary engines 5500rpm to reach peek (477ft-lb), but 1500rpm to fall off the map, or that V8's making peek toque of anywhere close to 477ft-lb at 5500rpm and then rev'ing to 7000rpm is in itself ridiculous lol what a joke!!!!!!!!!!! Ridiculous example & flawed in so many ways........ You must of realized that American V8's making 477ft-lb of torque @ 5500 rpm then rev'ing to 7000rpm is ridiculous and there ain't one like that, let alone 2 with a 100hp gap at 7000rpm, lolololol.

    MY POINT. 2 engines making the same torque at the same engine speed that rev up to the same limit will not be as different as the imaginary engines you have imagined, unless there is some critical differences that have not been imagined yet, lol. Use REAL examples please...

    I'm the wrong person Buddie ;) :sly:
     
    Last edited: Mar 31, 2010
  4. peterjford

    peterjford Premium

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    So if he called them 2 hypothetical engines it would be ok?
     
  5. Lancia stratos

    Lancia stratos

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    Guys! Dont go murdering each other now!:sly:
     
  6. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    Blah blah blah, lol

    Hypothetical example using a real ENGINE.

    Yeah BOTH those engines were imaginary and based of his imagination, Had 2 REAL engines been used (like my hypothetical example) & giving details on How in the hell there can be a gap like that at the end result with all other specs exactly the same, it would be understandable and being as the example would be based on a real engine we could use the info on that engine to proporly calculate the numbers NOT TO MENTION they would make sence.

    Lets not forget HIS original point, & that he uses his 2 imaginary engines with rediculous imaginary figures (And unlike ANY American v8 in existance) to tell us how American V8's behave......

    PLEASE somebody show me an American V8 that makes 477ft-lb @ 5500rpm then keeps reving to 7000rpm.

    If you can show me ONE we can keep this up, but you cant because it doesnt exist, let along a second engine having all the same but making 100hp difference @ 7000rpm for no aparent reasonreason.

    THanks, this is great :)
     
  7. peterjford

    peterjford Premium

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    I am sure somebody made a SBC in a shop in a small town in South Carolina that does this. But you are correct when it comes to production cars.
    The 2005 Chevrolet Corvette C6 Z06 used the LS7 engine, so there is a production example:

    wikipedia

    So its only 470 and not 477 and it comes 700rpm earlier. But its pretty damn close. I am sure some good ol'boys could get it to 477 at 5500.
    The LS9 engine (in the Corvette ZR1 that is in the game) has the torque, but I think it only goes to 6500 rpm.

    Just to keep this going a little longer...

    How about 2 engines that both make 200hp at 5250 rpm. The first engine is tuned to just barely make it to 7000 rpm and is way down on hp by then. The second engine is a high revving engine that is still making better power at 7000 rpm. In this case two engines could have the large difference in power at 7000 rpm. These two engines would most likely not have the same peak power and it would not occur at the same rpm.
     
    Last edited: Apr 1, 2010
  8. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    Yeah that MUCH better a example usig a real world car, do you have a second one making peek the same peek torque at the same rpm, reving to the same limit, BUT have that there 100hp difference?

    Yeah thats getting closer, not quite as extream as the imaginary cars, but good enough for me.

    Lets use that engine as our base and continue the convo around that engine (I love the LS engines)


    Here is where I have a problem (no biggie)

    If they both make the same torque at the same RPM, then its safe to assume that they are identical, inorder for one of the 2 to have a different tune, YET still make the same tq at the same rpm, then there is aditional tech that allows it to do so, I would assume there is a variable valve timing system on the engine that allows the engine to make the extra power (pertinant detail) Even still the gap wouldnt be 100hp over a 1500rpm gap.

    For example the Integra LS engine vs the same engine using V-tec. The second cam profile of the v-tec cams would alow a increase of air flow that the normal LS doesnt have giving it the ability to keep making power after the non V-tec engine has crapped out.
     
  9. peterjford

    peterjford Premium

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    I was thinking of 2 very different engines. Like a big American V8 vs. a racing engine. Lets say a small block chevy vs. a F1 engine. Both could make the same torque at the same rpm, but the peak torque would be different, and at different rpm and the rev range would be different. At 7000 rpm they could have a huge difference in horsepower.
     
