360 vs 383
EPA,SMOG,GOVERNMENT MANDATES. Had to go with lower compression,unleaded gas etc.
And yes a stock 78 400 was a pig and sucked gas. Best of 8 mpg.I had one in 1978. What a turd..
Also rising insurance premiums for high performance cars.
One of my proudest carb tuning achievements was getting 13mpg out of a lo-po 400. it was in a heavy brick of a '70s, 2WD truck with 3.23 gears and a granny tranny truck 4 speed. The P.O. put a .484" MP cam in it with a stock bottom end. The pistons were almost .125" in the hole so it basically had no compression. Also had an RPM intake, headers and a Holley 750 vac. sec. Totally mismatched combo but somehow it ran. That 13mpg was without any vacuum advance in the distributor either so I may have done better had I tried to tune with it. But I digress.
Bottom line is that both the 360 and 400 in the '70s were just laughable with each having half or less the horsepower per their respective displacements but the 383 was really not that much better. To me, performance should mean the engine can rev past 5,000 rpm and like I said in my earlier post, the 383 in my Coronet would barely go past 4,300 even with my foot to the floor. That's despite having the factory 10:1 compression pistons slightly above deck and the 335 hp cam that was in Road Runners and Super Bees. Probably worn out to a degree but still you'd expect it to get closer to 5,000 rather than 4,000.
Prior to the performance car market boom, 383s were kinda like station wagon engines. The Golden Commando 383 was an exception but mostly they were pretty pedestrian.
There's certainly 360-
based dirt track or Super Stock engines out there making close to 2hp/cube but I rarely if ever hear about 383-based engines putting up those kinds of numbers. 600, seems reasonable but 7-800... I don't think so.