BOV placement
Thread Starter
Running Guns & Moonshine
Joined: Aug 2001
Posts: 12,449
Likes: 7,152
From: CT
BOV placement
Does it matter where the blow off valve is mounted? I am wondering if there is a reason A&A places theirs 6 inches away off the side of the charge pipe pre-intercooler. That placement is fine and I may as well cut into the pipe and weld the adapter on for the new 50mm I bought, but why would I not want to put it some place more easily serviceable between IC and TB?
If the intent is to relieve pressure when the TB slaps shut, why wouldn't we want it closer to the TB itself? Would that be counterproductive on a stick car to have it relieving pressure between each shift?
It's an interesting point of education for me.
If the intent is to relieve pressure when the TB slaps shut, why wouldn't we want it closer to the TB itself? Would that be counterproductive on a stick car to have it relieving pressure between each shift?
It's an interesting point of education for me.
Burning Brakes
Joined: Oct 2016
Posts: 1,205
Likes: 363
From: Massillon Ohio
Anywhere in the charge pipe is fine, but yes, you would generally want it as close to the throttle body as possible if it is an option. A&A puts it where they do because there is space there for it
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
I was advised you want to dump before the intercooler
does putting the BOV closer to the throttle make it respond better?
Not sure I understand what the advantages are. What the folks said about mounting before the intercooler was that you didn't have the pressure drop from the intercooler impeding the dump and it was better performing closer to the blower
does putting the BOV closer to the throttle make it respond better?
Not sure I understand what the advantages are. What the folks said about mounting before the intercooler was that you didn't have the pressure drop from the intercooler impeding the dump and it was better performing closer to the blower
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
I'm getting the A&A "plumbing" kit to mount up the d1x and compressor surge on the big blowers needs to be managed.
Racer
Joined: Jul 2015
Posts: 442
Likes: 103
Location doesn't matter. Just make sure it's large enough to vent efficiently. I had an a&a 38mm on my procharged c5z when I bought it. At 5lbs the bov couldn't evacuate the air volume correctly. Didn't Matter how I adjusted it. Put a 50mm on it and problem solved. And it sounds better.
Melting Slicks
Joined: Nov 2017
Posts: 2,306
Likes: 747
Same here. My 38mm sounded like a pissed off rattlesnake at 5-6+ psi, so I swapped it with a Big Bubba. I'm sure it would have been totally fine considering that's what they ship thousands of kits with, but just didn't feel right to me. Bypass valve closest to the blower to reduce impeller surge makes a lot of sense, as well as venting that post-blower HOT air instead of post-intercooler air that's already been cooled makes sense to me as well.
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Safety Car
Joined: Oct 2007
Posts: 4,196
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From: South Florida
Always place the blow-off (bypass valve) as close as possible to compressor.
They make turbochargers now with integrated bypass valves.
This is done for couple reasons
1. To protect the compressor, it must be near the compressor wheel to minimize the volume of air between the compressor wheel and bypass valve. The more air between the two the more volume must be released to see a pressure drop in the pipe.
2. To avoid loading the intercooler with unnecessary airflow volume. Intercoolers have a capacity and load based on flow through mass, thus any mass you flow through the intercooler and then eject to the atmosphere is lost intercooler efficiency.
Always use a dedicated vacuum hose for the bypass
They make turbochargers now with integrated bypass valves.
This is done for couple reasons
1. To protect the compressor, it must be near the compressor wheel to minimize the volume of air between the compressor wheel and bypass valve. The more air between the two the more volume must be released to see a pressure drop in the pipe.
2. To avoid loading the intercooler with unnecessary airflow volume. Intercoolers have a capacity and load based on flow through mass, thus any mass you flow through the intercooler and then eject to the atmosphere is lost intercooler efficiency.
Always use a dedicated vacuum hose for the bypass
Platinum Supporting Vendor
Joined: Jul 2011
Posts: 2,076
Likes: 224
Pre-intercooler works well to protect compressor from surge. Less wasted energy releasing the pressure pre-intercooler as well. Easier fitment pre-intercooler too.
It can also be helpful to mount near the throttle body, only if you don't have a MAF sensor tune. If you are running Speed Density then it's an option to mount one near the T/B. I've had a few builds over the years that needed a 2nd BOV near the T/B to solve the Reduced Engine Power that kept happening when hitting rev limiter. **side note: If you mount a BOV near the T/B don't forget to shield the hood liner from the air that will be rushing out, as it can rip your hood liner apart. First time I mounted a 50mm on charge pipe near T/B it destroyed the hood liner after a night of racing. Welded a shield over just the top of the BOV and solved that issue.
It can also be helpful to mount near the throttle body, only if you don't have a MAF sensor tune. If you are running Speed Density then it's an option to mount one near the T/B. I've had a few builds over the years that needed a 2nd BOV near the T/B to solve the Reduced Engine Power that kept happening when hitting rev limiter. **side note: If you mount a BOV near the T/B don't forget to shield the hood liner from the air that will be rushing out, as it can rip your hood liner apart. First time I mounted a 50mm on charge pipe near T/B it destroyed the hood liner after a night of racing. Welded a shield over just the top of the BOV and solved that issue.