289 horsepower rating?

[thunderbolt]

It's not so much about being realistic as it is realizing that that most of the arguement here is centered on two different HP rating systems. The first, gross hp of the C code 289, and the second which was posted at the very beginning, rwhp. The two are about as far away as you can get. I have seen dyno results for rwhp on old mustangs and they are really low. Modern engines are rated as net HP. (Not RWHP either) General rule of thumb is multiply gross number by .75 and it gets you into the net ball park. The next general rule is multiply by .15 to .25 for driveline loss to get rwhp. We don't like to admit our old muscle cars don't have the power of new cars but amazingly enough, 30 some odd years of technology and the need to improve effeciency have resulted in some pretty phenomenal power. At its heart though, the old 289 isn't much differnt from a 5.0 and so a 289 can make these same kind of numbers with the right work.