How to Install the Efini Y Pipe
By Rob Robinette
Why do you need an Efini Y pipe?
The stock Y-pipe gathers the compressed air from the two turbos and
sends it out to the black plastic crossover tube that goes to the intercooler and passes
between the alternator and air pump.
Efini Y-pipe and crossover tube
The Efini Y-pipe replaces these two pipes with high quality aluminum
pieces. The black plastic crossover tube has a tendency to crack on both ends and the
rubber connector between the Y-pipe and crossover tube has a tendency to split. These
cracks can be the source of hard-to-solve boost problems. The cracks can't be seen unless
you remove the tube and pry it open, and yet under boost pressure the cracks open up and
vent your boost (which is sometimes accompanied by a loud whooshing sound from under the
hood). The Efini pipe also moves the air-bypass valve connection out of the air flow so it
should breath a little better than the stock pipe.
Where to get the Y-pipe
I got the Efini Y-pipe from Mazda Competition, (800) 435-2508
714-727-6943 (FAX) Just tell them you need everything to install the Y-pipe and they will
include all the gaskets and such. My total price was $218 for the Y-pipe, crossover tube
and the three gaskets. I couldn't get the two metric nuts and washers needed from Mazda
Comp so I took the Y-pipe to the local Ace Hardware and bought them for $1. To qualify to
purchase parts that are available at a Mazda dealer, you need to register and send race
results from 2 events within the past six months (any race including local autocrosses).
This is worth it because you can get parts cheaper than the Mazda dealers can. You
can purchase racing parts not available at the dealer from Mazda Comp, such as the Efini
Y-pipe, without qualifying. They take credit cards.
Installing the Y-Pipe and Crossover Tube
The Efini crossover tube isn't polished so I had to sand it down and
polish it before I installed it. See the Polish Aluminum How-To. You'll have to
remove the air pipes that run from the air box to the rear turbo and the small pipes that
go from the air box to the two blow-off valves. Then loosen the crossover tube clamps and
unbolt it. This is a good time to disable
your EGR valve. You can remove the metal bracket the
crossover tube was attached to, the Efini pipe doesn't use the bracket.
Ready to remove the crossover
To get the old Y-pipe out you have to remove the metal intake pipe
that attaches to the rear of the rear turbo. It's held on by two 10mm nuts that can be
accessed from below the car and by a 10mm bolt accessible from the engine bay. The lower
nuts are just above and to the left of the pre-cat (or down pipe). I used a 1/4 inch
ratchet and 10mm socket to remove the turbo air pipe nuts. Make sure the exhaust is cool
before you attempt this.
Rear half of Y-pipe separated
from front half
With the intake pipe off you can remove the two 10mm nuts that hold
on the rear half of the Y-pipe. Remove the two 10mm nuts that hold on the front half of
the Y-pipe and pull the entire Y-pipe out just enough to twist and pull the Y-pipe apart.
It isn't necessary to remove the small vacuum lines that attach to the rear half of the
Y-pipe. There are two vacuum hoses connected to the engine side of the front half of the
Y-pipe, disconnect them before you yank the Y-pipe out.
New Y-pipe installed
Install the new parts--remember to use new gaskets everywhere and
replace the rubber O-ring that goes between the two Y-pipe halves. I reused the gasket on
the rear turbo metal intake pipe. Some people have reported that the new Y-pipe and
crossover tube didn't line up with the intercooler so they had to loosen the turbo
assembly and adjust it a little to make the pipes line up properly. Mine fit fine.
How to Make It Work With the ASP Race Intercooler
Question: How does the Efini Y pipe fit with the ASP Race
Intercooler? I assume based on the picture of how it looks that there will have to be some
modification to the Efini Y pipe in order to fit with the ASP Race
I modified an Efini Y-pipe to work with an ASP I/C. The Y-pipe was
cut about ¾" below the flange face. Then, the neck was machined round and a bead was
heli-arced around the edge, giving a sealing surface for the silicon connector hose. The
rest of the install was standard stuff.
I looked at a lot of install options. Before measuring, I had planned to weld a flange
onto the ASP pipe to match the Efini studs, but the height of the Efini flange face was
too high to allow the ASP pipe's arc enough vertical clearance. Also, the front stud is in
the same plane as the ASP pipe's route. The only solution was to go back to the silicon
connector hose and clamps.
After all the BS, the benefits from the Efini piece are probably negligible. It is a lot
of work just to get the valve boss out of the pressure stream. Did anyone else do this
install? I'd like to see their solution.
Brad Barber http://home.swbell.net/bradrx7