Once again another reminder of how much information is crammed into this forum! The title might change, but the idea is a really interesting discussions that went further than just the basics. Links found so far, and there will also be topics hidden away in other threads. 4-vs-8-injectors 9A-ABF-comparison 16V-Forged-Piston 20v-N-A 20V-N-A-Engine 2-0-NA-Audi-Sport-20V-OEM 200bhp-on-a-single-plenum-16v ABF-cams-specs ABF-internal-crank-trigger-wheel-removal ABF-race-engine-design Crankshaft-Counterweights-relation Crank-pulley-vibration-dampers crank-sensor - OEM crank-sensors-in-high-revving-16Vs High-compression-ABF ITBs-with-a-turbo Knife-edging-cranks-pros-cons Oettinger-Graf-KR-and-ABF-heads-How-much-do-they-flow And of course reference threads: 8-valve-engines-OEM-tuned-race-outputs. 16-valve-engines-OEM-tuned-race-outputs 4-cylinder-bore-&-stroke-combinations Conrod-dimensions-reference-thread 4 cylinder crank differences & interchangeability Many more to add I'm sure