[blakblur]

The 1974 454came with a measly 250-270hp, that just makes me sick when i think of how they disgraced that engine. Anyway, where does one start to bring the horsepower up to where a 454 was in lets say 1971 with about 375-425hp? Or better yet, what did they do to it to take away horses so I could just reverse the process?

[molevolent_creations]

it probly has a lot to do with emissions,
lots of engines lost power due to there new emision laws they had put out

[LostKnight]

Didn't they also change the way that horsepower was rated during that time frame?

[MI2600]

Yes, the ratings prior to '72 were inflated because of the way they were tested.
I don't know much about BBCs, but the changes in SBCs involved reducing compression, less cam, less timing, and adding pollution equipment.
You can reverse that, but you run into a reduced octane at the pump.

[65 Imp SS]

Yes emissions. They went to an oc head which opened up comb chamber (good idea) but lost comp. To see what you have get the #'s and reference http://www.mortec.com/. Headers help alot on the BBC because the manifolds are restrictive plus a little more cam and after market intake. It dosn't take much to increase the HP and TQ #'s on BBC.

[Auto-Part]

Originally posted by blakblur
The 1974 454came with a measly 250-270hp, that just makes me sick when i think of how they disgraced that engine. Anyway, where does one start to bring the horsepower up to where a 454 was in lets say 1971 with about 375-425hp? Or better yet, what did they do to it to take away horses so I could just reverse the process?

Ok 1st off I am in the same position I have a 1973 454-Vette rated at 275 hp and 400 lbs of torque. The ratings changed If you rate these engines the same as the 70's stuff you actually have 330 HP and 400 lbs of torque " Note the torque is the same. Torque is a much more important measure because Torque is responsible for all the power or the work done by the engine. Forget HP for a second and also Note that a BB engine generates all or most of this power a 3,000 rpm Vs 5,000 for a SMP. You say So-what, Well what this means is that you will blow the doors off a SMB off the Line. Get the picture your engine is not as bad as you think. If you are not feeling a lot of power then your BB is worn-out or not set-up well

Having said the above. I added a few things on my BB to wake it-up a Bit. I installed the following, 272 Crane cam, Headmann Headers, Roller Tip Rockers, Had the Q-Jet rebuilt by a Bro. The main tune-up was done on a dyno and this baby is Pulling 350 HP at the back wheels That is closer to 450 HP if rated by the old day standars. That is what counts forget all this crap abought this HP and that HP at the crank. It means squat on the street. Rear wheel HP is were it's at. Enjoy

[lluciano77]

I think those were the years that they went from using gross horsepower to net horsepower figures. Also, they started lowering the compression significantly. It is hard to make decent power normally aspirated with 8.5:1 compression and lower. The "Win on Sunday, Sell on Monday" concept was fading fast.

Don't worry about horsepower figures from yesterday. It isn't really a matter of reversing what they did in order to make your car fast. First figure out how fast and driveable you want your car. Then do your homework and buy the right parts for what you are going to build. Finally, remember, if your car makes massive horsepower it will always make massive horspower. To do this usually means you will sacrifice driveability. Can you live with your car always running like a popcorn machine, or do you want to sacrifice some power for comfort and reliability?