GM 6.0 liter performance upgrades 2002 GMC Sierra 2500HD

My 2002 GMC Sierra 2500HD 6.0 Vortec

This is my work truck. It's a 2002 GMC Sierra 2500HD with a 6.0 Vortec V8 motor
that comes stock with about 300 horsepower and 360 ft.lbs of torque. Mine has
much more power than that now thanks to some simple modifications I have done.
Here is how I got a ton of power out of my 6.0.

The stock 6.0 is a very powerful V8 motor, but like everything, there is always room for improvement.
I was happy with the power of the truck when unloaded, however when I would pull my Dodge or
Jeep, there would be instances when I wanted more low end power so that I was not constantly
downshifting and screaming along at 5000 RPM's. My truck actually had a K&N drop in air filter
and a Hypertech Power Programmer 3 already installed from day one, so I know it was running
better than a stock 6.0. Like I said, there is always room for improvement. I got with T Byrne
Motorsports and ordered a few items that would definitely help me with the power I needed.
I purchased a BBK 80mm throttle body, Granatelli mass air flow sensor, and Volant cold air intake.
Each item was about $300 and I would say that the throttle body was the best upgrade for the
money, but all three work together very well to draw more air into the motor and give noticeable
performance gains. The BBK throttle body also gets rid of the throttle sticking problem that
these trucks have, when you try to push on the accelerator and it won't move.

The first thing I did was pop the hood and let the truck cool down. You do not want to be
working on this right after you have driven home from work. When you remove the throttle
body, you have to undo a couple of small coolant hoses and the coolant needs to be
cooled off, as well as relieved of any pressure. So just let the truck sit for a while and
wait for it to get nice and cool before you work on it.

Stock 6.0 Vortec

When you go out to work on the truck, the first thing you do is remove the small
bolt that holds the plastic engine cover in place. Tilt the cover up from the front
and then you simply slide it forward to release it from the fingers that hold it in the
back. This exposes the weird looking Vortec motor.

Engine cover removed - now you can see why they put one on there!

To work on the throttle body, you need to remove the air tunnel. Since I was putting
in a new air intake system, I just removed the box and all. The hole thing uses hose
clamps to secure each part, so you undo a few hose clamps and everything slides
out, leaving the air box. Pop the top off of the air box, pull the filter out, and then
you can see how the air box is held down. Just pull up on the air box and it will
come out.

Air box removed

After removing the air tunnel, you can see the stock throttle body. There are
three nuts that hold it in place, and you will also need to undo the TPS and
IAC motor wires, as well as the throttle and cruise control cables. On the
bottom of the throttle body, there are two small coolant hoses, you will also
have to undo them. Oh, and the PCV hose that is attached near the throttle
cable will need to come off.

Stock throttle body

Here is the clip that holds the cruise control cable onto the linkage. You will
need to remove this clip before the cruise control cable comes off. I had a
hard time with it so I thought I better mention it. I just used a little pick I have
and popped each side up, then used needle nose pliers to pull it up and
out of the cable. Then the cable comes right off.

C clip that holds cruise control cable onto throttle linkage

With all of that removed, the throttle body comes out. You then take a small
socket and remove the three bolts that held the throttle body in place. There
is a fitting on the end that will allow you to bite on the bolts and turn them
counter-clockwise. The BBK throttle body comes with new bolts. You also
need to wipe down the stock gasket on the intake and make sure it will seal.

Throttle body removed

Don't mind the bolts I just told you to remove, I just put this adapter on to see how
it would line up. This piece is about an inch thick and is the reason why you have
to extend your throttle cable plate.

BBK throttle body adapter plate

Here is the new throttle body. It's a very quality piece of work! This
throttle body will get rid of the throttle-sticking problem that the stock
units are so well known for. The spring on the linkage is much stiffer
so you have to get used to pushing down on the accelerator a little
more once you install this, but this thing is worth it's weight in gold.

New 80mm BBK throttle body

For comparison, the two units are exactly the same width, but you have to use
the adapter plate for the BBK unit and that is why it sticks out further, which
can be a problem when you put on a Volant air intake. More info on this later.

