Tow RPM's

[Parshal]

I'm sure this has been discussed but I thought I'd ask it anyway. I bought a larger travel trailer and towed it about 800 miles this past weekend. I weighed it at a weigh station and it was 3600 lbs. on the axle connected to the truck.



Anyway, I noticed that, after driving it for an hour, the truck seemed to have a bit more power and was able to accelerate on some of the hills whereas it was only able to maintain speed on similar hillls earlier. I'm assuming the computer was compenstating. Possible?



I was wondering what RPM's I should be looking at for best acceleration. Sometimes, I had to slow down to 35 mph to go through a small town and then go back to 65. It seemed to pull best starting from 35 mph right about peak torque. I thought that you'd see best performance accelerating near peak HP. Doesn't torque give you starting power and HP keep it there?

 

[MattSt]

Well since over 300 people looked and didn't try and answer you I will give a stab at it. Granted I have only towed once with this truck and was over double what you towed but here goes.

Originally posted by Parshal: I weighed it at a weigh station and it was 3600 lbs. on the axle connected to the truck.



Anyway, I noticed that, after driving it for an hour, the truck seemed to have a bit more power and was able to accelerate on some of the hills whereas it was only able to maintain speed on similar hills earlier. I'm assuming the computer was compensating. Possible?

I would say your truck is still getting broke in and likes the weight behind it or you were more into the "sweet" spot of the hp/tq range and it just felt stronger. You didn't say if you had the cruise on or not but I know mine does some funky stuff. Sometimes it will go all the way to the floor when climbing hills and sometimes it will only go 3/4 throttle and slow down and loose speed. What really pisses me off is when I crest a hill it will gain about 5 mph before the cruise catches up. Sooner or later that is going to cost me a ticket!

Originally posted by Parshal:

I was wondering what RPM's I should be looking at for best acceleration. Sometimes, I had to slow down to 35 mph to go through a small town and then go back to 65. It seemed to pull best starting from 35 mph right about peak torque. I thought that you'd see best performance accelerating near peak HP. Doesn't torque give you starting power and HP keep it there? [/B]

For me towing about 10,000 #'s I needed to keep the RPM above 1900. So slowing down to 35 would include downshifting. I have been told and witnessed what lugging a CTD can do to EGT's so I would suggest downshifting and keeping the motor up in the RPM range.



With the old 01 pulling 13,000 #'s with the Edge chip on 5 any hill I tried to pull under 2000 RPM sent the EGT's over 1300. It was still pulling fine but that is bad bad bad!

 

[Parshal]

Re: Re: Tow RPM's

Originally posted by MattSt

With the old 01 pulling 13,000 #'s with the Edge chip on 5 any hill I tried to pull under 2000 RPM sent the EGT's over 1300. It was still pulling fine but that is bad bad bad!

So, even if a stock truck pulls fine in the lower rpm range I should downshift to keep the rpm's up to avoid high egt's?

 

[CATCRACKER]

come on guys you know the rules no hugging i mean lugging!:-laf

 

[Parshal]

Originally posted by CATCRACKER

come on guys you know the rules no lugging!:-laf

Wait a minute, I didn't say it was lugging in the lower ranges. I'm asking that if it is pulling fine, with no lugging, in a lower rpm range should I be worried about egt in a stock truck?

 

[MattSt]

Originally posted by Parshal

Wait a minute, I didn't say it was lugging in the lower ranges. I'm asking that if it is pulling fine, with no lugging, in a lower rpm range should I be worried about egt in a stock truck?

The question you have to ask yourself is: Do I know what lugging the motor is?



I can feel it, and since I watch the boost and EGT gauges like a hawk I can "SEE" when lugging the motor. Low boost+lots of fuel=lugging=high EGT's.



EDIT: With a stock truck your not dumping in as much fuel so you won't be getting the high EGT's that a guy with a chip will at low boost levels. I'm getting gauges in a few weeks and will be towing after that. My empty gooseneck weighs about what your load does. I will do some testing for ya and report back with the results.



I can't tell you at what point your lugging the motor. With this new engine, total GVW unknown etc. Someone with more experience will have to chime in here. Sorry!



But I can tell you staying above 1800-2000 rpm when pulling will keep you in the safe zone since you don't have gauges.

 

[CATCRACKER]

I know what you said, i was just kidding. have a good weekend.

 

[jimnance]

I don't feel like I'm lugging the engine while towing my fiver as long as I'm 1500 RPM or above on the flats, and 1800 RPMS or above on the hills.