Monday, June 28, 2010

4.6 Liters, the magic size for V8 engines

Way back at the beginning of time (1956) Chevy introduced their famous 283 cubic inch V8. The plain jane two barrel carburetor version produced a mere 190 hp, using the 1950's more generous SAE rating system (no accessories, carburetor inlet temp corrected to 68F) This engine, and its 327, 350, and 307 cubic inch descendants powered GM cars for 40 years. 283 cubic inches is just about exactly 4.6 liters.
Then sometime in the 1990's Ford introduced an over head cam 4.6 liter V8 which is still in production. It started out as power for Lincoln, and spread to the Crown Vic and Mercury Grand Marquis variants of the Ford large sedan. Using the less generous SAE rating system of the 1990's, the first version of this mill had 210 horsepower, and was jacked up to 240 horsepower after improved cylinder heads were introduced right around the turn of the century.
The last entry is the Cadillac Northstar 4.6L engine, an all aluminum, double overhead cam, powerplant for the Deville. This masterpiece produces 275 horsepower, nearly one horse per cubic inchin standard trim, and 300 horse in the performance version. It gives the Deville way more power than the Ford large sedans. The extra efficiency of the Northstar allows the Deville to handily best the Fords on gas mileage.
It seems that 4.6 liters or 283 cubic inches is the optimum size for a V8. Various improvements have raised the specific power output from 0.67 horse per cubic inch in 1956 to 1.06 horse per cubic inch today.
Marketing is more difficult today. Used to be engines were known by their displacement in cubic inches. Numbers like 283, 327, and 409 live on in hot rod song and story, and sold plenty of cars. Lately is has become fashionable to size engines in liters the way the Europeans do, but no such engine has developed the fan base of the older cubic inch mills. The closest we have seen is the "Hemi" marketing campaign by Chrysler.

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