Unique Products for Your Boat
  • CMI-72-IR - 72A Universal Diesel Internally Regulated Marine Alternator

    $399.50 $339.50


    We Do Not Ship Alternators Internationally 

    IMPORTANT: If you are unsure about fitment, or compatibility with LiFePO4 batteries, please use the "Contact Us" tab at the top of this page.

    The CMI-72-IR

    This is the only 72A Leece-Neville / Motorola frame alternator with custom adjustable internal regulator that is specifically designed and built from the component level ready to drop into a Universal or Westerbeke diesel with a 3/8" belt. The CMI-72-IR is directly built on the same frame as the factory original 51A 8MR2049K or 8MR2049KA only with a 72A output & a custom settable regulation voltage set point. This alternator does not exist anywhere else because we specifically build it here as a direct replacement for the original 51A unit. While we strongly advise the externally regulated version of this alternator, the CMI-72-ER, we recognize some just don't have that in the budget.

    What sets this alternator apart from an off the shelf unit are the components chosen to build it and make it ready for installation. High copper content brushes, heavy duty diodes, high volume fan, ignition excite, just like your stock alternator, & a custom billet machined pulley make this the ideal replacement alternator for a Universal Diesel engine.

    The amperage of this unit was specifically chosen to work in concert with the stock 3/8" width v-belt to minimize belt dusting and maximize amperage performance.

    The CMI-72-IR includes a custom billet machined 3/8" belt pulley (not cheap stamped steel), an upgraded high copper content brush assembly, an ignition-excite regulator that we can pre-set to your desired voltage, heavy-duty rectifier and a 2" foot that accepts a 3/8" bore bolt. Please ensure your alternators pivot bolt is 3/8" OD before ordering.

    All of these features are all by Compass Marine Inc. so you have a ready to run unit. Even if you were to source the parts and build this alternator yourself you simply can't beat this price.

    Internal Regulator: 
    The internal regulator used for this alternator is custom made to our specifications. It is internally adjustable, by us, before we ship the unit. We had been using an externally adjustable Leece-Neville regulator but too many folks messed with it, and the salt air on the external trim-pot ruined too many of those regulators. The adjustment trim-pots are extremely delicate so we had our regulator manufacturer provide us with a regulator where the adjustment is not outside the regulator, but rather sealed inside it. Please specify the target voltage you desire when ordering so that we can set it during build/testing phase.

    IMPORTANT: We do not advise that customers adjust the voltage. The adjustment pot is extremely sensitive and over turning it can ruin the adjustment pot. It is only recommended to adjust this on a test bench where the bench is stable and not vibrating. If you need it re-adjusted the alternator needs to be shipped back to us.

    CMI-72-IR Specifications:

     This 72A internally regulated alternator is intended to replace the stock alternators found on many Universal Diesel or Westerbeke engines. It will fit any Universal or Westerbeke engine that uses a 2" foot 3/8" bolt bore 8MR style alternator. This alternator fills the gap between a true high performance alternator (see our other alternator offerings) and the very, very expensive factory internally regulated alternators. It was designed to meet a price and performance niche not available to boaters previously.


    The CMI-72-IR comes standard with a tachometer output stud (stator tap) for diesels that run the tachometer sense off the alternator. Not all engines drive the tachometer from the alternator, but most Westerbeke and Universal engines do. The CMI-72,series is also available with external regulation (highly recommended).

    Special Features:

  • Intended to fit Universal & Westerbeke diesels that use an 8MR Leece-Neville
  • Direct replacement for the 51A 8MR2049, 8MR2049K or 8MR2049KA
  • Adjustable (by us) internal regulator for bulk>absorption only (does not have a  float stage)
  • 72A cold rated, with good high idle performance
  • Can be wired for remote sense
  • 14GA top quality stator magnet wire means better cooling and higher temperature tolerance
  • Epoxy coat finished both inside the case and outside
  • Precision machined rotor and slip rings for greater contact at all RPM.
  • High performance diodes
  • High Volume Directional Fan (A bi-directional fan is an option)
  • Billet Machined Pulley - 2.6" Diameter X 3/8" or 10mm Belt (1/2" v-pulley available)
  • Brushes are high copper content not run of the mill carbon brushes
  • Stator Tap for tachometer
  • 2" Foot With 3/8" Bolt Bore
  • This alternator is case grounded
  • Hand assembled/built by Compass Marine, from raw components, in Maine, USA

    *All CMI Alternators are custom built and may require a 1- 2 week lead time.