cobalt

Has anyone had the need to replace their bypass valve? What have you heard about the Billet version they are advertising at 20% discount on the 911 forum. How difficult is it to replace and were is it located? I heard the factory one has a cast housing weighing 6 pounds more and fails more than we would like.

Any input, Thanks

emilios

Hello Anthony,

I had mine replaced as the stock plastic item (made by Bosch) operates with a diaphragm rather than a piston like most aftermarket ones and is VERY prone to failure. I got an adjustable valve from Stratmosphere, took me literally 10 minutes to replace- made a noticeable difference especially during hard acceleration, the car urges forward after every gearchange with considerably less turbo lag.

The new valve fits in the stock position with absolutely no modification whatsoever - it is located just in front of the intercooler on the left hand side as you stand looking at the car's engine.

Best regards

Emilios

P.S. Total BS about the weight saving- the plastic stock item probably weighs 100-150 grams, the aftermarket slightly more as it is metal / aluminium.

cobalt

Thanks Emilios,

No weight savings but worth the $104.00 US in response. I think I will give it a try.

I'll let you know.

Regards

Anthony

KeithC2Turto

The weight savings is on the 930's. The C2T's have the light Bosh valve.

With the stock valve you should hear a "woosssch" between shifts at higher rpms. If not your's is bad.

I bought the Stratmosphere adjustable also and miss the Woosch sound some.

Keith

emilios

"miss the Woosch sound some"

Keith,

remember you're driving a Porsche and not some Jap modded car!

Best regards

Emilios

P.S. By the way, how do we adjust the stratmosphere valve - any suggestions/recommendations Keith?

KeithC2Turto

Emoilios,

Confuesed here.

Porsche deisgned it to make the woossch sound.

The aftermarket valve is designed as a replacement for Bosch valves that I don't think are on the Asian imports.

W the aftermarkedt valve it no longer makes the stock sound. I think because of the weight & style of the aftermarket valve. It dose not relly make much of any sound.

If you still have a stock valve and it dose not make that sound it is likely the valve is bad.

As to adjustment to the new valve, it is more of a marketing thing I think.

I tested the signel vac at idle and cruse and tested the point where my valve reacted at both ends of adjustment. Even at the tightest spring tension I suspect it will function close to the stock valves.

There are some other peramiters I did not test like how much vac there might be in the intake tube that it dumps into might be effecting things.

I had mine set at the softest when I bought it and put it to the tightest. Though it helped but am very suspect.

Keith

special tool

Yup, and I have to say that I just got a Forge racing adjustable recirc. valve (as opposed to a blow off valve - which vents to atmosphere) and it makes a little more noise than I would like. It also works better than the 993.

Staffan

I use the Forge recirc one after I found my Bosch was toasted.
Perfect fit, took 5-10 minutes to install.

cobalt

So I installed the Billet bypass valve (I liked the sound of lifetime warranty and for $104.00 what the heck). It took ten minutes like you said.

Test drove the car and it feels like I just gained fifty horses. The power feels like it comes on much stronger and earlier. Now the concerns. The boost gage is reading .1 bar as early as 22-2400rpm? It never showed any boost until 2800rpm in 1st previously. However it does feel as though the boost is coming on much earlier and stronger. The boost stays up much longer allowing me to shift and retain boost levels through the shift verses loosing boost by the time i hit the next gear. When I am cruising at 80+ mph the gage is reading .3 bar, previously it read 0. When I got home and sat in the driveway the gage was reading .2 bar for about three min and then .1 but would not drop to 0.0. I restarted the car and everything appeared to be working properly. The boost would come on low as before but when coming to a rest it dropped down to 0. The gage still reads .3 bar at 80+mph with lite throttle. I am very impressed on how the car is responding the power appears to be much stronger spinning the rear wheels with half throttle in first and if I punch second will continue to spin them. Couldn't do that so easily before. I know the temperatures being in the high twenties may be attributing and I don't think it was cold rubber because I drove the car hard felt the tires and they were adequately warm. Does any one have any comments.

Staffan

Your old CBV was most probably toast, could have been stuck, probably closed at all times.

I had the same experience in regards to keeping full boost between shifts when I had mine changed. Your new CBV keeps the turbo spinning between shifts, but it's not possible to have 0.3 bar turbo pressure standing still on the driveway (only on competition WRC and similiar cars), so that is really strange, can't see how the CBV change could give you these strange readings.
What gauge are you refering to, the stock digital one ?

