I'm sure you have some basis on only getting .8HP per cubic inch but it made me wonder.....
In 1957 Chevy amazed the auto world by producing a 283 HP 283 cube engine in the Corvette and passenger cars. By 1961 that same 283 was giving 315 HP. Their 327 cube job was giving as much as 350 HP with a carb and 375 HP with fuel injection.
Ford had the hi-po 289 cube engine that did 271 HP and although not quite what Chevy was getting it is still a respectable .93 HP per cubic inch.
Ford's 406 engine was offered in a 406 HP version.
Mopar had 413/413, 425/426 hemi, 375/383, and so it goes.
These are all engines of the 60's vintage and didn't have the electronics and black boxes of today's engines. Todays smaller engines with all their electronic and other features are close to or over 1 HP per cubic inch. My wife's Sebring with a 2.5L ( 152.5 CI ) V6 has a net rating of 155 HP as measured by todays horsepower rating methods.
If you are talking about just adding bolt on parts to an otherwise unmachined 250 inch Chevy inline then I agree 100% - you'll do well in pulling 200hp from it. As mentioned before though with proper attention to head flow and compression it can easily exceed 1 HP per cubic inch and still be naturally aspirated and on pump gas only. Thats how the factories did it back in the 60's.
Still the cheapest way to get horsepower is to just buy an air cleaner decal that says 450 Horse Power Turbo Jet and put it on the 194 in your Nova.
Mike G
