Thread: any gains in porting the boost bypass passage?

like i stated, is there any gains or anything advantageous at out if porting either or both in/outlet of the boosy bypass passageway? i can imagine it'll run lean at idle and cruise or basically during vacuum. kinda like home-porting a stock throttlebody w/o fiddling around the areas of the tb blade.

Originally Posted by my97gtp

If your ported it larger than the plate in it im sure you would loose boost. I dont think their are any gains to be had by porting it unless you were turbo.

lets assume the outlet(bottom portion) is ported and not the top/inlet, boost would be generated the same since the BBV plate is shut anyways. i think this would only be changed, if any, at cruise and idle when no boost is initiated.

why would you want to bypass more boost?

just an observation and a 'what if' question ^_^;

Hmmm... it would definitely make you slower, since at the time when a percentage of air could be going through the s/c it would bypassing it. fwiw when my BBV was broken it was closed all of the time. It made boost a lot faster and I noticed no additiona; KR as some people have claimed.

It is good to wonder about the affects of change. I compliment you for your curiosity.

Originally Posted by Reptile

Keep in mind that the air is still going through the rotors as well, even when the bypass valve is open. IF you eliminate the butterfly alltogether, you're only gonna make about 6 psi max.

Why would you only make 6psi max?

Originally Posted by Reptile

Because the air recirculates up through the Bypass valve and back into the rotors. The flap is there to keep air from bleeding off and keep that from happening.

recycled boost?

Originally Posted by IndeedSS

It is good to wonder about the affects of change. I compliment you for your curiosity.

Exactly! Everything you come up with may not be the best idea, it may not be the worst, but its an idea. Even if you came up with the worst idea ever, discussing it and looking at it from different perspectives may bring forth other better ideas.

That said, I cant personally see how there would be any gains in porting the Boost Bypass, but hey, here's to discussing intelligently and see what we come up with.

well I was discussing this with another member and he mentioned that the bottom section of the boost bypass if ported 'may' be benefitial for guys with Ics. I dunno but its another possibilty lol

Porting a gen 3 blower and LIM can be beneficial for those with an IC, but bypassing what gives you the power seems like it may have the opposite effect of what you are looking for. That said try out the BBV mod, and see what effects it has. If your car is like mine and it doesn't give you knock, then you will quickly find out the result of blocking off the BBV. Then you can figure the opposite may be true in opening it up further...

disclaimer: most of the time I don't know what I'm talking about...so experiment at your own risk.

I dont know enough to really contribute, but I can work with 'may'. Its a chance, and it may come down to someone having to port one and see, but who knows what kind of knowledge we could gain on the journey there.

Thats why Im watching this thread. You got my attention and interest. So while I may not be able to contribute anything really useful, I'll watch and see if I can learn something. Keep up the good work, hopefully other will come in here and get the discussion moving along good.

This has been done...I'm looking for the forum I followed the thread on.

Originally Posted by IndeedSS

Porting a gen 3 blower and LIM can be beneficial for those with an IC, but bypassing what gives you the power seems like it may have the opposite effect of what you are looking for. That said try out the BBV mod, and see what effects it has. If your car is like mine and it doesn't give you knock, then you will quickly find out the result of blocking off the BBV. Then you can figure the opposite may be true in opening it up further...

disclaimer: most of the time I don't know what I'm talking about...so experiment at your own risk.

Okay, let me ask something here, well maybe several somethings.

1. The BBV obviously Bypasses boost. Isnt that valve also open when you are not in boost? In other words, is it in the normal intake track channeling air to the motor and when you go into boost it closes off? If that is so, wouldnt opening that up allow more air flow for when the engine isnt in boost? Just thinking and questioning out loud here folks. I dont know what if any benefit it would be, just thinking.

2. If the BBV opening was ported, that would release boost faster, correct? How would this affect boost decel in the PCM and the possibility of flash KR? Though if you have let off the gas, I dont think this would matter much, but just something that crossed my mind.

3. How would this affect fueling. With the BBV not being either opened or close, rather it can be just about any where in between, how would this affect fueling?

1. I've only seen the BBV opened or closed, except the time before mine completely stuck open. Then it was bouncing up and down at idle. I assume it is either open or closed and doesn't operate at a partial position like your throttle blade does. What I do know is when the BBV is open (low load) the air goes through the BBV and the rotors. Under heavy load it is rotors only.

2. I don't see how it would release boost faster. I know what you are saying, but am not seeing it, I guess.

3. I never notice a change in KR or MPG. Assumption would be that more air would require more fuel.

I would love to here someones take, that builds performance engines, because I'm giving best guesses.