APT
SE Michigan
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Joined: 06/09/2010
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I have a newer 6.0L and wish I had a 3000rpm stall speed torque converter. You are right, power is noticeably stronger over 3500rpm. Keep it in 3rd gear for now and let it downshift to 2nd gear and 4000rpm when you need to. IMHO, not worth $1500 to swap axles.
A & A parents of DD 2005, DS1 2007, DS2 2009
2011 Suburban 2500 6.0L 3.73 pulling 2011 Heartland North Trail 28BRS
2012 VW Passat TDI
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allen8106
Burrton. KS
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Joined: 01/31/2012
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marcus6701 wrote:I read that towing a TT the RPM should be around 2700-3000 RPM. I'm at around 2300 @ 60 mph in 3rd gear. What RPM are you towing at?
2500 rpm at 70 mph, with tranny locked into 5th gear and tow mode engaged. 2009 GMC with 6.0L vortec gas engine.
2010 Eagle Super Lite 315RLDS
2009 GMC Sierra 2500HD 6.0L
1983 DW (love of my life)
2010 Pit Bull Terrier (Jake)
2010 Camping Nights 45
2011 Camping Nights 75
2012 Camping Nights 127
2013 Camping Nights 12
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BenK
SF BayArea
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Joined: 04/18/2002
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My last try in trying to educate on the matter and best to reference another
thread where the OP didn't understand how things stack up as a whole system
and that taking anyone component by itself is out of context.
Changing Axle ratio on New F150 , Void the Warranty
BenK wrote:Thigh bone is connected to the knee bone the knee bone is connected to the ankle bone...
Some of you folks are talking out of context and the age old saying above is
to try and show that some folks are talking about the ankle bone, others the
knee bone, etc
Changing the diff ratio is the last link in the chain of this food chain. So
yes it matters or is the bottom line.
The stuff upstream is affected by that end component...the diff ratio...but...wait,
there is another bone in this food chain and that is the tire dia, which is the
final food chain link to the pavement
The tire dia change is the same affect as changing the diff ratio...it affects
EVERYTHING upstream all the way to the fly wheel
Didn't know that GM offered several TC stall speeds and will have to check that
out. Still say it's not a good towing stall speed, more boy racer than towing
-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...
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BenK
SF BayArea
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Joined: 04/18/2002
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Oh, since on this, here is what mine is running on the highway and then should
this be an absolute for all ICE's, TC stall, tranny gears, diff gears and tire dia's ?
that is with a 7.4L big block, 4L80E auto tranny (don't know the stall speed),
4.1 diff's and LT265/75R16E's
When towing am generally in 3rd, so that would be around 2,800 RPMs
at around 60MPH-65MPH
It all starts at the characteristics of the ICE. Here is a TBI 7.4L. Mine is
7.4L vortex but don't have a copy of it's HP/Torque curve, but this one is
close enough (mine is a bit higher...410 ft/lbs torque instead of 380)
That torque curve telling on where I should be towing at, no matter what gear
am in
Then notice that my red line starts at around 4,200 RPMs, where small
blocks are just getting into their sweet spot
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traildog66
MD/DC Metro
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Joined: 03/12/2012
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4.0L V6 Auto w/3.36 gears @ 60-65 mph = 2350-2750 rpm in 4th on the flats. @ 55-65 mph up grade = 3250-4000 rpm in 3rd.
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marcus6701
Central PA
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Joined: 08/07/2011
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BenK,
You are correct. All of the components work together and isolating one from the rest technically can't be done. My 3.73 rear gears now act like 3.42 gears due to my tires being oversized at 285/75-r16. I did not choose these, they were on it when bought. Not to mention 65 mph is not 65 its close to 70 mph due to the larger circumferance. This affects the high stall converter. It causes the vehicle to feel like it is starting out in a higher gear, say 2nd gear. This now causes a need for extra throttle and some rpm to overcome the high gearing. I am switching to factory size tires to get the full 3.73 gear ratio back for towing. The difference in tire size is 30.5" vs 33". Enough to drag the burb down on power.
2008 30ft Aerolite, white interior, 2003 Suburban 6.0L 3.73 gears
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marcus6701
Central PA
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APT,
I was quoted $2000 for new gears in my burb. Maybe if I had some extra cash. A custom tune will net some more hp and torque and will be cheaper for me.
Traildog66,
What vehicle do you have? Just curious.
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#40Fan
Colorado
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Joined: 02/13/2011
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BenK wrote:
Don't use that intersection of the two lines as your "sweet spot" because the X-axis aren't symmetrical. An NA ICE will always overlap the tq/hp numbers at ~5250 rpms.
2005 Keystone Outback Sydney 31RQS
2011 Ram 2500 CC LB CTD G56 3.42 Mineral Gray
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Turtle n Peeps
California
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Joined: 06/23/2008
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You beat me to it #40. Unless this chart is in something else besides HP and ft/tq, something is very wrong with it. 
What happend to 5252?
~ Too many freaks & not enough circuses ~
"Life is not tried ~ it is merely survived ~ if you're standing
outside the fire"
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BenK
SF BayArea
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Joined: 04/18/2002
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meant on the tach...
Not the HP/Torque curve
Trying to show how the comments are out of context, as most have small blocks
that can spin up to 2x where a big block can't do.
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