  10. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    I figure the best thing would be to compare 2 engines that perform nearly identical up until after peek torque, then differ after that point. A small displacement V10 vs a V8 are too far apart (not to mention the HUGE rpm difference), the Integra GSR & V-Tec engine are the same motor minus the V-tec. V-tec Honda motors even though not V8 would illustrate you point better, no we wont get that 100hp difference, but at this point I don't care about that, the convo has become too interesting as is..
     
    Last edited: Apr 1, 2010
  11. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    But we can go both directions and compare 2 similar engines & 2 very different engines.

    however lets use 2 engines that are in GTPSP

    What I don't like about using an F1 engine, is that its built to last one race and one race only. In a perfect world, the F1 engine would blow right after crossing the finish line, meaning they extracted every bit of performance out of the engine inside the regulations, limit of the engine, & duration of the race. While engines in street cars are built to last a lil longer.
     
    Last edited: Apr 1, 2010
  12. peterjford

    peterjford Premium

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    They are only allowed 8 engines all season, so its 2.375 races per engine. And those engines have to be used for practice and qualifying too.

    But I see your point.
     
  13. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    That's cool, I wonder how long its been like that, I'm glad you see what I was getting at.


    RS200 anybody lol
     
    Last edited: Apr 1, 2010
  14. Mookster

    Mookster

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    Oops. You've kind of shot yourself in the foot there. First of all, I don't know how much gold there is in the engine bay of a McLaren (not McLauren) F1. But if various sources on the internet are to be believed, there are 25 grammes. The cost of this gold in 1992, the year the F1 was released? Somewhere in the region of $300. Hardly a huge chunk of the almost $1 million price tag.
    Secondly, the gold wasn't there to 'dissipate the heat', it was there to reflect the heat away from the expensive carbon fibre bodywork.
    If you're going to ridicule other people's information, it's probably best to get your own house in order first. Glass houses and all that...
     
  15. Lancia stratos

    Lancia stratos

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    Aw crap. This thread is not gonna end well.:scared:
     
  16. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    Shot myself in the foot?? Okay there buddie... rofl Ur kidding right, lol

    By what? Asking "do you know how much gold is in the engine bay of the McLauren F1? " Is there not gold in the engine bay. Are you okay??? Where do I say Its all because of the pounds and pounds of gold? You feeling alright? Gold/Carbon Fiber/Titanium the car uses expensive materials in its construction, That is my point...

    [​IMG]

    Dude that's pretty sad arguing semantics like that,

    My Point is It wasn't profitable partially because of the materials being used, Gold being one of them, regardless if its (lol) only 25grams, that's quite a bit more then most cars, and serves my point. I never said that gold was the sole reason, but indicated gold was in the engine bay. I never said how much. dissipate/reflect your arguing semantics, lol LAME. Practice what you preach, get your house in order first.


    dissipate

    Main Entry: dis·si·pate
    Pronunciation: \ˈdi-sə-ˌpāt\
    Function: verb

    1 a : to break up and drive off (as a crowd) b : to cause to spread thin or scatter and gradually vanish <one's sympathy is eventually dissipated &#8212; Andrew Feinberg> c : to lose (as heat or electricity) irrecoverably
    2 : to spend or use up wastefully or foolishly <dissipated the family fortune in reckless business ventures>intransitive verb 1 : to break up and scatter or vanish <the clouds soon dissipated> <the team's early momentum has dissipated>


    Now take your foot out of your mouth... :)
     
    Last edited: Apr 3, 2010
  17. Mookster

    Mookster

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    I don't have the time to bother with someone who tries to argue sense whilst capitalising, using the words 'dude' and 'lame', and can't spell or use an online dictionary properly. I've got better things to do with my time.
    Oh yeah, congratulations on using the word 'semantics' correctly.
     
    Last edited: Apr 3, 2010
  18. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    ROFL!!


    Thats what I thought, lol :) have a Coke & a Smile!
     
