RPM's when towing uphill?

jerem0621 wrote:
The Available RPM is the figure that kinda makes me chuckle some....nobody ever talks about it though.

My dads 03 Cummins has a 3200 RPM redline
My old 99 V10 had a 5800 rpm redline IIRC

My Daddy consistently had to run his Cummins at around 2600-3000 RPM over some of the hills around here (Monteagle, Hwy 111 from Dunlap to Soddy Daisy. This is from 81-93% of the available RPM for the Cummins

My truck did these pulls at about 4500-5000 rpm... this is 77-86% of the available RPM for the motor .

Seems strange to me that people with diesels are content to run them at 81-93% of the available RPM all day long... since its numerically lower RPM (but as high or higher % wise) but a Gasser running 77-86% of the available RPM is disturbing to them.

The Ford 3.7 V6 with a 7,000 RPM shift point... that should be a FUN test to do a TT pull up a hill with. I wonder what RPM % it has to use. LOL

Thanks!

Jeremiah

I'll bite..... Anywhere between 3500-6500rpm, for as long as you keep your foot into it!
Ignore the tach, and it's a smooth running gem of a base motor, that happens to have a lot of power, when revved. I ride every type of toy on the planet, so running at rpm is a non issue with me. Not so much with many others.

Keep in mind, 300hp is 300hp, whether occurs at 2000rpm, or 6000rpm, once the transmission multiplies the speed in exchange for torque, it all amounts to the same think at the axle. Torque is a variable, and 600ft lbs at 2500 rpm is less power than 300ft/lbs at 6000rpm for example....

I have a Dodge 4.7 with a 5 speed manual tranny. When I bought it new I was surprised to see the tach did not show a red line. I later learned it was about 5000 or so. (Can't remember exactly.)
I tow at 60 mph in 4th at about 2600 rpm. When I need to go up a medium hill I drop to 3rd at about 3500 rpm and this maintains 60 mph. The steepest hill I have ever encountered was on Hwy 65 near Branson and that required 2nd gear at 4200 or so to maintain 35 mph. That was the most I've ever heard that little 4.7 scream. I really preferred to stay a bit shy of the red line.

I tend to back off and not push things to the max. Up the steepest hills I kept my speed to around 40mph-45mph. My 2004 Hemi 5.7L Durango doesn't allow me much gear selection, just 1-2-D with a tow haul button to lock out 5th. Keeping the RPM's down and not pushing the engine helped keep engine temp as well as tranny temp way down. I now have 140,000 miles on it, mostly towing and zero problems after 10 years.

I let mine rev that high with no worries. The computer won't let it over rev.

I have had my Hemi as high as 5500 RPM climbing mountain grades in 2nd gear with my 12,000# 5er in tow.

Lynnmor wrote:

Dog Trainer wrote:
The 3950 Peak torque number is the one you want to run when climbing. This is the peak efficiency of your motor. At that point it is breathing well and living longer.

At peak torque the pistons, rods, crank etc. are loaded the maximum amount. How this translates into living longer, I don't know.

Just because you don't know does not make not so. An engine that does not breath does not live.

BenK wrote:
Both my daughters motor sports bikes (one a twin v, other v 6) are good for
a 14,000 or so red line. Eldest daughter's husband said his Monster is
good for 16,000 rpm red line

That got my attention. What is that v6 motorcycle?

Dog Trainer wrote:
The 3950 Peak torque number is the one you want to run when climbing. This is the peak efficiency of your motor. At that point it is breathing well and living longer.

At peak torque the pistons, rods, crank etc. are loaded the maximum amount. How this translates into living longer, I don't know.

I was watching an episode of top gear last night.
The Bugatti they were testing appeared to idle at about 2200 rpm.
The McClaren it was up against showed 2700 on the tach.

steve-n-vicki wrote:
since I don't have a tach , I just hold it on the floor and let the computer take care of the engine

:E

since I don't have a tach , I just hold it on the floor and let the computer take care of the engine