Why is the cummins soo slow

jstacey8 · Mar 13, 2016

Tried out a new cummins yesterday and was quite let down with the performance. I know it can pretty much haul a house but as far as merging onto the highway it's like I'm in my old ford ranger. Do deletes and a tune really wake these up or do they need more exstesive work to wake the sleeping giant :naughty:

charonblk07 · Mar 13, 2016

It's a night and day difference with deletes and a tune. The emissions really kill the power on the diesels if you're looking for 'fun power' but the engines will still pull a metric crap tonne of weight with the emissions intact.

jstacey8 · Mar 13, 2016

I'm just looking to have some good all around power Im not looking to have something that will boil the tires off at 50 but it it could atleast set you back in your seat some id be happy

kg93 · Mar 13, 2016

lol if i bought a cummins(wish i could afford one) I would have it at a shop getting stacks and deleted in the first week....yes im the guy who would have stacks, love that **** lol

spoon059 · Mar 13, 2016

Its slow because it has lower HP than either hemi and the diesel is designed to spend most of its time in the lower RPM range, not up high where the HP is made. I didn't buy a Cummins to race, I bought it to pull a trailer.

That being said, when you are merging on to a highway and stomp on the pedal and the turbo's start to spool it will push you back in your seat and get up and go... as good as 7000 lbs can get up and go.

If you want a race car, look at the Hellcat.

MN-Ram · Mar 13, 2016

My friend has a 2015 Outdoorsman with the Cummins, and he just got the new PCM flash. He said the truck has more power than ever before. But you would think the 2016 Rams would already have that update.

I got a similar PCM flash on my 6.4 Hemi, and I gained a noticeable amount of acceleration when I drove it out of the dealership.

tjfdesmo · Mar 13, 2016

A lot of it also has to do with torque management. The Cummins is a tall-deck, long-armed work motor. It's not a high winder by design. Tow heavy for a while, and you'll quickly learn to appreciate what it is all about. Otherwise, you're sorta barking up the wrong tree IMHO.

Underarock13 · Mar 13, 2016

Because you need to quit eating Big Macs before test driving vehicles... Lol j/k

TWILLIAMS9 · Mar 13, 2016

I originally wanted a cummins but the price kind of made me uneasy as I didn't have a NEED for one and did not plan on having a trailer for awhile. Test drove one and thought the same, maybe it is because I am unfamiliar with them and have never towed with one. I drove the 6.4 and thought wow this is powerful. Now that I have my trailer I want to get the diesel. The 6.4 can yank it all day, I just want that ease of pulling the diesel and exhaust brake give you while towing.

w6pea · Mar 13, 2016

TWILLIAMS9 said:
I originally wanted a cummins but the price kind of made me uneasy as I didn't have a NEED for one and did not plan on having a trailer for awhile. Test drove one and thought the same, maybe it is because I am unfamiliar with them and have never towed with one. I drove the 6.4 and thought wow this is powerful. Now that I have my trailer I want to get the diesel. The 6.4 can yank it all day, I just want that ease of pulling the diesel and exhaust brake give you while towing.

I have to agree with this statement. There is an Apples to Oranges difference between the 6.4L Hemi and the 6.7L Cummins Turbo Diesel !
I wanted a 4x4 but it ended up being more of a want than a need.

You want a "Drag Racer buy the "Hemi". You want Pulling Power and Torque buy the "Cummins Turbo Diesel" .
There is a learning curve to both.
Good Luck.
If you are starting to look at new trucks you will probably end up with Analysis Paralysis !

SilverStreak88 · Mar 13, 2016

kg93 said:
getting stacks

I hope you're joking

Sent From The Automotive Proof S5

gofishn · Mar 13, 2016

charonblk07 said:
It's a night and day difference with deletes and a tune. The emissions really kill the power on the diesels if you're looking for 'fun power' but the engines will still pull a metric crap tonne of weight with the emissions intact.

What he said.
Guy , at work, worked the exhaust system on his 3500 Cummins and flipped over both the performance increase and the fuel mileage.

