Blackbird

I am going to be going draw thru with my custom ATI setup and I am wondering if the trusty Bosch bypass valve like I used on my Powerdyne will be up to the task? They claim good to 20psi or there-abouts, but of course it's more about volume of air than psi since 10psi of boost on a geo metro is alot less air than on a LS1.

Thanks in advance.

Pro Stock John

iTrader: (34)

18-22 pulleys on my car, I have the Vortech Mondo Bypass.

frcefed98

iTrader: (16)

I wouldn't trust it, go with a HKS SS or the like. I have a Turbo XS Type H on my ATI kit, was easy to put on too but I will be upgrading to the HKS soon.
J

Blown Ta

iTrader: (20)

can i use the vortech mondo or hks bov on 5 psi?

Blackbird

I am talking bypass valve not blowoff. I believe the bypass is normally open and slams shut under boost where a blowoff is normally shut and blows open under pressure. So I am pretty sure neither of those you mention would work for me.

The only thing I have seen so far is the Vortech Mondo but that ****** is so freekin pricey.

frcefed98

iTrader: (16)

Nope the your are thinking wastegate, it opens when too much boost pressure is present. The BOV's I listed do the same thing as the vortech mondo. It is a blow off valve(Vortech Mondo). When you let off the gas they all(vortech, hks ss, turbo xs and other blow off valves) open up and vent the boost pressure to atmoshpere. When under vacuum, the are open, under positive pressure(boost) they are closed. They open to vent boost from reversing and slamming into the impellar blades of the s/c which will cause damage to the impellar and break s/c belts on decel or when boost isnt needed i.e crusing, idling at a light.
Get the HKS SS or the turbo XS type h or RFL. They will do what the vortech mondo does, which is vent under cruise, decel and hold boost under WOT. Trust me my Type H works just fine on my car.

99tran I would go with a Turbo XS smallest valve, that will handle 5psi no problem, or just stick with the bosch bypass those do the job just fine at those boost levels.
J

frcefed98

iTrader: (16)

Here is a vid of my BOV in action,
http://home.comcast.net/~jsbird98/bov.mov
3.6megs
When I let off the gas after my burnout is done, it opens. You will hear it "whistle" or blow off the boost pressure so it doesn't reverse in the intake tract and cause damage to the s/c or belt.
J

Blackbird

I understand what your saying J but I want a bypass, not blow off. when you use a draw thru maf (pre blower) you vent the air back into the intake track preblower, not the atmosphere. that's the difference between a bypass and a blowoff. Your setup the maf is post blower mine it will be pre blower. If I vented to the atmosphere it would go super rich because the air has been metered but will never get to the engine. on yours you will notice your blow off valve is pre maf so the air never makes it to the meter thus never metered and as such you don't go super rich. I find the noise blowoff valves make extremely annoying plus it seems harder to tune a push thru setup thus wanting to do drawthru and needing a bypass which is open under vacum, closed under boost. Very different than a blow off valve.

Hopefully all my mumbo jumbo and run on sentences makes sense

frcefed98

iTrader: (16)

Perfect sense, I missed the pre blower bit. Sorry about that. Turbo XS makes one for mass air flow cars, and so does HKS. They(HKS) sell's an extension that you hook up a rubber hose to your inlet hat on the s/c and to the bypass/bov. They are quite but move a lot more air than your standard bosch type and do exactly what you want. Here is a link to the HKS unit
http://www.hksusa.com/products/?id=798
bigger pic of the extension
http://www.hksusa.com/images/?id=1162
Summit has the Turbo XS mass air bypass/bov on their site*edit* didn't find it go here www.turboxs.com/racing_bypass_valve.htm Racing Bypass Valve Type-H34- 189.00 not bad...*
J

Blackbird

thanks J.

I may have to break down and get the turboxs.

i would hate to cheap out and trash my blower because of it.

although my brother pushes 9psi thru his 331 on his mustang using the bosch valve with no problems.

oh decesions decisions.....

S_J_H

I'm using a Vortech Mondo. It's pretty large with a 1.75" valve and 2" outlet.
They are very high quality valves.

Crunch

The Vortech V9 G-trim kit comes with a bypass valve. Yes, it runs from the aftercooler back into the intake tract before the supercharger. I have no plans to change it.

S_J_H

yes the Vortech kit comes with the trusty plastic Bosch valve.
Crunch, If you plan on really spinning your G trim high, I would plan on changing it first.

StalkerLS1

I had an Apexi BOV on my V9 G-Trim not long ago and for that matter not long at all. It sounded cool at first but definitely got old QUICK and dumping metered air was causing havoc on my tuning so I put the bosch bypass valve back on it.

slow

iTrader: (7)

it is also not so much boost, but volume as well, that determines need, you said custom install, how big is the intercooler, ect, how much piping blower to Tb?

more piping, = more air, so you need to size accordingly. I know of people using 2 and 3 Bosch style ones, with intercoolers, due to volume, But a large high quality one is best imho.

Ryan.

black_yukon

If you already have a setup for the bosch valve, there are plenty of upgrades for it that fit the stock setup. The bosch valve is the same ones used in the turbo Audis, VW's and Porsches, and a lot of those guys are upgrading from the bosch. Here's one option. http://www.forgemotorsport.com/valve...oduct=FMCL007P
You can check audi S4 forums and do a search on diverter valves for more info.

Blackbird

thanks, they look good. I emailed them to see if they knew how much cfm they will flow. hopefully they flow enough. The look and price are both pretty good.