Carbureted 454 - how many HP?
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Need more info on the cam to even begin to guess, a cam is the brains of the operation.
A low performance 454, with a 750 carb, and a small aftermarket cam, should be somewhere around 300HP.
It also depends on which heads you have. They had the aluminum large squared port heads which you probably don't have. Then most came with cast iron oval ports. But some came with the very small ports for low rpm/high torque like in a motor home or work truck. Those won't make high horses but are great for ripping the tires off of your wheels. If you have the normal oval port heads with a good cam and carb you can expect to see around 300-350 horses at the rear wheels. Also, this will depend on if you have a low rise intake manifold or a high rise.
Range, running decently, upper 200's-400+.
Some factory engines did go 425+ HP.
Some factory engines did go 425+ HP.
Ah, the good old days!
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Depends on the year and the power tabulation method. My 78 454 in my C20 was (I believe) only 235 hp. I believe there was a different way of calculating hp back then. I think my 75 350 only had 165 under the same standard ...yet my 92 3.0 Caravan is rated at 145 (140-150??) ......which is nuts.
These motors were very popular in boats. If memory serves, the later marine versions (Gen IV) made 300 carb'd.
Under the old rating system (gross, before accesories) a SMALL block chevy as described would be around 300, assuming headers. A general guess for a 454 would be around 350, with tons more torque. Note that the base 396 was factory rated at 325 HP with stock manifolds under the old horsepower rating system, although this engine had higher compression than the mid 70's models.
[ March 01, 2004, 01:16 AM: Message edited by: TooManyWheels ]
[ March 01, 2004, 01:16 AM: Message edited by: TooManyWheels ]
I had a '71 corvette with stock 454 factory rated at 365 horses. In '72 the same motor with no changes was rated 270. The difference is that it was measured at the wheels rather than the crank. The main reason for this change was to help curb insurance costs. The insurance company's really don't like those high numbers. Today's motors are making more power than the old motors if you compare apples to apples. BTW, the old 450-425 HP LS6 454 from 70-71 had the aluminum large square port heads and came with a mechanical lifter cam and high rise intake (Chevelle, Vette had a low-rise after the L-88's were gone) with a Holly carb. The motor in my vette, the LS5, cam with oval heads, low rise intake and hydrolic cam and Rochester carb. Both motors made the same amount of torque, but at different rpm's.
[ March 01, 2004, 02:51 PM: Message edited by: glxpassat ]
[ March 01, 2004, 02:51 PM: Message edited by: glxpassat ]
Kestas
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From memory, I know that horsepower generally peaked out at 70-71, and went downhill from there. The highest horsepower I've seen on the books was over 400 HP from the 454 engine.
That's right JonnyO, the 454 LS5 vette in '70 had 10.25:1 compression and was rated at 390 horses. The compression ratio dropped to 8.5:1 in '71 and was rated at 365 hp. There was supposed to have been a LS7 in 1970 that advertised 460 hp and was never built. It was basically the L-88 in 454 cubic inches. The L-88 was a 427 racing motor with 12.5:1 compression that was conservativly rated 425 Hp. Only a few them were made. This motor with the extra cubic inches would have been a monster in 1970, but due to corporate pressure was never built. The 454 came out in '70 and the LS6 was the highest hp motor chevy made at 450 HP. It dropped to 425 hp in 71 with the lower compression. But even the 450 hp rating in 1970 would translate to about 350 hp today, right where the current vette is.
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