Is it possible to replace the factory bypass valve with the aftermarket one?

 

Please excuse my ignorance but, why would you want to?

 

And who even makes an after market one????

 

The factory SC bypass valve is usually not adjusted properly and, when it is adjusted properly, still lets some boost pressure escape when fully closed. This is because the butterfly does not close completely in the throat due to its less than precise design, manufacture and alignment.

Much exists on the boards about removing and adjusting the bypass valve butterfly and its set screw. Mine was way off and I corrected it to a point, but I could still see a bit of light throught the edges of the closed butterfly.

It's anyone's guess what the difference in boost is between an improperly adjusted valve and one that has been adjusted. I'm willing to bet that it is not that great...but every little bit helps, especially if it doesn't cost anything!

Randy Webb looked into the cost of producing replacement bypass valves that had some more accurate reengineering done to them. The problem was the cost for this reengineering was too high for the gains that could be expected.

So, as long as you have the right tools and can handle some intricate mechanical work under the bonnet, I would recommend removing the bypass valve and adjusting the alignment of the butterfly and the set screw the determines its fully-closed position. This is not for the faint of heart, however.

Theo

 

Koopah, So by reseting the Butterfly did you see any improvement on boost lose or is it really not noticeable. Reason asking is i remeber seeing another thread about this and now u just reminded me, i have a brand new bypass valve and am not tempted to take it off and see if it is adjusted right.

 

There is a retooled bypass valve available from NAM Sponsor Detroit Tuned. Find it on their web site here.

 

Why don't we just use a BOV? SPI has two on their twin charger. One after the turbo and one after the super. Gas mileage would take a big hit but you wouldn't loose any boost. Oh and you would have the whoosh!

 

I've got an 04 MCS and also was not sure if the poor butterfly fit was particular to earlier models or continues to be an issue. So I bought the aftermarket BP when it was called the ryephix#2 (properly fitted butterfly and stonger spring). I basically waited for a convenient time to have the OEM BP pulled when I was doing other work. Guess what, when I finally got the OEM out and looked at it, it was VERY VVVEEERRRRRRYYY poorly fitted. So, needless to say I swapped it out with the aftermarket. Did I feel any immediate difference. Don't know, I was having other issues and mods done at the same time. But I will tell you this, my OEM BP would not appear as the poster child for quality of build. I have half a mind to take it back to the dealer and asked them where else in their car this sort of trash existed .

 

The 'woosh' is almost always just for posing, d00d. They are only necessary for over 20 psi, if I remember correctly. Plus, cars with BOVs have bypass valves too [wastegates], also to my recollection. Only in really high psi cases where the boost could feedback and hurt the charger would it be useful. We're not running near that with just an SC. I think that SPI even said that the second BOV was essentially unnecessary anyways. Gas mileage would be hurt, yes, and at no return I think it would be just another pointless mod.

 

Hey! I like that....the question is how to install it?

 

No where near that with just a supercharger? I'm seeing over 19 psi with my setup. Also why do you say at no return? SPI claims that throttle response was improved.

I would much rather pay 100-200 for a BOV than pay over that for a properly seated by pass valve. But that's just me. I guess a nitrous purge valve and the "whoosh" just does it for me, and it scares the crap out of who ever pulls up beside me.

 

Sorry that I underestimated the boost you're making, but honestly I have gotta say that I really believe you are barking up the wrong tree at 19psi. You really should get some head work, and concentrate on bringing down boost if you wanna make it through your runs for years to come. I'd hate to see your car _spill_ its guts prematurely. Sorry, had to !

 

Anyone know where the how-to for the bypass valve is? I'm sure its in the yo-yo chronicles, but not sure what page.

Nik

 

Spillman, just so you know, there is no possible increase in throttle response with a blowoff valve in a SCed car. You will need to understand the difference between a turbo and an SC to understand why: the function of a BOV in a turbo is to quicken spooling of the turbo, cause exhaust gases blowing into an engine not under load [ie between shifts...] will not be able to keep the turbo spooled, so an extra outlet for air is maintained to keep the turbo spooling [and the pressure in the TC from building up while too little air is entering the compression chambers]. A supercharger is not driven by exhaust gases, it is driven by the crank, so no matter what, as long as the rpms are at xxxx, the SC is spinning at whatever mechanical advantage is built into it through the pulley. Therefore, short story, a BOV cannot possibly increase throttle response in a SCed car.

