"upgunned" Spiders

[Bill Bain <BBain@xxxxxxxxx>]

This is also one of those subjects that surfaces every once in a while.
Using an Alfa 6 drivetrain and V6, it is possible to "upgun" a 105/115
chassis without much weight penalty.  Hans Milo has done this for a '73
GTV and we toyed with the idea for a Spider.  Hans chose the GTV because
it has more room under the hood (it's still tight) and because the coupe
body is more rigid than the Spider.  You would definitely have to add
the chassis stiffener to keep the Spider from buckling at the rear wheel
arch, and the hood would most likely need a scoop to clear the intake
plumbing.  There used to be a Web page on Hans' "73 GTV6".  I think the
AROO pages pointed to it at one time.

The real question is "why bother?"  The stock V6 delivers around 190 hp
and the block weighs around 100 lbs more than the 2L 4 block. The rest
of it is heavier, too, which will affect balance and steering.  Getting
to 150 hp for the 4 cylinder is not terribly expensive (all things
considered), and only marginally impairs streetability (emissions issues
aside).  A 150 hp Spider with all the other "go-fast" bits (wider tires,
rims, LSD and proper rear axle ratios, brake upgrades, shocks, springs,
swaybar upgrades, Panhard bar, among others) is a real "rocket", plus
the Alfa Competition Manual that was put together by AROC years ago lays
it all out -- you don't have to re-invent the wheel.

I recall that you have a Bosch Spider.  Boosting HP is mostly a matter
of improving the engine's volumetric efficiency.  Make it breathe and
flow better:  headers and free flow exhaust system, K&N intake, polish
and port the head, blueprint the injectors and fuel pressure regulator.
Install high-compression pistons and oversize valves and stiffer valve
springs.  Get the DiMatteo rework of the L-Jetronic brain box to prevent
high-rev mixture leaning and move the rev limiter up.  Note that I
didn't say anything about cams.  I'm gonna catch some flak on this, but
I have it on very good authority that you should do the cams LAST since
the gain from cams is usually high up in the rev band and drivability
often suffers.  If you then want to try new cams, at least the rest of
the engine won't have to be torn down twice to make the changes needed
to accommodate "hot" cams.

You could do all that for $3-5K easy.  Stuffing a 6 or 8 into a Spider
is a $10-15K project.

My $0.02 worth.  YMMV.

Bill Bain
President AROC Atlanta
'83 Spider (still a blast to drive with "only" 117 hp).

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