observations about our trucks powercurve
#1
observations about our trucks powercurve
one thing I have noticed is my truck always has a surge of power when taking off and when the RPM gets to about 2k, sometimes its difficult to control exactly how hard it hits, but it will break the tires loose at 30 mph. I slow down to make a right turn onto a neighborhood street the truck is accelerating and moving the 7000# trailer like its a rag doll at those slow speeds. but at freeway speeds I don't have this surge of torque. I am wondering if our engines defuel at those speeds because they can't manage the EGT's for extended periods of time. my truck doesn't have the ummph when I step on the gas at freeway speeds but at the same RPM at 25 mph its got enough torque to bark the tires with 800#'s of ball weight on it. it could also be why ford didn't do well against chevy in some of the pulling contests.
#4
Cummins Cowboy,
Read my thread 6.7 Power Loss Towing
Mine is seems to loose torque when pulling at about 60mph. I posted a vid of my gauges when I floored it at about 65 up a 6% grade pulling about 8,000 lbs and it did not pick up any speed! You can see the rpms go from 2000 to 2700 but no speed increase.
Seems there is some issue, just don't know what. I just had my truck into the dealer and they said it was fine. they did the sensor reprogram. I had received a letter from ford telling me to go in to get the new programing. They said this did something to the tranny as well and to see if it helped on my next tow. I am going next weekend and will post another vid of the gauges.
Thanks
Read my thread 6.7 Power Loss Towing
Mine is seems to loose torque when pulling at about 60mph. I posted a vid of my gauges when I floored it at about 65 up a 6% grade pulling about 8,000 lbs and it did not pick up any speed! You can see the rpms go from 2000 to 2700 but no speed increase.
Seems there is some issue, just don't know what. I just had my truck into the dealer and they said it was fine. they did the sensor reprogram. I had received a letter from ford telling me to go in to get the new programing. They said this did something to the tranny as well and to see if it helped on my next tow. I am going next weekend and will post another vid of the gauges.
Thanks
#5
You guys are gonna think I'm nuts, but passing at highway speed with just two sleds on my trailer and I don't think it has the umph it should, almost unimpressed with it actually for such a light load. But from a dead stop pulling out onto the highway she will pull out like the sleds and trailer aren't attached. I just thought its because the truck makes most of its torque at lower rpms??
#6
I agree. With some heavy hitch weight we can break the tires free. That's crazy torque.
I think I get a real nice hard pull when I'm in M5 climbing a grade, 2000-2300 RPM and 21-22PSI boost. But while M6 will take care of most interstate rolling hills, it's a dog on a long grade. I don't have trans. Slip like 500 does though.
Cummins, try rolling into 100% throttle in M, shift through all the gears at 2100-2200 rpm. Keep your foot planted and tap the + button as long as its safe. The rate of speed gains is amazing all the way for me, I don't feel any dead spots except slow gear changes.
I dunno, keep thinking. I will watch close for a while.
I think I get a real nice hard pull when I'm in M5 climbing a grade, 2000-2300 RPM and 21-22PSI boost. But while M6 will take care of most interstate rolling hills, it's a dog on a long grade. I don't have trans. Slip like 500 does though.
Cummins, try rolling into 100% throttle in M, shift through all the gears at 2100-2200 rpm. Keep your foot planted and tap the + button as long as its safe. The rate of speed gains is amazing all the way for me, I don't feel any dead spots except slow gear changes.
I dunno, keep thinking. I will watch close for a while.
#7
Just thinking
Maybe someone with this issue should start a thread and include their build date, then other people with the same issue while towing could respond with their buid date to see if there might be a commom time line or period that could show a bad batch of torque convertors.
I'm in Florida and its about as flat as its gets so might not be the best example. But while towing around 8000lbs at any speed even at 65 or 70 if I put it the floor to make a pass she pulls hard all the thru. Does seem like this could be a convertor issue.
Maybe someone with this issue should start a thread and include their build date, then other people with the same issue while towing could respond with their buid date to see if there might be a commom time line or period that could show a bad batch of torque convertors.
I'm in Florida and its about as flat as its gets so might not be the best example. But while towing around 8000lbs at any speed even at 65 or 70 if I put it the floor to make a pass she pulls hard all the thru. Does seem like this could be a convertor issue.
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#8
well, if the RPMs increase 700 right in the optimum torque band and the OP just stays at the same speed, sure sounds like torque converter which may be a hardware issue, or if Spartans tunes work well at speeds above 55 maybe they changed something in the transmission control module lock lock up or slip...just thinking out loud. But my truck pulls pretty hard after 50MPH with a 5th wheel attached and it is an early 2012.
#9
#11
It has to do with the gear ratios in the tranny.
The Ford is geared really low compared to the GM in the 1-2 gears. Due to the torque muliplication, it is indeed crazy torque. Many thousands of pounds. But the trade off is that since both trucks have 6 speeds, then the advantage in gears 1-2 means that it will have a disadvantage in the other gears. You can easily see this in the acceleration tests and it is also a big part the exhaust brake performance.
I did the math on this once and posted it somewhere. I will try to find it and post it here...I do remember that the differences of TQ in gears is staggering.
