Why is the cummins soo slow

[Csanders1992]

We have to remember, they no longer design these for us, there are designed to satisfy the EPA and other government regulators.



Simplest way to view torque and horsepower is this, torque is the amount of twisting action applied, horsepower is how fast the torque can be applied.

To add to the horsepower/torque thing. Think of horsepower as you would with watts on a light bulb. The higher the wattage the brighter the bulb. Watts is the same measurement as horsepower, 765 watts = 1hp. I think the 765 is right, I didn't look it up. Torque is a force whereas horsepower is energy.


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[drittal]

Torque management.

 

[theviking]

They certainly don't seem slow with a good tune. But yea, torque management sucks on these things.

 

[SouthTexan]

1. As other saids, torque management is the major reason for the truck feeling held back in first and second. All the current diesels do not give you 100% power in the lower gears and if they did then you would not able able to hook up off the line. You would also be replacing tires and transmissions every year if you completely took it out. While the Cummins with torque management still gives you more torque and power than the gasoline equivalent at the same rpm, it still feels held back. Once you hit third then you are getting 100% which is why it feels like the truck just pulls you when you hit third.

2. You have to know how to drive a Cummins(or any diesel). It is not like a high revving V8 that you just floor it and go. You have to roll into the throttle gradually ramping it up utilizing the strength of the diesel which is its massive amount of low end torque.. If you are going about 40 on the access road and floor it get on the highway on-ramp, then the truck will drop down to second gear where you are not getting full power(torque management) and you will be going nowhere fast. Not only that, but due to the low max engine speed of only 3,000 rpm in the Cummins, you will not be in second gear that long wasting even more time shifting to third. If you learn how to roll into the pedal to accelerate while remaining in third then you will be hitting 75 mph before you know it. Trust me, the Cummins has enough torque to pull you quickly onto the highway in third gear. You just got to learn how to utilize all that low rpm torque and how to make the truck accelerate without downshifting.

Same goes for when you want to accelerate at highway speeds. If you want to go from 65 mph to 75 mph, you don't floor it . With a Cummins, you just barely roll into the pedal keeping it in 6th or 5th and the torque will pull you to 75 mph quicker than flooring it would. Spend a few weeks behind the wheel of one and you will know what I am talking about.

3. As BossHogg said, you don't have to delete any emissions equipment to get the power or better fuel economy with the current engines with SCR. You can add a lot of power that you can feel while keeping the emissions equipment on. Just prepare to beef up the transmission to accommodate for the newly found power.

 

[theviking]

Welcome back, thought maybe you got stuck in the mud along with your truck!

 

[Hemi450hp]

I miss my 07 5.9 Cummins. With just an intake, 5" exhaust, and Crazy Larry tune, it ran 13.9 in the 1/4 and made about 450hp/900tq to the wheels. I then put a simple 64mm turbo and 90hp nozzles on it, and went 12.8 @ 108MPH (On the 37's). Made 606hp/1200tq with that setup. Even on 37s, I could light those tires up from a 20-30 roll. That thing was a monster on the highway and surprised a lot of fast cars.

 

[w6pea]

1. As other saids, torque management is the major reason for the truck feeling held back in first and second. All the current diesels do not give you 100% power in the lower gears and if they did then you would not able able to hook up off the line. You would also be replacing tires and transmissions every year if you completely took it out. While the Cummins with torque management still gives you more torque and power than the gasoline equivalent at the same rpm, it still feels held back. Once you hit third then you are getting 100% which is why it feels like the truck just pulls you when you hit third.

2. You have to know how to drive a Cummins(or any diesel). It is not like a high revving V8 that you just floor it and go. You have to roll into the throttle gradually ramping it up utilizing the strength of the diesel which is its massive amount of low end torque.. If you are going about 40 on the access road and floor it get on the highway on-ramp, then the truck will drop down to second gear where you are not getting full power(torque management) and you will be going nowhere fast. Not only that, but due to the low max engine speed of only 3,000 rpm in the Cummins, you will not be in second gear that long wasting even more time shifting to third. If you learn how to roll into the pedal to accelerate while remaining in third then you will be hitting 75 mph before you know it. Trust me, the Cummins has enough torque to pull you quickly onto the highway in third gear. You just got to learn how to utilize all that low rpm torque and how to make the truck accelerate without downshifting.

Same goes for when you want to accelerate at highway speeds. If you want to go from 65 mph to 75 mph, you don't floor it . With a Cummins, you just barely roll into the pedal keeping it in 6th or 5th and the torque will pull you to 75 mph quicker than flooring it would. Spend a few weeks behind the wheel of one and you will know what I am talking about.

3. As BossHogg said, you don't have to delete any emissions equipment to get the power or better fuel economy with the current engines with SCR. You can add a lot of power that you can feel while keeping the emissions equipment on. Just prepare to beef up the transmission to accommodate for the newly found power.

Very well put.

 

[BossHogg]

Very well put.

Yup, SouthTexan nailed it. His explanation solidified my experiences pulling last year. I didn't realize torque management played in so heavily. Looking forward to pull again.

