Ok, I have a 2006 Dodge Ram. 3.7 V-6, Manual Transmission. When Im running 75 on the highway, Im running 2700 rpms, and at 80 Im running 3000 or more. To me this seems a little high. My last truck was an 08 Dodge 4.7 V-8, automatic and it ran under that at both speeds. Anyone know what it might be, and how i can fix it?

 

you are not using a V8.

your rpm sounds about right. I have a 04 with V6 and manual transmission.

the math is easy. to double your speed you need 4 times the horsepower...

so going from 30 to 60 ...4 times the power.. you only have 200 horsepower.... and its a truck.. not a bullet nose car.

 

What? It's a manual trans, to double the speed, you gotta double your rpm. Power has nothing to do with cruising speed.

Only way to lower your rpm at cruising speeds is to shift to another higher gear if possible, or get larger tires and correct for an inaccurate speedometer. Or change rear end to higher gearing (lower numerical ratio).

The autos cruise at lower speeds due to different gearing and the torque convertor.

 

Easy enough to work it out. What is your rear gear and what is your final tranny gear? The cheapest way to reduce the rpm is larger tires, but to significantly reduce the rpm, you'll need a REALLY large tire, probably larger than would fit. My truck with 3.55s, final drive of .67 and 285s turns 1,980 at 80.

 

Power has EVERYTHING to do with cruising speed. Torque gets it moving, power keeps it moving. To double the rpm against the wind, road friction, etc. will easily require 4X the power.

 

Yes but at cruise you only use a small amount of the available horsepower, even the v6 trucks have more than enough power to go 100 mph. Lack of power has nothing to do with how many rpms a vehicle with a manual transmission turns at a given speed. It's 100% due to gearing and tire size.

 

but he is complaining of the RPMS at 80,.....

my truck will not accelerate at 80 in 5th gear with a head wind. .. it will in 4th gear..
I have 3.55 rear gears and 17 in tires...

a v6 ram is limited to 3,500 pounds of trailer...
a 4.7L v8 ram can pull 6,000 pounds of trailer....

its all about gearing.. and in todays WORLD.. gas mileage...
the v6 ram is geared for gas mileage for its weight.

 

Man, those are some tiny tires! Since 17" is the smallest wheel that can be used, your tires must be 190/05x17 or so.

 

TSRSP245/70R17 BSW All Season Tires
TZHP Michelin Brand Tires
WF1S17" Steel Spare Wheel
WF2P 17X8.0 Steel Chrome Clad Wheels
WLYC All Steel Wheels
WMJP Center Hub

Stock from factory... you are mistaken....

 

Your tires are NOT 17", they're 30.5". Wheels and tires are different things, you know.