Difference betwin 454?

PSYCHO6 · #1 08-23-2011, 11:15 AM

hello guys, as some know, I have a 72 chevelle with a 454 from a 73 chevelle that develops about 250 HP ...
What I want to know is what is the difference between a 450-hp LS6 454 and mine?
And also how to increase a little the power of my 454? thank you

smokenjoep01 · #2 08-23-2011, 01:24 PM

I dont have any first hand comparisions between 454's. But I can tell you that differences in hp and tq numbers for the same displacement motors are do to different combos.
Cylinder head flow and combustion chamber designs. Piston design (flat top, dome, etc) Compression ratio and camshaft profiles all have a part in the total output of a engine.
I would guess that if your motor had the proper compression, good flowing heads and intake. And a cam that matched cylinder head flow. You could make just as much power as a LS6. JMHO

PSYCHO6 · #3 08-23-2011, 01:52 PM

I have an Edelbrock performer pipe 2.0 and a holley 850 cfm carb, what could I put a tree like cams?

smokenjoep01 · #4 08-23-2011, 01:55 PM

No comprenday

PSYCHO6 · #5 08-23-2011, 02:00 PM

what cams can i use for this? sorry i'm french

smokenjoep01 · #6 08-24-2011, 09:01 AM

You need to get a total package. Talk to a head porter and get there recomendations

earthquake68 · #7 08-24-2011, 07:47 PM

Another thing to keep in mind is horse power ratings. In 1972 they rated gross horse power. That is, they measured the horsepower at the flywheel. Since you lose horsepower through the drive train, the numbers were misleading. In 1973, they switched to a net rating. They actually measured horsepower off the back wheels. This gave a much more realistic rating, albeit a depressing one. A 350 horse power car in 1972 was only rated at at say 290 in 1973 with no changes to the combination.

Primarily what changed was compression ratio dropped and cam profiles changed. GM opened up the combustion chambers and dropped lift and duration on the cam. Since a 454 bore and stroke remain constant, a new set of pistons, heads and cam will start pumping horse power like a big dog. None of this is easy, but it's definitely doable.

PSYCHO6 · #8 09-21-2011, 12:13 PM

HELLO EVERYBODY,
could you help me to choose performance parts that can be put on my block?
What is the best solution for more power by keeping a reliable engine?
cylinder head rectangular port or oval, camshaft, and I confess that I would like to put a blower but I do not know if my original engine can handle ...
thank you

Berg · #9 09-29-2011, 12:03 PM

Hi, I think you need to not duplicate an LS6 but rather build the engine you already have for more power. I think an LS5 would be easier to duplicate with what you have if you are trying to clone an engine. The LS6 came with a 3963512 casting block with 4 bolt mains, Forged Nitrided steel crankshaft, 7/16 HD connecting rods 11.25:1 compression TRW forged pistons, and there were a few different casting numbers for cylinder heads but the 3964291's were the most popular if I remember correctly. I think they were Rectangular port closed chamber heads and the engine used a solid lifter camshaft combo.

Your 1973 454 is most likely a 2 bolt main 361959 block with cast crank, 3/8 rods, flat top or dished pistons, and smaller oval port heads. There is no reason you can't build up what you have into something fun that makes plenty of power on pump gas. There are many magazine articles in archives online if you did a google search on a good pump-gas 454 build. The engine will make good torque with your original heads if you did a valve job and changed out the pistons for a little more compression. There are hydraulic camshafts that are far better than anything that was made in the 6o's and early 70's. You can find something with a good amount of lift and duration, maybe even a dual pattern camshaft. You can get coated pistons and low friction rings, keep the 3/8 rods and have them machined with quality bolts and stud the main caps. A properly balanced rotating assembly will give years of reliable service.
The best place to start is pull your valve covers and see what the casting numbers are on the heads. If they are decent heads, rebuild them and run them. If they aren't so desirable you could step up to a set of aftermarket heads. The secret to big block and any internal combustion engine really is to be able to move air and fuel in and out as efficiently as possible. For a street engine larger oval port heads will provide good low end torque which most people don't realize is more important than horsepower. Sorry if this was a little long but I wanted to help you understand what you have and what you could build with what you already have without spending way too much money. I hope this helps you out

PSYCHO6 · #10 09-29-2011, 04:29 PM

Thank you for the explanation, now I know I need to watch and I hope you will soon present to guide me if I have other problems because you look good to know my engine I'm a little frenchie who does not know too the operation of the big block .... (at home more often you drive with 1.4 liter or 1.8litres engine of 90 to 150 horsepower ... lol