Torque and RPM

Discussion in 'Ford Raptor Engine Discussion and Performance Mods' started by Jeff-Ohio, Dec 1, 2016.

  1. BurnOut

    BurnOut Full Access Member

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    ...that you don't need 300+ ft/lb to maintain cruising speed, so why burn the fuel to make power that you don't need?

    The area of the power curve where there's low torque is between idle and 2100 or so... and if you're spending a significant amount of time in that part of the tach, you're not using the truck aggressively. If you ARE using the truck aggressively, you'll be out of that part of the rev range soon enough.

    If you watch the TFL Truck vid of the 0-60 runs, the truck doesn't seem to have much trouble coming "on to" the motor under heavy acceleration (granted, it IS unloaded acceleration); I expect that most of the, say, 1400 RPM "dead zone" (between an assumed idle speed of 700 RPM and 2100 RPM where the HO 3.5L surpasses the torque of the 6.2L) is eaten up by the flash stall speed of the converter. Hell, I'd be willing to bet that it's damn near the same case with the existing 6.2L trucks (again, under WOT conditions). Under cruising conditions, I can see an advantage for the 6.2L trucks if, for some reason, you didn't want to allow the transmission to downshift. However, personally, even in V8 powered vehicles (granted, I have never driven a 1st gen Raptor), I want them to downshift when accelerating from cruising speed (say, moving from a 50 mph zone to a 75 mph zone), as there's just not enough ass below 2k RPM to give me the acceleration that I want. Add in the tighter gear spacing (and faster shifts) of the 10 speed, and if I had to guess, even accelerating from cruise speeds will favor the new truck. In regard to fuel consumption, high load/low RPM (the only place the 6.2L has an advantage) is a mileage (and engine) KILLER.
     
  2. Jeff-Ohio

    Jeff-Ohio Full Access Member

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    Does anybody know how the Ecoboost motor in the previous F150 and the 2017 F150 compare to each other from a torque curve perspective? How does the 2017 F150 Ecoboost torque curve compare to the Raptor's torque curve? I'm just wondering if the latest Ecoboost motors are trading off lower end torque for higher overall torque numbers? Is anybody else really bothered by the torque curve? I would personally trade a higher overall torque number for more low-end torque.
     
    Last edited: Dec 5, 2016
  3. EricM

    EricM Full Access Member

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    Nearly 100% of the time, I'm not driving the truck aggressively. Who in the hell drives a 6000 lb truck aggressively more than every now and then, especially on public streets? Maybe I'm just getting old- and I know it's a "racetruck" and all- but damn, I have a car with 600 HP and a stick shift if I want to mash the gas, rip around corners and stand on the brake pedal at every stop.

    So yea, for me the area from 2100 and down is by far the most important area for the engine to deliver loads of torque with very little throttle input.

    That 3.5L at light throttle (ie not in boost) will be a dog compared to the 6.2L. Gears and weight will help, but the old saying will always be correct. Repeat after me class, "There is no replacement for displacement". Don't even start with the turbo argument- cause the bigger engine can use one of those just as easy as the smaller engine. Get used to that 10 speed shifting a lot.
     
  4. Jeff-Ohio

    Jeff-Ohio Full Access Member

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    I am definitely not an expert, but don't motors with turbo chargers typically generate a lot of torque at very low RPMs due to the turbo chargers? What happened here? Can something be done with the mapping to generate a lot more torque at 1000 RPMs?
     
  5. SilverBolt

    SilverBolt Hired Gun

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    Turbos generally generate big numbers at higher RPM's. Superchargers generate the big numbers at lower RPM.
     
  6. NASSTY

    NASSTY Full Access Member

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    The Gen 1 3.5 Ecoboost reached 90% peak torque @ 1900 RPMs.

    [​IMG]
     
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  7. EricM

    EricM Full Access Member

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    If you mash the throttle, it'll go like a scalded dog. Its a boosted engine. As soon as you get the turbo producing boost it pulls hard. If you stay out of the boost though, which is what is needed to get that nice city MPG rating, it's gonna be well over 100 ftlbs tq short of the 6.2L. A lot of words to say that the 6.2 is a way better choice if ya drive it like a grandpa trying to maximize fuel mileage and minimize mechanical wear.
     
