The Stovebolt Site Forums The Shop Area General Truck Talk 454 engine ratings?

Howdy,

So, I'm considering the idea of putting a 454 from a 1974 Chevy 3/4 ton into my '56 GMC 1/2 ton but before I do that I'm trying to do some research on its power specs.

I've found several pages like this one
and this one

But what I cannot figure out is why the horsepower is stated to be 240 HP net. It doesn't make sense when these big blocks were producing double that only a couple of years earlier.

Can anyone fill in the blanks? Would a 1974 454 engine still be a stump puller or did GM take the wind out of its sails?

Thanks,
Zeke

1974 is probably the worst year in terms of the impact of emission requirements on performance. It was the first year many of the new US regulations took effect and its before computer controlled systems were able to better manage timing and fuel to get the power and milleage performance of today.

Its still a powerful motor and one from a pickup was not hurt as much as a car motor. And changing heads and manifold and other pieces of the combination will wake it up some.

I love my 454 and want to put one in every truck I own.

HP ratings are all over the place on same size engines, even within the same year.

I don't know alot about the subject, but i've been pretty supprised to see some pretty gutless HP ratings on some pretty big engines in the past.

I used to think 'bigger meant more horses' but the more I read, that's clearly not the case.

Alot of it has to do with the engines intended use.

They also changed the SAE horsepower ratings around that time to reflect a different standard... those Engines still have lots of power..

My dad put a 454 out of a '74 truck into his '67 truck. It ran circles around my '67 that had a 283. He could also pull large trailers up big hills without slowing down.

RROd is right, in the early 70s manufactures had to change from gross ratings (stripped down engine) to net: engine with all the exhaust, power accessories, alternator, air filter, etc. installed

I had a 74 454 ElCamino for a brief time. It was a dawg. It was in good tune and I didn't want to hack the air pump and other stuff off it at the time but it was a slug. I owned it for all of two months. The 1974 350 equipped truck could out accelerate it. There was a Road&Track article in the day that compared the two. Now, that's not to say that a set of heads and an intake manifold wouldn't wake it up. As produced however, the 1974 454 was a real slug. Cam, heads, compression all combined to make it so. Cheers, MV

Three words Smog Smog and Insurance. Bad words I know but thats why the horsepower went away. Emissions standards knocked down the power and insurance companys killed you in the wallet if you had more horsepower. Not a good time for muscle.