View Full Version : What rpms do you run while towing?
12-21-2007, 04:37 AM
I tow my fourwheeler back and forth to MS from AR about twice a month, around 300 miles mostly highway. It's a 5x8 trailer and the wheeler weighs about 800 pounds. I have 4.56's in the truck and a 3.0 auto with a programmer and exhaust. I usually run in overdrive but sometimes I'll switch it off on the slower roads and the rpms will run around 3200. I will switch it back to overdrive on the interstate where I usually run 70-75mph it'll shift down on slight hills but for the most part stays steady as long as the rpms stay above 2500. Will it hurt anything running it out of overdrive on the highway at steady high rpms or should I just keep the od on and let it shift in and out when it wants.
12-21-2007, 04:20 PM
just let it do its thing. the 3.0 is an engine that likes to run at higher rpms. the 1200lbs of the trailer and the quad wont bother it.
12-21-2007, 11:02 PM
Don't tow in Over Drive. It's hell on your A%&$ tranny. The 3.0 is a high rever. Run it at 3,200 it loves it and will actually improve mileage, even while not towing. Give it a try.....pretend the truck doesn't have an O.D. Button. An engine gets it's best mpg and work less harder a little above it's peak tourqe. That sweet spot happens to be at 3,200. Oh, and you will not hurt anything to run it at this rpm.
12-21-2007, 11:10 PM
ranger44 said it all. your more likely to hurt the transmission than the engine by towing in OD...and you will likely see your best economy over 3k rpm.
12-21-2007, 11:30 PM
No, you won't get better mileage at 32k than at 23k. You won't ever get better mileage running your engine harder. Yes, it's harder on the engine running it not in O.D. Your only towing an ATV not another truck. You don't take it out of O.D. every time you bring a friend or 2 with you, why would you for an 700 lb. ATV? Your tranny will be just fine. If it's not shifting multiple time a minute, your tranny is doing exactly what it's designed to do.
That's just my opinion, I could be wrong ( but I'm not )
12-21-2007, 11:41 PM
No, you won't get better mileage at 32k than at 23k. You won't ever get better mileage running your engine harder.
at 32,000 RPM your motor would be dead.
hate to burst your bubble...but your wrong on mulitple points. higher rpm does not mean higher engine load. internal combustion engines will ALWAYS make their peak fuel economy near their peak torque RPM at the same given load (over 3k for the 3.0). i can go from a consistant 20 mpg to 24 just by running down the highway in 4th gear rather than overdrive (about 3000 RPM vs 2100).
and worrying about turning 3,000 rpm in a 3.0 is like worying about hurting a fish with water.
12-22-2007, 01:04 AM
It runs pretty high rpms with the 4.56s out of OD. I have 33's on it, its geared a little lower than stock I believe, I'm not a math wiz though. Had 3.73's stock. It may run closer to 4K at highway speeds with the OD off. I was just wanting to make sure it wasnt going to hurt anything running at that rpm for a couple hundred miles. Sounds like it will be alright if its high rever.
12-22-2007, 01:46 AM
if your turning 4k with the overdrive off, then you should be near 3k with it on...which is about where you want to be.
That's not enough weight to worry about anything. Leave it in OD. If it's an auto, only take it out of OD if it keeps down shifting by itself. That down-up shifting and converter clutch kicking in and out builds up heat.
With a manual and that light of a load I don't think you'll need to downshift much. If you need a bunch of throttle to keep it going, downshift. I usually keep my foot in the same position and use the tranny to adjust speed. Having a vacuum gauge would be better. You set a limit--like 5"--and when you need enough throttle to drop the vacuum below that point, downshift.
I would not drive down the road lightly loaded and spinning 3,200rpm in 4th. The overdrive is there because it provides the final gear needed it to meet the fuel economy requirements.
12-22-2007, 10:22 PM
Do you not get that is where the engine is getting better gas mileage??? At 3,200 rpm? It's not working harder, or using more gas....it's working easier, and using less gas. All engines are different. This may go against everything you've been told, but try this with a 3.0 and you'll understand. 4.0's, 2.9's, and 2.3's are different. They find their better economy at lower rpm's. All depends on the engine design. Most trucks do have there peal tourqe at lower rpm's. But the 3.0 is a sedan engine. A whole different breed. My dad tried this with his full size though(no O.D.) He gets 2mpg more. Once again running slightly above peak tourqe. Which is 3,200 for the 3.0. Leave it out of O.D. esp, when towing, your engine will work easier and you'll have better fuel economy. Take Wicked's word for it. Or just try it for yourself.
