TurboXS RFL Type H Blow Off Valve BOV Turbo XS
Joined: Jul 2003
Posts: 30,677
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From: Dallas, PA
Rep Power: 607 
very efficent bov.........although the guys on honda-tech don't like turbo xs bov's. It is made for 30psi...........dober cut a couple coils on it and he likes the sound of it now.
Joined: Oct 2001
Posts: 560
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From: OKC, Oklahoma, US
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That BOV works great for high or low boost applications, a friend has it on his WRX and has never had a problem.
It's REALLLLLLYYY loud... but if that's what you want, you'll be very happy with it.
It's REALLLLLLYYY loud... but if that's what you want, you'll be very happy with it.
I went with Greddy Type S 
sorry to thread jack, but are there any differences in sizes of bov's? I want the HKS SSQ, but im wondering if size has anything to do with it? Also what else besides a flange and a welder is needed to install on charge pipes?
Thanks
Thanks
Joined: Oct 2001
Posts: 560
Likes: 0
From: OKC, Oklahoma, US
Rep Power: 0 Size does matter somewhat... some BOV's only have one pressure release, while others like the HKS SSQ and Apex'I Twin Chamber have two, one small and one big. The small one opens up faster (because it's smaller and requires less pressure to activate) and gets some boost out quickly, while the bigger pressure release opens up under higher boost (above 4.5psi to be exact) and lets a lot more air out. The small valve helps to relieve pressure faster and eliminate compressor surge, while a monstrously huge BOV or one with only one pressure release valve that is bigger might get just a little bit of surge before the pressure release is fully open.
Many BOV's have twin pressure releases, and that is the cause for the different sounds under low boost and high boost on many BOV's. Usually they will be called a Twin Chamber or Sequential BOV if they have more than one pressure release valve.
Many BOV's have twin pressure releases, and that is the cause for the different sounds under low boost and high boost on many BOV's. Usually they will be called a Twin Chamber or Sequential BOV if they have more than one pressure release valve.
Originally Posted by SODJAZERO
Thats pretty much it. To get the flange welded on and to install. You gotta tune it tho, other than that its pretty simple.
Originally Posted by RiceBurnrEX
Size does matter somewhat... some BOV's only have one pressure release, while others like the HKS SSQ and Apex'I Twin Chamber have two, one small and one big. The small one opens up faster (because it's smaller and requires less pressure to activate) and gets some boost out quickly, while the bigger pressure release opens up under higher boost (above 4.5psi to be exact) and lets a lot more air out. The small valve helps to relieve pressure faster and eliminate compressor surge, while a monstrously huge BOV or one with only one pressure release valve that is bigger might get just a little bit of surge before the pressure release is fully open.
Many BOV's have twin pressure releases, and that is the cause for the different sounds under low boost and high boost on many BOV's. Usually they will be called a Twin Chamber or Sequential BOV if they have more than one pressure release valve.
Many BOV's have twin pressure releases, and that is the cause for the different sounds under low boost and high boost on many BOV's. Usually they will be called a Twin Chamber or Sequential BOV if they have more than one pressure release valve.
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Joined: Mar 2003
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From: Dallas, Tx
Rep Power: 0 Well some bovs are adjustable and some are not. Like type s and the hks ss, those are adjustable. They have a screw at the top to adjust the "stiffness" on the spring that determins when the bov opens. The one that came with my maxref kit is not adjustable. Adjustable bovs give you more options for tunning. Like you dont want the spring too limp or it will leak under boost, and you dont want it too stiff or it wont open when the tb valve closes. RICEBURNREX would know more about it.
Joined: Oct 2001
Posts: 560
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From: OKC, Oklahoma, US
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Originally Posted by SODJAZERO
Well some bovs are adjustable and some are not. Like type s and the hks ss, those are adjustable. They have a screw at the top to adjust the "stiffness" on the spring that determins when the bov opens. The one that came with my maxref kit is not adjustable. Adjustable bovs give you more options for tunning. Like you dont want the spring too limp or it will leak under boost, and you dont want it too stiff or it wont open when the tb valve closes. RICEBURNREX would know more about it.
Size of the blow off valve does matter... a bigger BOV can vent more air at a time, but that also means there is more of a delay while opening the larger valve, and it usually takes more of a pressure differential to open the valve, leaving you with some compressor surge. That's why dual stage or dual chamber BOV's are so effective, they release fast and a lot of air.
^okay that makes sense. So any suggestions on what size HKS to get? I saw a couple different sizes 50mm and 60mm, and I figured after reading you'rs posts that a smaller one would better suit a low/moderate boost set-up.
Joined: Oct 2001
Posts: 560
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From: OKC, Oklahoma, US
Rep Power: 0 If you are not going above 15psi, the 50mm is more than adequate. You can go bigger as long as it is a dual chamber/stage BOV, but there really is no need to.
^thats how I feel, but sometimes people get mad!
Thanks again for all the help...hks should be on the way soon!
Edit:what size mm is the turbo xs valve? The HKS one im looking at is 50 mm, but ive heard that 32mm is a better size for my application. Is this true? Or is it only because the turbo xs only has one stage of venting compared to the two stages of the hks?
Thanks
Thanks again for all the help...hks should be on the way soon!
Edit:what size mm is the turbo xs valve? The HKS one im looking at is 50 mm, but ive heard that 32mm is a better size for my application. Is this true? Or is it only because the turbo xs only has one stage of venting compared to the two stages of the hks?
Thanks
Last edited by Big Baller L; Jul 6, 2004 at 08:50 PM.
Joined: Oct 2001
Posts: 560
Likes: 0
From: OKC, Oklahoma, US
Rep Power: 0
Originally Posted by Big Baller L
^thats how I feel, but sometimes people get mad!
Thanks again for all the help...hks should be on the way soon!
Edit:what size mm is the turbo xs valve? The HKS one im looking at is 50 mm, but ive heard that 32mm is a better size for my application. Is this true? Or is it only because the turbo xs only has one stage of venting compared to the two stages of the hks?
Thanks
Thanks again for all the help...hks should be on the way soon!
Edit:what size mm is the turbo xs valve? The HKS one im looking at is 50 mm, but ive heard that 32mm is a better size for my application. Is this true? Or is it only because the turbo xs only has one stage of venting compared to the two stages of the hks?
Thanks
50mm is not too big for a BOV, it would be for a wastegate, but not for a BOV.
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