    Last edited: Apr 3, 2010
  19. Mookster

    Mookster

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    Wow, such a shining wit. Look up 'spoonerism' while you're using an online dictionary for those words you find difficult.

    Like McLauren...
     
    Last edited: Apr 3, 2010
  20. Lokomotiv

    Lokomotiv

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    Come on guys, I don't think anyone (including yourselves) enjoys this argument very much. Let's try to get the thread back on track ok?

    Interesting stuff about the overdrive gearing, seems I had some misconceptions about those.
     
  21. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    WOW, that's it? That's the best you can do? Still going on about a spelling mistake? lol If this were a battle of wits you brought a knife to a gun fight. Ill just holster the Desert Eagle .50, and let you be on your way, you obviously bit off more then you can chew.
     
  22. Mookster

    Mookster

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    Yeah, sure. I thought I was enjoying a little late night, light hearted verbal jousting, but I was clearly wrong.

    Personally I rarely drive American cars, as they seem to have the 'wrong' kind of handling for me. I prefer to drive stuff that is set up for making it round corners quick, rather than straight line grunt. Obviously there are plenty of exceptions to this, and I quite enjoy the frustrations of licence tests with US cars, and the resultant exultation when you get a gold. It's that whole 'underster, understeer, understeer, whoops, my back end is in a tree' sense of uncertainty that you get.
     
  23. Lancia stratos

    Lancia stratos

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    Anyways,

    I just drove a 180hp pontiac concept. It only went up to 128 mph on test course in R3 tires. Did they put overdrive gears in it too? A hyundai tiburon went 30 mph faster.
     
  24. Greycap

    Greycap Premium

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    Not a 100 bhp difference, only a 20 bhp one, but still. The old Volvo red block, B230F vs. B230FX, 116 bhp vs. 136 bhp.

    Both engines produce 185 Nm of torque at 2700 rpm but the 'FX goes on to produce another 20 bhp on the basic 'F at 5500 rpm. While the 'F is built as a low range torque engine and has more torque below that 2700 rpm its effectiveness drops off after that point far more severely than that of the 'FX which has a better flowing head, a better flowing exhaust and a more aggressive cam. Its low end is slightly inferior to the 'F but the torque dropoff is much less pronounced and as a result it produces more power near the limiter. The torque curves are different, they just pivot around the same point which happens to be at 185 Nm at 2700 rpm.
     
  25. Lancia stratos

    Lancia stratos

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    Now I'm kinda suspecting that the Dodge viper concept comes with 2 overdrive gears as well. Anyone mind doing a little research on that?
     
  26. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    Yeah 5th gear is set to 7.04:1 & 6th is set at 5.00:1 both are overdrive gears
     
  27. Lancia stratos

    Lancia stratos

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    As I suspected. I never thought dodge would do it too.
     
  28. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    pretty much all tranny's have overdrive gears, the more sport oriented the car the more aggressive the gearing will be.

    In a 5spd 5th is the overdrive Gear, in a 6spd 5th & 6th are usually overdrive gears.

    THe Viper Concept I don't get why they have such ridiculous 5th & 6th gearing, I would expect them to be overdrive gears but they are ridiculously geared for a car that should be all about the "Sport" in Sports Car. I can only assume the gearing is because of the high torque the engine produces and low rev limit.

    Pretty much most manual gear boxes have 4th gear at or closest to a 1:1 ratio, gears above are overdrive gears.

    While yes they are overdrive gears they allow you to continue accelerating after you have passed the 1:1 gearing. If we remove overdrive gears then 1:1 will be the max speed gear ratio and to hit a faster speed the final drive gear would have to be streatched. This will be at the expense of the rate of acceleration.

    So with no overdrive gears you either have a car that gets to a high top speed slowly, or you have a car getting to a low top speed very quickly. The overdrive gears allow us to maximize the acceleration rate while extending the top speed. Not to mention they help us save money on gas while highway cursing.
     
  29. Mookster

    Mookster

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    Was that a deliberate mistake? Very apt if not. :)
     
  30. GTCr@zyPSP

    GTCr@zyPSP (Banned)

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    lol it wasn't on purpose, but I like it like that, lol. :dopey: