Hi Guys-<br><br>What is the lowest RPM I can nail the throttle at? What about EXTREMELY light throttle at low RPMs like when I'm just cruising through my subdivision? <br><br>To me, lugging is like pornography: I can't always describe it, but I know it when I see it. What are the guidlines here? <br><br>What are the optimal shift points I should use on the 6spd for general driving?<br><br>Thanks!<br><br>100 Proof<br>

 

You can't tie it to an rpm. Any rpm at which full throttle doesn't produce acceleration is technically 'lugging' the engine. At high rpm, lugging is tolerated fairly well. At low rpm, it isn't. Probably an egt is the best way to tell.

 

Agreed. If you apply go-pedal pressure, and you don't accelerate, you are (typically) lugging the motor. RPM is a tough rule of thumb for this one, as it is dependant on many factors. Myself, I shift around 18-2000 under normal driving, and will cruise around city streets and neighborhoods anywhere right down to idle. Usually, for say 25MPH zones, I will stuff it into 3rd. 35-45 zones, 4th. Up above that, it's 5th or 6th. Those obviously change depending on traffic conditions and what type of driver is following me ... Also strongly agree with the EGT being the best judge on this one.

 

OK, somebody correct me, but the torque for these engines is right around 1500 RPMs and up. Empty you can cruise around all you want at 30-50 at 1500 and no lugging at all. This is a smaller version of the big-boy semi engines and will have very similar characteristics based upon stroke length to piston diameter and compression ratio/ turbo characteristics etc. There are a lot of big rigs that pull from 1300RPMs and are limited to about 2500 RPMs max, some are significantly lower yet. <br>If you are weighed down really heavy, stomping at 1500 rs could put you in the really bad zone but 1800 seems to be pretty safe from what I've found. Mine also pulls well at 1500 loaded if I keep off the throttle, ie no stomping it without a preliminary downshift, still no lugging. I was used to driving the ford V-8 diesel and this cummins sure does not have the noticeable lug characteristics that I had with the ford, these engines are super load-monsters! That new 6.0 ford is a definite acceleration monster though, one blew my doors off the other day. No way I could ever have kept up with him, even if I wasn't rowing 6 gears. Load him up with 10,000 pounds of trailer and he couldn't have even tried to keep up though.<br>JMHO Monte