But, like every exceedingly tuned car, the project didn't just come together
overnight. For Ralph, the center of his tuning efforts was dictated . by the
choice of turbo. "I've tried four different turbos to get the power to the
level I wanted." And of course a change ,of turbo isn't a simple plug and
play operation. Each turbo will have it's own unique flow characteristics,
which mean unique tuning requirements. "It took around six months to get the
car rolling, and about a year to work out the bugs." Which actually is a
testament to the capability of the team at Groundzero. Very few tuners in
the world can lay claim to developing over 700hp on a 13B-REW block, and
this project was done almost completely in-house.  Hold on there! "700hp?"
you say? Actually it's more like 800hp. Ralph's RX-7 has produced a maximum
of 712 rwhp @ 32psi on a Tn Q-trim, 1.15 AIR divided turbo built by XS
Engineering. 

And that number was produced without the help of nitrous. When I asked Ralph
"Have you ever even used the nitrous?" His reply gave even more appreciation
for his tuning skills, "No, it's crazy enough as it is, it's stupid. I think
it's time to take the nitrous out. I run 25psi on the street minimum, I have
a 22psi spring in my wastegate. I was going to use it to spool the turbo,
well, turbos are getting so good that we don't need it. Now with this GT
wheel that'll spool even faster and flow more, I think it's time to get rid
of it and redo the interior." I keyed on the words GT wheel, "so you're
getting a new turbo?" I asked.  "Yea, I think it's called a PT70GTS, 70mm GT
wheel, so it's a lot more aerodynamic and efficient than the Tn, and will
flow 10%-15% more. 

The car should be pretty much dialed as it is, so it'll be running by
Monday." I'm writing this on Friday.  In talking with Ralph, I almost feel a
bit stunned at how easy he makes it all sound. But I know it's anything but
easy to squeeze these kinds of astronomical number from a 13B, so there must
be some secrets. As we know, in a rotary, fueling and tuning is everything,
and Ralph has paid special attention to the fuel system. "We sumped the
stock tank, and run that into a pressurized surge tank. This keeps me from
popping a motor by running the tank to low and getting fuel starvation. All
it takes is a second and your motor is gone, the surge tank keeps the fuel
flow consistent." 

Well, there's one secret. "Other than that, we run the Magnaflow 600 pump,
it'll flow some ungodly amount. We run a -12 and split into pair of -8s that
run into both rails, and then a -8 return. Running into both ends of the
rails keeps the pressure constant." 

There's another secret, or more accurately, just tedious attention to
detail. And even with all this fuel system overkill, Ralph says his main
problem with each new turbo is getting the fuel system to keep up. "Right
now we're adding two new injectors. With our 850cc x two primaries, and
1600cc x two secondaries at 68psi base pressure, we were running 100% duty
cycle at 32psi of boost. So we're producing a totally new intake manifold
that will allow us to plumb in a couple more secondaries. For the GT turbo,
I'll probably run four 1,600cc secondaries, and drop the rail pressure back
down to 45psi or so." 

Of course there's more to making 700hp than just fuel system and turbo, you
still have to tune, and you spark still plays an important role. Ralph uses
the tried and true combination of a Power FC and the Datalogit. To get the
low impedance 1,600cc injectors to work, Ralph put his electronics degree to
good use. "I just put some big heatsinks on the output transistors to keep
them cool, and that did the trick." 

All the tuning is done by Ralph either on his in-house Mustang chassis dyno,
or on the street. Mixture is monitored by a FJO wide band. Ralph says that
he's done a lot of research into proper tuning, "I've run EGT's on both
front and rear rotor, and the rear seems to run 250 degrees hotter because
of the manifold layout and more air into the rear." So with his newest turbo
setup Ralph has developed a manifold that he says will equalize flow from
the front and rear rotors, and hopefully keep the mixtures even. "Every
motor I've blown has been the rear rotor, so we made this manifold to keep
that from happening." 

More examples of iniquity can be found in the ignition system. Ralph found
that the car was easier to tune with no wasted spark, and by having no split
timing. "I tie the trailings together, and run no split. I ran the car on
the street this way for a year and a half at 25psi, and it just seemed
easier to tune." Other pieces used are a pair of MSD HVC ignition boxes,
combination of MSD coils and stock coils, and a B&M NuVolt to raise the
voltage to 22v.