You don't need to make it a rolling Coal Burner to get much better performance out of them

jstacey8 · Mar 13, 2016

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

RoadDog66 · Mar 13, 2016

MN-Ram said:
My friend has a 2015 Outdoorsman with the Cummins, and he just got the new PCM flash. He said the truck has more power than ever before. But you would think the 2016 Rams would already have that update.

I got a similar PCM flash on my 6.4 Hemi, and I gained a noticeable amount of acceleration when I drove it out of the dealership.

What PCM flash? Did you ask for them to do this or did they just do it when you took it in for service, like a recall notice?

And for a 7100 lb monster this thing will get up and go. Only problem is the crap gear ratios of the 66rfe. Gotta keep the foot on the floor to make sure the 1st to 2nd upshift stays above 3000 rpms on the shift...otherwise it's like a mid 90's turbo spooling effect as it winds up the rpm range then finally a burst of thrust.

MN-Ram · Mar 13, 2016

The PCM flash was: 181906FF Module, Software 2 Flash for PCM

That was for my 6.4L. I do not know what the Cummins flash is. My dealership did the flash when I went in for my last oil change 2 weeks ago. It was a tech bulletin I think.

RoadDog66 · Mar 13, 2016

MN-Ram said:
The PCM flash was: 181906FF Module, Software 2 Flash for PCM

That was for my 6.4L. I do not know what the Cummins flash is. My dealership did the flash when I went in for my last oil change 2 weeks ago. It was a tech bulletin I think.

Awesome thanks. I won't be going for service for a few months yet (only 9K miles), but would like to squeeze all the potential I can out of my 6.4 while its still stock/under warranty...then the real fun begins.

mtofell · Mar 13, 2016

This is interesting to me as I went from an 06 Duramax (pre-DPF emission stuff) to my 6.4 Hemi. My Dmax would smoke the 6.4 off the line in a heartbeat. There may be a half second lag with the diesel spooling but once it did lookout. I'm thinking there really must be something to the new emission stuff killing the quick power of these newer diesels.

BossHogg · Mar 14, 2016

jstacey8 said:
Tried out a new cummins yesterday and was quite let down with the performance. I know it can pretty much haul a house but as far as merging onto the highway it's like I'm in my old ford ranger. Do deletes and a tune really wake these up or do they need more exstesive work to wake the sleeping giant

A new truck has to go through a bit of learning, pedal response, transmission behaviors, etc. I believe the owners' manual states around 500 miles of driving before the learn process is done.

Pulling a 15K pound fifth wheel RV, I don't have any issue making highway speed for an entry ramp merge.

Deletes do not make any difference on MPGs or performance anymore. Several tuners make emission equipped tunes but really, at 370HP, 800 ft. lbs, for the middle of the power line, just how much do you need. A few years ago, guys were spending thousands to get to today's factory performance levels and were delighted. I see you are 19, I get it.

For under 2K you can get the tunes but you will need to drop 3 or 4 thousand on transmission updates since they are the new weak point. Visit the Cummins forum, a lot of information on tunes.

avolnek · Mar 14, 2016

spoon059 said:
Its slow because it has lower HP than either hemi and the diesel is designed to spend most of its time in the lower RPM range, not up high where the HP is made. I didn't buy a Cummins to race, I bought it to pull a trailer.

Horse power really has only a little to do with it really...

horse power is merely a calculation of torque over a period of time. 550 ft pounds of torque over a period of one second. So while horse power is important it's really only part of the situation... The cummins as mentioned is a long arm machine creating tons of torque but doesn't rev nearly as fast as the v-8 competitors.

What really affects the off the line performance on the newer trucks is the programming and the throttle lag. A tuner will take a lot of that out.... Also, assuming you drove a 3/4 ton cummins you were most likely sitting on 3.42 gears which are slow off the line with out a doubt... they put the 3.42's in to help reduce the rpm range while cruising which boosts the fuel economy while empty...

BossHogg · Mar 14, 2016

avolnek said:
they put the 3.42's in to help reduce the rpm range while cruising which boosts the fuel economy while empty...

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.

Why is the cummins soo slow

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