best rpm range
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Junior User
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From: north branch michigan
best rpm range
HI guys I have a 1997 f 350 with the power stroke diesel it has 35 inch tires and 355 gearing my question is what the rpm the engine should be at in high gear? right now its running 1400 rpm at 63 MPH and 1800 at 77mph thinking may be going to 3 73 gears?
Posting Guru
Joined: Jun 2003
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From: southwest michigan
What type of roads do you drive on?
How fast do you usually drive?
Do you tow trailers at all? Regularly?
What transmission do you have?
Is there a reason that you feel your current gearing is not performing the way you like?
My opinion... If there is a problem in performance that you can feel that can be addressed by a gear swap, you will be looking at a bigger change than 3.55 to 3.73.
How fast do you usually drive?
Do you tow trailers at all? Regularly?
What transmission do you have?
Is there a reason that you feel your current gearing is not performing the way you like?
My opinion... If there is a problem in performance that you can feel that can be addressed by a gear swap, you will be looking at a bigger change than 3.55 to 3.73.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Are those GPS verified speeds? Unless it's been recalibrated the speedo is way off with those 35s so you would actually be moving even faster than that. And what is high gear in this truck, does it have an OD trans? Taken at face value those engine speeds should produce really good fuel milage but it's not optimal for heavy hauling, for that you would want it to be turning about 2000rpm at cruising speed.
Posting Guru
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From: VA
For a 7.3 Powerstroke you want it to be at about 1900 RPMs at cruising speed. That seems to be the best spot because it's right before the turbo really comes in. Good cruising mpg and you just gotta step in it a little to really make it go. Not sure what gear that would be, but probably 4.10
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Junior User
Joined: Nov 2011
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From: north branch michigan
rpm range
yes the truck has over drive and yes I check the speed with my garmin the spedo is about 3 mph fast the reason I am wondering about my low rpms is because the truck seems to need to down shift alot and I was thinking that may be it was using more fuel because of the rpms so low that may be the motor was actually bogging at that range I appreciate all the input from every one
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Posting Guru
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From: VA
Have you tracked fuel mileage?
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Posting Guru
Joined: Jun 2003
Posts: 2,314
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From: southwest michigan
yes the truck has over drive and yes I check the speed with my garmin the spedo is about 3 mph fast the reason I am wondering about my low rpms is because the truck seems to need to down shift alot and I was thinking that may be it was using more fuel because of the rpms so low that may be the motor was actually bogging at that range I appreciate all the input from every one
I've never owned a powerstroke, but I have driven them for work for many years and I would have thought that those revs would have been OK for highway speeds if the truck was unloaded.
M trucks runs almost the same RPM's at a given speed as your truck and it's borderline bearable at highway speeds unloaded (1450@63 & 1750@77). If I put any kind of load on that truck at all, it falls on it's face.
You still haven't answered these questions:
How fast do you usually drive?
Do you tow trailers at all? Regularly?
What transmission do you have?
I'm leaning towards a 4.10 set, like the other members have mentioned.
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