Normal driving shifting RPMs?
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Cargo Master
Joined: Oct 2008
Posts: 3,330
Likes: 13
From: Eaton, CO
Normal driving shifting RPMs?
This is probably a dumb question, but I want to make sure I'm not beating on my truck here. 1986 F250 6.9L IDI 4WD T-19 4.10's with 183,000 miles on it... What RPM's should I be shifting at? I've been shifting at 2,000 RPM and it seems like the gears are pretty far apart. I tried a 2,500 RPM shift and that seemed better, but I don't want to wail on the motor. Then again, going 55mph I'm taching 2450 RPM.
I've gotten used to watching pissed off folks behind me freak out until they can pass me when accelerating away from a stop sign or red light.
I've gotten used to watching pissed off folks behind me freak out until they can pass me when accelerating away from a stop sign or red light.
Lead Driver
Joined: Dec 2006
Posts: 6,496
Likes: 94
From: So. Jersey
First let me say dyoung14, we know, 4400rpm, right.
But seriously what your shifting at now isn't going to hurt anything. There's people that rode the govener for hours on end with no problems, these motors can take it. What ever rpm youtranny shifts the smoothest and gives you the best torque just go with it. If fuel milage is your thing the lower the rpm's the better.
But seriously what your shifting at now isn't going to hurt anything. There's people that rode the govener for hours on end with no problems, these motors can take it. What ever rpm youtranny shifts the smoothest and gives you the best torque just go with it. If fuel milage is your thing the lower the rpm's the better.
Posting Guru
Joined: Apr 2008
Posts: 1,614
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actually i wasnt going to say anything about 4400rpm
but beilieve it or not i drive normal everynow and then, and when i do i get around 20mpg
but beilieve it or not i drive normal everynow and then, and when i do i get around 20mpg
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Fleet Owner
Joined: Jul 2006
Posts: 20,357
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From: Mi'kma'ki
oh wow.so 2500 rpm is still a very economical rpm for these.impressive!
man,i wish i had gotten into diesels sooner.
man,i wish i had gotten into diesels sooner.
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Post Fiend
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From: Faibanks Ak.
If you have 4.10 gears running 55 even though you are turning 2500 rpm's it doesn't take much horsepower to maintain 55. your fuel mileage has a direct relation to the amount of horsepower you use.
The wind drag is substantially less at 55 than it is at 65 or 70, so with 4.10 gears IF you will keep it at 55 it is possible to get better fuel mileage than running 65 or 70 with 3.55's
If this is makes any sense. lol Mine with 4.10 gears back in the national 55 speed limit days would average 20 all day every day, but you have to remember we have had 2 fuel downgrades since then. I don't here 20 much anymore.
The wind drag is substantially less at 55 than it is at 65 or 70, so with 4.10 gears IF you will keep it at 55 it is possible to get better fuel mileage than running 65 or 70 with 3.55's
If this is makes any sense. lol Mine with 4.10 gears back in the national 55 speed limit days would average 20 all day every day, but you have to remember we have had 2 fuel downgrades since then. I don't here 20 much anymore.
Senior User
Joined: Jul 2006
Posts: 302
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I usually shift my 5sp (4.10's) around 15-1700 rpms. The motor doesnt lug and the truck seems to float down the road.
When I had the 7.3 in the truck, I could shift a lot sooner than that. It seemed to be a little more gutsy down low then my 6.9 is. Oh well, the 6.9 will pull a 10k trailer at 65-70 without trying, the worn out 7.3 stuggled to do 55.
When I had the 7.3 in the truck, I could shift a lot sooner than that. It seemed to be a little more gutsy down low then my 6.9 is. Oh well, the 6.9 will pull a 10k trailer at 65-70 without trying, the worn out 7.3 stuggled to do 55.
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Cargo Master
Joined: Oct 2008
Posts: 3,330
Likes: 13
From: Eaton, CO
I haven't pulled anything with my truck yet. I do need to go out to my folks place and grab a ton of grass hay. I suppose I could just toss it in the bed of the IDI, but the spring bushings are beat.
I go around 450 miles and put in ~25 gallons of fuel. So 18mpg average.
I go around 450 miles and put in ~25 gallons of fuel. So 18mpg average.
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Cargo Master
Joined: Oct 2008
Posts: 3,330
Likes: 13
From: Eaton, CO
I've got the CC LB 6-speed manual 4x4 F350 w/ 3.73's PSD, so it's a big friggin' truck. Plus with the farrier setup in the bed, it's heavy. I'm averaging 16mpg. You have to keep the PSD under 2000 RPM or else fuel economy will decrease rapidly. I typically shift my PSD between 2000-2300 RPM. At 65mph in 6th gear, it's taching 1950 RPM.
That's why I've been shifting my IDI at 2000 RPM and feel bad taching it at 2450 RPM while driving 55mph. I haven't been rough of the IDI, not even one WOT acceleration.
That's why I've been shifting my IDI at 2000 RPM and feel bad taching it at 2450 RPM while driving 55mph. I haven't been rough of the IDI, not even one WOT acceleration.