MAF

[Greg Hermann]

>Thomas,
>The MAF is indeed a freq. generator.  After looking at my 95 LeSabre Series
>I 3800, a bigger MAF isn't necessary and may cause driveability problems...
> I have my exhaust opened up to 2 1/2" dia and a gutted cat, no resonator
>and a Walker Ultra-Flow.  At 5300 RPM and WOT in 1st gear, my MAF only
>registers 170Gm/Sec airflow... 255 would be max for the unit.  If you were
>to go with a bigger MAF, you'd require a re-write of your MAF tables
>(Assuming it didn't measure the same exact freq per reading) to make it run
>right.
>For a turbocharger, contact Dave Buckshaw at EFIPERFORM at aol.com.
>Later,
>Dave
>
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!) Going to a much bigger MAF could
definitely help things, to the tune of another 6 to 12% power at the top
end. Doesn't much matter where you put corks in a system, things don't
really get freed up until you pull out the last cork. No way a 25 mm
orifice is NOT a serious CORK on a 3.8 l. engine---with one carb barrel per
cylinder (Webers) SIX 30 mm venturis would be pretty restrictive on a 3.8
l. 6 cyl.--I once built a Jag 4.2 (6) which ran FINE with SIX 42 (!) mm
chokes (one in each of the six bores of its 3 (48 mm throttle) Webers). If
one cannot run a MAF with a FAR bigger hole in it than this one (like at
least 60 mm) without getting "driveability problems", it is time to either
throw the  MAF's away and go with MAP injection, or go back to (GOOD)
carbs!!!>

Regards, Greg

>
>At 02:18 PM 11/2/98 -0600, you wrote:
>>I have a 91 Bonneville with the Series I 3800.  I would like to put the older
>>larger MAF from a "3" or 3.8L V6 on my engine to increase airflow.
>Eventually add
>>a turbocharger.
>>
>>The MAF I have now is the Hitachi, and has a small 25 mm air passage.  It
>has a
>>small 10 mm (approx) port to sensor air for the MAF itself.
>>
>>Can I swap these units?  What sort of output does the MAF has?  Is it a
>constant
>>voltage that varies with airflow, or is it a higher frequency output?
>>
>>(should I drag out the O-Scope to view?)
>>
>>Thanks!
>>Thomas Martin
>>
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