L Jetronic Alfa Spider Performance

[AlfaNeely@domain.elided]

      I have been asked what to do to wake up the performance of the L
Jetronic Alfa Spider.  With nothing more than proper tuning and a free flow
exhaust, these cars will pull strongly to 6200 RPM and will turn over 7000.
 They can be very responsive and a joy to drive.
      A relatively stock L Jet Alfa Spider is not going to run with a Honda
CRX, which is the only Honda worth having since they look like an Alfa Junior
Z.  Nor will they run with a Mazda Miata or a Viper.

      The first thing to do to any car is tune it up.  If the air and gas
filters are dirty and the spark plugs, distributor cap and rotor are old, the
car is not going to perform as desired.  You should also run the compression,
check the cam timing and valve clearances.  If compression is pretty even on
all cylinders and above 150 you are in good shape.  If compression is below
120 or if cylinders vary by more than about 10 percent it is time to think
overhaul.  Be sure to check compression with the throttle open.
      If any cylinder is much lower than the rest, squirt a bit of motor oil
down that spark plug hole.  If the compression comes back up, the problem is
rings.  If compression does not change, the problem is leaky valves.

      If the engine is in good shape, the first modification is to open up
exhaust flow.  In the case of all Alfa spiders from 1975 through 1989, that
means to fit 74 or earlier or the late Motronic cast iron exhaust manifolds.
 On my 82 I did that with a new 74 head pipe.  The head pipe was cut off at
the resonator.  I welded on the lead pipe from an old muffler center section.
 I made a fitting for an O2 sensor, although I run with it disconnected.
      I bought a catalyst from a late 1970's spider or Alfetta (see the Alfa
Ricambi ads in Alfa Owner where such a bolt in cat is pictured).  This cat
will bolt to the flange for the stock center muffler from the 82 and later
spiders.  That is why I used an old muffler to provide a flange to weld to
the 74 head pipes.  The rest of my exhaust was a stock center section with an
Ansa rear.  I later welded up a straight pipe to replace the center muffler
and I replaced the Catalyst with an Ansa "test Pipe."  The test pipes are no
longer available, but is basically a resonator that replaces the cat.  With
the straight pipe the car is not as loud as many Harleys, therefore, it must
be legal.  <grin>
      As the rear section burns out from age, the car is getting too loud or
I am getting too old at 53.  I may weld up a 12 inch glass pack for the
center section.  I may also weld up a similar set up for my wife's too quiet
91 spider.
      I am not big on tube headers for street.  They hang a bit low and tend
to become flat on the bottom.  They are harder to keep tightly bolted in
place.  They are louder and do not last as long.  However, they do produce
more horsepower.
      I bought a set of IAP headers for my race car.  I returned them as they
are not a good design.  The front edge of every tube hangs over the exhaust
port at the head about 1/8 inch.  The response from IAP's tech guy was that
they were OK for the street.  The Centerline headers have the same problem.
 I ended up with Shankle headers, which I recommend for the price.  If you
want to spend more money, Paul Spruell and Sperry both make wonderful
headers.

      The next modification is a K&N or other free flow air cleaner.  Not
much else can be done with the intake tract.  It would be nice if there were
a better flowing air meter available, but I know of none that will bolt up.
 Another possibility would be to change over to an aftermarket computer
system.  
      I think that computer modifications are going to be the way to make
horsepower in the future.  Some of these might even allow you to do away with
the airflow meter.  Eric Storhok gave me this web link for a low cost EFI
computer: http://www.bgsoflex.com/megasquirt.html  Haltech and Electromotive
offer nice high buck systems.  Eric and others are going to have to lead in
this area.  My technical abilities are such that I would just slap on a set
of Webers and pretend I was making all the horsepower possible.

      The third (or is this the fourth) modification would be to install
camshafts.  The IAP catalog suggests that good gains can be had by replacing
only the intake camshaft.  Alfa did exactly that on the Motronic engine, so I
believe them.
      The last modification would be to go inside an otherwise perfectly good
engine.  I would fit 10:1 Motronic or the Bosch 10.4:1 pistons.  The head
could be ported and fitted with larger valves.  Once inside the engine, the
sky is the limit.  Most of the engine modifications to my spiders are
mentioned below and were intended to make the engines bullet proof.
      Rather than do all the above, why not just go buy a Motronic spider.
 The Motronic already has all the above modifications.  I own two stock 91
spiders and two modified L Jetronic spiders.  They are all fun and they all
run about the same.

      A bit more about specific engine modifications I made to my spiders.
      As a bottom feeder, both my 82 street racer Alfa spider and my 84 SCCA
ITB race car arrived not running and needing an overhaul.  I paid $850 for
the 84.  I paid more for the 82 as it was low mileage with a great body and
decent upholstery.
      I build the 82 in 1995 and the 84 was built in 1999.  Both were built
with SCCA race and solo rule books in mind.  The 84 is a dedicated race car
and was built for the Improved Touring race class.  The 82 was sort of built
as an IT car, but with thoughts of SCCA Street Prepared class too.  Both rule
books require stock camshafts.
      The rule book for IT requires a basically stock engine with a stock air
flow meter, stock intake manifold, stock camshafts including VVT.  The IT
rule book allows head cutting to achieve up to half a point increase in
compression.  The IT rules also allow 0.040 inch (1 mm) oversized pistons.

      Both engines were overhauled.  Both got valve grinds on the original
valves.  Both got new valve guides and both use the original valve springs
and camshafts.  The head on the 84 was milled 0.025 inches.  The camshafts
are set up with more overlap than stock.  On the race car the intake valves
were set at 0.010 inches and the exhausts are at 0.012.  The street car has
the normal 0.017 and 0.019 inch clearance.
      Both engine blocks were drilled for full pressure oiling to all five
main bearings.  The connecting rods were magnafluxed to check for cracks.
 The beams of the rods were polished, the small ends were re bushed and the
large ends were checked and made round again as required.
      The 82 engine got new 10:1 Motronic pistons and liners, which are not
legal for IT.  The 84 got oversized 9.0:1 compression ratio 85 mm J&E pistons
from Paul Spruell.  
      The 82 crank was OK.  The 84 crank was turned 0.010 inch undersize and
renitrated.  Both cranks were drilled and tapped for set screws.  Finally
both engines were balanced.
      At the moment both are running stock air cleaner housings, although the
rules allow modifications.  The 82 has cast iron headers as described above.
 The 84 has Shankle headers with 2 1/2 inch exhaust to the rear where there
is a Super Trapp muffler run with no end plate.  The 2 1/2 inch exhaust is
probably too large, but that is the size of the U Bends I had in the attic.
      Since the 82 is a street car and occasionally autocrossed in Street
Prepared, I could modify it further.  The SCCA Street Prepared class allows
pretty much unrestricted intake.  That means Webers are legal.  I am not sure
what all can be done legally with an EFI in this class.  I guess I need to
read the rule book I just bought.
      Both cars have modified suspensions and wider sticky tires.  I could
write a whole other article on that.

Ciao,
Russ Neely
Oklahoma City

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