Relentless

Now that turbos are on the market, I thought it might be a good time to talk about the different blow off valves on the market. Philodox has the GReddy Type S BOV. The GReddy car (shawrf1's car) has the new GReddy Type RS, and the PTP turbo car has the HKS SSQV.

I was looking at the Tial BOV, but from what I've read it might be too big for the level of boost we're running. Here's the list of contenders. Anybody with thoughts and experiences or sound bites, post them.

GReddy Type S
GReddy Type RS
HKS SSQV
Blitz Super Sound
Tial
TurboXS RFL

army_rx8

here is a page that has some sound/video clips to various BOV's...enjoy:D

http://www.935motorsports.com/bovmedias.htm

Dookie_Rx-8

anyone prefer one over the other? To me i prefer the one that looks like the sliver bullet it looks cool haha....other than that i dont know the differences

shelleys_man_06

Doesn't Tial have different sized BOVs? Also see what Turbosmart has to offer.

The only thing I know for sure about these devices is they relieve pressure on the compressor side, preventing damaging compressor surge. Plus, they make an awesome "pfft" sound. :D

RX-Nut

whats the alternatives to BOVs..

VelociRedBeast

I love the BOVs sound..send chills down my spine..

RXE16T

I prefer the louder ones, so definitely the Blitz would be my pick.

Relentless

HKS Super SQV
http://www.hksusa.com/products/?id=792

"The HKS Super Sequential Blow-Off Valve (SSQV) is a dual stage pull-type relief valve. Unlike typical push type blow-off valves, the SSQV will not leak under any level of boost because the boost pressure in chamber "C" keeps the valve closed against its seat. The SSQV releases excess boost when there is a pressure alteration in chambers "A & B", not by the rate of boost pressure or vacuum in the line. This ensures a quick valve response and complete closure during idle.

Many competitors use a push-type blow-off valve design with a large valve to accommodate high boost / high horsepower applications. These large valves react slowly and require high pressure to open, and are not able to activate and prevent compressor surge at light-load conditions. On the other hand, smaller, fast reacting push-type valves do not discharge the airflow capacity required for high horsepower applications and tend to slowly open and leak as boost pressure overpowers the spring.

For maximum performance, the HKS SSQV incorporates both a small primary valve for ultra quick activation, and a larger secondary valve for additional discharge capacity. The SSQV is engineered to initially open the small primary valve at light throttle and load conditions, then sequentially opens the secondary valve for additional relief capacity under high boost and load conditions.

The SSQV is constructed of polished billet aluminum, which ensures long-term durability and a high luster look. The mounting base utilizes a circular mounting flange that combines with a C-clip snap ring and O-ring gasket to insure an excellent seal. The triple-fin discharge port design produces a powerful, unique and aggressive blow-off sound."

http://www.hksusa.com/products/more.asp?id=792

Relentless

GReddy Type S and Type RS BOVs
http://www.greddy.com/

"GReddy Blow Off Valves are easily adjustable to prevent both premature boost leakage and compressor surge. Each is made of durable cast and billet aluminum frame and the valve to diaphragm ratio provides performance that cheap piston types cannot offer. The spring stiffness adjustment screw and 3 different sizes give the GReddy user the option to match vehicles with mild upgrades to heavily tuned engines. Also available in an easy to install kit form for many turbocharged vehicles."

Relentless

Blitz Super Sound BOV
http://www.blitz-na.com/Blitz_Blowoff_DD.htm

"The Blow-off valve is essential to all turbocharged vehicles. The purpose of the BLITZ Blow-off Valve DD is to relieve compressor surge without reducing compressor speed. It controls boost pressure that is built up by the turbo and vents it into the atmosphere when the car is not under load (in between shifts).

This prevents pressure from backing up into the compressor housing, causing the turbo impeller blade to rapidly stop or even worse, to spin backwards (compressor surge or backspin). Doing so can be potentially destructive to the turbine wheel and shaft. Repeated stress over time can cause eminent damage to the turbo charger and eventually lead to turbo failure.

A blowoff valve is actuated by pressure changes only, ensuring quick valve responses and complete closures at idle. The BLITZ blow-off valve not only improves performance and response, but also increases the life of the turbocharger."

Relentless

TiAL BOV
http://www.tialsport.com/

"For use on turbo-charged and super-charged applications (Paxton, Vortec, etc.). The body and all internal components are CNC-machined from 6061 aluminum alloy. It features a large 1.98 in (50.5mm) valve; we believe this is the largest valve available with the highest flow capacity.

