I am active on 3 main forums (67-72chevytrucks, Expedition Portal, and CK5) and on average I get 3 to 5 PM’s and emails each week related to 8.1L swap questions from people all over world into every imaginable vehicle. While it is fun to answer each and every PM, it eats up a lot of time. Since don’t have time to write a book and make a profit on it I am hoping to make this thread the main resource thread to steer people to in the future . The following information is a cumulation of information from GM Powertrain Application Manuals, Technical Data Sheets and GM Service Manuals L18 8.1L vehicle applications: 2000-2011 Workhorse Custom Chassis Transmissions: 4L80E, Allison 1000, Allison 2200 2001-2002 GMT400 3500-HD trucks (these were the 1988-2000 body style chassis cab trucks with leaf sprung I-beam front axles. All left GM as 2wd but many were converted to 4x4 in the aftermarket). Transmission options: NV4500 & 4L80E 2001 – 2002 Chevrolet Express/GMC Savanna (G-Van) Transmission option: 4L80E 2001-2006 GMT800 2500HD/3500 (& 2007 GMT800 Classic) Transmission option: Allison 1000, ZF S6-650 6 speed manual 2001-2006 Suburban/Yukon XL/Avalanche 2500 Transmission option: 4L80E 2001-2009 GM Medium Duty trucks Transmission option: Allison 1000, Allison 2200, ZF S6-650 6 speed manual, Eaton 5 speed manual GM Powertrain also sold the L18’s to various Marine engine manufacturers where they marketed it under their own names. The two main users were VolvoPenta and Mercruiser. Both had a few different versions of the L18 with different HP ratings. L18 HP and torque ranges depending application: 340HP/455 LB. FT to 420HP/505 LB. FT (Marine) L18 GVWR Ranges: 8,600 lbs. to 44,000 lbs (Medium Duty & RV) PSI is building a Gen VII Big Block based on the 8.1L if you will. The new big hoss is an 8.8L version initially being fueled by propane for on-road vehicles. Navistar's IC Bus (School Buses) will be the first on-road vehicle to use the new 8.8L, which are launching in Q4 2015. The 8.8L has already been in production for a few years as a stationary engine for well pumps, gen sets, etc. I've seen the 8.8L and had the opportunity to tear one down to little bite size pieces. The 8.8L is a BEAST! It's hard to believe the 8.1L could have been improved upon so greatly. More details on that engine in the future. Notable items: - The L18 8.1L is 496 cubic inches, not 502. The marketing name was Vortec 8100, not Vortex. - 2001-2003 L18’s use a return type fuel system. This means there are two fuel lines at the fuel rail. One supply and one return. There is an adjustable fuel pressure regulator on the fuel rail return side. - 2004-2010 Silverado, Sierra, G-Van and Workhorse L18’s moved to a returnless fuel system. The purpose of moving to a returnless system was done for the purpose of reducing evaporative emissions by eliminating hot fuel being returned to the fuel tank. The fuel pressure regulator looking thing on the fuel rail is actually a fuel damper. Fuel pressure is regulated by a non-adjustable regulator in the fuel module assembly located in the fuel tank. Marine went returnless in 2005 while medium duty went returnless in 2006. 2004 also brought a new design intake gasket set and change in intake bolt lengths to address oil and coolant consumption. - 2003 brought a new design throttle body with a much smaller motor. This seemed to help address the touchy throttle on previous years. The harness connector and TAC modules are different between the early electronic throttle body and later. Make sure you know what you have before ordering a harness. - 2003 also brought new bare aluminum valve covers - 2004 brought new designs with the Cam and Crank sensors to improve durability. The later designs work great! Prior sensors, especially the crank sensor, are extremely prone to premature failure. There seems to be a lot of mystery around the Cam sensor (CKP) availability. Some say the 2001 - 2003 sensors is discontinued but GM shows it’s actually the 2002/2003 sensor that is discontinued. 2001 sensors seem to be readily available from GM/AC Delco meanwhile all three sensors appear to be readily available by Standard Motor Products. RayLar has a great write up on the cam sensors with their respective timing chain covers and timing chain sprocket. The only inaccuracy is their year cut-offs don’t jive with what the parts catalogs indicate. 2001: AC Delco 213-1063 or Standard Motor Products PC948 2002/2003 Discontinued through GM & AC Delco although it shows available through Standard Motor Products PC949 2004-2010 213-3826 or Standard Motor Products PC620 - EGR was also eliminated with the 2004 model year - In the GMT800 truck application, the L18 makes 355 LB. FT. of torque at 800 RPM with a peak torque of 455 LB. FT. at 3,200 RPM. That is over 300 LB. FT. of torque at idle! Not many stock gasoline engines can claim that much twist at idle. - The L18 is one of the only engines to pass the "Marine Dock'' test, in which it is run at full throttle for 300 consecutive hours, and a minimum of 1000 hours at full-throttle operation for truck applications. Not many engines carry this accolade. The Ford V10 has not passed this test and there is no documentation where the Gen III "LS" engines have met this accolade either. - All L18 engines from 2000 to 2011 ran on the Delphi P59 ECM, while the later small block LS engines moved onto E38 and E78 modules. GM Service Bulletins related to L18 engines: 01-06-01-018: Engine Tick Noise at Valve Train Speed/Loss of Power (Replace Push Rod): June 2001 02-06-01-035 High Oil