Drivetrain› Automatic Transmissions and Components

Circle D Industries

HP Series 11-Inch Torque Converter

$899.00

SKU: 57-08-19-2A

Special Order
Special Order
Ships in 4–6 weeks
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Circle D Industries HP Series NAG1 Torque Converter is an 11-inch torque converter designed for street cars up to around 600 whp. It is based on the factory core but features adjustments for stall speed and power handling capability. Key features include custom stall options, improved clutch pack surface area, a damperless turbine, and HD Torrington style bearings.
Show original supplier description
The Circle D Industries 11" HP Series NAG1 Torque Converter is engineered to enhance performance for street cars with power outputs up to approximately 600 wheel horsepower. This converter builds upon a factory core, incorporating significant internal adjustments to optimize stall speed and power delivery, aiming for stronger performance while maintaining smooth drivability. Key enhancements in this HP Series converter include custom stall speed options, allowing users to select from ranges such as 2600-2800, 2800-3000, or 3000-3200 RPM to match their specific application. Internally, it features an improved clutch pack surface area for better engagement and durability, a damperless turbine for more direct power transfer, and heavy-duty Torrington-style bearings to ensure robust operation under demanding conditions. As a custom-manufactured product, please note that a build time of 4-6 weeks is typically required. The selection of the proper stall speed is crucial for achieving optimal performance and drivability, and Circle D Specialties advises contacting them directly to ensure the correct setup for your vehicle's application.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandCircle D Industries
Part Number57-08-19-2A
CategoryDrivetrain
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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

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