Overhead MPG and straight pipe

[JohncJordanIII]

I used the search button and headed to cummins forum and I think it's called Bombers forum but all the answers seem to pertain to modified trucks and can't seem to get answers for 03/04 bone stockers with autos, 4.10s. so my question for bone stock, long beds quadcabs 4.10s stock tires is the overhead kinda accurate? I don't care about MPGs as I have a 35 mpg beater daily driver. The fact this truck gets 15-16 on town with an auto impresses me according to overhead and it tells me about 18-19 on highway at 1900-2000 rpm at 65ish.

Now my real concern is straight pipe. I hear lost of low end torque and cab noise/drone and then other claims but again it's trucks that arnt stock or those that make the switch to larger exhuast so it's hard to really get good answer. So again for us stockers that retain the 3.5" and not go bigger what's the deal? Thanks again y'all

Btw love this truck. Did full grease service and sent fluids for analysis and everything looks great, this thing sips fuel compare to 3/4-1 ton gas rigs that are 4 doors long beds

 

[cerberusiam]

The OH is overly optimistic most times, as much as 2-5 mpg. Ig want to know tank to tank and different conditions then hand calc is the way to go.

Stiraight pipe is just to noisy and I have hearing loss. The sound is also too snarly, a good resonator will tone that down and sounds much better IMO.

 

[JohncJordanIII]

Yea that's what I figured like I said just was curious and I actually found a YouTube of one finally and as much as I love diesels I couldn't stand to listen to that while towing. Looks like nice resonator is in site. Thanks again cerberusiam you been awesome since me being new here

 

[slowmover]

The overhead is usually off by a percentage.

The correction factor for mine is 3/4-mpg at 60-mph.
This is based on solid averages over tens of thousands of miles (records).

Truck needs to be stock for relevance. I use mine to check as condition changes, mainly wind direction and force. Then terrain and temperature (assuming highway miles as trips under 45-miles are too short).

Straight pipe just makes noise with no help to mpg. A low-backpressure muffler is the thing. They’re not necessarily louder, it’s that the tone is different.

Exhaust system performance is going to depend on how the truck is used. A heavily-loaded non-aerodynamic trailer is going to have the truck in a higher rpm range than a solo truck either loaded or empty.

A 4.0” system from a reputable manufacturer (entire assembly) may not pay itself back or give seat-check performance changes, but it beats hell out of the trash truck coming down the street. Which is how EVERY loud Cummins sounds. Just add rattling garbage cans being tossed.

I simply changed muffler on mine to ROKKTECH. The 3.5” piping isn’t challenged by my loads.

Empty pickup mpg hasn’t meaning. It’s how well you and it adapt to loads that matters.

An empty pickup means should have bought a car.

.

 

[Zoomschwortz]

When I bought my used 2006, the overheads said something around 13 1/2 mpg. On my way home from buying the truck, refilling the tank, resetting the trip meter and driving empty, the mpg gradually started working it’s way up and after an hour or so of driving finally worked it’s way into the 18’s.

I am starting to think that it really wasn’t designed so much for tank to tank mpg, but more for an average over thousands of miles.

I’m curious about how far off it would be after 10 or 20 tanks of fuel and comparing the hand calculated average for 20 tanks to the overhead average.

 

[JohncJordanIII]

Slowmover I agree. I do have a beater car just for that reason. If my truck can't at least drive 10-15 miles one-way it doesn't move. when she does move I make sure she gets excercise properly (mpgs low but engine never ever lugs except idle). I know big rigs from owner operators I work on they sometimes like straight pipe full and when by time I shift to 10th gear I'm already done with the drone. And the overhead was exactly why I asked. I don't care about mileage. I do as a reference like you mention when situation changes either mechanically or base on wind/load now granted I don't want mileage of big V8 or v10 gas but not looking for car mpg either. I grew up with diesels burning 900 gallons a hour on ships to 7-9 mpg on big rigs so anything over 12 I'm happy lol

 

[ranger 393]

I don't like the straight pipe either. I installed an FTE resonator and there is no drone and still has a deep sound without being obnoxious.

 

[JohncJordanIII]

I don't like the straight pipe either. I installed an FTE resonator and there is no drone and still has a deep sound without being obnoxious.

Thanks for the tip! I just can't get into looks and noise that draws attention to me like that. I also enjoy talking with my wife and my three kids too and at the same time I'd rather hear my engine and turbo then exhaust.