Drivetrain› Automatic Transmissions and Components

Circle D Specialties

300mm HP LS Torque Converter

$859.00

SKU: 05B-07-09-1A

In Stock
In Stock
Ships by Sep 9
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Circle D 300mm HP LS Torque Converter is a performance torque converter designed for daily driven vehicles with 4L80E transmissions. It offers excellent street manners, only flashing high when desired, making it a durable option for everyday use.

This converter features a 300mm (12-inch) diameter and offers adjustable stall speeds ranging from 1800 to 3200 RPM. It is hand TIG welded and includes a woven carbon lockup clutch lining, heavy-duty Torrington bearings, an exclusive CDS bearing retainer, and an anti-balloon plate.
Show original supplier description
The Circle D 300mm HP LS Torque Converter is engineered for performance daily drivers utilizing the 4L80E transmission. It provides a balance of excellent street manners with performance capabilities, only engaging its higher stall speed when acceleration is demanded. This converter is built to last as a durable option for everyday driving. Constructed with a 300mm (12-inch) diameter, this unit offers customizable stall speeds from 1800 to 3200 RPM to suit various driving needs. Key internal features include hand TIG welding for robust construction, a woven carbon lockup clutch lining for durability and performance, heavy-duty Torrington bearings, an exclusive CDS bearing retainer for enhanced reliability, and an anti-balloon plate to prevent excessive flex under load. A billet front cover upgrade is available, which allows for the use of a factory 6-lug 4L80e flexplate and increases the horsepower rating to 750HP. Without this upgrade, the converter is rated up to 600HP and is designed for the dished 3-lug LS-style flexplate. Please note that Circle D converters are built to order and may require a 5-6 week build time. Furthermore, these torque converters are NOT compatible with Corvette/Camaro applications and are intended for GM truck use only.

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 Specialties
Part Number05B-07-09-1A
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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