Editing Chevrolet big-block engine (section)

===454===
[[File:2014 Rolling Sculpture Car Show 47 (1970 Chevrolet Chevelle SS 454 engine).jpg|thumb|454 in a 1970 Chevelle SS]]

For 1970, the big-block was expanded again, to {{cvt|454|cuin|L|1}}, with a [[Bore (engine)|bore]] × [[Stroke (engine)|stroke]] of {{cvt|4+1/4|x|4|in|mm|1}}. The 1970 [[Chevrolet Corvette]] LS-5 version of this engine was factory-rated at {{cvt|390|bhp|PS kW|0}} and {{cvt|500|lbft|Nm|0}}, and the LS-6 engine equipped with a single 4-barrel {{cvt|800|cuft/min}} [[Holley Performance Products|Holley]] [[carburetor]] was upgraded to {{cvt|450|bhp|PS kW|0}} at 5600&nbsp;rpm and {{cvt|500|lbft|Nm|0}} at 3600&nbsp;rpm of [[Machine torque|torque]].<ref>{{cite web|url=https://www.supercars.net/blog/1964→1972-chevrolet-chevelle-ss454/|website=supercars.net|title=1964→1972 Chevrolet Chevelle SS 454|access-date=July 5, 2018|editor=Nick D. |date=March 29, 2016}}</ref><ref>{{cite web|url=https://heacockclassic.com/articles/the-best-muscle-car-1970-ls-6-chevelle/|website=heacockclassic.com|title=The 1970 LS-6 Chevelle Was America's King Of The Streets|access-date=July 5, 2018|editor=Paul Zazarine |date=November 14, 2014}}</ref>

The AHRA ASA (Showroom Stock Automatic) Class record-holding Chevelle LS-6 for the 1970 racing season posted a best-of-season trap speed of {{cvt|106.76|mi/h|km/h|0}},<ref name=Chevelle454>{{cite web |title=1970 Chevelle 454 LS-6 |url=http://www.chevelle454ls6.com/1970_chevelle_454_ls6.htm |access-date=November 1, 2014}}</ref> which suggests something on the order of 350 "as installed" (SAE Net) HP for a {{convert|3900|lb|0}} car-and-driver combination.{{citation needed|date=October 2021}} Indeed, ''Super Chevy Magazine'' conducted a chassis dyno test of a well-documented, well tuned, but stock 1970 LS-6 Chevelle and recorded 283 peak HP at the wheels<ref name="superchevy1" /> – a figure that lines up quite well with the previously referenced 350 SAE Net HP figure.{{citation needed|date=October 2021}}

An even more powerful version of the 454, producing {{cvt|465|hp|kW|0}} and {{cvt|610|lbft|0}}, was dubbed the LS-7 (not to be confused with the modern, mid 2000s, 7-litre [[Chevrolet Corvette]] engine that powered the [[Chevrolet Corvette C6|C6]] Z06, which is an LS7). Several LS-7 intake manifolds were individually produced and sold to the general public by a few Chevrolet dealers as optional performance parts. The LS-7 was later offered as a [[Automobile engine replacement|crate engine]] from Chevrolet Performance with an officially rated power minimum of {{cvt|500|hp|0}} gross.

In 1971, the LS-5 produced {{cvt|365|hp|0}} and {{cvt|550|lbft|0}}, and the LS-6 option came in at {{cvt|425|hp|0}} and {{cvt|575|lbft|0}}. In 1972, only the LS-5 remained, when SAE net power ratings and the move towards emission compliance resulted in a temporary output decline, due to lowered compression, to about {{cvt|270|hp|0}} and {{cvt|468|lbft|0}}. The 1973 LS-4 produced {{cvt|275|hp|kW}} and {{cvt|468|lbft|N.m}}, with {{cvt|5|hp|0}} and {{cvt|10|lbft|0}} gone the following year. Hardened valve seats further increased reliability and helped allow these engines to last much longer than the earlier versions, even without the protection previously provided by [[Tetraethyllead|leaded fuel]]. 1974 was the last year of the 454 in the Corvette, although the Chevelle offered it in the first half of the 1975 model year. It was also available in the full size Impala/Caprice through model year 1976.
* 1970–1976 [[Chevrolet Caprice]]
* 1970–1975 [[Chevrolet Chevelle#1970 Chevrolet Chevelle|Chevrolet Chevelle]]
* 1970–1975 [[Chevrolet Monte Carlo]]
* 1970–1975 [[Chevrolet El Camino]]
* 1971–1975 [[GMC Sprint]]
* 1970–1974 [[Chevrolet Corvette]]