Tial QR BOV - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Bleakley · 08-09-2014, 05:44 AM

Okay, I finally wrapped my head around how the QR bov from tial operates. For those who are also familiar with how it works, here is the question I present:

Since it is going off of vacuum and will seemingly ONLY open when the throttle plate is closed, then technically under WOT it will just let my compressor boost into oblivion w/ no cutoff. This will leave me relying solely on my wastegate and I do not think I am comfortable with that. While the design is superb and I like tial's products (hence them being my first choice for a bov), due to this feature I think I am going to have to move to a competitor's bov.

:'(

Before I do so though I was wondering if anyone has anymore info/comments/suggestions? Am I wrong and do not fully understand? or No, I fully nailed it and understand? Any help is greatly appreciated. A BOV is the last major component I need and my project will be on the streets.

jr_ss · 08-09-2014, 08:10 AM

Part throttle and spool into oblivion don't belong in the same sentence. Since boost is throttle dependant, you're not going to boost large amounts. I think you've missed some key things here.

Part throttle, such as cruising, creates a vacuum condition. It also only allows a limited range of RPM. Once again, I think you've over thought exactly what a BOV does and how it all works together.

ultimateirving · 08-09-2014, 08:22 AM

You missed it completely. Bov does not regulate boost. Get the tail and be happy.

feito · 08-09-2014, 08:32 AM

U wont see boost at cruising speeds, even without a bov. Bov's arent even necessary until wot and here they should either be fully closed when on throttle or fully opened while shifting. Bov's dont control your boost levels either.

Bleakley · 08-09-2014, 10:17 AM

Jr_ss. Probably. Edited my OP (thanks). Sorry for missing key points. Also, thanks for taking the time to answer my questions. I see your posts/expertise all over and I am constantly learning.

Ultimateirving and Feito. Not even a little bit? And I would love to.

And I guess to recap, I'll be going for 12-16 psi with 20-25 psi in the future. Get the tial and I will be alright? I am putting my SR in really soon and will be using the stock T25 and internal gate and will be ramping up my build very quickly, very soon. With the tial BOV is it, basically, giving me what I need? EDIT: I should note, the 20-25 psi will not be with the stock 2560...

Luvs2slide · 08-10-2014, 06:51 AM

Your bov only blows off extra air. When ur boosting and u let off the as, the throttle body will close. All the air that was going towards the TB now has to go in the opposite direction back towards ur turbo‥ this is known as turbo flutter, which will in theory want to cause ur compressor blades to turn inthe other direction. Having a BOV will blow off all the excess air. This is known to extend the life of ur turbo. Also, sometimes not having a bov can throw off the ecu because of the already metered air.

Luvs2slide · 08-10-2014, 06:52 AM

However some compressor housings have built in anti surge holes which help tofight off the flutter or surging

08-09-2014, 05:44 AM	#1
Bleakley Zilvia Addict Join Date: Apr 2011 Location: Near Pittsburgh, PA Posts: 637 Trader Rating: (1) Feedback Score: 1 reviews	Tial QR BOV Okay, I finally wrapped my head around how the QR bov from tial operates. For those who are also familiar with how it works, here is the question I present: Since it is going off of vacuum and will seemingly ONLY open when the throttle plate is closed, then technically under WOT it will just let my compressor boost into oblivion w/ no cutoff. This will leave me relying solely on my wastegate and I do not think I am comfortable with that. While the design is superb and I like tial's products (hence them being my first choice for a bov), due to this feature I think I am going to have to move to a competitor's bov. :'( Before I do so though I was wondering if anyone has anymore info/comments/suggestions? Am I wrong and do not fully understand? or No, I fully nailed it and understand? Any help is greatly appreciated. A BOV is the last major component I need and my project will be on the streets. Last edited by Bleakley; 08-09-2014 at 10:18 AM..

08-09-2014, 08:10 AM	#2
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,415 Trader Rating: (35) Feedback Score: 35 reviews	Part throttle and spool into oblivion don't belong in the same sentence. Since boost is throttle dependant, you're not going to boost large amounts. I think you've missed some key things here. Part throttle, such as cruising, creates a vacuum condition. It also only allows a limited range of RPM. Once again, I think you've over thought exactly what a BOV does and how it all works together. __________________ My SR20VET Does your VTC gear rattle in your S14/15 SR? PM me.

08-09-2014, 08:22 AM	#3
ultimateirving Zilvia FREAK! Join Date: Nov 2010 Location: arizona Age: 37 Posts: 1,521 Trader Rating: (1) Feedback Score: 1 reviews	You missed it completely. Bov does not regulate boost. Get the tail and be happy. __________________ Z32 with lq4 swap Desert Street Scene \|\| Dssevents.com

08-09-2014, 10:17 AM	#5
Bleakley Zilvia Addict Join Date: Apr 2011 Location: Near Pittsburgh, PA Posts: 637 Trader Rating: (1) Feedback Score: 1 reviews	Jr_ss. Probably. Edited my OP (thanks). Sorry for missing key points. Also, thanks for taking the time to answer my questions. I see your posts/expertise all over and I am constantly learning. Ultimateirving and Feito. Not even a little bit? And I would love to. And I guess to recap, I'll be going for 12-16 psi with 20-25 psi in the future. Get the tial and I will be alright? I am putting my SR in really soon and will be using the stock T25 and internal gate and will be ramping up my build very quickly, very soon. With the tial BOV is it, basically, giving me what I need? EDIT: I should note, the 20-25 psi will not be with the stock 2560... Last edited by Bleakley; 08-09-2014 at 05:35 PM..

08-10-2014, 06:51 AM	#6
Luvs2slide Zilvia FREAK! Join Date: Oct 2006 Location: NW Florida Age: 43 Posts: 1,490 Trader Rating: (81) Feedback Score: 81 reviews	Your bov only blows off extra air. When ur boosting and u let off the as, the throttle body will close. All the air that was going towards the TB now has to go in the opposite direction back towards ur turbo‥ this is known as turbo flutter, which will in theory want to cause ur compressor blades to turn inthe other direction. Having a BOV will blow off all the excess air. This is known to extend the life of ur turbo. Also, sometimes not having a bov can throw off the ecu because of the already metered air. __________________

08-09-2014, 08:32 AM	#4
feito Nissanaholic! Join Date: May 2007 Location: Texas Posts: 1,999 Trader Rating: (1) Feedback Score: 1 reviews	U wont see boost at cruising speeds, even without a bov. Bov's arent even necessary until wot and here they should either be fully closed when on throttle or fully opened while shifting. Bov's dont control your boost levels either.

08-10-2014, 06:52 AM	#7
Luvs2slide Zilvia FREAK! Join Date: Oct 2006 Location: NW Florida Age: 43 Posts: 1,490 Trader Rating: (81) Feedback Score: 81 reviews	However some compressor housings have built in anti surge holes which help tofight off the flutter or surging __________________