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
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
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.
Elite Diesel Engineering