1 bov vs 2 bov
 

I am just curious if I would get the same performance out of running 2 smaller bov's with the same surface area equivalent to one big one. I am simply asking this for cost effective purposes. Right now I already have 2 TurboXS Type H25 BOV from the previous setup (25mm x 2 = 50mm) or I was possibly thinking about getting rid of them and running a Tial 50mm bov.

I got a new intercooler setup and I can get these BOV's working with the new single setup for next to nothing if it would work, it would be the preferred route cost wise.

So my question is will I be ok? and if so where should I place them (hot vs cold side). I just dont want to go out and do a pull and get hit with the most epic surge known to man and see my exhaust wheel spinning like a top in the middle of the road somewhere.:scratch:

BOVs don't really enhance performance, so unless you are experiencing surge to the point where a single BOV can't handle the load, then one is just fine.

In theory, the BOV should be placed as close to the throttle body as possible. In practice, it doesn't seem to matter so much.

After crunching some numbers contrasting surface areas...2 bovs at 25mm x 2 is still half the surface area of one big 50mm bov...but I guess the volume of air they can release is more important.

I guess my real question is, will running (2) H25 be sufficient, or will I need to spend the money for a bigger Tial

25MM is a tad small. I don't know if I've ever seen a BOV that small. Then again, how much air are you trying to get through it? Turbo and boost pressure?

I guess Ill just upgrade to a Tial...Ill just take the guess work out. Better to be safe than to be sorry I suppose.

Not really. You are just wasting your money. Changing the "BOVs" doesn't do anything on the FD.

Some people want a louder sound and change the primary turbo "BOV" to an aftermarket unit so that it makes more noise. If your primary purpose is more noise, replace the primary turbo "BOV". No need to do both.

Its a bit much for some noise but its your money.

Read the FD FAQ thread to learn about replacing the BOV and to learn about modding the FD and what works.
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/

I upgraded to a single turbo, sorry I forgot to mention that.

Ah. I see.

Most single setups I see use one appropriately sized BOV.

the only advantage i could see to running dual BOV is the response you would get when off the throttle.

smaller being lighter, moving faster. but in reality i think this might take of up to a millisecond or something un-noticable. im sure someone has figured it out.

just make sure your spring is for the appropriate pressure, and you flow match them to your turbo setup.

ie. how much air "Y" does your turbo move at "X" psi (go to your turbo manufacturers website for flow charts)
find BOV that can handle "Y" amount of airflow while having a spring set "x" psi