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The complex shape around the exhaust header on the passenger side was taped together at first. These sections were then tack welded in the car, removed, and fully TIG welded on the bench to make a single panel. The shape of these panels will give the most interior room and allow for the unique, above floor exhaust routing.
Additional interior panels behind the driver compartment are shown in a later section. Plus there was some bleed over of work from the firewall panel fabrication in the interior panel task, due to the complex nature of the dry sump enclosure, which I will show below.
ALUMINUM FIREWALL PANELING & COWL
The firewall paneling took a chunk of time, but there was also a steel upper cowl structure being added, as well as the side sections that joined the firewall to original front unibody sections (under the A-pillars). Not to mention the complicated panels around the dry sump tank. I've broken up this task into sub-sections, which spanned over 5 different days of work.
FIREWALL - MAIN FLAT PANEL
The first main firewall panel was the biggest and easiest to make. Big flat section that covers 80% of the firewall. That was made from the same .063" aluminum 3003 as the interior panels, which is appropriate for fire protection, strength, and weight.
This was clamped to the square steel tubing added previously, which replaced the rusty OEM cowl section starting from about 4" below the base of the windshield.
An outer section on the driver's side was bisected to go around two chassis/cage tubes ties into this main flat panel section, shown above. Moving the engine back significantly required these custom firewall panels, of course.
FIREWALL - UNIBODY STEEL SIDE PANELS
Part of the new tubular cowl structure had been built when the car was still on the chassis table, shown below. But there were still large open gaps between this section and the forward portion of the unibody, as well as at the vertical edges. We needed some metal paneling here to keep air / fumes / fire / fluids from coming out of the front fender wells into the cabin.
We also needed to strengthen the original sheet metal that makes up the door hinge structure right behind this pair of panels. The side panels below were patterned, cut from 16 gauge steel sheet, then bent and added to tie this upper square tube firewall structure to the rest of the Unibody and hinge structure.
These steel side panels work to join the custom aluminum firewall with the original structures, and strengthen the door hinge areas as well. These were later welded to the tubular structure and door hinge sections.
FIREWALL - UPPER COWL STRUCTURE
The cowl section this car came with was a modified version of the OEM parts, but clearance for the set back engine was too tight. It was also hacked up, rusty, and needed complete replacement.
The remaining OEM section of the cowl is there to give the windshield a place to seal, and it has been blasted, primed and painted.
We needed to join this to the new, tubular firewall structure with a steel panel that has several compound curves and bends. Like the side panels above, it will be welded in and gives additional structure to the windshield base.
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