The Ford is geared really low compared to the GM in the 1-2 gears. Due to the torque muliplication, it is indeed crazy torque. Many thousands of pounds. But the trade off is that since both trucks have 6 speeds, then the advantage in gears 1-2 means that it will have a disadvantage in the other gears. You can easily see this in the acceleration tests and it is also a big part the exhaust brake performance.
I did the math on this once and posted it somewhere. I will try to find it and post it here...I do remember that the differences of TQ in gears is staggering.
#12
Here is one I found about the 1-2 gears only. The difference shrinks and actually reverses some in the other gears.
Of course the other rearend ratios that Ford is available in may change this some, depending on tire sizes.
Ford final ratio 3.73X 1st gear 3.97=14.80 X 800 TQ=11,840
GMC final ratio3.73X 1st gear 3.10=11.56X765 TQ=8,843
Ford final ratio 3.73X 2nd gear 2.32 =8.65X800 TQ=6,920
GMC final ratio 3.73X 2nd gear 1.81=6.75X765 TQ=5,163
Of course the other rearend ratios that Ford is available in may change this some, depending on tire sizes.
Ford final ratio 3.73X 1st gear 3.97=14.80 X 800 TQ=11,840
GMC final ratio3.73X 1st gear 3.10=11.56X765 TQ=8,843
Ford final ratio 3.73X 2nd gear 2.32 =8.65X800 TQ=6,920
GMC final ratio 3.73X 2nd gear 1.81=6.75X765 TQ=5,163
#14
the gear ratios are not it. I can tell differences in gearing and throw out that variable. I think our trucks are designed to do what they are doing. I think ford figured out a very clever way of saving the motor and drive train but still be able to show big HP and torque. put the truck on a dyno or at slow speeds and the motor will put out the advertised numbers. long pulls on the highway up steep grades is where this engine doesn't deliver advertised number.
my '06 dodge with smarty tune which should have put me about 400hp and 750 ish torque at the flywheel would flat out walk off and leave this truck on a big hill with a load. see for yourself try flooring the throttle with a load going 70 mph, frankly its pretty umimpressive for a truck rated at the kind of numbers these trucks are. it also explains why ford got its tail handed to it by chevy pulling loads up I70 in colorado.
another thing is IMO our trucks don't have an exhaust brake, its just well matched and timed downshifts. not complaining my truck works great for my needs, just calling it as I see it. and the break the tires loose torque at 30mph aint there pulling a load over parleys canyon
my '06 dodge with smarty tune which should have put me about 400hp and 750 ish torque at the flywheel would flat out walk off and leave this truck on a big hill with a load. see for yourself try flooring the throttle with a load going 70 mph, frankly its pretty umimpressive for a truck rated at the kind of numbers these trucks are. it also explains why ford got its tail handed to it by chevy pulling loads up I70 in colorado.
another thing is IMO our trucks don't have an exhaust brake, its just well matched and timed downshifts. not complaining my truck works great for my needs, just calling it as I see it. and the break the tires loose torque at 30mph aint there pulling a load over parleys canyon
#15
the gear ratios are not it. I can tell differences in gearing and throw out that variable. I think our trucks are designed to do what they are doing. I think ford figured out a very clever way of saving the motor and drive train but still be able to show big HP and torque. put the truck on a dyno or at slow speeds and the motor will put out the advertised numbers. long pulls on the highway up steep grades is where this engine doesn't deliver advertised number.
my '06 dodge with smarty tune which should have put me about 400hp and 750 ish torque at the flywheel would flat out walk off and leave this truck on a big hill with a load. see for yourself try flooring the throttle with a load going 70 mph, frankly its pretty umimpressive for a truck rated at the kind of numbers these trucks are. it also explains why ford got its tail handed to it by chevy pulling loads up I70 in colorado.
another thing is IMO our trucks don't have an exhaust brake, its just well matched and timed downshifts. not complaining my truck works great for my needs, just calling it as I see it. and the break the tires loose torque at 30mph aint there pulling a load over parleys canyon
my '06 dodge with smarty tune which should have put me about 400hp and 750 ish torque at the flywheel would flat out walk off and leave this truck on a big hill with a load. see for yourself try flooring the throttle with a load going 70 mph, frankly its pretty umimpressive for a truck rated at the kind of numbers these trucks are. it also explains why ford got its tail handed to it by chevy pulling loads up I70 in colorado.
another thing is IMO our trucks don't have an exhaust brake, its just well matched and timed downshifts. not complaining my truck works great for my needs, just calling it as I see it. and the break the tires loose torque at 30mph aint there pulling a load over parleys canyon
And as I pointed out before,,,since both trannys have the same amount of gears (six) then gearing lower for power in the 1-2 gears will mean that it will lack performance at other road speeds. This shows up big time in the exhaust brake performance. The GM is able to enagage 2nd gear at a higher speed that the Ford which is in 3rd. So at higher speeds the GMs EB has a big advantage over the Ford.
At any rate, I have no way of proving or disproving the theory of the fords not maintaining rated power..The gearing advantage in the 1-2 gears though is easily proved by simple math calculations.
It is very possible that both theories are correct.