NC Miata "Build Audit" Part 1

Customer brought us this car for failure analysis, possible rebuild, and also build-verification. Customer supplied us with the receipts and build sheet from the shop that performed the work.

The original concern of the customer was that his motor kicked the bucket since he hear loud knocking noises and threw the belt a few times. The good news is it's still a viable motor and we found no metallic particulate in the oil pan and only the crank pulley has failed.

Short list of build sheet:
-2.5L block (stock is 100mm stroke)
-Cometic head gasket
-2.3L Ecoboost crankshaft (94mm stroke)
-Keyed crankshaft and crankshaft pulley
-ARP flywheel bolts
-Esslinger engineering 10.5:1 pistons/rods for 2.4L combo (2.4L resultant displacement from 2.3L crank in 2.5L block)
-Esslinger engineering stage 3 cams & springs
-CustomAge 625+ head studs
-ARP main studs
-ARP cam bolts
-ARP crank bolt
-"Rebalanced" OEM crank pulley

Verified deviations from build:
-Stock crankshaft (100mm stroke verified)
-Esslinger engineering 10.5:1 pistons for 2.5L
-Non-keyed crank nor pulley
-Manley rods
-BC cams & springs
-No ARP main studs
-SK crank pulley ($48 rock auto)