For those of you who want to upgrade your throttle body on your GA16DE powered
cars, there are a couple of options out there that you can do. You can have the
one on your bored out by a reputable machine shop (i.e. JG engine dynamics) or,
if you can get your hands on one, bolt on the throttle body from an SR20DE.
What's the difference in the two you ask? Well I'll tell you the advantages and
disadvantages in installing the two. The GA16DE's throttle body's anatomy
compared to the SR20DE throttle body is almost identical. The bolt patterns,
coolant hook-ups, and vacuum lines all match up the same. But the only
differences lie with the bore size, and the TPS configuration. With the 1.6
throttle body bored out to its maximum specifications, overall bore size will
still not be as large as the stock bore size of the 2.0 throttle body. Which
also leaves us to consider how much more potential there can be had with the 2.0
throttle body! If you can get your greasy hands on one of these throttle bodies,
I'll let you guys know of some of the obstacles that will be encountered on
making this modification work. Necessary parts: There was not much needed here.
You will need to purchase brand new throttle body gasket from the dealership. It
only cost me about $4.50 with the Se-r discount at Puente Hills Nissan. Without
the discount its about six bucks. You will also need to make sure that it is for
an Se-r! Otherwise the bore size of the 1.6 gasket will not match the bore size
of the throttle body. You will also need to get an aftermarket intake setup, if
you don’t already have one. The factory rubber intake tubing will not fit over
the throttle body. If you have only the filter with the MAF adapter plate,
you'll need to go out and get the mandrel bent intake pipe with the proper sized
couplers for the Se-r. You can also go out to Home Depot and make your own. If
you do that you'll need some 2" abs pvc, 4 hose clamps and 2 2" rubber
couplers. The Home Depot couplers will be a very tight fit on the TB, but it
will fit. You'll just need to stretch it over the mouth of the TB. I also went
out and bought a couple of brass fittings to tap into the side of the PVC for
the necessary vacuum hoses. These can be purchased at a Pep Boys autoparts store
for less than five bucks. Installation: Everything matched up perfectly, with a
few exceptions. There are two connections on the bottom of the TB for the
coolant hoses. You will have to slightly bend these so that they pint straight
down, otherwise they will be hitting against the manifold. I heated them up on
my gas kitchen stove, but if you have access to a butane torch then good for
you! Heat up the connections a little bit (NOT RED HOT!) , and use a shop hammer
to gently tap the tubing straight. You should be tapping the base of the body as
you are not trying to actually bend the tube, you just want it to rotate in its
base. The most challenging part of the throttle body mod will be with making the
1.6 TPS work on this unit. As I am still trying to figure out how to do this,
I'll tell you what I have encountered so far. On the 2.0, the TPS lever sits
towards the front of the throttle body, rotating clockwise from the seven
o'clock position to eleven o'clock. On the 1.6 the TPS lever rotates clockwise
from the one o'clock position to about five o'clock. The same goes with the
lever on the TB that moves the TPS switch. One thing I tried to do was flip the
1.6 TPS around and bolt it backwards, with the plug end facing the intake
manifold. The levers made contact with each other to make the system operable,
but I was questioning its inability to then be unable to be adjusted. This set
up caused the TPS lever to be out of spec with its position slightly opened up,
even though the throttle was completely closed. Installation on the car was
slightly difficult as the TPS also got in the way of a few vacuum hoses and
rested against the intake manifold. Not good if you begin to wonder if the heat
would cook the plug in connector on the TPS. After starting up my car, I could
immediately hear the difference in sound. It actually sounds a lot healthier
with all the extra air going in the engine. Engine response was incredibly
awesome as the RPM's just shoot to redline without any delay. The only bad part
was that the engine was idling way too high at about 2k. After taking a little
test drive around the block, the increased power was second to none, as I was
even able to get some 2nd gear peel out on my 16"s. Another bad part
though, after the initial run down the street, engine idle was now at 3-4k!! My
suspicions were of my poor, mis-calibrated TPS sensor. With the sensor mounted
backwards, adjustability was not going to be possible. That little fraction of
an inch that was needed to get the TPS sensor in the closed position caused the
high engine idle. What to do now? My next idea was to shave down and bend back
the lever on the TB so that it would let the TPS lever rest back a little more.
This also proved ineffective as engine idle stayed the same. The next idea I had
was to spot weld a matching lever on the one o'clock position of the lever.
Problem is I don’t have access to a gas welder at the moment so that idea was
chucked out the door. Last but not least, my idea was to completley disassemble
and reassemble the throttle body's internals and make it so that its TPS lever
was pointing towards the back. I managed to get the linkage assembly removed so
far. Also another small detail I'd like to point out. On back of the throttle
body, in the area where the TPS mounts on, there is a small tower that it rests
on. You only need the two towers that the TPS bolts onto, so the third one that
rests in the 3 o'clock position will have to be leveled off with a hacksaw. This
is so that the TB's throttle position lever will move freely on that side. Well
that’s all for now. As soon as I can figure out how to take apart the
butterfly valve, and its related assembly parts, I'll finish up part two. I'll
also include some more SOTP test results and also give my impressions of the
port matching job that I'll be getting from JG Engine Dynamics.