IE Tall Boy Billet Steel Main Caps (VW 4 CYL)

$702.99 CAD $739.99 CAD

Integrated Engineering

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Product Features

• Ultimate solution for girdle plate installations

• Replaces factory cast main caps

• Reduces main bearing wear

• In-house CNC machined 

• Manufactured in USA 4140

• Stable crankshaft platform


These main caps are specialty designed to work with a crankshaft girdle plate. Typically, the installation of girdle products requires machining small spacers, which go between the main cap and the girdle, bringing it up to the same level as the pan rails. We have found that using spacers is very difficult to machine to the correct height, even when done with extreme care. Often times this process compromises the installation and results in a warped girdle. IE Tall Boy Main Caps offer the ultimate solution, standing slightly proud of the pan rail as they come out of the box. They are then machined level with the pan rail, resulting in a perfectly flat surface for the installation of your girdle plate, and the most rigid foundation for your crankshaft possible.



The stock main caps are cast and lack the rigidity required for a reliable high powered build. We recommend upgrading to a set of IE Billet Main Caps when building a performance engine exceeding 500HP, or when installing a girdle kit to help reduce crankshaft and main bearing wear. These VW/Audi 4 cylinder main caps are carefully crafted in-house from USA 4140 alloy steel. They provide extreme rigidity to the main bearing and crankshaft, which is a necessity for high horsepower engines. In addition, the large profile and high strength material is much stronger and stiffer than the factory main caps. 


IE Tall Boy Main Caps require machine work for installation by a certified machine shop. The main caps sit taller than the block and will require to be machined down to fit your installed girdle plate, this ensures the main caps are an exact fit to your individual block and girdle plate. All IE Billet Main Caps also require an align bore and hone, be sure to check that your machine shop can perform all the required machine work on the mains before ordering. The main caps will need to be align bore and honed using the main bolts or studs of your choice, be sure to supply your machine shop with this hardware as well for proper fitment.  Main journal housing bore size: 2.3228"-2.3236".