12-22-2007, 10:49 PM
I appreciate all the input, gives me a piece of mind knowing that it'll be alright running at higher rpms while towing.
Do you not get that is where the engine is getting better gas mileage???
Are you talking to me?
I disagree with everything everyone here is saying.
A pop quiz--it's multiple guess, you might get it right.
Why did every manufacturer put overdrive onto their trannies when the government mandated fuel economy requirements.
A) to **** with us
B) to confuse the USSR
C) it got better mileage
D) it didn't, it got worse mileage but they wanted to pay the massive per-vehicle penalties for each vehicle that exceeded the limits--God Bless the USA!
The problem with everyone's arguments is that the airflow is way different between full throttle at max torque rpm and gentle throttle at max torque. Those torque specs are obtained with the throttle wide open and the dynometer loading the engine down to the rpm given. If you give a 170ft# fuel economy test with a 2.9, yes, that's the rpm you need. But you only need 30hp to cruise at 70mph and that's maybe 75ft# produced by the engine.
The curves traced with fuel consumption per mph are not produced. But you cn bet your ass they didn't go to the expense to add a 4th gear to every tranny because it was fun. And the heavy-duty lines were the last to get it--and were the last to get fuel consumption requirements slapped on them.
12-26-2007, 10:29 PM
Wait a second, wait, I choose them all but C... Do I get some sort of prize.
I always tow with OD on in the F-250. The only time I will kick it out is if I forsee a hill I have been up before and already know the truck is going to downshift halfway up, or when I am towing more than 6K faster than 40mph.
The b2. I usually don't get on the freeway with anything big enough not to need OD.
12-26-2007, 10:43 PM
I choose E.
E) First C, then B, and finally A
12-26-2007, 11:38 PM
they put overdrive in vehicles because:
MANY engines produce peak power much lower than the 3.0 does
more gears means closer together gearing (better for getting a load moving)
engines are louder and rougher at 3,000 RPM than 2,000 RPM (manufacturers have noise requirements to meet, and people are more likely to buy a smoother vehicle over a rough one).
people just dont like winding their motors up that high. the average consumer would much rather keep their motor at a lower rpm.
your right that max torque and power ratings are taken at WOT...most people know this. thats why i say your maximum fuel economy will be NEAR your peak torque rpm.
we could go back and forth all day with this (i already did a while back over at RPS...what a bunch of obstinate individuals on that site)....but ive tried this several times in all 3 of my vehicles....and all 3 give the same results:
the truck goes from a consistant average of 20 to 24 by dropping 5th gear unloaded on the highway (tested for 10 tanks....1 tank with o/d, next tank without...and so on. this with 90% highway driving at 60MPH).
my escorts cruise at 2600 RPM in OD at 60MPH already, so the result is less obvious with them, but the blue one goes from about 32mpg to around 34...and the red one from 34 to 35....all 3 under the same circumstances (my commute to work).
12-27-2007, 02:56 PM
Are you talking to me?
Yes I was. Do you realize that the 4.0 and the 3.0 are two different engines? Both with different power bands, Right? So it's safe to assume that the 4.0's is lower than the 3.0's? Therefore a 4.0 would benefit from having overdrive more than a 3.0 would. Despite what you think, engines are not all the same, and each needs to be driven differently. When I drive 55-60, and leave my truck in 4th I get 24mpg. Now with over drive, it drops to 20mpg....Hmmmm. I still agree with Wicked. A 4.0 is a different beast, and the way you drive it may be correct, but it's not safe to assume that it's the way every engine should be driven.
Not to mention, pulling in O.D. is a strain on the transmission, and can damage the O.D. Gears. O.D. is gear division, while 4th is usually 1:1.
12-29-2007, 09:35 AM
Thanks for all the input fellows, sounds like I was doing the right thing running it at higher rpms. Tough little motor it is.
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