The bypass valve and venting to atmosphere.
#1
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The bypass valve and venting to atmosphere.
Well, before I did the install I bought a bypass valve from BEGI, but then of course afterward when going to put this on I realized there really isn't a spot after the AFM that I can route the air back into at least not without getting some custom piping of some sort.
This may seem like a stupid question, but will it mess things up if I connect the thing and just vent it to atmosphere rather than back behind the AFM?
This may seem like a stupid question, but will it mess things up if I connect the thing and just vent it to atmosphere rather than back behind the AFM?
#2
You could have issues with idle, since it could leak and allow un-metered air into the engine. You'll also get a rich condition anytime it vents and un-metered air escapes. For some this isn't a problem, for me I found it to make the car buck when lifting slightly. This was not acceptable as it affected drivability so I ended up plumbing it back into the intake. Now I don't have an AFM and no longer worry about it.
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One bandaid that can be applied when running VTA with an AFM is a one-way check valve on the BOVs exhaust port. This will prevent it from leaking at idle and drawing in unmetered air.
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I talked with a guy at BEGI and he basically said that the only problem I should encounter is the possibility that it bogs because I lose air and it adds too much fuel when I shift. Otherwise he didn't seem to think losing air at idle was an issue.
What would be a way to plumb the thing back in with the stock Greddy setup? I assume my option would be to add some sort of inlet on the pipe coming from the airbox.
What would be a way to plumb the thing back in with the stock Greddy setup? I assume my option would be to add some sort of inlet on the pipe coming from the airbox.
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A couple of folks have even drilled and tapped the AFM itself. There's enough space on the end to do it- useful if your AFM is hanging directly off the turbo.
#6
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I think if I did it I would probably just do the pipe as if I want to put it back to stock having a hole in the AFM might look bad.
As it is I'm contemplating drilling the pipe and putting some sort of fitting on there. What's the advantage to drilling and tapping over just drilling and welding something on?
For now though is it better to just let the thing blow back (I'm at around 4.5psi with the IC) or should I throw the bypass on and let it vent to atmosphere to avoid that and let it go rich during shifts? When I talked to the guy at BEGI he seemed to think it was better to put it on even with the AFM issue.
As it is I'm contemplating drilling the pipe and putting some sort of fitting on there. What's the advantage to drilling and tapping over just drilling and welding something on?
For now though is it better to just let the thing blow back (I'm at around 4.5psi with the IC) or should I throw the bypass on and let it vent to atmosphere to avoid that and let it go rich during shifts? When I talked to the guy at BEGI he seemed to think it was better to put it on even with the AFM issue.
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For now though is it better to just let the thing blow back (I'm at around 4.5psi with the IC) or should I throw the bypass on and let it vent to atmosphere to avoid that and let it go rich during shifts? When I talked to the guy at BEGI he seemed to think it was better to put it on even with the AFM issue.
I personally drove around for several months with a VTA BOV using a check valve (this was before I removed my AFM) and there was really no downside. Anyone with a logging WBO2 sensor will see that the mixture goes way rich during shifts no matter what. Just the way things work.
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Well, I have already bought the anti-surge valve that BEGI sells.
http://www.bellengineering.net/Images/ByPass_Sm.jpg
I think it is a Mitsubishi valve, have to look at it again.
The guy at BEGI didn't seem to think that leaking at idle would be an issue, but before I put it on I think I will try altering the intake piping to route the air back in. Right now the car is running well except for the compressor surge during shifts. Also, the danged inlet on the valve is a lot larger than the outlet coming off the IC pipe that goes into the intake manifold. Gonna have to find some way to mate things up.
Would JB Weld be a bad choice in this situation?
http://www.bellengineering.net/Images/ByPass_Sm.jpg
I think it is a Mitsubishi valve, have to look at it again.
The guy at BEGI didn't seem to think that leaking at idle would be an issue, but before I put it on I think I will try altering the intake piping to route the air back in. Right now the car is running well except for the compressor surge during shifts. Also, the danged inlet on the valve is a lot larger than the outlet coming off the IC pipe that goes into the intake manifold. Gonna have to find some way to mate things up.
The fact that I happen to own a number of NPT taps, however I suck very badly at welding aluminum.
#13
Well, I have already bought the anti-surge valve that BEGI sells.
http://www.bellengineering.net/Images/ByPass_Sm.jpg
I think it is a Mitsubishi valve, have to look at it again.
The guy at BEGI didn't seem to think that leaking at idle would be an issue, but before I put it on I think I will try altering the intake piping to route the air back in. Right now the car is running well except for the compressor surge during shifts. Also, the danged inlet on the valve is a lot larger than the outlet coming off the IC pipe that goes into the intake manifold. Gonna have to find some way to mate things up.
Would JB Weld be a bad choice in this situation?
http://www.bellengineering.net/Images/ByPass_Sm.jpg
I think it is a Mitsubishi valve, have to look at it again.
The guy at BEGI didn't seem to think that leaking at idle would be an issue, but before I put it on I think I will try altering the intake piping to route the air back in. Right now the car is running well except for the compressor surge during shifts. Also, the danged inlet on the valve is a lot larger than the outlet coming off the IC pipe that goes into the intake manifold. Gonna have to find some way to mate things up.
Would JB Weld be a bad choice in this situation?
#16
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Drill bit I might have. I actually need to measure the outlet from the valve to get an idea of the size hose I need.
I have a tap kit, but it is one of those ones they sell at Autozone so the biggest it has is about a 1/2" NPT I think.
#18
I used a metal threaded pipe coupler from HD cut in half for my BOV routing, as well as for the idle valve hose. I think it was about $1. Drilled into the IC hose, tapped, screwed in, and got a nice seal with some JB Weld, smoothed it out, and sprayed it black. Doesn't look half bad, and is fully functional.
#20
When you drill into your charge pipe, install the brass fitting, and seal it up good with JBweld... then dremel out the threads in the inside to the pipe is smooth. One of the heavyduty Dremel cutting wheels goes through brass like freakin' butter.
Here's how bad VTA was on my 1.6:
https://www.miataturbo.net/diy-turbo-discussion-14/freeway-speeds-vta-02clamp-6149/
Here's how happy I was recirc:
https://www.miataturbo.net/diy-turbo-discussion-14/recirculated-today-awesome-8069/
Here's how bad VTA was on my 1.6:
https://www.miataturbo.net/diy-turbo-discussion-14/freeway-speeds-vta-02clamp-6149/
Here's how happy I was recirc:
https://www.miataturbo.net/diy-turbo-discussion-14/recirculated-today-awesome-8069/