Lionheart240

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 am actually running this setup currently, and believe it or not, it DID work. I ran her through 1st, 2nd, and 3rd, and got GREAT solid 8psi in 1st gear, and 10 in 2nd and 3rd. Afterwards, I let her idle for a couple minutes, revved it once, and then started having the same damn underboosting problems that everyone else seems to be having where I don't get proper boosting from the primary turbo, and then in maybe 3rd gear on, it'll nail 10psi right after 4,500RPM.



>_<

Lionheart240

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.

rx7girltk

Take off the old bov and put the new one in. If it is not an fd3s specific kit it wont go into the stock spot. After installing the bov run a vacuum line from the nipple on the bov to a nipple on the uim like in the picture.

Lionheart240

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



Works great! Many of my underboosting/overboosting problems have been virtually fixed. I'm so happy.



I now have it hooked up just as I pictured, and works just fine. I'm surprised too. hehe. Makes sense though, without the sequential system, the CRV is pointless. So, now that the two turbos are basically working as one, it only makes sense to have them both Y"-d into the same BOV to vent air out. :]



It's getting a solid 8psi in every gear..but when I first start her up, if I go WOT in 1st, it'll overboost real bad. After a minute or so, it doesn't do it anymore in 1st. Is 8psi running the Poor Man's Non-Sequential, how much boost I SHOULD be getting?



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. Since it doesn't spool as quickly either under only 20% or so throttle (According to S-AFC II), I should also do much better on gas.



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?



P.S.



Just another quick question about those 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?



I see in your picture that the BOV is on the right nipple, and the boost gauge on the left. Is there a reason why it HAS to be that way?



I think I'll hook mine up like that tomorrow, I figure you guys know alot more than I do if you're showing me that's how it's supposed to be.

rx7girltk

No reason it HAS to be hooked up like that. I kept my crv even though I went full non-sequential because I had nothing to block off the hole where the crv goes. I would get a boost controller of some sort and set it to 10psi or .7 bar unless you have an aftermarket ecu and can run higher boost.

Fd3BOOST

You can run those lines to anything you want off the manifold. They are all the same vacum source. If you don't use them just cap them off. As far as the overboosting. I don't know what you are using for boost control but you should have a boost controller of some sort running between the turbo pipe nipple (single turbo would be from the compressor housing) and the wastegate actuator nipple on the passenger side. The lower nipple that comes off the driverside of the actuator needs to be capped off. If for some reason that is not capped and airtight you will get overboosting because there will not be enough pressure to open the wastegate flapper. It might not close all the way and be causing that 7psi also. Address that wastegate acctuator & I think that will fix your boost problems. On stock fuel levels keep it under 12psi.

Lionheart240

Could you show me a pic of the wastegate actuator you're talking about and just what nipple needs to be properly capped off?



BTW, I AM running a dp, cat, then catback exhaust.

Fd3BOOST

Posted pics in the FAQ thread for you.

nopistons94

Honestly, theres no reason the seq twin setup on the car can not be predictable and reliable as well. Going non-seq is either a ghetto way to fix a problem on a FD , or you actually have a reason you WANT to be non seq for. A street driven FD, for the most part, should stay seq because its nicer to have that power down low, but this is also just *my* opnion.