Second BOV as a boost release system?


As there is no wastegate like turbos to regulate the maximum boost pressure in supercharger systems,can we use a second blow off valve without connecting it's vacuum hose to the intake manifold?
Using a mityvac hand pump we can find the right spring for us to blow off excess pressure at WOT.
What do you think of that?


i was also thinking about this to "regulate" max boost.
But i think the BOV will "chatter" under load.
sorry for bad terms. What i mean is it will flatter between open and closed as the outlet is to big.

I thought also about a "secure valve" available in different ratios. pe a valve that opens exactly at 0,8bar or 12PSI valve that
Please take this just as a sample what i think of. Maybe these are all to small for our aplication but may not chatter.

If this idea is stupid please explain why.



Perhaps this helps to keep boost steady. long will it last doing this job ?

link i posted was missing ,sorry for that.New try : Google-Ergebnis für
What i was thinking about is a smaller valve that would stay open and let boost stay at a max level. (waste of power and energy anyway)
Other idea i had was just use a wastegate as BOV.

Have some car buddies that do some kind of boostcontrol with electric pressure sensors and solenoids.

The easy way i will use for the tune is setting the rev limiter by ecu flashing. On chargers boost rises with rpm ,so i can cut it and go in steps with the mapping. Should be a bit easyer as with a turbo.
Maybe unusual but i am new to boost and dont want to blew it up.


Donating Member
Are you taking the concept of a burst plate that can reseal as needed....using a pop off gage of sorts (like rebuilding carbs)....seems doable / practical. some have this design built into the cases...

plate spring.jpg


There is another thing i worry about.
On turbos using wastegate,you're regulating the mass flow of exhaust going into the turbo which slows down the compressor. On the blower using some kind of spring valve,you're still spinning the compressor the same speed but varying the load you're placing on it.

I think that this varying load is not good for my Rotrex internals but who knows for sure about that?:1zhelp:


look at the post of Big CC.

you will see one Tial BOV and one TIAL wastegate on the inlet. i think that it uses a fair overdrive ratio. to achieve high, low rev torque.