Now, if you look around you should be able to find a scan of SPI's article in Sport Compact magazine [or something like that] where he is asked why he has two BOVs. He says the post-SC one is there essentially 'just cause...' Hope this answers you.

 

DSM -

I can't say that I noticed much of a difference. However, I did gain peace of mind knowing that it was adjusted as well as it could be. It also made me feel better about doing mods (like the JCW) and knowing that I was not losing anything to an issue with a stock component.

TA -

Yes, Ryan Malcolm has done a terrific job working with the bypass valve. However, the two things he has done to the valve are:
1. to adjust the stock component as well as its factory design allows, and
2. installed a heavier duty diaphram return spring the "mask" the effects of the dreaded yo-yo.

So, technically, the only "retooling" is the diaphram spring which really doesn't address the issue of the butterfly fully sealing the throat from leaking boost. However, you can be assured that he has adjusted that puppy as well as it can be!

Cheers,

Theo

 

Any aftermarket BOV kit out there available for our car?

 

an improvement in throttle response should be expected if you ditch the by-pass valve completely (at the expense of poorer mpg). With the bypass in, the transition from closed throttle as you enter a tight corner (max vac between tb and sc) bypass bypassing, and full throttle as you gas it coming out (ambient pressure) is limited by the ability of the valve to close so you can build boost.

 

My OEM BP butterfly was very poorly aligned basically providing all the sealing quality of a noodle strainer. It relly could not have functioned as a valve as it never could keep gases from leaking. Ryehix's BP butterfly was adjusted such that it let no light thu. If you don't get the aftermarket for the tighter spring, a personal choice, at a minimum take out the OEM and adjust it yourself. There really is no excuse why such trash was used in this car.

 

I suggested to Ryan that he should provide the service of having a properly sealing BV with his ryephix#2. This was before he started selling them like hotcakes. He did. But if you want to have a properly sealing BV and not the ryephix#2, just go the the dealer and buy a stock one that seals properly. Before you pay for it, look into the valve with at light behind it and see if you can see any light passing by the sides of the butterfly. If you can see the light, ask for another one. They are like $30. So it is cheap.

I am a big believer of the ryephix#2. I have been driving my car with it for over a year now.

There is another alternative to this mod, it is the VGS. link below:
https://www.northamericanmotoring.co...&highlight=vgs
Depending who you ask you will get different answers on to which is better. But everyone will agree that they fix the same problem Yo-Yo and add some performance.

I am the only person that I know that is running ryephix#2 and VGS at the same time!! I did this to get some of the torque that I lost when I added my Cat-back system. For those in the know, the combination is not ryephix#1. Try it, if you have ryephix#2. My fuel economy is in the 25/32 mark.

Bomboasy

 

bomboasy,

How to take out the bypass valve? Are there 2 screws holding the bypass?

 

If anyone knows a way to upload a Word document on internet, I have Detroit Tuned instructions, with pictures, to remove the bypass valve...

 

I've found a free one, probably not the best, but it works!

http://www.megaupload.com/?d=25QZIPDU

 

so this bov thing, is it even possible with our set up, i know yes with a turbo and a vortech like supercharger, but what about the roots type????

 

Really, find out what the system is for before thinking about bolting it onto the car. If you want improved throttle response with our cars, in order of impact.
1) VGS - uses posative feedback to prevent oscillations (get vacuum from high pressure side of SC).
2) Ryphix II. This is the stronger spring. BP doesn't open all the way, and opens at higher vacuum level. Means it closes earlier in the RPM range, and it closes HARD (very abrupt transitions).
3) Ryphix I. (Wire tie valve closed). PRetty much like removing it.

I too ajusted my bypass. Not to hard at all if you do one trick... Take two of the studs of the Intake so you can put that Al IC-Intake runner in without goiing trough every swear word you know. Cut or trash the BMW hose clamps, and use two new screw type ones. It's less than a hours work, including the 15 min to get the nerve to take it all apart!
Some have reported about a pound of boost increase with the fix. I didn't log any data, but mine was pretty bad. There are photos in the Yo-Yo chronicals.

Matt

ps, some want an aftermarket BP valve (there's one available in Japan) because as normally connected, very, very high boost can push it open. So the aftermarket unit with ajustable spring... Allows you to set max boost as well. I think the VGS system isn't as prone to this. Under boost, the valve is pushed more closed......

 

Is that link for the instruction download?