Up side… cheaper
Down side…
- Need to build:
- Rotating mass clamps on unused journals
- Hollow piston like mass on another cylinder for first order balance
- Better sensor access than multi-cylinder but still restrictive
- Typical stock block doesn’t have (or have room for) a replaceable wet liner; scratch a bore… have a significant issue
- Expensive headache to change deck height, even worse to change bore offset
- Not flexible, stuck with that model. Makes bore/stroke/head/rod-length changes issues
- First order force balance only, so:
- Adds noise to force sensitive cylinder-pressure sensors and their high impedance driven cables. Also fuel flow data is worse with vibrating fuel lines.
- Expensive sensors and all cabling doesn’t last as long
- Modern “downsized” production construction:
- Gives uncertainty of piston position derived from the crank shaft encoder due to crank/block/maincap/ flex. This affects all combustion analysis numbers.
- Bore roundness at high loads questionable
- Wear out fast at high loads and abnormal combustion. Not the same brake results in long term tests start to finish.
