zyounker

iTrader: (1)

Ok, i have a type-s on my evo and noticed the initial problems.. i hooked the lower nipple up to the WG line and it actuates much quicker. I currently have it adjusted almost all of the way out and it does open a little when not under boost.. (i need to adjust it a little)


It works much better this way then leaving the lower line open.. i will probably try taking one of the springs out today and seeing if that is better..


BTW you should not plug the lower nipple from my understanding.. when not hooked up it is a vent to the diaphram..


-Zach

Incognito

iTrader: (8)

Stock BOV
Pro: You already have it. It drives good. No compressor surge.
Con: sounds weak. looks weak. IS weak. Doesn't hold much boost over stock.

GReddy Type S modified
Pro: holds boost (to a point), very quick response, drives like/better than stock. Recirculating
Con: sounds really gay with the chirps, and when it does blow off, it's weak.

HKS SSQBOV
Pro: design, sound, holds as much boost as you're willing to run
Con: vent to air design causes a little bit of surge/dropping below 800rpm at traffic lights

Either the GReddy or HKS will work fine for you. It's just personal preference pretty much. If you drive 100000 miles a day and need the car to be super smooth, get the GReddy and modify it. If you like the funky sounds that an aftermarket BOV makes, and is looking for something that looks real nice, go for the HKS.

This is irrelevent, but the HKS one is vent to air, so the car WILL run rich for maybe 1/2 second after U let off the gas. With that, it's made my car a fire breathing monster, lol. I was doing a top speed run last night, and a little before I ran out of road, I let off, and the car shot out 2 fireballs. My sister witnessed it and thought it was cherries from a cop car. I will try to get a video clip of it (just have to find someone willing to chase me on a top speed run). Oh yeah, don't buy the HKS BOV because I shot fireballs. Your car might not. No guarentees, lol.

Liandrin11

What the hell??! How did the SSQV make your car shoot fireballs? Was the mixture so rich it didn't burn completely until it was out of your tailpipe?

Incognito

iTrader: (8)

Yes. U answered your own question.
I think it only does it at high rpm, when the car has been run for a little while. Gas doesn't just ignite. The inside of the exhaust pipe has to be hot enough (but then again, the exhaust does get pretty hot, even at idle).

eslai

The SSBOV does have an adaptor you can buy to allow it to recirculate the expelled air so you don't have the "run rich" problem. Check the other thread that one of your members made that outlined his SSBOV install.

zyounker

iTrader: (1)

Ok, i tried this on the Type-s/.. taking the smaller spring out.. and it works fine like this..

SILVER SURFER

Oh it's not the nay saying that I was referring to, it's all the time and energy, we have spent rehashing the same info on a modification that is relatively minor regarding performance. I guess this kind of goes with posting in an open forum. Sometimes I think that I do not come across well in print, I know my grammar sucks.

Eslai,

The Dejon site you pointed to does recommend using the assist barb, but they also are using an additional pilot valve. Quote from there site:

To seal we want no boost pressure under the BOV diaphragm until the TB closes - then we want full boost to open the valve. The solution is:
1-drill and tap a hole in the side of the BOV flange to intersect the small hole in the valve's flange bottom (which goes vertically to the underside of the diaphragm), insert a 1/8" hose fitting and seal the hole in the flange bottom with a 10-32 set screw.
2- now we have to switch the pressure to this fitting between atmospheric pressure when manifold pressure = boost, and boost pressure when manifold pressure drops. We do this with a small 3-way - pilot pressure operated valve, using the manifold pressure to operate the pilot. (activate the valve) It requires 15psi to switch. So with pilot (manifold) pressure less than 15psi the valve sends boost pressure (from a tap in the intercooler piping) to the underside of the diaphragm to operate it normally, and at boost over 15psi the valve switches, venting the diaphragm's underside and sealing the BOV. Leakage almost completely seals!

END QUOTE

If you do it this way then yes, I think the assist barb would work well. If you connect the assist barb directly to the manifold before the TB without this Pilot valve IMO the BOV will leak under boost.

I have no testing with this pilot valve configuration, but IMHO getting the right spring tension will work just as well and is less complex.