Consumption: October 2002 PI01586A 8.1L Changes in Heads Bolts and Gasket for 2004.5 Engines: December 2003 04-06-01-018 Information on Revised Design of Intake Gasket and Related Bolts for 2004 Mid-Year Enhancement: June 2004 PIP3193B Excessive Oil Consumption: July 2005 06083: Product Safety - Crankshaft Position Sensor Engine Stall: December 2007 Engine Type V8 • Regular Production Option (RPO) L18 • Displacement 8.1 Liter 496 CID • Bore 107.950mm 4.250in • Stroke 111.00mm 4.370in • Compression Ratio 9.1:1 • Firing Order 1-8-7-2-6-5-4-3 Lubrication System · Oil Filter Type PF454 or PF1218 · Oil Type 5W-30 Oil Capacity • With Filter Change 6.1 Liters 6.5 Quarts • Without Filter Change 5.7 Liters 6.0 Quarts Oil Pressure - Hot • Minimum 34 kPa @ 1,000RPM 5 psi @ 1,000RPM • Minimum 69 kPa @ 2,000RPM 10 psi @ 2,000RPM Part Numbers used for my swap: Keep in mind, my part numbers are for use with a manual transmission, mechanical throttle body and return type fuel system along with the G-van/Workhorse/Medium duty accessory brackets. Part Number Description 52445253 A/C compressor 11516360 A/C compressor bolts 12581203 Belt tensioner 11516367 Belt tensioner bolt 12578330 Coolant Crossover 12571593 Coolant Crossover gasket 12575172 Crank Sensor 12575123 Dipstick 12570590 Dipstick tube 12559976 EGR Cover 12580673 EGR Cover gasket 12574560 Engine Cover 12567370 Engine Cover Ball Stud 12562957 Engine Cover Bracket 12562958 Engine Cover Bracket Stud 12582964 Flywheel 12563485 Flywheel bolts EP381 Fuel pump W0000393 HOUSING ASM - PCM 12580771 Idler on alternator bracket 213-298 Knock sensor - Drivers side (this sensor requires being moved to a different hole in the block) 213-2829 Knock sensor - Passenger 12573337 Oil Cap 12573337 Oil Cap 12581140 Oil Fill Tube 11518950 Oil fill tube stud 12568356 Oil pump drive 12575055 RAIL KIT,M/PORT F/INJN FUEL 17096144 Throttle body (1998 L29 7.4L) 12570168 Throttle body gasket 1000LS1U Throttle cable 20416 Upper rad hose (Gates) When swapping one of these engines into a 67-72 or 73-87 (91 square body) truck, the ORD HD engine crossmember works perfectly to address oil pan clearance. Taking a torch to the stock crossmember is just hacky…buy a nice ORD piece. Don't be a hack Swap info: - The L18 8.1L has the same foot print as older BBC engines and will bolt in the same as any other older SBC and BBC. In fact, the L18 will accept any exhaust manifold or header from older BBC engines. The starter motor from any older SBC and BBC for use with a 168 tooth flywheel will also fit the L18. Any transmission from an old PowerGlide, TH350, TH400 to Allison, to NV4500, etc. will bolt on to it as well. - It is not required to run electronic throttle control on these engines. If you choose to keep it simple and reliable like I did, you can use a 1996-2000 L29 7.4L cable operated throttle body on the 8.1L. Cruise control could be adapted to mechanical TB buy using the cruise control controller from a L29 as well. An aftermarket TB spacer is required to be able to use the L29 TB in order to allow room for the arm to swing. - These engines love higher than spec fuel pressure. Crank it up to about 67-68 psi and watch it come alive! (The adjustable fuel pressure regulator makes the early 2001-2003 fuel rails more desirable). - There are several accessory bracket designs used on these engines. In my experience, the G-van/Workhorse/GM Medium Duty accessory brackets are ideal for swapping into a vehicle with A/C as the A/C compressor is located up high on the driver’s side whereas the Silverado/Sierra brackets position the A/C compressor down low on the passenger’s side which causes a major frame clearance issue during swapping. To convert a pickup truck L18 to the the high mount compressor design the water pump, crank pulley/balancer must be replaced as well. Don’t be that guy to hack up a frame to make room for the A/C compressor! If not running A/C, the Silverado/Sierra brackets will work fine. More information on that below. Wiring: Like any late model engine swap, there are many different avenues for wring these engines. I personally do not like going the route of reworked donor truck harnesses. There is just too much that needs to be removed from a donor harness to bring it down to a manageable/clean size and the margin of error while rewiring it is just too great. In my opinion the only way to go is start with a fresh stand- alone harness from Howell Engine Development or one of the many other good harness suppliers out there. Identification Photo’s: This is the most commonly found accessory bracket design, as it is the Silverado/Sierra setup. The location of the A/C compressor causes frame interference when swapping into an older truck. If installing into a non-A/C vehicle these brackets are great. Just remove this compressor and eliminate the belt. This setup moves the compressor to high towards the driver's side like older engines. This setup is found on G-van's, Workhorse and GM Medium duty. The power steering pump in this picture is a ZF, not the typical Saginaw type pump although a Saginaw pump will fit this type bracket. If you would like to order any of the pieces for this set up use VIN 3GBKC34G61M101958 for part number look up. Same as above but with the heavy duty industrial/marine oil pan Same brackets as above but with A/C delete Now, if you want to get real crazy with onboard air this high GVWR range Medium Duty truck with air brakes set up is for you. This set up still allows for the clutch fan to be water pump mounted in addition to the option in this picture.