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Thread: HP or Torque ? for lower lap time ?

  1. #101
    Senior Member bellwilliam's Avatar
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    my mind can't get around to all the engineering mumbo jumbo. I use a GPS data logger to determine my shift point. I will try one, and another, till I find lowest sector time.
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  2. #102
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bawareca View Post
    Attachment 3670
    You can tell me what exactly would I gain going past 6300-6400 RPM on 4-5-6th.The car has also a heavy and uneficient aero.
    I need your gear ratios to tell you exactly. (Disclaimer: first time I have done this math, so I might screw it up) Let's say you have miata gears. 3rd is 1.33:1 , 4th is 1:1.

    If in 3rd gear at redline you make 1.33 * 210ft/lbs = 279ft/lbs. 4th gear's rpm would be something like 4800rpm, which is 360 ft/lbs * 1.0.

    Yep. Shift earlier. And I could have saved myself this math if I just looked at how low your powerband is. Wow, your engine can't breathe for crap.

    But having the high rev limiter is still useful for fast laps. Sometimes you just don't wanna shift. Also useful if you ever decide you want to make some power and let your engine breathe.

  3. #103
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by J. Tyler View Post
    Well.... Again, it's about maximizing HP curve area usage for each gear, not rwtorque. (Of course, rwtorque is related to HP...but I think you get the basic idea )
    I said "usually" on purpose

  4. #104
    Senior Member psychoazn's Avatar
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    Quote Originally Posted by bellwilliam View Post
    my mind can't get around to all the engineering mumbo jumbo. I use a GPS data logger to determine my shift point. I will try one, and another, till I find lowest sector time.
    Well, when you start factoring in turns, sometimes its better to just bang off the limiter, and sometimes its better to short shift....

  5. #105
    BMW Master bawareca's Avatar
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    Quote Originally Posted by robburgoon View Post
    I need your gear ratios to tell you exactly. (Disclaimer: first time I have done this math, so I might screw it up) Let's say you have miata gears. 3rd is 1.33:1 , 4th is 1:1.

    If in 3rd gear at redline you make 1.33 * 210ft/lbs = 279ft/lbs. 4th gear's rpm would be something like 4800rpm, which is 360 ft/lbs * 1.0.

    Yep. Shift earlier. And I could have saved myself this math if I just looked at how low your powerband is. Wow, your engine can't breathe for crap.

    But having the high rev limiter is still useful for fast laps. Sometimes you just don't wanna shift. Also useful if you ever decide you want to make some power and let your engine breathe.
    It is not bad for a late 1970's 2.7 liter stock 2 valve engine with undersized turbo.I will be happy to comment on something that you actually made with your hands,but that is not matter of that discussion.
    Actually from the very beginning my opinion is that for a lighter car you want higher revving engine (more hp) and that is example of what you DONT want to see on the track.
    Last edited by bawareca; 08-30-2011 at 03:25 PM.

  6. #106
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bawareca View Post
    my opinion is that for a lighter car you want higher revving engine (more hp)
    Ghaa! It burns! It burns!

  7. #107
    BMW Master bawareca's Avatar
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    Quote Originally Posted by robburgoon View Post
    Ghaa! It burns! It burns!
    It only smells for now

  8. #108
    "Shoe"
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    Quote Originally Posted by robburgoon View Post
    I need your gear ratios to tell you exactly. (Disclaimer: first time I have done this math, so I might screw it up) Let's say you have miata gears. 3rd is 1.33:1 , 4th is 1:1.

    If in 3rd gear at redline you make 1.33 * 210ft/lbs = 279ft/lbs. 4th gear's rpm would be something like 4800rpm, which is 360 ft/lbs * 1.0.

    Yep. Shift earlier. And I could have saved myself this math if I just looked at how low your powerband is. Wow, your engine can't breathe for crap.

    But having the high rev limiter is still useful for fast laps. Sometimes you just don't wanna shift. Also useful if you ever decide you want to make some power and let your engine breathe.
    You also need to factor in the final drive ratio to each gear ratio.

  9. #109
    BMW Master bawareca's Avatar
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    Quote Originally Posted by Stuntman View Post
    You also need to factor in the final drive ratio to each gear ratio.
    Hm,his looks to be 1:1

  10. #110
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by Stuntman View Post
    You also need to factor in the final drive ratio to each gear ratio.
    Mr. Shoe, are you sure about that? I believe those cancel out.

    Would it help to think of those numbers as tranny output torque?

