[alfa] Re: Quadra flow and horsepower

["Jim Steck" <4sfed@xxxxxxxxx>]

I don't doubt John Norman's dyno study . . . but it doesn't represent
the real operating conditions.  To compensate for day-to-day
weather conditions, dyno results are generally corrected to reflect
expected results at standard temperature and pressure.  That's
70 degrees F and 29.92 in Hg . . . so the Quadra flo is better at
high RPM when inlet temperatures are the same.

In the car, the Spica airbox is easily 50 degrees cooler than the
Quadra flo . . . a cold air box in Colaizzi's Giulietta vintage racer
dropped the inlet air temperature by 70 degrees.  Fifty degrees will
make a _5%_ difference in Hp.  If we accept Stevan's premise that
the Quadra flo only helps with high output (airflow) engines, we
have to conclude that on a stock engine, the Spica airbox is
5% better because of the difference in temperature.  The truth
probably lies somewhere in between with the Spica still ahead.

-- -- --
Jim Steck, AutoComponenti
8906 Darke County Line
Brookville, OH 45309
ph: (937) 884-5142
fax: (937) 884-5144
email: jim@domain.elided
web:  www.autocomponenti.com



>> The original claim of "average 7 horsepower increase over the stock
>> Alfa air filter", according to the Alfa Ricambi manual, has always been
>> questioned.  The theoretical increase in flow is offset by the hotter
>> engine bay air at the intake, as opposed to the fresh cool air rammed
>> into the Spica airbox.  The solution?  K&N filters for the Spica box.
>> Proven beneficial?  I think not.
>
>
>John Norman has a dyno list for state of tune, stage 1. 1974 - 2000
> Spica fuel injection, stock exhaust system, 9.2 CR (head cut .020),
> porting, polishing and valve work, 45mm oversize in-let valves,
>stock cams (105.20), stock air cleaner, 74 ex-system
>stage 2. same as stage 1 with Euro cams (105.48)
>stage 3. same as stage 1 with 11mm (lift) Pittatore cams
>stage 4. same as stage 1 with oversize throttle
>stage 5. same as stage 1 with Shankle Quadra flo airbox
>stage 6. same as stage 1 with high performance F.I. pump
>
>             Stock       1           2          3           4         5
6
>
>3500       86        89         88        85          89       86
88
>4000       98      100         99        95        100       98       100
>4500     108      116       114       110       115      117      119
>5000     118      126       127       131       130      134      140
>5500     116      130       135       139       142      146      154
>6000     110      128       136       142       147      150      159
>6500                              127       143       146      155      162
>7000                                                                    143
152
>
>
>Unless you do a lot of other engine work and change cams, it probably
> doesn't  matter.
>Stevan Thomas
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