65standard

Is the GM 8.1L vortec considered an LSx motor? I know it is based on a tall deck big block, but most everything else is LSx style.

Is there a sub forum for these motors?

JROC

IDK but I'll sub for some tech on the motor. It seems like its been forever since GM used this motor and I remember when it was introduced in the 1999 year model I believe.

handyandy496

iTrader: (9)

Yeah BB not Ls. How many cubes is it?

panic

Easy tell for family relationship: matching bore pitch. If not identical, engines are completely different.
All SBC since 1955 including LS = 4.40"
All BBC since 1958 including 8.1 = 4.84"

1 FMF

iTrader: (1)

it's 496 cubic inch. it's not the same as the previous generation 502" big block and is more like the LS blocks because it is distributorless. look up on google for the bore and stroke dimension. the 8.1L has coil per plug like the LSx, has crank & cam sensor. but it does not have a crank mounted oil pump like the LS1, it's a traditional style with a pump shaft at the rear of the block which you have to take off the intake manifold to undo from the top side then you can pull the oil pump out from below.
the oem engine is cast iron block with cast iron heads. in my 2006 2500hd the motor does not have EGR. nor does it use a pcv valve, there is a little nipple on the bottom of the intake manifold that always sucks the crankcase, and air enters the crankcase via a little hole in the throttle body that connects to the crankcase- where the oil filler tube is.
the oem pistons in the 8.1L are more like slugs, it has recessed rings i believe... i forget what is was called, maybe interference piston or something.
the gasoline powered 8.1L i believe has much less efficiency than the 6.0L and 6.2L LS engines, but the displacement allows more broadband torque and was a decent alternative to a diesel motor in the 3/4 and 1 ton trucks.
It was rumored (i remember reading don't know how true) that the 8.1L was also used or mostly used industrially and when running on natural gas i believe in the oil industry made enough power to meet whatever that need was... and was a good solution, where fuel consumption and economy wasn't necessarily an issue.
The last time the 8.1L was used in on-road vehicles was 2006 as far as i know. Whether they are still made i do not know.
my impression is between ~1999 to 2006 when the LS engines took off, where GM migrated from the previous generation small block having a distributor to distributorless ignition with cam and crank sensors and full engine computer, they did the same with the old 502" bbc into the 8.1L 496" engine (having similar longer stroke compared to previous generation) and marketed it in the 3/4 to 1 ton trucks. also mercruiser uses the base engine in medium to large size boats requiring a certain power level... again where fuel economy is less of a concern.

65standard

My 8.1 is a 2002 motor. Will anything from a 396, 427, or 454 fit these motors. Even the heads on the 8.1 have symmetric ports. Normal BBC's have two long runners and two short runners.

Thanks for the infor on these. I hope to use this 8.1 in my '87 Monte Carlo SS race car and put it back on the street. My only dislike is the heavy iron heads.

murphinator

iTrader: (2)

I sold many of them in boats both Mercruiser and Volvo Penta marinized them. Also had them in company trucks , suburban ,avalance and my favorite regular cab long bed with 8.1/Allison/4.11 G80 - truck pulled HARRD for a truck around 2000.

Raylar marine was/is into modding them , they take well to mods

nothing from old school BBC will work

1 FMF

iTrader: (1)

http://www.hcdmag.com/81l-vortec-engine/

2009 article: http://www.competitionplus.com/drag-...rine-big-block

http://www.summitracing.com/search/p...s-included/yes

8.1Skylark

The 8.1 will fit nicely in there. They have mounting holes for traditional BBC or LS motor mounts. You will need to get a custom oil pan from STEF's that is 2" shorter than the stock pan. It will come with the correct oil pickup tube. Mate it to a 4L80E or Tremec and you should be good.

Rogermija

Which of these injectors would be applicable to an 8.1L Marine (Mercruiser, Volvo, PleasureCraft)? 17124531, 17114927, 17114503, 25343789, 532-11184, 532-11161, 25348180, 17113739, 25176061, FJ10471, 881693002, 25343789? I see every injector attached to the 8.1L Marine. I am very confused. If not all, please indicate why certain ones will work.

Thank you.

dawgs74

I have one od these motors in my eagle 230 eliminator, on a good day I could scratch 80 mph if the water is calm and my trim is spot on!!

dawgs74

Last night I went to hook up the garden hose to my boat and start her up to keep the batteries alive, she started right up but after about 3 minutes or so I noticed no water coming from the exhaust. .....I've had this boat for about 7 yrs now, I guess I'm overdue for a impeller replacement. ......seems easy enough just not much room to get in there at it.........and to top it off it is Christmas week and looks like rain all week here in the S.F. gay area. .......fml.......anybody out there have a eagle 230eliminator with the 496 mercruiser. ....is this an easy task or is it something I might wanna drop $$$$ on and take to a shop???...... I'm fairly confident that I can do it and I just don't trust shops....I hate to spend $1k for the installation of a $40 part....lol

pdxmotorhead

Lot of motor.. Had a buddy with a 8.1 in a Suburban. Towed his sand toys well.
It filled the front of the suburban, must be like working on a 454 1 ton chevy van in a boat..

Always wondered what it would do with a pair of turbo's off a big diesel.