what RPM to shift?

[Mingoglia]

I'm going to stay out of this debate but I'll just jump in real quick and point out that everyone needs to compare apples to apples... some folks in this thread have 3. 55 gears, some have 4. 10, some have 12v, some have 24v, and the last poster had a 3rd gen truck (and 3. 73 gears)... all these variables affect when you need to shift... I for one will run my '01 3500 right up to the redline (while towing at GCWR) when I know it will give me an additional 2MPH (over being a gear higher)... . even though I know my MPG is probably dropping by 5MPG.

 

[johncameron]

normal easy driving, I like to shift around 2000. When my blood starts to boil, 3000 seems to sound nice. By the way, 112MPH@3200 is all she said. Oo.

 

[NNogueira]

1400 to 1600 rpm shifts are ...

1400 to 1600 shifts are recommended for the cummins n14 and new ISB's in the class 8 trucks with a displacement of 12 to 16 litres, I can't see cummins recommending that for the little 5. 9 we have in our trucks.



I have owned a n14 for 4 years and yes 1400 to 1600 shifts is where I ran it to get the best mileage and power out of it. I'm new to the new 04 Ram I just purchased but I don't think I'll ever shift it at anything much below 2000, with more likely shifting at 2500 or above when hauling a load.

 

[nickleinonen]

now that i have my cummins and have gotten use to my own driving habbits, i find myself shifting so that the engine drops to about 1000 rpm then start pulling. now all my driving has been empty and this engine has not complained at all about being driven like that. 6th gear i will pull from 900-1000 rpm on flat with no real load on the engine, and if there is some hills, i'll drop to 5th to turn some 1400-1500rpm. driving around empty, i see no need to ever see past 2000rpm, unless you are having fun... doing that, my engine has been to about 3500rpm before [wot in 2 or 3 and shifting at 3000 will rev to about 3500 for an instant. . ]

 

[johncameron]

900-1000 seems a little low to me. Mine will pull slowly at those RPM's but it feels like it is lugging. Maby the new HPCR engine is that much stronger down there, but I can't say cause I've only tried a new auto slushbox! 1200 seems to be the lowest they should be run at empty. Pulling don't let them run under 1600. Just my . 02$ Try that with a 6. 0 powerjoke!!!!!!

 

[nickleinonen]

in stop/go traffic, i am not really driving it hard or trying to accelarate quickly. in 6th, yeah it is a little low in go, but in 5th at the same rpm's it's not bad. i don't see it as lugging since there is no load [an empty truck with nothing but a shell on the bed and no trailer is no real load]



i've never had a really high rev'ing gas engine so i don't know how to drive at high rpm. my old 6. 5TD tahoe slushbox drove around almost always under 2000 rpm and a little higher like 25-2600 when accelarating a little harder. that 03 gasser 1500 i drove most of the time under 2000 rpm and it was just fine with that [not much torque in that 4. 7v8 in 4th turning 1200rpm] and now with my 04 cummins, there is good torque down low in the powerband and it makes enough torque at 1000 rpm to move along nicely. the slower you turn, the less fuel you burn, the better the fuel economy [as long as the egt/boost is low too... ]

 

[johncameron]

Hey Nick, I've got a 20k drive to work and back. I've found that reving 1650 in 5th gets better MPG than 1250rpm in 6th. Doesn't really make sense that higher revs gets better economy but hey, inline-6 lots mo power than v-8s. Can't wait to try the new "600". Oo.

 

[nickleinonen]

i've got about 25 km drive to work. and i get to leave to work in like 10 minutes. gotta love working afternoon shift

 

[MCummings]

I can pee farther than you?

Originally posted by johncameron

By the way, 112MPH@3200 is all she said. Oo.

On the street ~3,500RPM at 143MPH is when I went ahead and let the Corvette win, later that day, 4,100 and ~161MPH is when I thought the dyno saw enough.



Merrick

 

[CumminsDZL]

For the guy that said his truck had a little over 100,000 miles, so he hated to rev it to hard. i wouldnt worry too much, my truck is just shy of 150,000 and when towing heavy (anywhere from 10-25K) i rev the crap out of it. usually 2600 in 1st, 2800 in second, sometimes 3 grand in 3rd so the revs wont fall so bad, and then i get to cruzing speed in 4th, and then go to 5th. it may sound mean, but thats what it has done since day one.



and just for the heck of it, i ran it out to 3400 in forth the other day, just to see how fast it would go in 4th. with a 5 speed, 3. 55s, and 305/70/16s it was showing an indicated 90, actually running probably 95-97. i think these trucks run well at high rpms, even stock. My truck is very strong from 75-105 and thats turned up pretty good. Dont be scared to rev it, itll be fine.

 

[CumminsDZL]

Re: I can pee farther than you?

Originally posted by MCummings

On the street ~3,500RPM at 143MPH is when I went ahead and let the Corvette win, later that day, 4,100 and ~161MPH is when I thought the dyno saw enough.



Merrick

Unreal man, thats just awesome!

 

[carson6]

115mph@3500rpm......

on my 315 tire's but the mirror slamming closed is what made me back off... . with no silly stick in my hand!(left foot relaxing on the floorboard)Oo.

 

[Neibe]

When I bought my truck new in 97 I got the 4:10 gears and when running down the highway I was running at about 2500 at 70 mph. I was concerned with this since redline is 3000. So I asked the guys at Cummins Michigan in Grand Rapids and they said," That motor is DESIGNED to run all day long at governed speed so you won't hirt a thing. " Of course they said you won't get very good fuel mileage.