where did the 70s take the horses

i recently had someone ask me if i still have the 318 that came out of my 68 coronet.

i told him "sure its still around, do you need a new engine for your dart sport?"......he has a 74 dart sport with a 318.

He said "well i would like to replace my 318 with the coronet one for more horsepower"

So the assumption is that the 68 318 is more powerful than the 74 318 and this assumption comes because literature out there suggests that the 68 318 has 230 horsepower and the 74 has 150 horsepower.

so its assumed that 80 horsepower is lost during the rise of smog controls between 68 and 74.

But here is where i stop you........if you take a look at a book titled "standard catalog of Chrysler" by John Martin lee......you will notice that the horsepower ratings are "Gross horsepower" before 72 and after 72 they are "net horsepower" ......what does that mean?

Gross horsepower: horsepower measured with engine on a Dyno at the flywheel.

Net horsepower: horsepower measured with engine in car with full exhaust and at the rear wheel.

So if its assumed that around 75 horsepower is lost through driveline with full exhaust in a real world application.......that suggests that not much was lost at all and its simply a numbers game.

So then comes the factor of a reduced advertised compression ratio, which on the 318 is a matter of 9.2 to 8.6 ......so that is a reduction of .6 which by definition should only be responsible for 5 to 10 horsepower in the application.

So my conclusion is that the 74 318 is superior to the 68 318 because according to number manipulation not much was actually lost to the compression reduction and that loss is most likely recoverd through the heads.......It would seem the later heads are designed to work in tandem with the lower compression and heads can overcome factors like that as seen with the 455 pontiac heads of the mid to late 70s.......its amazing.

So my recommendation would be to stay with the 74 318 and add a modest 4 barrel because the 8.6 compression can handle more than the leaned out 2 bbl. of 1974 and add headers!!! possibly add a cam, but only if you know what your doing to not overcam it.

The result will be an unleaded friendly (hardened valve seats on the later heads) that will meet or exceed the performance of the 68 318.

Do you guys see my logic on why the 74 318 could be the better engine of the two or am i overthinking it??