  11. #111
    BMW Master bawareca's Avatar
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    Quote Originally Posted by robburgoon View Post
    Mr. Shoe, are you sure about that? I believe those cancel out.

    Would it help to think of those numbers as tranny output torque?
    Be a man enough and admit that you dont know crap

  12. #112
    "Shoe"
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    Quote Originally Posted by robburgoon View Post
    Mr. Shoe, are you sure about that? I believe those cancel out.

    Would it help to think of those numbers as tranny output torque?
    The torque multiplication at the tire is a combination of the transmission gear ratio and the final drive (aka:rear end/diff/ring&pinion -whatever you wanna call it) ratio.

  13. #113
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by Stuntman View Post
    The torque multiplication at the tire is a combination of the transmission gear ratio and the final drive (aka:rear end/diff/ring&pinion -whatever you wanna call it) ratio.
    Right, but we are comparing 3rd gear and 4th gear and deciding when to shift.


    output torque = engine(rpm) x tranny(gear) x diff


    We are comparing

    engine(rpm for 3rd) x tranny(3rd) x diff
    and
    engine(rpm for 4th) x tranny (4th) x diff

    Divide each side by diff.

    Algebra folks.

    (and yes, I know I am ignoring wheel & tire dimeter. That divides out too)

  14. #114
    BMW Master bawareca's Avatar
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    Quote Originally Posted by robburgoon View Post
    Right, but we are comparing 3rd gear and 4th gear and deciding when to shift.


    output torque = engine(rpm) x tranny(gear) x diff
    ...........................
    You are dragging yourself in a very big hole.......

  15. #115
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bawareca View Post
    You are dragging yourself in a very big hole.......
    if you say so...
    J. Tyler likes this.

  16. #116
    Smack-Talkin' Member J. Tyler's Avatar
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    Quote Originally Posted by psychoazn View Post
    You need to read my previous posts. We've already done the graphing and mapping for the different s2k engines and transmissions.
    Ok I read your earlier posts, and seems like you get it and I misunderstood your recent post. I was thinking in generalities, not specifically the F20C S2000; my bad. Like you said in your earlier posts, and what I've been saying all along, is you need to set your shift points to maximize AUC.

  17. #117
    BMW Master bawareca's Avatar
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    Quote Originally Posted by robburgoon View Post
    Right, but we are comparing 3rd gear and 4th gear and deciding when to shift.


    output torque = engine(rpm) x tranny(gear) x diff
    ...........................
    So,according to Rob:
    Nissan GTR output torque=6500(rpm)x1.248(4th gear)x3.7(rear diff)=30014.44(whatever it is,the number looks good)
    Mazda Miata output torque=6500(rpm)x1(4th gear)x4.10(diff) =26650(I was expecting bigger difference....)
    Who the f*** needs a dynoIMHO mismatching the torque and rpm and road speed equations is like hitting the gas pedal instead of the brake.

  18. #118
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bawareca View Post
    So,according to Rob:
    Nissan GTR output torque=6500(rpm)x1.248(4th gear)x3.7(rear diff)=30014.44(whatever it is,the number looks good)
    Mazda Miata output torque=6500(rpm)x1(4th gear)x4.10(diff) =26650(I was expecting bigger difference....)
    Who the f*** needs a dynoIMHO mismatching the torque and rpm and road speed equations is like hitting the gas pedal instead of the brake.
    The stuff in the parens are inputs, not units. You figured it out for the tranny, but not for the engine for some reason.

    engine is a function that takes rpm as an argument. engine(6500) = 210 ft/lbs, engine(4000) = 360 ft/lbs

    tranny(3rd) = 1.33
    tranny(4th) = 1.0

    Sorry that wasn't clear.

  19. #119
    BMW Master bawareca's Avatar
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    Quote Originally Posted by robburgoon View Post
    The stuff in the parens are inputs, not units. You figured it out for the tranny, but not for the engine for some reason.

    engine is a function that takes rpm as an argument. engine(6500) = 210 ft/lbs, engine(4000) = 360 ft/lbs

    tranny(3rd) = 1.33
    tranny(4th) = 1.0

    Sorry that wasn't clear.
    The ratios are:
    3rd-1.66
    4th-1.22
    But how much is the final drive ratio

  20. #120
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bawareca View Post
    The ratios are:
    3rd-1.66
    4th-1.22
    But how much is the final drive ratio
    Right, those are your ratios, I was using miata ratios for my example.

    Final drive? Now you're just playing dumb. I'm sorry I insulted your beloved car's honor, but if it works for you, enjoy it.

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