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How does torque make you faster?

Discussion in 'SRT10 and SRT10 Coupe Discussions' started by black mamba1, Jul 5, 2008.

  1. black mamba1

    black mamba1 Enthusiast

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    Ok, before you rip me apart I did a search on this topic and came up w/ no real answers.

    The reason I am perplexed is b/c my car dynoed at 557 rwtq a couple of weeks ago, 23 more ft-lbs of torque than when dynoed this winter, but my power came in at 512 rwhp, 16 less hp than when dynoed this winter. Yes, I used different dynos, the latter was a Mustang dyno and the prior was a dyno jet.

    Now, using Tators dyno factor loss of 13% thru the tranny, that gives me between 589 to 606 hp and 617 to 640 ft-lbs of torque using flywheel ratings. The torque ratings are quite a bit more than a stock Gen 4.

    My questions is this: Does the higher torque rating make me as fast or faster than a Gen 4 from 0-150 mph?

    I ask this b/c I raced an 07 911 TT and a C6 Z06 yesterday and walked them both pretty good. Can someone explain this torque effect on racing once and for all??????
     
  2. Vipermann

    Vipermann Viper Owner

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    Personally, I think 14% drivetrain loss is more realistic.

    But, to your question, don't forget about total TQ and HP 'under the curve' vs. just 'peak' TQ and HP on the dyno ...on the road, everything under the curve matters for speed, not just 'peak'
     
  3. johnk

    johnk Enthusiast

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    [
    Given all the other factors, Mustang dynos generally register ~10% lower than the typical Dynojet.

    Your torque went up and your HP went down... Completely different STYLE dynos, and I'd bet a significant difference in ambeiant temp between a winter and summer pull
     
    Last edited: Jul 5, 2008
  4. RTTTTed

    RTTTTed Viper Owner

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    A simple way to think of torque and horsepower is to "think" that torque gets you going and is most of the 'power' to pickup speed and rpm. Once you have some rpm hp takes over and continues to push the car forward. Shift and you're back into the torque.

    Not very scientific, but I think it explains what happens.

    Dyno numbers are just that, they give an indication of power potential (compared to the weight). The power and torque CURVES tell you were the engines power is produced. A flat power curve (like the Roe supercharger) means more power available at more engine speeds - hence more power. A peaky curve shows where the power is lacking and where it is strong.

    A Nitrous power curve is flat. ie: It makes the same hp and torque with no curve, or the rpm makes no difference to the hp and tq produced.

    Drag racing numbers (ET and weight) will calculate out to give you actual hp produced to get the given weight down the quarter mile in the specified time. That's what's important, not what #s came from a machine while the car was sitting still. Dynos don't take into account airflow, CD, weight, traction, and average hp produced.

    A dyno is just a tool used for tuning the engine properly and giving an indication of what the vehicle MAY be capable of doing.

    Ted
     
  5. Grant

    Grant Viper Owner

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    Torque doesn't make you faster, all that matters is power.

    However, peak power doesn't really affect anything, its all power over the car's rev range. Torque almost always peaks lower in the RPM range than horsepower. If you take two similar cars with similar motors, one making 200 hp and 160 ft-lbs and the other making 200 hp and 200 ft-lbs, the later car is going to have a broader powerband and thus accelerate more quickly than the former.

    Or, thought of another way, torque at the rear wheels is what accelerates the car. Torque measured at the engine is multiplied by the driveline, and so means nothing in and of itself.
     
  6. plumcrazy

    plumcrazy Enthusiast

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    i know keiths first set of dyno runs were on a dyno jet, im not sure what padddock has for a dyno but just the dyno's being different will give you different readings along with the second set of dyno runs being in hot weather, i don't remember when he did the ones at romar but i bet it wasn't as hot or humid.

    and i was told that torque is really the only thing that matters and that HP is derived from your torque number.

    HP=pressure and torque=volume if we were talking about air or water. if that helps
     
  7. wallbanger

    wallbanger Enthusiast

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  8. VENOMIS

    VENOMIS Viper Owner

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    Some food for thought. You have your pickup going up a hill pulling a trailer. The engine is rated for 450 h.p. at 5500 rpm. 500 ftlbs of torque at 4500 rpm. So your floored and doing 75mph. Thats all she has. You look down at the tach and your at around 4500 rpm. Why? Because the engine has reached its maximum torque. Horsepower doesnt meen that much when it comes to load. You want the torque more than horsepower. Another example is a diesel truck or engine. My peterbilt is rated at 400 h.p. and more than the viper. Now do you think that V10 could pull an 80,000 load like the cat engine in the truck? No, because it has about 2000 ftlb of torque. But the engine runs way different than a gas engine. Now we come back to horse power. Of course the car would beat the truck in a drag race cause of has more horse power and is a different type of engine. I know that is not comparing apples to apples, but it was to give a little insight between torque and horsepower. When you hit that wall where the car does nt go any faster its because the engine isnt making enough torque to make the car go any faster. I tend to think that horse power determines how fast the engine is going to rev and "get there" but the torque is how it pulls "getting there"
     
  9. ViperTony

    ViperTony Enthusiast

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    Keith, install the Paxton and all your questions will be answered.
     