Kind regards,

Eric

Mach V Dan

iTrader: (19)

Nice science work, Eric. Thanks for the info.

We sell a ton of atmospheric BOV's, but I try to stress to our customers that they don't do anything for performance. We also sell the TurboXS H-34, which is a bypass valve, but that's a much slower seller. The kids love the BOV noise!

For a long time I've pondered making a solenoid-actuated bypass valve. In theory, that could have infinite ability to handle boost, but would also have perfect response...it would also be ridiculously complex and expensive...

--Dan
Mach V Motorsports
MachEVO.com

jfh

iTrader: (38)

Anyone done any testing on the Forge MotorSports Diverter Valve? Uses a single piston (no diaphram) controlled by springs which should be able to be changed to decrease pressure differentials and improve response and drivability as demonstrated by Silver Surfer with the Greddy Type-S.

SILVER SURFER

Thanks Dan,

I had the very same thought

Regards,

Eric

emulous

iTrader: (2)

IMO you come across very well in print. I just picked up my EVO less than a week ago and have noticed the partial throttle stumble and yes have heard of a BOV, but didn't know much about it. Your post and the replies educated me more than when I walked upon this thread, so I know that I benefited from it. Yes, you had to defend what you posted, but you did it well and showed that you actually read the responses.

It's great to see someone that doesn't accept the status quo and get's his hands dirty to make something better suit his needs. To get a little philosophical, I think it was Ayn Rand that said something like an animal adapts to it's surroundings, man has the ability to make his surroundings adapt to him.

This has caught my interest enough to go out and see if this solves my stumbling/bogging problem.

I guess what I'm trying to say is Thank You for posting and hopefully you will see for yourself that it was a worthwhile post.

FQ300

Hello Guys. So basically on the subject of BOV's the Forge venting to atmosphere type is the way to go? I'm about to buy one that vents to atmosphere, but am torn between Forge and HKS super sequential BOV.

RENN-ART

iTrader: (11)

eh.. no.. if u would have read this thread you would know that the concensus is that it's the recirculating version that is the best, not the vented to atmosphere...

SILVER SURFER

Thanks for the positive feedback, I am glad this info was useful and that most seem to understand the points I was making.

Emulous,

I also wanted to thank you for your post on the aftermarket cruise control, that's on my to-do-list also.

FQ300,

It is not my intention to recomend any specific BOV, I think most valves will work well as long as they are properly calibrated. As spooldswede already told you, I do think that a recirculating valve is a better way to go in this car.
I have not inspected/tested the valves that you mention(HKS, Forge), but there are several posts about them (take a look). From what I have read, it seems the standard spring tension in the HKS may be to high for our application, I am sure it can be adjusted to work well. Some have also claimed that this valve works better at holding boost, I don't know why it does, they never explained how it is better.
The Forge looks like it will fit well in the stock location and it is supposedly already calibrated for our cars. If that is true, the slightly lower cost and plug and play feature could make it an attractive option for some. From the pics it does not look to have a spring compression adjustment. So each seems to have it's pros and cons, with cost, features, and basic design.

This is what I look at when evaluating a BOV:

Will it easily fit in the stock location?

Is there a rubber seal on the valve?

Does it have a good actuator piston to valve area ratio, the bigger this number the better (unfortunately most manufatureres don't give this spec).

Does the actuator piston chamber have a rubber seal making it air tight? Some that I looked at did not, this could adversely affect performance.

Can I easily adjust spring tension?

umiami80

iTrader: (1)

That is probably the worst thing you can do. The car meters air through the MAF system, you shoot the air off into the stmosphere, the car still thinks that it is there, and dumps the fuel based on the reading. But no air, so you run rich, and stumble, and **** the car up as it runs very rich between shifts. The HKS SSQBOV is a nice piece but the sprongs are so tight that they do not open to vent unless you have WOT, so the car gets compressor surge all the time and causes you to studder and actually stalll a lot.

Best bov? Buy a Crushed 1G BOV for Buschur racing, it'll hold 25+ PSI, and works just like a stock unit.