ATI Releases 139-Tooth SFI Flexplate Kits For LS, LT, And Vortec Performance Applications

Creating a high-horsepower build is fairly easy in the LS/LT world, especially when the conversation centers on cylinder heads, camshafts, or forced induction. It’s also easy to forget about all the components that make those big horsepower builds actually perform. Tucked between every high-dollar engine and expensive transmission sits a piece that rarely gets the spotlight it deserves: the flexplate. ATI Performance Products just reminded builders how important that connection is with the release of its new 139-tooth SFI flexplate kits for GM LS, LT, and Vortec engines.

Created as a durable solution for high-performance drivetrains, the kits give LS and LT builders a stronger, more precise connection between engine and transmission, exactly where reliability matters most. Currently offered in two configurations, they feature an SFI 29.1 flexplate, a precision-machined crank adapter, and ARP bolts. The 6-bolt setup (P/N 915578) fits popular GM LS1, LS2, LS3, LS6, LS7 and L98 racing applications. The 8-bolt setup (P/N 915579) fits GM LT1, LT4, ZL1 Z-body, and CTS-Vs with LSA or LSX power. While the kits do require an aftermarket converter and a 10dp starter, builders do not need to purchase an LS length pilot or adapter.

High-performance builds require high-quality components. Every ATI flexplate is manufactured in-house at the company’s Baltimore facility using certified American-made materials that exceed SFI safety specs. Each plate is machined on modern CNC equipment before being double MIG and TIG welded by robotic welders on-site. Additionally, every plate is manufactured and toleranced directly from OEM engineering drawings to ensure proper fitment and geometry. Finally, each plate is inspected for flatness and run-out tolerances before being precision balanced with a resolution of one-tenth of an ounce to maintain smooth operation at high RPM.

For over 60 years, ATI Performance Products has specialized in producing high-performance products for drag racing and street applications. The company has earned a well-deserved reputation for cutting-edge tech, rigorous testing, and great attention to detail. While flexplates may not be the most glamorous component in a performance build, they’re one of the most important. ATI’s latest kits make sure that critical link between engine and transmission is ready for whatever horsepower you throw at it.