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You can see how the roll cage
is used to tie to the front sub frame by way of round
tubing (tubing follows the floor pan alongside the
rocker panel. The rules are liberal enough so that
a fiberglass dash panel is allowed, as are aftermarket
seats and aluminum skinned doors. |
Another issue to consider is the Rulebook. In any form of
racing (automobile, boat, aircraft, motorcycle, etc.), as
the categories evolve, so do the regulations. And in the
case of a front wheel drive car such as the example Sunfire,
competing in the Turbo magazine “Hot Rod” category,
the Rules are a wee bit tougher than you might first think.
Let’s look at some of the Body requirements first (not
all of the respective Rules are shown here; only excerpts – for
a better look at the rules, pick up a copy of the NHRA Sport
Compact Rulebook or download it at: www.nhrasportcompact.com ):
Body: “Any FWD, 4-cylinder automobile, import or
domestic, permitted. 6-cylinder FWD must be of import manufacture
or domestic-labeled, joint-manufactured platform. (Examples
are Chrysler Conquest, Dodge Colt, Dodge Stealth, Eagle
Talon, Ford Probe, Plymouth Laser.)
 When
you check out the roll cage from the rear, the differences
between FWD cars and more conventional RWD jobs become
pretty clear. Where a considerable truss work of tubing
is used on a RWD car to accommodate suspension links, shock
mounts and even accessory components such as the fuel cell
and battery boxes, none of these bits are evident in the
FWD combination. The cage does tie into the rear shock/strut
towers and it does completely surround the driver, but
it is definitely different – particularly if you’re
more used to looking at traditional drag cars.
Mild customizing, body kits, and chopped roofs permitted,
but must retain full-bodied appearance, with minimum 2 functional
doors. Doors must open and close from inside and outside.
OEM glass may be replaced with Lexan or other shatterproof
material, minimum thickness 1/8-inch.
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| So far so good,
but check this out. Things are about to get complicated.
Because the front half of the car is tasked with the
jobs of harnessing both the horsepower and traction
(not to mention steering and most of the braking),
the framework has to become stout and complex. This
pair of photos shows the GM-built Sunfire under construction
(and a long ways from completion). |
OEM shell (roof panel, A-pillars, rocker panels, rocker
boxes, quarter panels, firewall floorpan, A-pillars, and
full unibody structure from firewall to front of strut tower)
must be retained, with original rear wheelwell opening. Other
body parts may be replaced with lightweight replacement panels.
One-piece, lift-off front ends permitted. Front spoiler/lip
permitted, maximum 1 inch.”
So far so good, but as you can see, in this class, you just
can’t build a tube frame car and call it done. In truth,
the body rules, particularly those associated with firewall,
floorpan and rocker boxes really restrict the creativity
of the builder. There’s more:
Firewall: “OEM firewall mandatory. See General Regulations 6:1, 7:4.
Floor: “Horizontal portion(s) of floorpan may be removed
from behind B-post or roll-cage main-hoop-attachment points
(whichever is farther rearward) to rear of car. Entire shock/strut
tower structure must be retained. Portion of floor removed
must be replaced with aluminum or steel, completely sealed.
Complete, unaltered OEM floorpan from B-post or roll-cage
main-hoop-attachment points (whichever is farther rearward)
to front of car mandatory. Complete, unaltered OEM firewall
mandatory. Excessive lightening of unibody structure, i.e.,
drilling of holes, etc., prohibited.”
Obviously, the stock firewall is mandated, but like other
NHRA categories, changes can be made to accommodate various
components. And much like a more familiar (to me, anyway)
Super Stock GT car, much of the original suspension mounting
and floor has to be maintained. Here’s where the construction
of one of these cars gets interesting:
This is the end of Part 1, check back in a couple of weeks
for Part 2!
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