I've seen A LOT of posts about making HP with a 318-So why is it so ???

I had done a cam swap on the dyno in an RPM headed 446.
What the real results of the cam swap were, was basically the opposite of what the DD predicted.
Said the new cam would make less...... but it made more.

I plugged the info for the low buck 1990 318 build into DD.
It’s showing 17 TQ too much, 15hp too little.
345tq/278hp....... so 67ft/lbs more than hp.
Reality was 35ft/lbs more than hp.
The DD is also showing the low end tq from 2000-3000 pretty optimistically compared to the actual numbers.