The V-Band design aluminum mounting clamp gives a very clean and unique appearance. The clamp is anodized and uses Stainless Steel hardware for a long lasting, corrosion-free appearance.

The valve seal utilizes a Viton O-ring that is clamped in place to prevent the possibility of sticking to the seat and pulling out. The valve stem and guide are Teflon-lubricated, hard anodize-coated for wear resistance. The Blow Off Valve also comes with our own machined aluminum banjo-type air fitting and bolt, with over sized 10mm hose barb for quick actuator response. The actuator has a high temp silicone Nomex-reinforced diaphragm for long life."

Relentless

Turbo XS BOVs
http://www.turboxs.com/BOV/bovproducts.shtml

Blow Off Valve Type-S:
The BOV Type S is recommended for small to medium sized turbo charged engines running up to 15 psi boost. Each valve is individually tested to hold 30 lbs. of boost. Sizing of valve is based on flow and not boost pressure.

Blow Off Valve Type-H-RFL:
A new larger billet aluminum body and a beefier piston ensures the valve remains smooth under the most demanding circumstances. This valve relieves compressor pressure surge caused by changing gears or backing off the throttle quickly and is designed for turbo charged engines running up to 25 psi boost.

If you need to ask this valve is too loud for you!

shelleys_man_06

A lot of small-frame turbo kits don't include blow-off valves. I believe they do so since there isn't much pressure on the intake side, therefore compressor surge wouldn't be much of an issue. Is it possible to live without one? Perhaps. Personally, since I plan on running greater than 12 psi (someone please hire me!), a BOV would probably be in short order.

philodox

I recommend the GReddy Type-S for any application under 18psi. If you want to hear the BOV, here's a link to a vid I shot for my Greddy Turbo Kit.

http://tyrannical.org/philodox1.wmv

Relentless

Hey Jon, you said you got the Type-S for $139, and the mounting flange for $26, right? Just curious where you ordered them from.

Jeff

philodox

Jeff, it was a typo. I got the Type S for $149. Still, it's probably the cheapest you'll be able to find. I bought it from an ebay vendor. Here's the link to his Ebay store.

http://stores.ebay.com/Kuruma-Motori...enameZl2QQtZkm

Virgil

I think I am gonna trust HKS and Greddy Blow offs, maybe go for greddy as thier kit most likely works best with thier blow off valves. Its seem greddy is very smart when it comes to versitility and the upgradadablity of thier kits.

philodox

Well, any BOV will work.. A Blow Off Valve just releives built up pressure.. and that pressure doesn't care which BOV you use But since I have the Greddy Turbo Kit, I wanted to keep everything with GReddy.

Broke_Apex_Seal

I had the HKS SS BOV on my FD so I went with the greddy type S and not that is matter the profec e-01 to boot. All greddy so far for performance upgrades.

BoxerGT2.5

If the kits use standard flanges you may look at GFB and Worx. Are you guys running 100% Atomosphere or 50/50? The worx bov can be adjusted for both and an adjustment for sound. Just an FYI. Congrats on the FI!!!

philodox

My Type-S is VTA all the way.

Muzz

Why do people vent to atmosphere? I always thought that the guys with BOV's making 'da big noise' were just posers.

Isn't it better to route it back into the intake to keep the turbo spooling between shifts?

Or does it not make much difference at all? On my supra my BOV was always venting straight back into the intake.

bureau13

The turbo won't stop spinning between shifts unless you take an awfully long time. I don't think rerouting it has any benefit in terms of performance as long as your engine management doesn't get confused (depends on location of MAF and whether or not the computer can account for the missing air, which the EManage can...I learn more from these threads every day )

There is nothing "poserish" about not taking an extra step to be subtle (like rerouting the BOV vent to the airbox to mute the sound a bit). If you want the living, breathing definition of automotive poser go here.

philodox

Well, if you have no BOV at all, the pressure built up after you let off the throttle bounces off the throttle body and goes back to the turbo itself. That's why when you don't have a blow off valve you hear that "quacking duck" sound. That's the turbo actually despooling and spinning backwards. Then when you get back on the throttle, the turbo needs to do a full blown spool up again. Not to mention that not relieving that backpressure can damage the bearings in the turbo housing itself.

-Jon