hey folks, i need some clarification on some parts of the turbocharger control system. for reference i have a 91 n/a that i am getting ready to drop in a jspec engine. I just want to make sure that I have all the parts i need. This is my first rx7 engine swap, so for simplicity in troubleshooting I am "planning" on keeping things as stock as possible for now.

On side of the turbo duct that runs to the intercooler there is a nice little vacuum hose. It is there that I assume the stock blow off valve connects. I don't have the bov in my possession yet, it is on the way.

On the turbo inlet duct (from the afm) there are two holes. One small hole in which a vacuum hose from the boost control solenoid connects with a check valve. The other hole in the tid is large and according to the fsm section F2-7 there is a part called an air bypass valve that hooks into that and has a vacuum source which is present on my engine.

I am somewhat confused by the fsm diagrams that show the air bypass valve attached to tid (f2-7) and the diagram that shows it near the turbo to intercooler duct (f2-6).

Are there actually two seperate parts, one that attaches near the turbo and one on the tid? in that is the case, then how does the bov vent back to the air intake system?

A little clarification on the parts and the vacuum routes would be appreciated.

thank you

jk

 

i have to say this is amusing.

I post a question based on numerous SEARCHES, and an actual reference to the factory service manual and no one has anything to say.


but when someone posts a "how do i turbo my n/a thread" or "how do i put in a clutch?" everyone is in rapid response with the "search newbie!" flame.

 

I am not totally clear on your question. The airflow meter mounts to the tid. The tid goes on the turbo, and there is a boost pipe coming off the turbo to the IC. The BOV goes between the boost pipe and the tid. When you shift, the bov releases the pressure from the pipe into the TID where it is dispersed. IT does this because that air has already been "metered" and fuel has been injected for it...if you vent it to atmosphere, that extra metered fuel results in backfires/flamage, and the factory tried to prevent that.

The bac valve draws air from the boost pipe as well. When extra load is on the engine, the bac opens, lets some PRE-throttle plate air into the intake manifold, bypassing the throttle plates...more air means more fuel, and the engine revs up, so it doesnt die under light load at idle such as a/c. The bac only works at idle, so it doesnt matter where its air supply is, so long as it's between the afm and the throttle plates.

 

they are both the same hose. your "air bypass valve" is your BOV. there is only one

 

You've just answered your own question. The BOV (or ABV, same thing) vents pressure from the compressor outlet pipe into the TID.

 

my confusion was that the fsm shows the air bypass valve attaching to the tid, when i know that the bov attaches to the turbo duct heading towards the intercooler, i scanned a picture, hopefully it attaches to this post so you can see what i am talking about.

thanks for the help.

jk

 

It attaches to BOTH. It has an inlet and and outlet as I explained above.

 

thanks dude,

that is exactly what i needed to know.

jk