Content deleted Content added
Right is the default image setting. |
→Design: Clarity. |
||
Line 54:
All three generations are [[overhead valve engine]]s, otherwise known as pushrod engines. Overhead valve engines have the valves mounted above the cylinder head, with a [[pushrod]] and [[rocker arm]] allowing the [[camshaft]] (which is mounted inside the block) to open and close the valves. The advantages of an engine configuration like this (as opposed to an [[overhead camshaft engine]]) is that since the camshaft is located within the engine valley, a pushrod engine will be shorter in height compared an overhead camshaft engine.<ref>{{Cite web |last=Silvestro |first=Brian |date=2018-04-25 |title=Why Pushrod Engines Have a Low Redline |url=https://www.roadandtrack.com/car-culture/car-design/a20062169/why-pushrod-engines-cant-rev-high/ |access-date=2023-03-21 |website=Road & Track |language=en-US |archive-date=July 27, 2023 |archive-url=https://web.archive.org/web/20230727171228/https://www.roadandtrack.com/car-culture/car-design/a20062169/why-pushrod-engines-cant-rev-high/ |url-status=live }}</ref> Another advantage is that there are fewer mechanical components such as [[timing chain]]s and extra camshafts, which increases reliability by keeping the engine simple.<ref name=":5">{{Cite web |last=Webster |first=Larry |date=2004-05-01 |title=The Pushrod Engine Finally Gets its Due |url=https://www.caranddriver.com/features/a15132711/the-pushrod-engine-finally-gets-its-due/ |access-date=2023-03-21 |website=Car and Driver |language=en-us |archive-date=April 2, 2023 |archive-url=https://web.archive.org/web/20230402020945/https://www.caranddriver.com/features/a15132711/the-pushrod-engine-finally-gets-its-due/ |url-status=live }}</ref>
[[File:Pushrod2.PNG|thumb|A [[pushrod]] configuration that would typically be found in a LS-based [[overhead valve]] small-block. Lobes of a rotating [[camshaft]] transmit upward motion through [[valve lifter]]s to pushrods, which open valves via downward motion transferred to them by a [[rocker arm]].]]
All three generations were outfitted with either [[aluminum]] or [[cast iron]] engine blocks, with all passenger car engine blocks being aluminum, whereas truck engine blocks could be either material. Every single engine was also fitted with aluminum cylinder heads,<ref name="oac1">{{Cite web |date=2017-09-21 |title=LS Engines 101: An Introductory Overview of the Gen III/IV LS Engine Family |url=https://www.onallcylinders.com/2017/09/21/ls-engines-101-introductory-overview-gen-iiiiv-ls-engine-family/ |access-date=2023-03-23 |work=[[Summit Racing Equipment|OnAllCylinders]] |language=en |author=Staff |archive-date=September 24, 2024 |archive-url=https://web.archive.org/web/20240924064328/https://www.onallcylinders.com/2017/09/21/ls-engines-101-introductory-overview-gen-iiiiv-ls-engine-family/ |url-status=live }}</ref> except for the 1999 and 2000 [[model year]] of the LQ4, which were cast iron.<ref>{{Cite web |last=Garbe |first=Eric |date=2022-01-21 |title=A Guide to LS Cylinder Heads |url=http://www.enginebuildermag.com/2022/01/a-guide-to-ls-cylinder-heads/ |access-date=2023-03-23 |website=Engine Builder Magazine |language=en-US |archive-date=March 20, 2023 |archive-url=https://web.archive.org/web/20230320224245/https://www.enginebuildermag.com/2022/01/a-guide-to-ls-cylinder-heads/ |url-status=live }}</ref> Other modifications to the cylinder heads included a redesign to include significantly better airflow, with evenly spaced exhaust and intake [[Poppet valve|valves]].<ref name="leg" /><ref name=":4" /> A deeper engine skirt meant that the third and following generations were slightly larger than its predecessors; the deeper skirts strengthened the block and improved rigidity. A deep engine skirt refers to an engine block which extends below the centerline position of the crankshaft within the engine.<ref>{{Cite web |date=1998-01-02 |title=Cylinder Block - Building, Inspecting - Tech - Hot Rod Magazine |url=https://www.motortrend.com/how-to/building-a-cylinder-block/ |access-date=2023-03-23 |website=MotorTrend |language=en}}</ref> Another feature across all generations was the {{cvt|4.4|in|mm|sigfig=3}} [[bore spacing]] and pushrods, the former of which is also in use in the [[Chevrolet Gemini small-block engine]].<ref>{{Cite web |date=2021-10-26 |title=Flat-Plane Crank DOHC LT6 to Power the 2023 Corvette Z06! Details and Specs |url=https://www.motortrend.com/how-to/lt6-engine-2023-corvette-z06-details/ |access-date=2023-03-23 |website=MotorTrend |language=en |archive-date=October 27, 2021 |archive-url=https://web.archive.org/web/20211027132036/https://www.motortrend.com/how-to/lt6-engine-2023-corvette-z06-details/ |url-status=live }}</ref> The use of aluminum allowed for further weight reduction; the 1997 LS1 was almost {{cvt|100|lbs|kg|sigfig=2}} lighter than previous cast-iron small-block iterations.<ref name=":4" /> GM also made extensive use of economies of scale for the LS: with the exception of the 4.8L and 7.0L engines, all variants used the same 3.622" stroke (with most of those variants using the same basic crankshaft casting), the 4.8L and 5.3L variants utilized the same block casting, and several variants used the same length connecting rod.<ref>2022 Chevrolet Performance catalog: The LS/LT Engine Family Tree</ref>
| |||