  10. Bonkers

    Bonkers VCA Venom Member Venom Member

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    MoparSteve summed it up best:
    Oversteer is when you hit the wall with the back of the car
    Understeer is when you hit the wall with the front of your car
    Horsepower is how fast you hit the wall
    Torque is how much of the wall you take with you.
     
  11. plumcrazy

    plumcrazy Enthusiast

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    GREAT analogy
     
  12. black mamba1

    black mamba1 Enthusiast

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    Very true Tony...you are the closest competition I have had since I got my Viper..and until you beat me...why bother with the Paxton!:D
     
  13. black mamba1

    black mamba1 Enthusiast

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    Thanks guys! I think the best answer I have heard here to explain this to me is how much area is under the curve is what really determines how fast you go. Right?

    I think this has been explained very well in some of the Roe vs Paxton threads also. Now it makes sense to me. Now, one thing I am curious about is that while my torque is some 60 ft-lbs to 80 ft-lbs higher than a stock Gen 4, my power is lower by a good 15 -25 rwhp according to the rwhp numbers I see posted. If I lined up w/ a Gen 4, seems to me I would have the advantage down low due to torque, but I guess again, it all boils down to power under the curve. One reason the Gen 4's are not running low 11's stock seems to be b/c while there was a 90 hp increase, the torque only went up by 35 ft-lbs.

    So, again, two cars being relatively equal. Say one is at 500 rwhp and 500 ft lbs of torque, and the other being say 480 hp and 540 ft lb of torque, if the torque peaks quicker on the 480 rwhp car resulting in more area under curve to red line, the 480 hp car will beat the 500 hp car in the 1/4 and probably all the way to 160 mph or so...right?
     
    Last edited: Jul 5, 2008
  14. black mamba1

    black mamba1 Enthusiast

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    Ok, I have read two things...the Mustang is lower than Dyno Jet by like 10%. Ten percent would be over 50 rwhp, right? So if I register 512 rwhp on a Mustang, divide that figure by .9, then I should register 569 rwhp on a Dyno Jet right? And using the 14% tranny loss instead of 13, I should be at 661 fly wheel horsepower, right?

    GEEZ!:headbang: I would love to believe those numbers are true! But something tells me those numbers are HIGHLY optomistic. That means my current mods would have given me 150 hp. Hmmmmm:rolleyes:
     
    Last edited: Jul 5, 2008
  15. mangle

    mangle Viper Owner

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    Horsepower = torque*rpm/5252. When torque is in ft-lbs, 5252 is a number that makes the units make sense.

    Torque is simply force times distance, and determines maximum instantaneous acceleration (multiply flywheel torque by total gearing ratio, divide by tire radius, divide by vehicle mass, and you have acceleration).

    Horsepower, on the other hand, is a unit of power. 1hp is equivalent to roughly 550 ft-lb/sec. Horsepower is defined as a rate of change of momentum. With 1-1 gearing you could determine how long it would take to move between two speeds with a given horsepower.

    Assuming the same gearing and similar shaped powerbands, the comparison of the two vehicles can be correctly made with either number.
     
  16. 00prowler

    00prowler Enthusiast

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    Mamba, If you are beating 911Ts and Zo6s your torque and HP are fine...You must live near Greenwich, I never find cars like that in my part of CT to woop...Al
     
  17. black mamba1

    black mamba1 Enthusiast

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    Yeah, it took a year and a half to see them all on one day and it not be some kinda car show. I see Gallardo's, Ferrari's, Vettes, Astons, etc all the time. I am just usually not in my Viper when I see them or I see one one day and another the next. Then, you gotta get them to play...

    It must have been something in the water this past July 3rd, cuz they came out, and they came out to play!
     
  18. black mamba1

    black mamba1 Enthusiast

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    I see rag after rag reporting that the Gen 4 gets to 100 mph in 7.9 sec. and the Z06 in 8.3 to 8.4 sec, but by the time they hit the quarter mile the Z has closed to w/in a tenth of a second.

    Why in the hell is that?
     
  19. Bosco

    Bosco Enthusiast

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    I saw someone else already answer this question, but I'll throw in my two cents to try to clarify.

    Horsepower is directly related to torque - it's a simple conversion. Generally, the higher the displacement, the higher the torque. Whether a motor makes good horsepower in the high RPM's is directly related to how efficient the intake and exhaust systems are. If the engine can maintain efficiency in the high RPM's, it will generally have more horsepower than torque. In motors such as those found in the S2000, they have relatively little displacement and don't require as much air (comparatively) to keep it building power in the high RPM's. Compare those 2.2 liters to a Viper's 8.3 liters, and you can see why the Viper can't maintain it's massive torque in the high RPM's. It loses efficiency higher in the tach, torque drops off, and the horsepower is the result of that effect.

    By the way, not a Viper owner here, but rather an admirer. I aim to own one this time next year. You guys rock.
     
  20. FE 065

    FE 065 Enthusiast

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    Torque is how much work you can do..

    Horsepower is how fast you can do it.


    ?
     

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