safe rpm range?
- Thread starter broncobuyer
- Start date
broncobuyer
Registered User
i dont tow 83mph but i had the truck going that fast to see what it was governed at, i checked the door tag and axle code is c5 which is 4.10 gears that doesnt really explain why its revving so high, if i went to a 285/75/16 tire would it help much?
Kevin 007
Full-floater
When im empty and just commuting: which I have been using my idi for a lot lately...I try to keep my revs as low as possible at highway speeds. 2000rpm tops. Sure, with a t-19 and 3.54's, I have to stay under 55mph but thats fine by me. when people pass me I just look over at them and grin....and people dont know what to think
When im towing I keep revs as high as it takes to keep the heavy smoke and egt's at bay. But im working it then and don't care about mileage. But for just commuting, its slow going for me...I even but some slightly taller tires on it (32's) to keep the revs down another 50 rpm or so.
I have actually never run an idi over 2700rpm, my old 90 with an E40d and 400,000miles on it has, never been over 2300!!! And with my wifes powerstroke, it hauls her horses or whatever around easy and never needs to be wound right up to make a hill.
When im towing I keep revs as high as it takes to keep the heavy smoke and egt's at bay. But im working it then and don't care about mileage. But for just commuting, its slow going for me...I even but some slightly taller tires on it (32's) to keep the revs down another 50 rpm or so.
I have actually never run an idi over 2700rpm, my old 90 with an E40d and 400,000miles on it has, never been over 2300!!! And with my wifes powerstroke, it hauls her horses or whatever around easy and never needs to be wound right up to make a hill.
SparkandFire
We're drinking beer
It seems the IDI actually likes rpm...
You're more likely to cause trouble from lugging the engine too low than running against the governor. High rpm's equal more airflow through the engine, more volume from the oil pump, more volume from the water pump (generally speaking), more volume through the radiator from the fan... etc...
This is the reasoning behind why diesels run much larger radiators. Because so much of the work they do is low in the rpm range, there is alot of heat generated that does not get dissipated quickly enough. So with more coolant volume, you have a larger thermal mass that takes longer to heat up and cool down.
I've noticed from towing the fifth wheel that my egt's and engine temp do not climb as quickly if I opt to downshift sooner rather than later when pulling a grade.
You're more likely to cause trouble from lugging the engine too low than running against the governor. High rpm's equal more airflow through the engine, more volume from the oil pump, more volume from the water pump (generally speaking), more volume through the radiator from the fan... etc...
This is the reasoning behind why diesels run much larger radiators. Because so much of the work they do is low in the rpm range, there is alot of heat generated that does not get dissipated quickly enough. So with more coolant volume, you have a larger thermal mass that takes longer to heat up and cool down.
I've noticed from towing the fifth wheel that my egt's and engine temp do not climb as quickly if I opt to downshift sooner rather than later when pulling a grade.
Kevin 007
Full-floater
10-4. I have never had an issue with EGT's providing that the revs are high enough. Even if im heavy on the throttle. Not only on my idi's, but on big rigs
you have to downshift when you are pulling a hill? I didn't know you have to do that?
SparkandFire
We're drinking beer
you have to downshift when you are pulling a hill? I didn't know you have to do that?
Come on man! All's I need to do is squeeze $1500 out of the bank without the wife knowing it and that hypermax intercooler is mine!
I'm getting there! Man. I'm getting there!
plywood
Recovered N/A
Maybe your tach is off. I have the same height tires with zf5 and I would say at 65 I am at about 2400, which is close to the gear calculators. I had 35s and rpms were better but for towing my fifth wheel at just over 60 and about 2300 rpm, it's purrrrrfect.
Matrix37495
The Amish Wolfman
Bronco, can you have a friend pace you or use a GPS to verify your speed? Something sounds off.
As far as the governor thing, i run our diesel tractors against the gov for 10-12 hours straight.... That like working up there...
As far as the governor thing, i run our diesel tractors against the gov for 10-12 hours straight....
That like working up there...
Come on man! All's I need to do is squeeze $1500 out of the bank without the wife knowing it and that hypermax intercooler is mine!
I'm getting there! Man. I'm getting there!
just to clairify...you have to downshift when you are pulling a hill? I didn't know you have to do that?
I'm giving s-n-f/nutless a bad time.
the hill we're talking about will make you drop three gears on a naturally aspirated ZF truck. it's CA17 both north and south. it goes from sea level to 2000ft(iirc) and back down to sea level in 20 mi.
i was "showing off" to him a few nights ago with the '92 and ran the hill in 5th with no bog. the only other time he rode in the truck was when we had a U-haul hooked to it's ass with his MBZ 300d as the payload. I drive much more conservatively when running a load, but the truck still acted like there was nothing hanging off it's butt.
