MAFs

[Matt Henson]

> 
> N/A can exist with nothing more then a butterfly
> right by the intake valve,
> and in that case a IR is the best possible.  It has
> the whole atmosphere
> filling the cylinder.  A turbo forces some ducting.
Okay.  yes.

> 
>   One must choose an
> > appropriatly sized pipe for the flow of the
> system.  I
> > suppose that the compressor could do something to
> > swirl(?) the incoming (and certainly the outgoing)
> air
> > but if we're talking about a significant distance
> > between the MAF and compressor then it shouldn't
> > matter, should it?
> 
> Ya, but that kills throttle response,  1 inch on my
> 4' long tract makes a
> noticeable difference..
I see.  Okay.  My app (turbo M3) is forced to have a
ton of ducting.  Right now it's maybe 12-13 feet. 
After my changes are done it will be worse - probably
closer to 18 feet.  That sounds crazy but, at least at
the current length, the response is just fine.  No
noticable difference from a stock M3 and still better
than most cars. 

> The air has to line up to go thru it, takes most of
> the votexing out of the
> air.   This allows the air to be presented to the
> MAF the same way all the
> time.  Which is critical.  If you can't get
> repeatable measurements on air
> flow, then at best everything is erratic.
Okay the IC removes the turbulence from the turbo. 
But there also shouldn't be a significant amount of
turbulence if you measure before the turbo (assuming a
bit of ducting in there).  I would conclude, then,
that if you've got to have the duct then you'd might
as well put it before the turbo.

> 
> Is he using one that is best for the application?.  
> If a film type MAF I
> readily understand that.   Where is does he use a
> PCV system?.   How well
> set up is the oil fume air seperator?.   That is
> darn near always over
> looked.  Mine is down stream of the MAF.    Not a
> problem.  Then I also use
> a  check valve in series with the PCV valve so  that
> if it doesn't seat
> perfectly, I don't pressureize the crankcase.

I think that he used the Ford MAF (I believe that the
75mm (?) Cobra MAF is okay for blow through).  He
wasn't using an air/oil seperator for the PCV.  I
think that he didn't spend a ton of time on this since
packaging didn't make it that beneficial to use it as
blow-through.

So you've got the PCV downstream of the MAF?  and the
MAF is blow through?  So how does that not pressurize
the crankcase when you're under boost?  The crankcase
won't vent until it exceeds the manifold pressure,
right?

-Matt

> Bruce



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