Editing Pontiac V8 engine (section)

===347===
[[Image:Pontiac Tripower.jpg|thumb|250px|Pontiac V8 engine with triple two-barrel [[Tri-Power]] carburetor setup]]

For 1957 the V8's stroke was increased to {{cvt|3.5625|in|mm}}, for a displacement of {{cvt|347|cuin|L|1}} and the main bearing size was increased to 2.625. For the first time, Pontiac offered '''[[Tri power|Tri-Power]]''', three two-barrel carburetors with a sequential linkage (replacing the previous dual-quad set-up). Power ratings increased with the increase in displacement and compression ratio:

(with manual transmission)
* Two-barrel carburetor, 8.5:1 compression, {{cvt|227|hp|0}} at 4600&nbsp;rpm, {{cvt|333|lbft|0}} at 2300&nbsp;rpm
* Four-barrel carburetor, 10:1 compression, {{cvt|244|hp|0}} at 4800&nbsp;rpm, {{cvt|350|lbft|0}} at 2600&nbsp;rpm

(with [[Hydramatic]])
* Two-barrel carburetor, 10.0:1 compression, {{cvt|244|hp|0}} at 4800&nbsp;rpm, {{cvt|350|lbft|0}} at 2600&nbsp;rpm
* Four-barrel carburetor, 10.25:1 compression, {{cvt|270|hp|0}} at 4800&nbsp;rpm, {{cvt|359|lbft|0}} at 2900&nbsp;rpm
* Three two-barrel carburetors, 10.75:1 compression, {{cvt|290|hp|0}} at 5000&nbsp;rpm, {{cvt|375|lbft|0}} at 2800&nbsp;rpm.

Several dealer-installed [[camshaft]]s were optional to increase power further to {{cvt|317|hp|0}}. which was seen on the hood of the 1957 Daytona Grand National winning car driven by Cotton Owens.

Standard only for the [[Pontiac Bonneville]] was Pontiac's first-ever [[fuel injection]] system. A mechanical system built by [[Rochester Products Division|Rochester]], it was similar in principle, but not identical, to a contemporary system offered as an option on the Chevrolet Corvette. Pontiac did not release official power ratings for this engine, saying only that it had more than {{cvt|300|hp|kW|0}}. Contemporary road tests suggest that it was actually somewhat inferior to the Tri-Power engines, although it did have better [[Fuel economy in automobiles|fuel economy]]. Only 630 Bonnevilles were produced for 1957, all of them fuel-injected.