Stock throttle body VS. BBK throttle body

The new throttle body does not come with new sensors, so you either need to
go ahead and buy new TPS and IAC sensors and replace your old ones, or just
reuse the old ones. This is a perfect time to replace them if your engine has a
lot of miles on it or if your truck is idling very strange (IAC sensor faulty).

Stock sensors that must be removed from the old throttle body and put in the new one

Okay, so you put the throttle body on and now you have to hook up the throttle
cables. In order to do this, you must undo these three bolts, install a bar that
comes with the throttle body, and then reinstall the plate. What it does is just
move the stock plate up an inch. I was not happy with the replacement bar
because it only uses two of the bolt holes, instead of all three. It's like taking
a step back in quality and reliability. But, I had to use it, so I installed it.

These bolts hold the throttle cable plate in place

Here is the finished throttle body install. Make sure and plug in your PCV
hose, coolant hoses, and sensor wires.

80mm BBK throttle body installed on my 6.0

VOLANT COOL AIR INTAKE

After installing the throttle body, I went ahead and put the new Volant air intake on.
The Volant cold air intake is different from other air intakes in that it is a true cold
air design... it seals the filter from everything. The box installs in the same location
as the stock box, so it sucks air from the fender as well as from a hole that is located
on the bottom of the air box. The top is sealed so that it cannot suck any air from the
hot engine compartment. While the design is great, I wish Volant would spend a
little more time making sure they are sending out a quality product. They left out
a couple of bolts and washers from my kit, and two of the four mounting holes for
the new air box were not even close to lining up with my stock holes. This is not
the first time I have had this problem but everything else goes together really well.

In order to put the new Volant air box in, you must remove the tray that the original
air box mounted to. I had to take out 5 bolts and it came right out. Then you just
bolt the new box down using the same holes. I could only get two holes to line up.

Stock air box tray removed

Then on the other end, you need to install the new Volant air tube to the throttle
body. This tube was designed to be used with a stock throttle body, one that
does not use a one inch thick adapter plate like the BBK throttle body does.
So what does that mean? The Volant air tube does not fit unless you trim the
fan shroud quite a bit. Actually, there is less than 1/4" of clearance between
the fan and the tube, which is a little scary, but everything is fine so far.

Here is how I trimmed the fan shroud, I used my Dremel tool

After test fitting the tube and getting everything worked out, I could install
the tube to the throttle body using a hose clamp. Be sure to reuse your
stock rubber gasket/grommet to seal this connection very well. Then you
hook up the other end of the tube to a supplied piece of plastic tubing using
two more hose clamps. The end of that plastic tube goes onto the mass
air flow sensor, and then the filter mounts to the sensor basically. The
plastic tube allows for movement in the tube and system and is a vital
part of this install.

The tube and air box installed

Here you can see the Granatelli mass air flow sensor installed to the side of
the Volant box. This is one nice thing about the Volant air box, it has three
holes so you actually bolt the mass air flow sensor into place, not just clamp
it on each end. Then you put a filter adapter inside of the air box and that is
what the MAF sensor bolts onto, using three supplied bolts. The filter then
simply slides into the box and clamps onto this adapter.

Better shot of the Granatelli MAF sensor and air box connection

After you put the filter in, you put this cool cover on the box and screw it down
using the five supplied screws. This looks like it is made of mesh but it's more
like a carbon fiber material. It does not allow any air to come through at all.

Air box cover installed

Finished system installed

So far, this system has produced a ton of extra power for my truck... more
than I thought I would get actually. I am anxious to pull a trailer now and
see how it does. Just driving around, I can light up my tires on blacktop,
which I could not do before. The Volant air intake sounds like a vacuum
or forced induction system, which I was not expecting, but it certainly
draws in a ton of air. The Granatelli MAF sensor is actually a special one
made for cold air induction setups only, so be sure you get that one if you
order the Volant system. Then the BBK throttle body takes the air that
passes through both of the other parts and pushes it into the intake with
much more volume than the stock unit could ever handle. All of this works
together extremely well, except for the problem of trimming the fan shroud.
I might install dual electric fans just to free up that space and keep from
tearing up the air tube in the future.