Where's the cheapest place to replace my bypass valve - stealership wants $126 for it!

If the spring is broken, can't it just be replaced? Instructions on components needed?

 

that seems to be the going rate for bypass valves ... you can get the Detroit tuned one though for that price and it will give you better response then stock.

 

from what i understand, the DT tuned one is basically a different spring rate

 

Correct. That, and the butterfly has been properly radiused to allow it to fully close. Stock BPVs have a notorious reputation for not fully closing due to a poor match of the butterfly to bore. The fact that both the stock and DT BPVs are comparably priced makes this a no brainer when it comes time for stock replacement...

 

Not quite so fast....Many tuners I've spoken to say that the stiffer spring in the DT makes it more difficult to feather the throttle.

 

Simply keep the spring off the stock BPV in the event that the DT one is too stiff. Swapping the spring is easy-peasy. I still think its a no brainer...

 

I think the OP believes his stock spring may be bad...

 

Anyone ever find out if you can get just the spring? Why spend the money on an entire new BOV if you can replace just the spring?

 

Good question. I already adjusted the valve and it closes nicely. If one could get a stiffer spring of the same dimension as the OEM, that would be great.

 

Well I went ahead and just ordered the DT BPV. I may try pulling it apart and looking at the spring before I put it on. Hopefully it will show up soon! The little mini is a slug without any boost!

 

did you get the dt bpv installed, and if so, how do you like it.

 

I have had a DT valve for a while now and never had a problem with it. In fact, the throttle response was a lot better. It does take a while to get used to but it is a good product.

 

how can i check the spring to test whether it is working properly?

 

You could zip tie the valve shut to see if you have more power. If you do the spring isn't closing it all the way. What year is the car and has the valve ever been replaced?

 

I was chasing a low boost issue on my mini and out of desperation removed the BTV for an inspection. The spring was working properly, as far as I know as it was closing th valve. The butterfly however was not sealing very well. I said to hell with it and removed the spring and stretched it and radiused the butterfly and adjusted the stop screw. While it was off, I removed the VGS mod which created more driveability issues than it helped. Once installed I noticed a pronounced supercharger whine when floored at low RPM and improved throttle response. I did this mod in may and there have been no driveability issues.

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Aside from getting a factory new spring for comparison then placing both in a spring tester, it would be difficult to determine if it is working properly. The spring is pretty simple though and I'm sure you could find something that would work in a carburetor shop. Probably not worth all the effort.

 

What does the bpv do exactly? What is a symptom of a malfunctioning one?

 

Ive got an 06 jcw, will look for a diagram in bentleys and see if I can figure out how to zip tie it shut for comparison

 

bpv closes off the s/c bypass, effectively creating boost by forcing all air through the s/c. A weak or leaking bypass gives the air an alternative (non-boosted) path into the intake manifold, thus reducing power.

 

Any details on this procedure? I get adjusting the stop screw, but how do you radius the butterfly? If it's too small, there's no option other than sourcing a new butterfly, no? TIA

 

If you have an 06 and it has never been changed, I would recommend you do it. Even mine is going to need it again soon.

 

BPV is short for bypass valve. The supercharger is linked to the crankshaft with a belt, so it's always spinning. Therefore, it's always pumping air.

Problem is, you don't always want boost. Under idle and low load conditions, it opens up, rerouting the boosted air back before the supercharger, essentially cancelling it out. It's open when there is vacuum in the intake manifold - basically when your foot is mostly or completely off the gas pedal.

When there is demand from the motor (no vacuum, foot on the gas) the spring shuts the valve. There no longer is anywhere for the pressurized air to go but into the engine. You get boost, and you smile.

In the above photo, the butterfly isn't close to fitting in the valve body. What that means, is that yummy boost that is supposed to go into the engine gets leaked back. The car would get lower than normal boost, especially at lower rpm levels.

A broken spring would cause the valve not to shut at all, and you would get little or no boost.

The DT BPV is a two pronged attack. One is that the valve is massaged to fit better. You can tweak your OEM one slightly - loosen the two screws holding it in and there is some shift tolerance, trial and error might get it to fit really nice for you. It did for mine. Second, it uses a stronger than OEM spring. This makes it shut harder, and also under lighter load conditions. Shutting harder is nice, but you also get boost under lighter than OEM load. Some people like this, others do not. Personal preference.

It was before I ever had a Mini, but supposedly some early cars had sort of a yo-yo effect under light throttle, and the stronger spring of the DT BPV solved this issue as well.

When I removed my BPV, the butterfly didn't fit too bad, but it wasn't great. I tweaked it with a little guess and check, and got almost no light pass though. I gained about 1lb of boost out of the deal according to my boost gauge. Not really enough to notice with the butt dyno. I autocross, so I like to have the partial throttle control of the OEM spring.

 

Eric,

You cannot adjust the radius of the butterfly, and I assure you It's the correct one. What you can do is adjust its position which I suspect is your problem. Check and you will see two torx screws that hold the butterfly. Loosen them a bit and move the butterfly around until you get a good fit.

Play around with that and the stop screw until you can't see any gaps when you hold it up to a light.

If it's properly done, you will see absolutely NO light coming through the edges of the butterfly. It takes a few tries, but it is definitely doable. Trust me.

I've seen two BPV brand spanking new from the dealer with terrible alignment...

 

Yes, they seem to be tossed together. They great things about the Detroit Tuned valve is that it is done for you.

 

Ah, that makes total sense. Thanks for the info!

 

well I found that little bugger, but springs seems to bounce back and close. It might act differently when in operation, so I will ziptie it later and see if there is any difference