This may or may not be a fair comparison being it's a list of Chevy V-8 heads and it's hard to compare flow testing from different sources and different engine designs.That and actual wet flow when using carbs is different than dry flow with port fuel injection.The two lowest flowing SBC chevy heads are the so called smog heads found on pedestrian 350 engines.Generally,the unmodified smog head can support about 280-300 hp at 5000 rpm on a 350 Chevy that's quite streetable.Both a 261 and 350 V-8 have about 44 cubic inch cylinders.The higher flowing heads make a lots more power at 6000 rpm and higher.The V-8 heads were tested at 28 inches of vacuum. Chevy V-8 head flow
