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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.
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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.
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Ready to remove the crossover tube

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.
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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.
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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.
Rob Robinette

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
intercooler, right?
I modified an Efini Y-pipe to work with an ASP I/C. The Y-pipe was cut about " 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

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