 

[jstacey8]

I've driven quite a few diesels so I know about rolling into the pedal but I was quite let down after driving a duramax. I'm not saying they are a slouch but there not what everyone praises them to be atleast not from my exsperinces

 

[Zeak]

I've driven quite a few diesels so I know about rolling into the pedal but I was quite let down after driving a duramax. I'm not saying they are a slouch but there not what everyone praises them to be atleast not from my exsperinces

It is just as others have been saying they are built for one thing and one thing only, hooking up a trailer and hitting the highway. Dodge and Cummins are not interested in competing with Ford and Chevy in who has the fastest HD diesel pickup. For those who tow with them they are what everyone praises them to be and for those who have money to burn they can be modded for power. I had an 11 Cummins that I deleted and tuned but I don't think I ever had it over 3/4 throttle. It just ran better that way. If was to go buy a new Cummins truck now I would leave it the way it is. They have come along way from the 07.5-12 in terms of the emissions but the TQ management is a downer from what I have read, however the trucks work as designed. Inline sixes take a little getting used to over a V8 or V6 as well. The 4.0 inline 6 in the Jeeps are a good example of that.

 

[69GWC]

well my buddys dad has a efi live tuned 5 max and it will set you back in your seat quite a bit and melt tires in 3 gear with little to no struggle and ive always heard about the power and to be honest my 5.7 with 37's will make a 6.7 look like a 4.7 as far as get up and go. i know the cummins is built to haul but id still like it to throw you back in your seat and a good burn out once a year (we have a huge car show for autism each year and end with a burn out contest it kind of like our proving grounds lol). i just didnt know if deletes and a tune would wake it up or if i would need to throw some twins on it to get it to go

Ha, wish we lived closer, I could show you a 6.7 that would make your 5.7 seem slow.

 

[lukedukem]

I miss my 07 5.9 Cummins. With just an intake, 5" exhaust, and Crazy Larry tune, it ran 13.9 in the 1/4 and made about 450hp/900tq to the wheels. I then put a simple 64mm turbo and 90hp nozzles on it, and went 12.8 @ 108MPH (On the 37's). Made 606hp/1200tq with that setup. Even on 37s, I could light those tires up from a 20-30 roll. That thing was a monster on the highway and surprised a lot of fast cars.

i have an 06 for sale on here...

Luke

 

[SouthTexan]

Welcome back, thought maybe you got stuck in the mud along with your truck!

Been busier than a one legged man in an ass kicking contest these past few weeks with a new acquisition at work and had on of our biggest cook-offs last weekend.


Had to call a wrecker service to pull the truck out. Luckily for me nothing broke pulling it out and the wrecker was free since he is a very good vendor of mine at work.

 

[SouthTexan]

I've driven quite a few diesels so I know about rolling into the pedal but I was quite let down after driving a duramax. I'm not saying they are a slouch but there not what everyone praises them to be atleast not from my exsperinces

You are not comparing your friends tuned Duramax to a stock Cummins are you? Add fuel and tune the timing in any diesel and it will be leaps and bounds better than its stock equivalent.

Although the big three diesel manufacturers don't make their diesels for drag racing on mind, if you are looking only to go fast then I would say go get yourself a rev happy (for a diesel) short stroke Duramax. Just hope that its CP4 pump doesn't grenade like a lot of others have had within 100k miles causing a 10k repair bill.

 

[Csanders1992]

I'm not to fond on the reliability of any newer diesel. If I were to buy one it would be a 06-07 5.9 or 06-07 lbz


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[THETANK]

I beg to differ on the new diesels being slow, in a race with an aircraft carrier (nukes included) I will take the RAM each and every time. HUH!

 

[tjfdesmo]

I've driven quite a few diesels so I know about rolling into the pedal but I was quite let down after driving a duramax. I'm not saying they are a slouch but there not what everyone praises them to be atleast not from my exsperinces

If you want a play diesel then you'll be happier with a Duradud or a Powerjoke. If you want a sure-enough industrial duty, tall-deck, long-arm, work engine, then the Cummins stands alone. Period.

 

[theviking]

Been busier than a one legged man in an ass kicking contest these past few weeks with a new acquisition at work and had on of our biggest cook-offs last weekend.


Had to call a wrecker service to pull the truck out. Luckily for me nothing broke pulling it out and the wrecker was free since he is a very good vendor of mine at work.

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I hope you had a friend with a good power washer

On another note, do you think they limit power on the gas HD models as well in the lower gears? I'm sure it wouldn't be nearly as intrusive but wondering if they have a similar strategy at play to save the trans.

 

[jstacey8]

I'm comparing stock duramax to stock cummins I drive both back to back and the duramax went noticeably better stock. I'm sure with 2500 between efi live and deletes a cummins would go good but from what I can see there not the fast truck like everyone around Maine and nh says they are

 

[jstacey8]

Ha, wish we lived closer, I could show you a 6.7 that would make your 5.7 seem slow.

My buddy just got his cummins yesterday (2016 cummins quad cab) and we lined them up stock vs stock and it was not even anywheres close to being a close race and I'm on 37's