Editing Chevrolet big-block engine (section)

==Generation VII==
==={{anchor|L18}} Vortec 8100 (L18)===
The Vortec 8100 L18 is a big-block [[V8 engine|V8]] engine primarily used as a [[truck]] engine. It was a redesigned Chevrolet big-block engine and was introduced with the 2001 [[Chevrolet Silverado|full-size pickup trucks]]. It is an all-iron engine (block and heads) with two valves per cylinder. It retained the {{cvt|4.25|in|mm|2}} bore diameter of the old {{cvt|427|CID|L|1|order=flip}} and {{cvt|454|CID|L|1|order=flip}} big-blocks, but the stroke was increased to {{cvt|4.37|in|mm|2}} for a total displacement of {{cvt|495.95|cuin|L|1}}. Power output ranged from {{cvt|210|to|340|hp|kW|0}}, and torque from {{cvt|325|to|455|lbft|Nm|0}}.<ref>{{cite web|url=https://www.motortrend.com/news/gm-vortec-8100-the-454s-forgotten-big-brother/|title=GM Vortec 8100: The 454's Forgotten Big Brother|date=6 July 2015}}</ref><ref>{{cite web|url=http://www.hcdmag.com/81l-vortec-engine/|title = 8.1L Vortec Engine Specs|date = 19 September 2018}}</ref><ref>{{cite web|url=https://itstillruns.com/specifications-81l-engine-7430500.html|title = The Specifications of an 8.1L Engine}}</ref><ref>{{cite web|url=https://m.roadkillcustoms.com/vortec-8100/|title=The GM Vortec 8100 ~ A BIG Gasoline Engine|date=24 October 2018}}</ref><ref>{{cite web |title=Service Manual: General Motors 8.1 L Powertrain |url=http://www.kohlerpower.com/onlinecatalog/pdf/tp6105.pdf |website=Kohlerpower.com |access-date=October 9, 2022}}</ref><ref>{{cite web|url=http://www.duramaxhub.com/gas/gm-8.1-vortec-l18.html|title = GM 8.1L Vortec V-8 Specs, History, & Information}}</ref>

Other important differences between the Vortec 8100 and older big-blocks include a changed firing order. The firing order of older big-block engines is 1-8-4-3-6-5-7-2<ref>{{cite web |last=Worner |first=Randy |date=December 21, 2022 |title=Chevy 350 SBC BBC Firing Order [With Diagram] |url=https://chevygeek.com/chevy-350-sbc-and-bbc-firing-order/ |access-date=April 25, 2023 |website=Chevy Geek}}</ref> while Vortec 8100's firing order is 1-8-7-2-6-5-4-3. Other upgrades of Vortec 8100 include a new 18-bolt head bolt pattern, longer connecting rods, different symmetrical intake ports, different oil pan rails, and the use of metric threads throughout the engine. The fuel-injection system for the Vortec 8100 is nearly identical to that used on Gen III small-block engines, right down to the fuel and spark tables in the ECU.<ref>{{cite web|url=http://www.carcraft.com/techfaq/ccrp_0709_auto_repair_questions/tpi.html |title=Automotive Repair Questions - TPI - Car Craft Magazine |publisher=Carcraft.com |access-date=2012-01-25}}</ref>

GM sold the Vortec 8100 to Workhorse (now a division of Navistar), making it one of the most popular engine choices in gasoline-powered Class A motorhomes during the early 2000s{{Citation needed|date=April 2025}}. GM stopped installing big-block V8s in the Silverado HD trucks when the GMT800 series was discontinued in 2007.

Vortec 8100s were built at GM's [[Tonawanda Engine]] plant while the engine block and cylinder head were cast at [[Saginaw Metal Casting Operations]]. The last L18 was manufactured in December 2009.

L18 applications:

* 2001–2002 [[Chevrolet C/K (fourth generation)#C3500HD (1991–2002)|Chevrolet/GMC C3500HD]]
* 2001–2007 [[Chevrolet Silverado]]/[[GMC Sierra]] 2500HD and 3500 (option)
* 2001–2006 [[Chevrolet Suburban]]/[[GMC Yukon XL]] 2500 (option)
* 2001–2002 [[Chevrolet Express]]/[[GMC Savana]] 3500
* 2002–2006 [[Chevrolet Avalanche 2500]] (standard)
* 2001–2010 [[Chevrolet Kodiak|Chevrolet Kodiak/GMC TopKick]] (including [[U-Haul]]'s {{convert|26|ft|m|adj=on}} truck)
* [[Navistar International|Workhorse]] Class A motorhomes
* [[T-98 Kombat]] armored vehicles
* [[Malibu Boats]], including the Wakesetter<ref>{{cite web |last=wildbill |title=Why did Mailbu stop using the 8100 Vortec |url=http://www.themalibucrew.com/forums/index.php?/topic/32987-why-did-mailbu-stop-using-the-8100-vortec/ |date=July 2011 |website=The Malibu Crew |access-date=June 14, 2015|display-authors=etal}}</ref>
* [[MasterCraft Boats]]