Just got me a '93 FD and have been searching this forum for many weeks, hence my low post count. I have a question I cannot find an answer to yet.

I am in process of doing a full non-sequential conversion along with many other mods like full exhaust, Power FC, upgraded intercooler, etc....

My new intercooler has a single aftermarket BOV on it. Can I remove the stock primary and secondary BOV's on each factory turbo or must they stay? I am just trying to make the vacuum system as simple as possible. All emissions will be removed as well.

Thanks!

 

If you intend to keep the turbos running sequential, then the intercooler BOV can replace the stock valve labeled 'ABV'. Leave the CRV or else your secondary won't spool and you'll have a bad transition. Make sure the aftermarket bov is vacuum actuated.

If you are doing a nonsequential setup, the CRV will be removed.

Dave

 

So there isn't a primary BOV and a secondary BOV? They are actually the ABV (air bypass valve) and CRV (charger relief valve)?

I am NOT staying sequential, I am in the process of a FULL non-sequential changeover. I don't want to keep anything that isn't REQUIRED. This includes ALL emissions.

Can my intercooler BOV take the place of both the ABV and CRV on a non-sequential twin turbo?

I am using this diagram as my complete source for vacuum routing.

 

Yeah, if you're going non-sequential, you don't need both. Some people do run both for better flow, and I've heard of people running one stock and one aftermarket - the stock one has great fast part-throttle response which many aftermarket BOV's lack, and the aftermarket BOV can flow more air.

But, in general, most people just cap that nipple up for the CRV and that's it.

Dale

 

Correct, there is not a separate bov for each turbo. The CRV is like the prespool bov, and the abv is "the" bov that vents either just the primary or both depending on which turbos are active.

Using that nonsequential setup you posted, you're actually running both the CRV and ABV together, and your aftermarket bov will replace both.

Dave

 

Dale, so you're saying that I may get better throttle response by keeping the stock ABV and also use an aftermarket BOV? The CRV will dissappear. I love keeping it simple.

Dave, thanks for confirming my research. There's so much information available on the FD's sometimes it's overwelming.

Anyone that has went non-sequential, is the above diagram confirmed to work fine? One of the notes says that all solenoids go away except for purge control. If I delete the charcoal canister I can remove that solenoid as well so all dissappear. True or false or are there some I MUST keep?