Is your fuel cut out switch grounded ?
If that is the case (which is common when using 1 bar spring) you could be in a situation when the car is producing more boost than whats healthy for your engine without you knowing about it.

Don't want to scare you, just be careful if your car starts to produce that much more hp. It could be a leak to the wastegate so it doesn't open up when it should. Only thing I could think of related to the CBV change, is that the small hose on the left side of the IC got disconnected one way or the other, that could produce more boost.

Lots of speculation on my part, I am just concerned about the increase in power, better safe than sorry! Keep us posted.

cobalt

Appreciate the input.

I was very careful not to dislodge anything in replacing the valve., I checked the ground cable on the fuel cut out switch prior to tightening the clamps. Is the small hose the one on top of the valve? That is secure but I will check to see that the clamp is not too high on the hose choking the flow. I did not see anything small coming from the IC prior to or after replacing the valve, the only thing I recall seeing is the plug and the connections for the valve itself. i will check closer when I get home tonight.

The reading was actually .2 bar which eventually dropped to .1. I knew this could not be correct so i turned the engine off and restarted it and ran the car for a while longer. The reading went away and did not repeat itself after that. However I am sceptical about the .3 bar reading while costing at 80mph with marginal throttle.

I am not so sure If I am overboosting as much as just experiencing the boost kicking in at lower rpms. SInce I have the crappy stock gage that only reads up to .7 bar I have no way of knowing for sure. I would like to replace the tach with one from a 993 if it is compatable.

I know with the B & B exhaust i should be spooling up earlier than stock but how much? I thought normal spool up was about 2800 to 3000rpm so should i be seeing boost kicking in at 22-2400rpm with the B & B. If the previous valve was leaking would this be a result of the change.

I'll be honest with you I think 1.0 bar spring is a bit to close to the edge. The previous owner had just installed It and I left it in. I am thinking about changing some exhaust components and reducing the spring a little to prevent any possible issues. I did notice a considerable improvement in how the car handled that off and on again pedal response when under load with the new valve in place.

I won't be able to test the car as we are supposed to get several inches of the white stuff soon. I will keep you informed when I know more.

Thanks

KeithC2Turto

The factory boost guage is tied in at the intercooler before the throtle body.

It is possable that at 80 you will be building boost.

However if you guage was hooked to the section after the TB and before the intake valves you would see that you are still pulling a vacunm unless you start ot accel.

It is interesting that you can hear the Billet valve. with mine it went the other way and got quieter. I assunmed it was becuse of the increased mas and bigger free opening that flows more air so it does not go wooosch, woosch...

Keith

69COU

Anthony

Can you take a picture of the new valve in place, also not sure if mine needs checking as i tried the test of hard accelaration and changing gears but never really hear the sound. I do notice that the car does drop power on gear changes.

Only concern is that if valve keeps some booast whilst cruising at 80 is will you fuel consumption take a dive.

Pierre

cobalt

I get awful gas mileage to begin with. I was just surprised to see a change from 0.0 to 0.3 under identical conditions.

I may try putting the old valve back for a comparison since it only took a few min. This weather may stop me for a while.

Staffan, I see the hose you were referring to now. I wasn't thinking clearly before. I checked the hose and everything appears to be correct.

Here is the picture of the valve in place.

Here is a picture

Staffan

Anthony

Just remember I am no expert on this.
Look at your picture, the orange thing on the intercooler is the stock boost sensor, just to the right is the fuel cut out switch. When boost reaches 1.1 - 1.3 bar (or so) the fuel pumps gets cut out to save the engine. The location on this sensor is not ideal since boost spikes are created in the intercooler.

Many owners who switch to a 1 bar spring and/or aftermarket headers and mufflers get boost spikes that activates the fuel cut out switch. The easy way out is to ground the fuel cut out switch, which is not the way to do it. The problem disapere but the lifeline is gone.

To be on the safe side I would check to see if the fuel cut out is grounded, That could be the case since you have 1 bar spring and aftermarket headers. If this is the case I think you should get a boost gauge of some sort, as you pointed out the stock one isn't helping here.

Once again, I am no expert and I don't want to scare you, but worst case would be that something is wrong, the car is producing to much boost and you don't know about it.

Also, the small hose on the left side of the intercooler is connected to the wastegate, it could be leaking further down where it connects to the WG.

But the structured approach to this is first to find out if the fuel cut out switch is grounded or not, post a picture if you are not sure. If this is the case next thing is to get a boost gauge.

Either you will find you have a problem and increase longetivity by fixing it, or you don't have a problem and will sleep better at night knowing your boost pressure is ok.