After reading over numerous boost-related problem threads, and vacuum line threads, I have come to a question myself.

Is it not possible to remove both the Air-Bypass Valve and Charge-Relief Valve by having one aftermarket BOV that uses that 1" thick vacuum-line to connect itself to the primary AND secondary turbo via a "Y"-shaped line? I suppose then the aftermarket BOV would act as both the ABC and CRV...that would be the idea I suppose.

I figure in my hypothesis, that I would want to keep the vacuum-line coming off the UIM that USUALLY plugs into the ABV, and have that one go into the aftermarket BOV, and either A) cap-off where the vacuum line coming off the LIM comes off of, and connect to after going through the CRV...or potentially B) Since I think most BOVS have a second and sometimes 3rd vacuum nipple, is it not possible to have that CRV vacuum line comin' off the LIM just go through one of those secondary nipples instead?

Here's the MS Paint-edited version of the "Simplified Turbo System" vacuum line diagram. I haven't DONE the simplified vacuum line setup, yet, but that in itself shouldn't effect this hypothetis of mine, I shouldn't think.

Anyways. Look, and tell me what you think.



I DO still have the CRV that came with my car if need be, and I understand there is no real NEED for an aftermarket BOV on stock seq. twins anyways...but if it works and causes no problems, then why not? I don't have the ABV though. It wasn't included with the car. >_<

Other question, and I can't seem to find the answer to this on ANY threads that I found through searching, but..if my idea in itself is a complete failure..can someone please SHOW me (via MS Paint?) just how the fudge you ARE supposed to properly install an aftermarket BOV?

My problem is that I don't have any of the original vacuum lines that come off lets say, the air pump, and usually go into the stock air box are missing. The one thicker (1"?) line that comes off the LIM I believe, has no where to go now. When I got the car it was atmospheric. CUrrently I put a little baby filter on it, cause aparently that bad boy IS sucking in air.

Just what is THAT line, and what does it do? What should I do WITH it?

 

P.S. I'm actually running the setup like this right now, except that the line coming off the LIM is just spliced into the BOV line instead.

lol..

It actually DID work.. for a couple 1st, 2nd, and 3rd gear runs. Solid 10-8-10 boosting...then I sat at idle for about 10 minutes. Revved it once. Ran it again, and then started having underboosting problems, as I've listed many times in numerous threads, but the thing is, the APEXi BOV I have on right now...I swear to God the thing is a POS and isn't even working...

Tomorrow I'm at least picking up a Greddy Type-S off a friend. At least I'll be working with a better quality BOV then.

I'm still reading up on various threads about the underboosting problem thx to the primary turbo not boosting properly. This BOV idea isn't an answer to the problem I figure, but I'm starting to prefer the idea of saving a couple hundred bucks and just fix the vacuum lines myself instead of going through a shop.

 

Above the CRV is that stupid line that comes off what appears to be the LIM. It wraps around the back of the motor, so it's hard to tell.

WTF do you do with that? My twin-intakes don't have ANY where for me to splice it, or the air pump into them.

 

Mate, I think you should read up some more on how the stock system works. Check out http://www.autosportracetech.com/RX-7/rx7stuff.htm as a good place to start.

I would not run the CRV and ABV hoses together to a single blow off valve, controlled by vacuum signal from the UIM.

The CRV is used to vent boost from the secondary turbo between 3000-4500rpm while it is pre-spooling. At this stage, the charge control valve is closed, which isolates the primary and secondary compressors.

If you run the CRV and ABV hoses to a single blow off valve, between 3000-4500 rpm the blow off valve will be held closed by the pressure signal from the UIM, and your pre-spool boost from the secondary turbo will have nowhere to go.

However, if you are running the stock twins non-sequential, you could do what you described as the CRV has no place in a non-seq system.

Hope that helps

 

So, for non-seq it'd be fine.

THat's cool. I get what you're saying.

If I run the CRV off the secondary turbo atmospher and an aftermarket BOV in place of the ABV atmospheric, is that OK?

 

Yes, the BOV = ABV. Just different terminology. If you aren't non-seq, leave the CRV alone and only replace the ABV.

 

More on the stock sequential system here:
http://www.davidgeesaman.com/rx7/TwinTurbo.PDF

 

isn't your car at mazcare? or did they quote you two years salary to fix the problem, hehe

your Vacuum Line Hypothesis makes no sense...

 

as you wish

 

You're an ***.

I just did the poor man's non seq. on my car. So based on what you guys had said, I can replace the CRV and ABV now by installing one BOV that connects to where they normally would.

I'll post results after I hook it all up and drive it a little bit.

 

You may as well go full NON-sequential, your just going to screw up the turbo control system messing with the poor mans version and not get the results your looking for and more than likely won't get back to the proper configuration for sequential any way.

 

I just completed the "Poor Mans Non-Sequential" tonight.

Works great. Boost problems are virtually fixed. I'm so happy.

I now have it hooked up just as I pictured, and works just fine, thanks. :]

It'll get a solid 8psi in every gear..but when I first start it, if I go WOT in 1st, it'll overboost real bad. After a minute or so, it doesn't do it anymore in 1st.

If I'm on the highway in 5th, and I downshift to 4th, it overboosts too. But if I go down to 3rd, it gets the solid 8psi.

Besides the overboosting, it's rock-solid. Feels nice and smoothe. I kinda miss the low-end "torque"..*cough*..but it just feels alot more..predictable. I'm happy, and proud of myself. I just saved myself a couple $100 and now I have a more reliable system to work with....and I learned alot about my the car.

Win-win situation. Anyone mind helping me figure out the overboosting issue, though? Has this happened to anyone else before?

EDIT:

Just another quick questeion about the 2 nipples on the UIM.

The left one closer to the firewall I have going to my boost gauge, and "T"-d to my BOV.

The other is capped off. Is that correct?

 

Double post. Sorry.

 

doesn't sound rock solid...the way you've described it.

generally, I don't like to T-BOV's off any line...weakens the "signal". but if you don't have compressor surge, party on.

did the guy you bought the car from say it was set up for seq? If it has all the components to run seq...I strongly suggest, figuring it out; its worth it.

running a car as a poor man's non-seq is a pretty ghetto fix...wired precontrol doors, and always open y-pipe butterflies, etc, etc.

sorry if I'm an ***, but I think of an FD as an awesome machine...and really hate to see them hacked or ruined. Help me help you

 

Well, you live in GA. Come over and lets FD it up.

:P

 

I'm outta town until this weekend, and moving next week...pm me with your phone number, or email dubulup@gmail.com