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Thread: HP or Torque ? for lower lap time ?

  1. #61
    Senior Member racebronco2's Avatar
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    Quote Originally Posted by vetteguy2005 View Post
    Attachment 3666The builder says it runs it at about 12.5/1 I think and the original engine tuner says 13.5/1 is in the safe zone.

    A stock ZO6 with 505 hp has about 450 whp, I only have 350 so I am down almost 100 whp from what a stock Zo6 has and what I thought I was buying.
    With the engine on the dyno the 508hp was gross hp and probably with open exhaust. The zo6's 505 is net hp (all accessories installed) but it is really closer to 530hp. If i remember correctly your car is an auto which will absorb 20% of the net hp. Remember back in the mid 70's when they changed the hp rating from gross to net and cars were down 100+ hp, lower compression was part of the reason. Back in the 80's hot rod magazine built a 400hp but the actual hp at the rear wheels were 260 with an auto. The % of loss from groos to rwhp is something like 35%. 508 x 65% =330hp. If you asked for more low end he might ahve put in a rv cam in which you would be less then stock but the tq should be flatter.

  2. #62
    Senior Member vetteguy2005's Avatar
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    Heads are supposed to be ported and a larger valve package. I paid an extra $1,000 for that and it did not raise the horse power even on his dyno from the stock heads and valves he claimed produced 510- hp.
    Here is the head and cam info: The camshaft lift is .566 in .554 ex dur @ .050 208in 220ex 117LSA the compression is 11.0:1 the intake valve has been increased to 2.02

    It definetly gets terrible gas mileage, like 18 mpg even on the highway when it used to get 27 mpg. The first cam he put in it, he admitted the duration was ground backwards on it, supposedly he replaced it after I took the motor out and brought it back to him. I will try to find a good engine guy in Chicago and test it a little.
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  3. #63
    Senior Member vetteguy2005's Avatar
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    Yes, I run an auto trans. The factory engine was rated at 400 fw hp and it dynoed at the wheels 359 HP. Thats only 11% parasitic loss. The same tuner who got me 359 out of it has tuned this engine 3 times and the best he could get was 350whp.

    With forged pistons, cam and head package I certainly should get more than a stock motor and less mpg. The torque on the stock engine at 359 hp was 357 and on the current 350 hp torque it is 328, so even my torque went down. Something is definetly wrong. I think I am coming after him!

    Thanks for all the advice, I appreciate it and apologies to William, I could not resist since it was about a topic so close to home.
    Corvette Specialty C6
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  4. #64
    Member samsam5886's Avatar
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    it's really quite simple

    horsepower = how fast
    torque = how much force being applied to obtain horsepower

  5. #65
    BMW Master bawareca's Avatar
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    Quote Originally Posted by samsam5886 View Post
    it's really quite simple

    horsepower = how fast
    torque = how much force being applied to obtain horsepower
    How does that apply to William's or Vetteguy's cases or tracking/racing reality?

  6. #66
    Senior Member Silversprint's Avatar
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    Someone wrote a program that will compare different cars based on weight, gearing, tires, drag coef, and dyno numbers (specifically torque).

    http://vlsicad.ucsd.edu/~sharma/Potpourri/perf_est.html
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  7. #67
    BMW Master bawareca's Avatar
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    There is another example:F1 is ~1100 lbs,~800 hp and the torque is probably subzero.Oli's corvette is ~3500 lbs,400 hp and a sea of torque.If someone switches the engines ,the corvette wont be able to take off,and the F1 car will only be smoking tires and will be able to accelerate only in a straight line(i doubt even that will be very dangerous).
    IMHO for a lightweight car higher revs and HP would be beneficial over more torque down low,in case the gear ratios are close enough and a suitable diff ratio can be choosen.

  8. #68
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bawareca View Post
    There is another example:F1 is ~1100 lbs,~800 hp and the torque is probably subzero.Oli's corvette is ~3500 lbs,400 hp and a sea of torque.If someone switches the engines ,the corvette wont be able to take off,and the F1 car will only be smoking tires and will be able to accelerate only in a straight line(i doubt even that will be very dangerous).
    IMHO for a lightweight car higher revs and HP would be beneficial over more torque down low,in case the gear ratios are close enough and a suitable diff ratio can be choosen.
    Now that's a load of horse****. The F1 engine can launch the corvette, the trick is having a clutch that can suffer a little to get the corvette rolling. Then the corvette will have a fun time trying to get the power down without spinning tires.

