What's a safe RPM range?

[Hutchew]

I'de love to go that high w/ the gear ratios, unfortunately, 3. 54 is the highest common ration for Dana 60/70. That would have been my first choice. As I have been told, Dodge did have a 3. 07 ratio in some first gen/ 3 speed torqueflite trucks, but those gears are not available anymore over the counter. BUMMER!!!!

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1985 Dodge W350 CrewCab Shortbed, soon to be Cummins powered. Still gathering ideas... ... have one?
James Hutchens
Albuquerque, NM

 

[BV]

If your lucky the 1st gens would hit 2600 the 2nd gens around 2800-3000 and the 3rd's (24v) 3400. This doesn't mean you couldn't tweak the 12v's to run a little higher. Personally I wouldn't want to run at the red line all day long and the 92 12v I have loved it between 1500 and 1800 - the 99 24v starts pulling real good around 1600 and drops off about 2600.

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'99, 2500, QC, blah, blah & blah

 

[Hutchew]

That's what I was afraid of... ... back to the drawing board I guess. Anyone know of an Allison w/overdrive that will fit? Don't forget I gotta transfer case in the way! #ad


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1985 Dodge W350 CrewCab Shortbed, soon to be Cummins powered. Still gathering ideas... ... have one?
James Hutchens
Albuquerque, NM

 

[Hutchew]

Hello all... I am trying to come up with a few ideas for a cummins transplant. I hear that the second gen motors are easier to make power with than the earlier models, and that they also safely rev higher than the earlier models. I am kicking around the idea of an Allison MT643 Trans, but final drive is 1:1, and I don't think there will be room for an overdrive unit, what with the transfer case and all. So..... I figure running @35" rubber and 3. 54 gears, my RPM's will be @2800 at 80 MPH. Can this motor handle that kind of speed? Anyone see anything I am missing here, or will it work? Bash me now if you have any reasons to think it won't, I'de rather take a whipping here than in my bank account. #ad

OOps... . forgot to ask this... . even if the motor can handle these RPM's, will it still be in the powerband at 2500-3000 rpm, or does that depend more on the way you set up the rest of the motor (injectors, fuel pump, exhaust, etc... ) thanks guys...

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1985 Dodge W350 CrewCab Shortbed, soon to be Cummins powered. Still gathering ideas... ... have one?
James Hutchens
Albuquerque, NM

[This message has been edited by Hutchew (edited 05-08-2001). ]

 

[Dieselnerd]

Best powerband is about 1700 to 2200. The 24 valve motor has so much electronics you would have to really get all the computer stuff to transplant it. That would be a pretty big job. These motors are governed so any speed you can run them is "safe" but efficiency is another matter. If you can't get an overdrive and don't expect to tow big loads, you would be better with a rear axle about a 3:01 ratio.

[This message has been edited by Dieselnerd (edited 05-08-2001). ]