superjet.1

I hear people talking about aftermarket boost bypass valves and adjusting them.how does one work and does it help a stock 951?where can i get one? <img src="graemlins/wave.gif" border="0" alt="[byebye]" />

*eurospeed951*

Poof! I just installed one on your car. It's the black plastic thing in your intake boot.

superjet.1

ha ha i know that much but what im getting at is does and after market adjustable unit provide any performance gains for a some what stalk 951 thanks guys. <img src="confused.gif" border="0">

Danno

no.... only a possible performance loss if your stock one has failed (one of failure modes). Otherwise no advantages in replacing the thing unless you're running monster boost and getting monster HP (like 300+rwhp).

superjet.1

thanks danno you always have great answers.

Seattle944t

I can vouch for the performance loss part. I just replaced the bypass valve in my car with one of the Forge 007's and my boost level when up 3PSI to 18PSI. I didn't do if for the extra boost, I was more interested in the residual pressure between shifts and the reduction of boost spikes. Some Audi guy(s) [The 1.8t's and S4 motors all use this same Bosch bypass valve] tested the factory valve vs the Forge one and this is was what sold me on it:

<a href="http://www.audiworld.com/tech/012301.html" target="_blank">http://www.audiworld.com/tech/012301.html</a>

I was using the newer factory 993 types with the brass 'door'. It was fairly new, just bought it about one thousand miles ago. Haven't checked to see if it's got a torn seal or not but at this point I don't really care .
I thought saw a thread here talking about the factory valve not seating properly and bleeding off boost even when they didn't have a torn seal, but a quick search didn't turn anything up for me.

At any rate the Forge valve is a pretty nice unit, the 007's are only slightly larger (about 1/2" taller and 1/4" bigger diameter) than the factory one so they fit in the stock location. The adjustments for it are done with different springs for the piston.
It also eliminated a moose/whistling noise from the stock valve from 2K-3K RPMs as the valve closes. But I may miss that noise cuz it was an audible clue (warning ) that full boost was on the way....

Konstantin

is your car faster now, does it build boost faster? what is better with the forge?

Konstantin

adrial

Seattle944T, is the 993 part for sale?
If so, how much do you want for it?

Email me privately if you don't want to discuss it here... adrial@cloud9.net

aka 951

If your boost went from 15 psi to 18 psi you may want to check something other than your blow off valve as there is something wrong with your car (blown hose, bad wastegate, etc.). It will be a cold day in heck..lol..when a blow off valve gives you 3 psi. Not to sound like a ***** but it just is not possible if your 993 valve is in good working order.

Seattle944t

[quote]Originally posted by Konstantin:
<strong>is your car faster now, does it build boost faster? what is better with the forge?
Konstantin</strong><hr></blockquote>

Well if I leave the boost level at 18PSI it will be faster - Right now I have it dialed back to 15PSI. Dyno session Saturday will tell me if I have enough fuel for 18PSI. I tried running 17PSI before but was too lean. Since then I have added a 3.0 Bar FPR so we shall see.
The boost does build faster - but only marginally, maybe two hundred RPM's at best.
As far as what is better - the constuction of the unit is all metal. The piston is all metal as well with rubber 0 rings to seal it. It's also completely rebuildable. The top of the unit unscrews to allow changing of the spring, piston, and or o rings. Also, the 007 version is a direct fit to a stock intake system, no fabrication or tube rerouting necessary.

[quote]Originally posted by adrial:
<strong>Seattle944T, is the 993 part for sale?
If so, how much do you want for it?</strong><hr></blockquote>

Sure I would sell it - but I don't know if it has a seal leak or not. I can a manually check to see. Say $20 shipped by US mail?

[quote]Originally posted by aka 951:
<strong>
If your boost went from 15 psi to 18 psi you may want to check something other than your blow off valve as there is something wrong with your car (blown hose, bad wastegate, etc.). It will be a cold day in heck..lol..when a blow off valve gives you 3 psi. Not to sound like a ***** but it just is not possible if your 993 valve is in good working order. </strong><hr></blockquote>
I would agree that this shouldn't happen, but it did. Factory 15PSI, Forge 18PSI, Factory back on, 15PSI. So the Forge valve did increase the boost w/o any other changes, no question.
Why? Could be either A) factory valve seal is torn (already), or B) factory valve doesn't seat properly at high boost.
If it's A) then the factory valve is near useless for higher than stock boost levels (only about 1,000 miles on this valve and it's toasted) If it's B) then it's the same thing. Either way I will not have this problem again so I am happy .

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Luke

[quote]Originally posted by Seattle944t:
<strong>.
If it's A) then the factory valve is near useless for higher than stock boost levels (only about 1,000 miles on this valve and it's toasted) If it's B) then it's the same thing. Either way I will not have this problem again so I am happy .

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> </strong><hr></blockquote>

I would most deffinately lean toward this one. We all know that the stock wastegate ins't suitable for higher than stock boost levels either.

lou951

I too picked up 3 psi when I installed the Forge valve. I have a Boost Enhancer that was set to 15 psi. My boost gauge confirmed that. After installation of the Forge unit, boost went to 18psi. I have an A/F meter and it reads safely at full boost (actually rich, guess it's the APE chips doing their job). I presently run the car @ 18 psi. I know that many have asked for a tangible result on the installation of the Forge valve. All I can say is that it is more of an insurance policy. I consider it part of the foundation for the bigger turbo I will be installing soon. (Hope to get into the 450 hp range along w/ other mods.) I wouldn't trust the factory valve.

danny951

Just noticed today that my valve is broken.. so I need a new one and just wondering if I should get a new stock valve or something that says it is better..

Not sure I understand how it could be better when all it does is keep my turbo spooled longer.. (not sure how it could give more boost).

stock part is like $30 right?

lou951

Basically you hit the nail in the head, it keeps the turbo spooled longer between shifts. Most importantly though, it protects the turbo by keeping it from spinning backwards. The stock valve is weak and prone to breakage, therefore it will not perform the above mentioned tasks correctly. That is why I installed the Forge valve. It works correctly. The reasoon that I picked up an additional 3psi is because the stock valve leaks, even when new! Not a good thing.

Ahmet

I see a few upsides to the stock valve, my guess with a good level of certainty is that it will open earlier... The website posted by Seattle944t also shows this. Secondly, I really have a hard time believing that a stock BOV with only a few 1000 miles on it would leak any pressure at ~15psi. However, at higher boosts, I suppose it's possible. Also, I should point out the stock BOV might open with less vacuum (very important IMO) at near stock boost levels, but I can see the design binding at higher boost levels. The actual piston in the Forge unit would increase contact area between the piston and the cylinder dramatically, and I don't think it's likely to bind, at any pressure one would run with a street engine.

Also another thing I should point out, the website also mentions that boost is used to keep the forge unit closed, this is not true as with all BOVs I can think of, (edit: after reading the post by TC, he's right spring pressure +boost is used to keep the valve closed, as with all the other BOVs, so the Forge unit's not that special in this aspect)spring pressure, and maybe a bit of friction from binding will hold the valve closed, until there's vacuum on the other side of the piston/diaphram. Basically the size of the bore, the rate of the spring, and the friction of the piston/cylinder determine how much pressure the valve will take to open. The forge unit has a larger bore yes, but I think the spring is way too stiff anyway.

What does this mean? Not a damn thing, I'm just trying to justify sticking to my 993 BOV (funny, I bought a stock BOV, than updated to the 993, and WAS considering the Forge unit).
Ahmet