blowoff valve questions

[Jukka Majanen]

Robert Hi


> On Mon, 18 Jun 2001, Jukka Majanen wrote:

No, it wasn´t me, but Chris, I just answered him ( I really do not know
anything about Japanese cars :)

> > > As an aside - those other manufacturers, Mitsu, Mazda, Subaru, etc. have
> > > blow-off valves AND MAFs.  How is this possible for them but not for our
> > > cars?

Mine was:

If the airflow/mass is measured after the turbo, at the throttle,
there is no problem because it doesn´t count the air...

> Sloppy language.

I see...

> The Mitsu I know for sure is a CBV, for some reason Mistu drivers refer to
> them as BOVs.  I expect the same it true for the others as well-- Sube's
> MAF is right at the filter, not the throttle, so likely it's the same way.

I agree and think no production car has B/O nowadays.

> > With nice sound Blow Off will: 
> > reduce lag, but toast cat... hmm -poetry :)

> Actually, a properly routed and sized CBV should reduce lage more than one
> that vents to atmosphere.  The pressure wave gets shoved through the
> compressor in the right direction- helping to keep it spun up.

Ok -that is possible, but in my opinion ( and the local rally people too ) mass
and energy of that routed air makes it only theoretical? So You can see all
WRC and smaller cars blowing fire, because of the rich mixture in pipe.
That small blow spools turbo while the B/P is open out and the throttle closed.
Also there is something rich allready, when the throttle again opens...

Well -hard to say, what is the right way...I myself have routed B/P from IC`s
in pass side to the last angle of turbo intake, quite long 1" line :)

Regards from Finland
j-pm