Billet Aluminum Fill Cap

The billet aluminum fill cap is a precision-engineered fuel cell closure designed for professional-grade racing fuel systems and high-performance automotive applications. Built to ATL Fuel Cells' exacting standards, this twist-on fuel cap provides a secure, repeatable seal on fuel cells with a 2.25-inch inner diameter opening. Whether you're running a dedicated race car, a heavily modified street machine, or a high-horsepower off-road vehicle, this aluminum cap ensures fuel containment and system integrity under demanding conditions.

Machined from billet aluminum and finished in vibrant red anodizing, this fuel cell filler cap combines lightweight construction with exceptional corrosion resistance and durability. The twist-on design allows for quick and intuitive installation and removal without special tools, while the anodized finish protects the cap against fuel degradation and environmental exposure. Weighing only 0.285 pounds, the compact 3.6 × 1.1 × 4-inch dimensions make it ideal for space-constrained engine bays where every ounce and millimeter count. The tight-fitting 2.25-inch ID opening accommodates standard fuel cell filler necks and prevents spillage during fueling or aggressive cornering.

This cap is essential for racers, fabricators, and serious enthusiasts who demand reliability and precision in fuel system components. It pairs seamlessly with ATL Fuel Cells products and other aftermarket fuel cells featuring matching 2.25-inch filler necks, making it a must-have replacement or upgrade part for any fuel cell-equipped vehicle. Installation is straightforward—simply twist the cap onto the fuel cell opening until snug; no adhesives or special procedures required. For anyone investing in a high-quality fuel cell system, this billet aluminum cap represents the finishing touch needed for professional-level performance and safety.