Horsepower is only created within the cylinders of the engine. From there, everything takes away from it. So, working to make horsepower as efficiently as possible is a huge part of the equation of laying down big numbers. Another part of that equation is how much horsepower does it take to get the power down to the ground?
By that we mean, how much horsepower it takes to spin the torque converter, the transmission, driveshaft, pinion, differential gears, axle shafts and even the wheels. Don't think it takes much? The next time you have the chance, try spinning a transmission in gear, or if your engine is out, put the truck in first and see if you can turn the wheels simply by twisting the input shaft of the transmission. On average, it takes about 20 percent of the engine's horsepower to move everything.
OEMs rate the horsepower of the engine at the flywheel, not at the rear tires, which is why when you dyno your truck, you lay down 260-280 or whatever it is and your vehicle is rated for 350 hp. The difference is your drivetrain loss.
In addition to the above-named components, components like alternators, power steering pumps, water pumps, engine cooling fans, air conditioning compressor and exhaust systems all take power away from the engine. While there are ways of reducing the power needed to work each of these, they are usually reserved for performance-oriented applications. For example, removing a water pump will yield around an 8 horsepower increase. But the life expectancy of an electric water pump is much less than a belt-driven pump. That's why the factory chooses to use a belt-driven pump.
One popular option though is to increase the size of the exhaust and open it up to flow better (i.e. less restrictive). With the 6.4 and many of the newer engines, there is emissions equipment that should not be removed. As a result, many companies offer DPF (Diesel Particulate Filter) back exhaust systems. These remain street legal and can free up a couple extra horses. For those who are planning on using their vehicle off-road, whether it is at the job site only or track, and/or anywhere off road, Elite Diesel Engineering has another option.
The company has recently released its new 4-inch aluminized straight pipe kit for the 6.4l Power Strokes. This kit is from the down pipe back and replaces the catalytic converter, DPF and muffler with straight pipe. The system is for off-road use only, but not for those who want a hood stack or something for hard core competition use.
After hearing about the system, we wanted to test it out. So we called Elite Diesel Engineering and informed them that we are building an off road only, chase truck and wanted to do a little testing of the system. We signed the release form and had it sent over. To make a kit like this work, custom tuning has to be used to let the computer know what we removed. So we also have a custom tuned SCT programmer done by Tadd at Elite Diesel Engineering on the way.
As soon as we told the owner of the truck about the new system being on the way, he got a little too excited. He started yanking the factory exhaust off. (See, we normally shoot an install article in one day. That's the removal and installation of the new system.) For this install, he pulled the vehicle on the lift and removed the muffler. On the 6.4s the muffler is welded to the pipe that is bent to go up and over the axle. So, he cut the muffler off to make removal easier. Later that same day, he called us to let us know the factory system was off and he was ready to install the new system. We had to let him know the new system was being shipped from Pueblo West, CO, and it wouldn't be arriving for another week or so. Not wanting to be without his truck, he decided to put a turn out pipe on the factory pipe where the muffler was and wash the underside of the truck. Consequently, that is why these pictures start out muddy but then they miraculously become squeaky clean.
The exhaust is bolted/clamped together in multiple pieces. As such, our owner started at the rear of the exhaust. From the muffler back is one piece. There are two hangers and one clamp that holds them on.
The top hanger was sprayed with Royal Purple's Max Film to help make removal easier. Then with a hammer, we gently persuaded the muffler to slide off of the factory pipe.
There are a couple of different ways to get the factory muffler off. Drop the spare tire and move the driveshaft out of the way or in our owner's case, cut the muffler off and slide the rest of the assembly over the axle and out.
After spending half of a day under the truck spraying and cleaning the mud off, the transfer case skid plate was removed.
There are four sensors that plug in the catalytic converter and DPF that were removed.
With all of the sensors loose, they were unplugged and set off to the side.
Then the DPF was removed and set to the side. If this vehicle ever plans on driving on the road, this will need to be reinstalled.
With only the catalytic converter left, the two bolts that hold the pipe on were removed.
To make removal easier, we removed the three nuts that hold the hanger on.
Next the catalytic converter was removed.
With everything off, we took the hanger mount off the catalytic converter. We could have done this in the vehicle, but it was easier to remove the entire mount instead.
With the hanger installed on the new mount, the first pipe was set into place.
Next, the first sensor was reinstalled and plugged back in.
With the first pipe in place, the next long pipe with three bungs was slid over the first pipe.
Next, the short pipe was slid into place along with the next mid length section.
The hangers that are part of the bent tube were slid into the rubber mount.
We sprayed the rear hanger mount with Max Film and slid the final hanger into it. Note the mount was loosened to make assembly easier.
All clamps were placed at the joints and hand tightened. Then the remaining sensors were re-installed.
With all of the sensors screwed in they were then plugged back into the factory harness.
With all of the sensors connected and the exhaust system connected, the final eye was given to make sure everything fit perfectly before we tightened it down.
Once everything was tightened down, the chrome 6-inch tip was installed.
The final part of the reassembly was to put the transfer case skid plate back on.
Elite Diesel Engineering