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Discussion Starter #1
I've been looking at Forge's website. Specifically, I have been looking at the dump valves. I want to get one for the Viggen. Not because I think it will make it faster, or because it's somehow better performance wise. But sometimes I like to go out at night and scare the local Import Owners with some healthy boost noise. But even with the open air filter element (which has since been replaced with a stock air filter) there was very little in the way of boost noise. Wouldn't run it around town normally, but this valve is "supposed" to work on Mass/airflow sensor cars. As it is TWIN piston and does not allow air in at idle:

http://www.forgemotorsport.co.uk/products....product=FMDV004

Looking at the other atmospheric valves, they say specifically that they are NOT compatible with mass airflow cars, but the two ram twin piston ones seem to be. Just curious if anyone has comments on it. They do have one with a filter on it. Which I thought was kind of neat.
 

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The Forge twin piston design does indeed work with mass metred cars, as does the Bailey DV26 Evo (also twin piston).

I ran a Bailey Evo dump valve for many months without problems until deciding to replace it with a Forge recirc unit as I was getting tired of the noise.
 

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Apart from the possibility of leakage which gives idle problems, I understood that the other reason atmo dump valves don't work with AMM cars is that at the point you dump the pressure, the engine will overfuel (possibly to the point of flooding/stalling) as the ECU is adding enough fuel for the air which it has metered but rather than going in to the cylinders, has now been lost...
 

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Adrian w,

I will be curious to hear the results. What bothers me the most is that there are tons of hypothesis why a dump wont work on a T7 car. Still there aren't actual tested results what really happens when a dump is installed.

Thumbs up from me
 

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Discussion Starter #5
Figure at the VERY WORST I get one REALLY GOOD WHOOSH out of it before it stutters and dies.
If it doesn't work after that I wasted about $140 but heck ... might be worth it for that one good whoosh. Sides I think it may very well work. An AMM car typically disregards the airflow sensor for a split second when shifting. Because when the air is being dumped the throttle is closed and when the throttle is closed the airflow gets pretty unpredictable, and the airflow sensor isn't really sensing anyway. Do wanna try it though. Now if I can just scrounge up $140 ... being in debt kind of sucks.
 

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Originally posted by Adrian W:
[qb]Figure at the VERY WORST I get one REALLY GOOD WHOOSH out of it before it stutters and dies.                  
     :fawlty:      If it doesn't work after that I wasted about $140 but heck ... might be worth it for that one good whoosh.  Sides I think it may very well work.  An AMM car typically disregards the airflow sensor for a split second when shifting.  Because when the air is being dumped the throttle is closed and when the throttle is closed the airflow gets pretty unpredictable, and the airflow sensor isn't really sensing anyway.  Do wanna try it though.  Now if I can just scrounge up $140 ... being in debt kind of sucks.    
 [/qb][/b]
Could you not just make a deal with the seller that you will try it and if it works you will then buy it? This can be hard to arrange if purchaced via internet.
 

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Discussion Starter #7
I think I would have to buy it Via the internet.
Might be able to arrange it anyway. Just give them the credit card number and "buy" it, but have them not actually charge it until I either refuse to give it back, or agree to buy.
 

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Discussion Starter #9
Like I care if the ECU doesn't like me!
That's why battery cables are detachable. Well aside from being able to remove the battery from the car, which could not have POSSIBLY been the primary purpose given that doing so resets the whiney ECU.
 

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Discussion Starter #13
Fuses shmuzes, nothing like the sight of a very unhappy baterry cable dangly oh so close to its terminal. It wants to be on the terminal, it NEEDS the terminal, much like the Mountain needs the storm, but alas ... DENIED!! Oh the SHAME!!
 

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I found this at an other saab forum:

I have a 2002 Viggen and I just installed an atmospheric dump valve. I can not be too sure if there is any performance increase but the sound that is produced is awsome. The combination of the Opti-Flow intake the dump valve and a freer flowing exhaust really make this SAAB sound great.

But I do have a problem. After long stints of hard acceleration the check engine light comes on. If I take it easy the light doesn't come on. While the light is on the car does not run any different.

Any Ideas?


He person did not mention what type of BOV he used.
 

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Discussion Starter #15
Probably just the ECU whining about the BOV.
We'll see if mine does it, but it appears as though I have a dyno day on my list of events first whence I get the money.
 

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I ordered a Bailey dump valve today for the 99. Spent an hour or so chatting to Bailey, as I wanted as little "whoosh" as possible. Eventually we decided to go with the atmospheric twin piston type, but with the stronger spring (used for boost pressures of up to 2 bar. This stronger spring slows the opening rate, and therefore the gas release rate slightly. Means the effectiveness of the valve is reduced a little, but hopefully not too much
 

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Here is some more info about the case I posted above.

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I had already purchased the BOV by the time I found this thread. I purchased the unit from Forge Motor Sport. The car ran fine with the CEL on. But it was annoying to look at. Restating the car did not reset it. And I drove with it on for a couple days to try the multiple start method. I may not have done it long enough though be cause it did not work. I had to disconnect the battery to reset it.

I called Forge in FL about the CEL but the guy I talked to had no idea that the BOV would not work on my car. They did offer to exchange the unit for the recirculating one though.

Vigge, was unable to get the code from the ECU, sorry.
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So no luck with the forge unit.
 

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Discussion Starter #18
Well ... no luck if you don't like the CEL on. I only want it to make some noise at the track when I finally get some finances back here. Might save me showing everyone the turbo on the car when they wonder why a lil 4 cyllinder Saab (why does this thread force ellipses on that?) was so fast. I don't wanna run it around town anyway. Most of the time the stock BPV is more than adequate at releiving boost pressure. Just not good enough at making noise.
 

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Well, if you are looking for the noise but don't want the CEL and perhaps stumbling or such from different fueling because of the atmospheric dump valve, there is an option. Get a BSR Optiflow intake. You'll hear the dump valve dump, just the same as an atmospheric one, and also hear the tubo spool up more and the intake whoosh as you get on and stay with the go fast pedal. The Optiflow comes with a barrier to combat uner hood heat and needs just a little bit of work to seal it off from the rest of the engine bay.

You can see pics of it at www.bsrab.se .
 

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 the engine will overfuel (possibly to the point of flooding/stalling) as the ECU is adding enough fuel for the air which it has metered but rather than going in to the cylinders, has now been lost...  [/b]
Presumably also increasing wear on the engine as the oil film is washed off the cylinders at the same time?
 
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