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EFINI "Y" PIPE HARD PIPES

Efini "Y" Pipe Kit: "Y" pipe, Crossover pipe w/capnuts, 2 metal "Y" pipe to turbo gaskets,
1 metal "Y" pipe to crossover pipe gasket, 1 "Y" pipe rubber o-ring coupling

The OE turbo outlet intake piping consists of an alloy turbo "Y" pipe connected via a rubber coupling to a plastic cross-over pipe. The plastic crossover pipe is held in place, bolted in two locations, by a steel bracket mounted atop the air pump. Why am I telling you all this? Because the failure points of this setup are numerous.
Comparison: '99 (left) '93 (right)
The rubber coupling commonly is blown off during high boost applications, the rubber itself also degrades rapidly under the very high temperatures seen local to the turbo's. The plastic crossover pipe frequently cracks at the bracket mounting points and at the rubber couplings usually due to over torquing the connector clamps, resulting in small hard to detect boost/vacuum leaks. The Efini "Y" pipe eliminates all of these problems. The crossover pipe (see above) is now aluminum so is not prone to cracking. This new aluminum piping also has a larger radiused bend for freer flow.
And the rubber coupling has now been completely eliminated and is replaced by a flanged bolted connection (see above left) using a metal gasket. And to top it off the OE "Y" pipe has a design that has been improved upon for the '99 model year. Specifically, the bung for the BOV on the older '93-'95 models protrudes directly into the compressor discharge flow path. (see below left) The '99 "Y" pipe has a flush fit bung (see below right) which provides minimal interference in airflow.

Comparison: '93 (left) '99 (right)

All this makes for a more reliable configuration and a mild increase in intake flow efficiency. Thus, the turbos don't need to work as hard to generate boost and one might add quicker throttle response although I doubt you could feel the difference while driving. The installation was fairly straight forward. Removal of all the intake piping is required along with the air pump and possibly the airbox and intercooler. The only difficult part of removal of the old assembly, separation of the "Y" halves, is made easy provided the rear half of the "Y" is also loosened from the secondary turbo compressor outlet (rear hard intake pipe must be removed to do this) so the two halves can be separated. Once this is done the '99 efini pipes can be easily installed. It is advisable that nothing be tightened down until the intercooler and crossover pipe are all connected as some minor adjustments are necessary to get everything lined up.
The "Y" pipe portion installed, New angle of BOV bung
required trimming of the respective hose to the BOV
There is one catch, the bracket used to support the old plastic crossover pipe also supports one end of the pressure chamber. You can choose to reuse the old bracket or do as I did and just fabricate a short bracket to support the end of the pressure tank and not worry about reusing the unsightly steel bracket. Overall I am pleased with the finished assembly and will eventually get around to polishing the crossover piping to improve the appearance.
The completed install

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This page last updated April 17, 2001
rotorphiles have visited this page since April 17, 2001

If you would like to contact me and converse about my experiences with my 7:
please feel free to send an e-mail to rotarypower@rx-7.net

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