$139 new aftermarket bypass valve

When I acquired my 355GTS, it was immediately obvious that my bypass valve was not opening at high RPMs. I soon discovered that the mounting bolts needed to be slightly loosened (wuz stuck) and this is when my fight with the bypass valve rattle began.

I tested the vacuum, adjusted the preload and finally had it neutered (de-balled) to no avail. Since the bypass valve was still vibrating a tad, it made it sound like aluminum cans in a bag (808). At this point, I knew it needed to be replaced.

Now the $1100 Capristo replacement valve is beautiful but IMO overpriced for the function. And let's face it, why throw good money at bad by staying aftermarket?

So I had been peeping this possible alternative for several weeks and decided to proceed (standard disclaimer, I don't know this dude). If you're still reading, make sure you get the normally CLOSED version cause dude also sells the normally open version (which may also be attractive if you are in the constant bypass no-CELS camp).

Stainless Steel Exhaust Control Valve Set Vacuum Actuator 2 1 2" 63mm Pipe | eBay

Some plagiarized details:
Fits with 2 1/2"/ 63mm approx. OD pipe
The pressure range: 2 psi - 5.5 psi
The valve is closed at free condition
Material: Stainless steel for all components
Rod end bearing linked between actuator and gate lever
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Now I knew from my measurements that this aftermarket valve was the correct circumference but was not wide enough alone to fully connect my factory Y-Pipe to my Tubi exhaust (rereading that sounds a bit naughty). Also for my setup, I had to contend with a male/female configuration as the Tubi provides an inner male sleeve that the rear side of the valve slips onto, however the corresponding inner sleeve on the front side of the valve is actually built into the factory bypass. That certainly sounds confusing but if you peep a factory valve outside the car, you should get my meaning.

So I purchased the adapter below and used my Dremel to cut the 2 1/2" side down to a 15-17mm ring to rule them all. I then banged it into the front side of the aftermarket bypass valve with my rubber mallet and prepared for install.

2-1/2 Inch Outside Diameter X 2-1/4 Inch Inside Diameter
ROL Gaskets 548551 - Exhaust Reducing Adapter | O'Reilly Auto Parts

 

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Once my wife arrived home that afternoon on her broom, I then used it to rock the Tubi back just enough to slide the aftermarket valve into place, tightened her down and buttoned her back up. I then replaced the vacuum line since the nipple was a different size (and aren't they all fellas?). Fired her up, let her idle and for the first time in our relationship, there was no buzzing (from the car either).

At $139, I felt like I had stuck it to the man. Not sure which man but someman.
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Here comes the money shot. You know you want it.
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Just in case you're not already spent, here is some more coming at ya:
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So in closing, I would like to add:

1. Thanks to all those that have contributed before me, without FCHAT I would not have taken the plunge
2. If you are not Subscribed, do it.
3. Eat your broccoli.

Thanks for reading,
Ken

 

Honestly, I was hoping some of the engineers here would scrutinize the specs and highlight any concerns. I'm not certain how to tell if it opens completely but of course it sounds great under the overpasses.

Can you recommend a simple test to determine if it is opening fully?

 

Done.

 

I thought that the valve only opened when the vehicle was in a gear. If that is not the case, then it will be easy to verify.

I may even try to get a capture of my wireless obd scanner and IOS Dashcommand app which should show at what precise RPM causes the valve to open.

That would be geek-tastic.

 

Thanks for the clarification. I will test it over the weekend and give an update afterward.

 

OK so sustained (3-4 seconds) revs all the way to 8000+ did not result in opening of the valve while the vehicle was in neutral. This was the same condition as the factory valve. Although I'm fairly confident in the vacuum line to the valve I think that is still the next thing to test.

I am looking for a vacuum tester with the following features:
1. vacuum testing to lower psi numbers (ie a gauge with 0-20 psi better than 0-100) since I will be looking for 2~5.5 psi per the aftermarket valve specs above.
2. would be nice to have a reset needle that identifies the highest reading achieved during the test

If anyone can point me toward an appropriate tester, I would appreciate it.