Vandenberg papers conclusion

[Norm Riffle <normriff@domain.elided>]

    Apologies to the list and to John H for my error.... as usual John
was quite right in quoting the conclusion of the article beginning ..."
This increase in power is small in both comparisons showing the
efficiency of the stock Alfa motor being relatively high for the
street......."

    However the real meat of the conclusion is in the paragraph before
that....

    "According to our testing, the best modifications for a normally
aspirated two liter Alfa motor were the
    two liter European cams, the
    Bosch distributor,
    Shankle air box,
    the 1977-79 exhaust (or 1972-74)
    with the 1976 FI pump set to 2% CO.
    This produced a 12 % increase in power compared to the 1976 motor in
table A and a 6% increase compared to the 1978 motor in Table B."

     Obviously, there are many possible modifications discussed here on
the list which are not mentioned, but in Vandenbergs opening paragraph
he sets the parameters of what was tested any why.....

    "The purpose the testing was to obtain concrete data on external
engine modifications and on many bolt on performance items currently on
the market".

    If we examine each item individually beginning with the cams i think
we can safely say that however modest the increase in lift and duration
the Euro cams (10548-032001) add "some" HP. over the stock  Spica cams
(105200-320000)  used from 1972 to 80?.
    the (way old) Shankle catalog list the stock cams as a 3 while the
Euros get a rating of 5.
    In between are the are the 1750  Spica cams  # 105020-320001 which
get a rating of 4.

    The benefits of the Bosch distributor were the steeper advance
curve. although the dyno test showed improvement only up to 4500 rpm
(and gives no spec for "at idle".  Vandenberg states "The Bosch
distributor 0231 110 041  has a faster acting advance curve than the
Marelli S103B." But that "any of the Marelli distributors could be
modified to duplicate the Bosch curve. Table G definitely show an
improvement at lower RPM."

    The has been much discussion about the Shankle airbox, which is
essentially  some curved airhorns clamped to the Spica throttle housings
with  some air filters attached. there are a couple different versions.
    Here, the dyno shows some trade - offs with a loss of one or 2 hp
below 4000 rpm and a gain of 3 hp at 5500 rpm.
    Owners tend to enjoy the sounds they provide, as comparable to a
weberised set up.
    Personally, I dislike the loss of the cold air intake (which isn't
factored into the dyno results), the noise,  the loss of the lower rpm
performance, and even prefer the appearance of the stock airbox. I will
admit to having some curved airhorns I seldom use.
     ya pays yer money and makes yer choices.

    Exhaust systems...... to quote Vandenberg
    "with exhaust systems being at the top of the list of aftermarket
bolt ons, tests of the exhaust systems were essential, Table E shows
that Alfa Romeo has done their homework.  Except in the model years
1975-76 , the 1972-74 and 1977-79 stock exhaust systems breath better
than all other units for the street with the shankle alfetta system
coming in a close 3rd,....."
    Keep in mind these test were done in 1980, predating many other
makes of headers although suggesting that adding headers to an
unmodified head is fairly useless. I wish he had tested GTA headers in
this application, although they were not very common then or now. My
reasoning for using the GTA headers are that...
1.    Jon Norman says "try these"
2     I figure my street 2 ltr produces about the same range of power as
the full race 1600's the GTA headers were designed for.
3.    I prefer to use the factory upgrades whenever possible.

    "with the 1976 FI pump set to 2% CO. "
    This differs from what Wes Ingram has since established.  In his
book "Manual for Alfa Romeo SPICA fuel Injection  Wes states, " for the
high performance units, the 255 Series works best."  referring to the 72
- 74 units.
    Later on he describes values of CO as being around 1.2 to 1.4 for a
correctly set system.

For further discussion of cams and timing i refer back to John Shankle,
in his catalog  (way old stuff here)
    "increased duration yields greater power at at higher RPMs  with a
reduction of low speed torque.  Greater valve lifts (without increased
duration) yields more power without much change in the nature of the
power curve."
"Cam timing and performance
 Two generalizations can be made about Alfa camshafts and cam timing.
One is that the lobe center position for maximum performance is about
the same for all grinds be it the mildest of the most radical,. The Alfa
engines all respond well to a lobe center of 100 to 102 deg  both intake
and exhaust for all around performance. Max horsepower is generally
achieved with lobe centers of 104 to 108 deg intake and exhaust although
the gain in top end power is usually less then the loss in low RPM
performance. Close lobe centers of 97 to 99 deg result in increased low
RPM power. The second generalization is that as duration is increased ,
high RPM power goes up at the sacrifice of low rpm performance."


    Admittedly this is all WAY OLD stuff that most of us moved past
years ago. however there still seems to be a need to provide this
information to fledgling hotshoe alfisti who don't know where else to
find it, or who to ask.
Hopefully somebody will post this someplace that is easy to find so we
won't have to keep repeating it, we can simply refer them to a web page.

    Norm
    73 Berlina
    Portland OR

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