# Cummins power at high rpm??



## dillyolboy

What mods do you Cummins guys do to your trucks to make them pull good past 2k rpms? The stock ones seem to kind of peter out around that point. Does the broader rpm range help a lot with driveablity and plowing? I have heard of 100+ mph quarter miles and the stock Cummins doesn't really go that fast. Just wondering how it's done.
Thanks 
David


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## wyldman

On the older trucks,with mechanical injection pumps,then changing the governor settings will raise the maximum RPM before the governor cuts back fuel.This is done by changing the governor springs\and or adjustment.

You can run the Cummins safely over 3000 RPM,a lot of other Cummins B series run 3400 continuously in stationary generators.

I have a 3000 RPM governor spring kit setup in my truck.Along with a custom fuel plate,injectors,and some minor air,turbo and exhaust mods,it pulls hard to 3000 under load and tops out at 3400 or snce you start making some power with the stock governor,it hits it pretty quick.Now I can use that power.They have a 4000 RPM kit too,but it's overkill IMHO as the engine doesn't benefit much at that RPM.If the truck is stock,you can adjust the stock governor springs a bit to help it run harder and get a few more RPM's.

The stock soggy factory Dodge convertor doesn't help as it stalls almost at the governed speed,so the truck will seem pretty dogish.A tighter convertor,a few more horses (and the torque that comes with it),and a few more RPM's make for a pretty mean machine.I haven't dynoed mine,as we don't have any dynos here capable of holding the torque numbers the Cummins makes,but guys with similar setups to mine are around 350 and up HP.It makes a 9000 LB truck feel like a rocket ship,if you can keep the tires on the ground.

The higher RPM's are of no use for plowing as you want to keep the engine down around it's torque peak.As for driveability,it keeps the power on much smoother,and acceleartion is much better.When mine was stock,it would hang sometimes between shifts,as the engine was hard on the governor,but he trans wouldn't shift up to the next gear due to the fact my foot was hard on the throttle.When it finally did shift,and the fuel came back,away it went.Not very pleasurable to drive.Now it just plants you in the seat and goes hard through the gears.

The newer 24V's have a much higher governed speed,around 3400 I think,so there isn't much need to go any higher.


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## John DiMartino

In addition to what wyldman said, the aftermarket governor spring kits are the best investment a 12V cummins owner can make. http://www.piersdiesel.com/ They have a 3000RPM kit,and a 4000RPM kit. Sled pullers regularly run the cummins to 4500RPM,it is an extremely rugged engine,for automotive applications they can be set to defuel gently at 3600,this is ideal,and gives a wide powerband,and no loss of low end. (that is the 4000RPM GSK) The 24V doesnt need any help at all,they defuel at 3200,and will rev to 3500.mine runs like a scalded dog,fighting for traction into 3rd gear on dry roads. One thing common to most high mileage 12V's is cable stretch and linkage play.This will result in the truck not getting full throttle even though your foot is planted to the floor.Have a helper floor the truck while you are looking at the pump,after he floors it push the lever .I bet there is another 1/4" of travel. That is why they peter out at just over 2000. My 96 Ram has that problem when i bought it. I ended up just taking a zip tie and using it as a spacer on the throttle cable to get the last bit of throttle.They should pull to 2500,then gently defuel, hi idle should be 3000RPM.


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## snowflake

john
got a dumb question for you 
is it a big job to put the govenor spring kit in i got a 91 12 valve
its gutless and has poor fuel mileage. was just wonderin if that kits would help it.
thanks
gary

  ones for you


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## John DiMartino

Gary,the GSK is for the 94-98 12V's with P7100 pump.You can turn up your pump to get more power. http://tstproducts.com/89-93_power_trial.htm You should also be able to get good power up to 2800 with your truck. A set of injectors will also help with power.Those 89-93's are capable of 250+ at the wheels pretty easy. If you have a late 91 (intercooled) the injectors ,a few turns of the pump screw and turbine housing will make a huge difference.Your turbo housing is huge,giving you lots of turbo lag. The 94-newer trucks have a 12CM turbo housing,you have a 18.5 or 21 cm, so you spool up much slower,the 16cm housing can be had for under 150 bucks.It will sharpen the throtle response,and make the turck much snappier.Go here this is your best source of info,everything you'd ever need to know about the early cummins dodge trucks is here http://www.turbodieselregister.com/forums/forumdisplay.php?forumid=11


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## snowflake

thanks john really appreciate it willl check it out. hopefully can wake this thing up some.


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## hyperpack

*3400 rpm generator*

You can run the Cummins safely over 3000 RPM,a lot of other Cummins B series run 3400 continuously in stationary generators.
Wyldman Are these direct drive AC generators, If so what country uses 56.66 cycle power? 
Hyperpack


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## wyldman

They are stationary AC generators.I'm not sure if they are direct drive or not.I know they have 50 and 60 Hz models,not sure about 56.66 Hz ?


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## orenlasko

*my truck.*

pulls like a son of a [email protected]#$$ all the up past 3200 rpm in third gear. i swear i have an H.O under the hood of my standard output. cant wait to bomb with an edge box...


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## dillyolboy

Thanks You guys know tons of stuff. 4000 rpms with a I6 diesel is amazing. Thanks for the links. I was told a Cummins ran out of steam at 2k=slow but now I really want one of these trucks. Just to prove them wrong of course  Thanks again


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## Evan528

My new dodge 3500 with the Cummins pulls like a son of a bi** also!! I got the standard output because that was all that was available when they did the search for one. I expected a deisel to pull better then my f-250 with the v-8 but I am blown away. The gasser didnt even want to go up a hill with the trailer loaded and this cummins dosnt even notice the weight its pulling. I was told by a friend that the HO only comes with the manual transmision... Is this true? I cant amagine what that Ho must pull like!!!


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## John DiMartino

Evan,you bought a Dodge!  . . Now you have a real pulling truck. You think it pulls good now,wait til you put some fuel to it,you have no idea how detuned these engines are as delivered.


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## Evan528

Heres a picture of the new baby taken last week the day I picked it up. Since then ive added a diamond plate tool box and stainless steel nerf bar running boards. I think im done with fords for a while


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## John DiMartino

Nice truck!! Those 14" brakes are killer arent they? Now that you've got a Cummins,a gas motor simply will not do. Good luck with the new truck. What a nice way to start a new season with a shiny new truck!


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## landscaper3

www.bluechipdiesel.com


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## Nozzleman

Evan528, There was late availabilty on the High Output with the auto tranny but they are now on the street. I have a 2500 HO/ auto tranny and all I can say is WOW, This truck has some serious socks.


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