  8. BurnOut

    BurnOut Full Access Member

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    EricM- I am VERY familiar with the "replacement for displacement" discussion, and was famous for using that very same argument ("apply the turbo to the bigger motor and you make more power") back in the days of heavy import modding. I hear you as well on the normal operating conditions of my daily driver, and again, I say that unless accelerating from a dead stop, you won't see the 300 ft/lb at 1k RPM of the 6.2L... because that torque is only achieved at WOT... and at WOT, the transmission will downshift and blow right past the 2100 RPM "equilibrium" (between the two motors) point. In other words, the only time you'll find yourself taking advantage of the area of the power curve where the 6.2L shines over the HO 3.5L is WOT from a dead stop... and even at that, I'm betting that most (if not all) of that part of the power curve is gone by the time the converter stalls and moves the truck. I can, though, see your point that at, say, 1500 RPM, the 6.2L will produce more torque than the HO 3.5L, given similar throttle openings (say, 25%). True. However, based on my experience with a 3.55 geared 2011 4WD 1st gen 3.5 EB (which I drove for three years), it doesn't render the vehicle undriveable by any stretch of the imagination. I was REALLY fastidious about watching the instant fuel consumption meter in that truck, and when I sold it, the lifetime MPG was 17.2, and that truck spent nearly its whole life in mixed suburban driving (read: VERY few road trips to run up the MPG). I rarely exceeded @2200 RPM in that truck, and never felt as though I was having a problem keeping up with traffic.

    Regarding the shifting of the 10 speed, I am fine with that... a good friend of mine used to do transmission calibration for Ford, and he was in town one time, and we were driving somewhere in my truck (at that time, I was driving a '05 4WD single cab F150 with the 24V 5.4L)... I had been bitching at him, saying that the transmission didn't downshift enough... for instance, at 50 mph and ~40% throttle on an uphill highway ramp. He told me that while I might think it doesn't downshift often enough, someone else might think that it downshifts too much. My response was something that you can probably imagine ("**** them, I'm right."). He laughed and said that the way that his team knows that they have a transmission calibration right is when half the people say it shifts too much, and half the people say that it doesn't shift enough... to which I replied, "So you consider the calibration to be right when no one is happy?" Again, he laughed, and admitted that that was pretty much the case. The point that I am making here is that generally speaking, I am fine with trading high(er) throttle position for high(er) RPM (read: I tend to prefer lighter throttle at a higher RPM to heavier throttle at a lower RPM) when wanting mild/moderate acceleration, as that seems to get me the acceleration that I am after more quickly, and get me back into steady-state cruising that much sooner. So, in the on-ramp scenario above, I left the throttle where it was, tapped the brakes to unlock the converter, and voila... got the mild acceleration that I wanted without having to boot the throttle enough to provoke a downshift.

    Jeff-Ohio- if you look at the torque curve, the HO 3.5L IS generating its torque lower in the rev range... the peak is 1k RPM below the 6.2L. Even if you look at the bigger turbo diesels, they don't really make too much torque (proportionally) below 1000 RPM:

    [​IMG]
     
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  9. gneissday

    gneissday Full Access Member

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    I'm interested to see how the new Raptor feels power/acceleration-wise. I was hoping that the torque curve would be similar to the old ecoboost (90% of max torque between 1,700 and 5,000 RPMs). The new Raptor looks like it has about 90% of max torque between approx 2,600 and 5,200 RPMs, which is still pretty awesome. Definitely a little different though, but maybe not an issue with the new transmission. I'm used to my V8 Titan, where you just touch the gas pedal and it immediately thrusts you back into the seat. Hmm...wonder how the Raptor will compare. I guess I'll know this spring (hopefully!).
     
  10. Jeff-Ohio

    Jeff-Ohio Full Access Member

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    Thanks for the graph. I am wondering why the torque curve on this graph is significantly different for the 6.2 than the other graph previously shared on this thread? Based on my brief test drive of the 6.2, I tend to believe this graph since I did not feel a ton of power with the 6.2 at the lower RPMs. The other graph would indicate that there is abundant torque at 1000 and 1500 RPMs. Which graph is right? If the second graph showing lower torque numbers at the lower RPMs is correct, then I may not be as dissatisfied with my new Raptor as I originally thought I would be when I saw the first graph.
     

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