    The corvette engine will do everything the F1 car needs it to do with no problems. It will just be half as fast and weigh too much and probably need a lot of fabrication since aren't F1 engines part of the frame?

  9. #69
    Gearhead gixxer_drew's Avatar
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    I guess so, if you are still tuning from the stone ages and have no way to control torque down?
    Andrew M Brilliant
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  10. #70
    BMW Master bawareca's Avatar
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    Quote Originally Posted by robburgoon View Post
    Now that's a load of horse****. The F1 engine can launch the corvette, the trick is having a clutch that can suffer a little to get the corvette rolling. Then the corvette will have a fun time trying to get the power down without spinning tires.

    The corvette engine will do everything the F1 car needs it to do with no problems. It will just be half as fast and weigh too much and probably need a lot of fabrication since aren't F1 engines part of the frame?
    I wish you have driven mine E30 with 2500 lbs and 360 wtq at 3300 rpm.
    I cannot find the picture i have of an F1 V10 engine-the clutch is like 6" diameter and probably weights 2-3 lbs with the flywheel-hence the 6000 rpm idle

  11. #71
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bawareca View Post
    I wish you have driven mine E30 with 2500 lbs and 360 wtq at 3300 rpm.
    I cannot find the picture i have of an F1 V10 engine-the clutch is like 6" diameter and probably weights 2-3 lbs with the flywheel-hence the 6000 rpm idle
    The clutch issue is a challege, but that's only only time that torque matters at ALL. Getting the car moving from a dead stop. Any other speed, and it just doesn't matter, it's just a bunch of gearing at that point.

  12. #72
    Senior Member Johnny_Se7en's Avatar
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    Quote Originally Posted by bawareca View Post
    I wish you have driven mine E30 with 2500 lbs and 360 wtq at 3300 rpm.
    I cannot find the picture i have of an F1 V10 engine-the clutch is like 6" diameter and probably weights 2-3 lbs with the flywheel-hence the 6000 rpm idle

    Ferrari F1 Clutch by addlightness, on Flickr
    If nothing happens and there is no one around why did it not happen?

  13. #73
    Gearhead gixxer_drew's Avatar
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    yah, multi plate clutch, much slippage much spin. This is a road course we are talking about here, worrying about getting out of the hole is dumb. Just let her rip and try not to run over your guys.
    Andrew M Brilliant
    Aerodynamicist / Race Engineer

  14. #74
    Senior Member DocNrock's Avatar
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    Since we're getting into definitions:

    Horsepower: how fast you hit the wall
    Torque: how far you take the wall with you.

    Last edited by DocNrock; 08-29-2011 at 06:38 AM.
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  15. #75
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by DocNrock View Post
    Since we're getting into definitions:

    Horsepower: how fast you hit the wall
    Torque: how far you take the wall with you.

    Update: still wrong.

  16. #76
    Senior Member DocNrock's Avatar
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    I think it's time to stop posting attempts at humor. Someone is always bound to take it seriously.
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  17. #77
    Senior Member robburgoon's Avatar
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    No, you nailed it, I wasn't attempting humor, I was serious. Torque has nothing to do with how far a wall will travel, even if you tried to push it unless you're starting from a dead stop. It's just another completely wrong and misleading torque expression.

    (and even from a dead stop if you have big enough gearing the torque doesn't really matter)

    Where I goofed is I thought you were at least half serious with it.
    Last edited by robburgoon; 08-29-2011 at 11:06 AM.

  18. #78
    Chest hair required Olitho's Avatar
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    Quote Originally Posted by DocNrock View Post
    Since we're getting into definitions:

    Horsepower: how fast you hit the wall
    Torque: how far you take the wall with you.


    The first one is mostly correct. HP does determine how fast you are going when you hit the wall.

    The second one is not right at all. Torque is measured by how bent out of shape Burgoon gets when he does not get the humor.
    robburgoon likes this.
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  19. #79
    Senior Member robburgoon's Avatar
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    Hell, it's crap humor at that. It doesn't even make sense. If you want to crack a joke about "so much torque it ripped the pressure plate off the flywheel", go nuts.


    (now Oli, THAT was funny!)

  20. #80
    Senior Member DocNrock's Avatar
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    The great thing about humor is that it is entirely subjective. What is "crap humor" to some makes other laugh. Sometimes, even the mere inaccuracy of the punch line is humor in and of itself. Of course, when a joke is over-analyzed, then any inherent humor is completely lost.

    And unfortunately, I don't know any pressure plate jokes.
    donutbob likes this.
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