Sorry this is so gassy, but it's got lots of info. Keep in mind, I live in a tree hugger state

History

I used to have the 5.9's mastered, My 04 would get 23 to 24 highway consistantly. But then I did a stupid thing and went for a 6.7.

For the last 3 years I have been misguided by the "Kids" on another forum and spent way too much money on this truck. That and there wasn't a whole heck of allot of things available for the 6.7 for years either. So I pioneered the disconnecting of the EGR, and blocking the tube with a freeze plug. Then came along the Bully Dog which was junk in retrospect to the H & S XRT and Black Maxx. I'm all for simple operation.

I've had several different Cold Air Filters, DPF delete systems, Simms, Dimms, Trims, and several tuners. I had clocked up to 23 a few times. If I can do 23 I can get better. The XRT to the Black Maxx has been the choice for the last couple of years.

Changes

This year I decided to do a Shibby Grid heater delete and install the in line heater. Truck ran soooo much better, but my MPG went into the dumper. 18 to 19! It was time to start following my years of experience and instincts.

Doing some research, and with the assistance from Shibby Engineering, we figured out the MAP and the MAF sensors were not getting the correct readings, I already had the Shibby Stage 1 air horn. The S & B intake would occasionally throw a code so there was a clue there. I took the S & B out, replaced it with the complete stock intake. MPG creaped up about .5 MPG, performance was about the same. The next step was to replace the Stage 1 with a Stage 2 intake horn. WOW! Without highway, I got 350 miles out of 1/2 a tank. The performance jumped.

2 last things remained. Since I have a stealth exhaust, I have been running hollow for a couple of years, I maintained the stock muffler. Suspecting the muffler being a bottleneck, I found a turbo muffler for $139.00. This made a hugh difference. I am impressed.

The last mod was opening up the intake. There are several stock intake mods to the bottom, but I'm not for sucking in more dirt, snow and whatever from the ground. I chose omething much simpler. I put a piece of dryer vent in the front and vented it to right behind the grill.

As all this went on, my EGT's gradually started dropping. This meant the Sensors were reading more accurately. The smoke from the XRT went way down, and frankly, my trans aint liken it. LOL

So here is my formula
*Stock intake modified for more inlet air
*Stock turbo
*BD intercooler
*Boost Tube
*Stage 2 air horn
*Grid heater delete
*turbo muffler

The last thing left is to change the turbo compressor wheel to a higher volume 8 blade. The whole trick here was to maximize the volume of air and not the pressure. Lower pressure, less fueling. More volume allows the combustion to be more complete and allows the burn in the cylinder to continue all the way through the ignition stroke. More complete burning, more volume.

Hope this guides you in the right direction

 

Polaraco,

I am a newbie to the site and the 6.7 cummins. Any pics you can share?

 

This gives me some ideas and we need to chat ..... LOL!


Can you do these mods without the BlackMaxx?




-Kris

 

I am a little surprised at the muffler finding. I put my arm clear into the stock one and could see its straight through with no baffles.

The Shibby problem I noted from another member I met that used it on his stock equipped truck and had other issues with it like cooling fan cycling and mileage losses.

Increasing the volume of air through the engine does have to do with pressure. Unless you drop intake air temperature significantly (like the BD IC) then the volume of air can't increase without pressure increase. A change in cam shaft or VGT control setting will help to increase that flow some with less exhaust back pressure during these conditions that you want optimal mileage. Just increasing the compressor size on the turbo without any other changes will change the map of the turbo and probably increase manifold pressure for less exhaust drive pressure.

This may be the increased flow you are after as when the engine manifold pressure reaches its setpoint for cruising (say 4 psi) It opens the VGT to slow down the turbo. This in turn would give you that increased flow you were after on the exhaust side for the same intake manifold pressure.

 

I was surprised at the muffler too. I would have thought it would have been a minimal with it being a pass through. . . But the Jeans Gauge says otherwise. That's why it was the last thing I did. I never suspected.

You can increase volume without pressure. If you think about it, the more you open up the system and the flow. The compressor needs to compensate.

 

You need to turn off the regens. It also turns off a couple of the noise injections they are doing. It will also clear the trouble lights on the dash, which can be annoying.

XRT is fine too. But the Black Maxx, as an example, set on 175 HP while cruising, also enhances the fuel economy. But you are definitely going to want to throttle the Maxx back when off the highway

 

Special Post for Newbies.

WELCOME

This is the most recent Pic I have. The rest is moot

 

I would agree to the point that there are only so many areas that can be increased to allow more flow and less pressure drop. Once you have reduced the pressure drop in the system with the IC, and intake horn/manifold, the rest is up to the dynamics of the engine (IE. Head flow and valve timing). The losses through the intake would be low in comparison.

I can see where these changes have made the ECM more precise in its fuel management and allowing better control of the air/fuel mixture. Conversely how the Shibby skewed the ECM to error on the other side of the economy curve.

 

I still think that if one could enhance how the mass air flow sensor can 'catch' more air, the engine will respond accordingly and you may find that the mpg and throttle will improve.

hint hint, wink wink.

 

The original Shibby Stage 1 was not designed to handle the additional flow. Shibby found the EGR ports we causing turbulance taking away pressure away from the MAP. The MAP readings must have changed when I did the grid heater delete. But it certainly didn't run as good as it does now. So it was causing the engine to fuel.

The same condition was happening in the Intake as well.

 

What I found out was the aftermarket CAF's are not tuned to the higher flows like the stock intake. The mod I did above is moot at low speeds. Since I did it, I've only driven 8 miles locally. But I did the same mod to my S & B intake and it lower my intake temps. Did it flow better? Who knows. Look at where the MAF is on the stock intake and where it is on the aftermarkets. My smoke went down immediately. But the Lie-o-meter seems to just hang there on 20.5 locally

 

did the bd intercooler change any of your sensor reading? Asking cause I'm about to get a 6.7.