When it comes to automotive technology, manufacturers stay within a hidden boundary of horsepower and capabilities in my opinion. When you insert defense into this, things change quite a bit. This is pretty much the only time these engineering geeks can really let their imagination fly. Automotive defense technology has always offered sweet projects but this new engine co-designed between Cummins and Achates Power is totally rad.
Cummins’ Advanced Combat Engine (ACE) sports a unique flat-four design along with super and twin-turbocharging which outputs 1,000-horsepower. Instead of having six or eight pistons in all separate cylinders, all in a row or even in the traditional “V” configuration, this 14.3-Liter engine has two pistons in each cylinder. These pistons work opposite each other sharing the same air/fuel mixture and resulting combustion.
Each side has its own crankshaft and the pistons face each other building enough compression as they meet to complete a power stroke. Also, the pistons move between top dead center (TDC) and bottom dead center (BDC) uncovering holes in the combustion chamber that allow air in and out which results in no valvetrain. Yes, you read that right. There is no valvetrain.
Each of the separate crankshafts is connected via gearsets which then turn a single output shaft. This 1,000-horsepower monster is obviously fueled by #2 diesel and uses a two-cycle operation versus the traditional four-cycle. Since it must have air forced into the combustion chamber to complete a power stroke, this is where the roots-style supercharger comes into play. Also geared, the supercharger is feeding this mammoth with oxygen.
Cummins and their partner Achates designed the ACE to glove into the tight engine bay of a tank like the M88. When you’re powering something that heavy, heat, horsepower, and fuel economy does enter the conversation. With this opposed-piston design, suggested 13-percent drop in fuel economy, and up 50-percent in power output, Cummins landed a $47.4M governmental contract for this low heat-signature engine.
Because of its low heat signature, these tanks are even harder for enemies to track. The ACE engine has been chosen to outfit the Bradley Fighting Vehicle and M88 armored vehicle so far although it could be used in virtually anything.