MAF

[Thomas Martin]

The diameter of the engine code "C" throttle body valve (Not the overall MAF) is
about 25 mm, maybe 35 mm at the max.  The sampling area is rather small, guess is
10 mm, may be smaller, can't get my finger into it (assuming one would
try....<g>).  Very small.  My old 1991 Lumina 3.1L ("T") had a MUCH larger throttle
body valve.  It was the same as the Q-Jet secondary.  Not MAF, Speed Density.  3800
would eat it alive in the top end, but the 3.1L would hold its own 0-50.

The "L" engine is very different on the top end, the intake is the "Tuned Port FI",
the "C" is the deviant like the "3" and the GN motors.  The "C" engine has the
newer heads.  (Like the Turbo 3.8L Trans AM??)

I know it is the Hitachi MAF, and it seem to me very small.  I will try to get an
accurate measurement of it tonight.  My motor is the 165 hp version.  Last year for
the 3800 "C".  The "L" motor showed up in Buick in 91, and the rest of the carlines
that used it in 92.  Then in 1995, the 3800 Series II (205 hp) showed up.  I drove
one, very sweet!  Leave mine behind!

Thomas Martin

Greg Hermann wrote:

> >soren wrote:
> >
> >> >170 Gm/sec works out to 300 cfm (and about 205 HP) (at sea level), which
> >> >works out to 84% or so VE--on the low side, which indicates a lot of
> >> >restriction from the MAF!  If the thing only has a 25 mm diameter throat,
> >> >your MAP at WOT can only get up to about 12.0 or 12.5 psia. (Basically ,
> >> >the MAF is throttling the engine!)
> >>
> >>     First of all, isn't the "95 3800 rated at about 205 HP? Second, after
> >> working in a Buick garage for 4 years, I am pretty sure that MAF sensor is
> >> not 25 mm in diameter!
> >
> >He prolly meant 25mm radius... 50mm sounds about right on a car putting around
> >200hp.
>
> I would agree--that amount of air-flor through a 25 mm hole would not be
> particularly within the realm of possibility for making 200 HP.-- But I
> will maintain that a 60 or 65 mm diameter MAF should give a substantial
> boost in top end performance over a 50mm (if that is what it really is) for
> an engine of this size with the other stated flow enhancements (bigger
> exhausts, etc.) If the available MAF instruments are not sensitive enough
> to give usable and repeatable readings with this much of a size increase,
> they DO deserve to be on the junk pile!!
>
> Another, possibly dangerous, thought: has anyone thought of running TWO
> throttle bodies (acting in progression, like the primaries and secondaries
> of a four-barrel carb, with TWO MAF's?? (maybe even a stock size primary,
> and a larger secondary one?? This would indeed be an interesting electronic
> project--come up with a way to combine the outputs from two, progressively
> used MAF's into an input which a (nearly) stock ecu would accept as if it
> had come from a stock single MAF sensor!! No deterioration at all in bottom
> end response or mixture control, and gobs more airflow whenever one cared
> to ask for it!!
>
> Regards, Greg
> >
> >Ciao,
> >Francois Dion (francois at hyperreal.org)
> >--
> >Member: FLU #1722, PCNA
> >http://www.fortunecity.com/silverstone/zagato/101/launch.html
> >Alfa Romeo, Fiat, Lancia, Peugeot, Volvo, Solex