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Will my road speed increase at same RPM with higher torque?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by smd5231, Nov 28, 2008.

Page 1 of 4
  1. Nov 28, 2008 #1
    smd5231

    smd5231 Bobtail Member

    15
    3
    Nov 23, 2008
    Guelph, ON
    0
    The way my truck is set up, I do 58 MPH at 1,300 RPM. This is with 1,650 torque (CAT C15). According to the formula (HP = Torque X RPM / 5252) my CAT develops 408 HP at that speed. If I increase the engine torque from 1650 to 1850, the engine will produce 457 HP at 1,300 RPM instead of the previous 408 HP. Where does this extra horse power go? Will my road speed increase to 65 MPH at the same 1,300 RPM?
     
    smd5231, Nov 28, 2008
    smd5231, Nov 28, 2008
    #1
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  3. Nov 28, 2008 #2
    underpsi

    underpsi Road Train Member

    1,266
    292
    Sep 18, 2008
    Toronto, Ont
    0
    No your road speed will not increase with a increase in torque. The only way to do that is by choosing different gears. Either the rears or the tranny
     
    underpsi, Nov 28, 2008
    underpsi, Nov 28, 2008
    #2
  4. Nov 28, 2008 #3
    lostNfound

    lostNfound Road Train Member

    3,506
    2,269
    Jun 28, 2007
    Home of the Stampede
    0
    No. 456789
     
    lostNfound, Nov 28, 2008
    lostNfound, Nov 28, 2008
    #3
  5. Nov 28, 2008 #4
    C16KIWI

    C16KIWI Medium Load Member

    575
    142
    Jun 14, 2008
    New Zealand
    0
    I had to read this TWICE.
    Every turn of your crank shaft then through your gear box on to the drive shaft into the diff then out to the tires no matter if you have 10 hp or 1021hp (550 show off lol) .
    Let me get this right.......you think if 60mph with 400hp is 1400rpm so you would think 60mph with 650hp is 1100rpm....???????

    Is that the way you are thinking?????
     
    C16KIWI, Nov 28, 2008
    C16KIWI, Nov 28, 2008
    #4
  7. Nov 28, 2008 #5
    C16KIWI

    C16KIWI Medium Load Member

    575
    142
    Jun 14, 2008
    New Zealand
    0
    I am a little shocked after 4 years of truckin you think like this:biggrin_25526:
     
    C16KIWI, Nov 28, 2008
    C16KIWI, Nov 28, 2008
    #5
    Semi Crazy Thanks this.
  8. Nov 28, 2008 #6
    smd5231

    smd5231 Bobtail Member

    15
    3
    Nov 23, 2008
    Guelph, ON
    0
    The way I'm thinking ... right now (with 1650 torque) I'll do 65 mph if I bring my RPM to 1450. At that RPM the engine will make 1650 x 1450 / 5252 = 455 HP. That's pretty close to HP I'll get at 1,300 RPM with new torque setting of 1850. This extra HP has to go somewhere. BTB, the torque is the only thing that's going to be changed. I have 3.73 rears with 13 speed (0.73 top ratio) and 512 revs/mi tires (LP).
     
    smd5231, Nov 28, 2008
    smd5231, Nov 28, 2008
    #6
  9. Nov 28, 2008 #7
    C16KIWI

    C16KIWI Medium Load Member

    575
    142
    Jun 14, 2008
    New Zealand
    0
    MAN you still dont get it.....The extra torque will get you to the top speed quicker THATS ALL!
     
    C16KIWI, Nov 28, 2008
    C16KIWI, Nov 28, 2008
    #7
  10. Nov 28, 2008 #8
    YukonTrucker

    YukonTrucker Light Load Member

    203
    51
    Dec 9, 2007
    Whitehorse Yukon
    0
    Also the extra torque will probably give you a little better economy.
     
    YukonTrucker, Nov 28, 2008
    YukonTrucker, Nov 28, 2008
    #8
  11. Nov 28, 2008 #9
    underpsi

    underpsi Road Train Member

    1,266
    292
    Sep 18, 2008
    Toronto, Ont
    0
    Ya 800 is right. Road speed to RPM is completely depended on the mechancal parts has nothing to do with power or torque. Power and torque just get you there faster.
     
    underpsi, Nov 28, 2008
    underpsi, Nov 28, 2008
    #9
    MNdriver Thanks this.
  12. Nov 28, 2008 #10
    smd5231

    smd5231 Bobtail Member

    15
    3
    Nov 23, 2008
    Guelph, ON
    0
    You always get excited this easy? I look at HP and the engine will make more of it ... so I decided to ask here if it'll make a difference.
     
    smd5231, Nov 28, 2008
    smd5231, Nov 28, 2008
    #10
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