L18 8.1L swap resource thread

[Kay86K5]

The O2 sensors I got (depending on you harness, and sometimes depending on the year motor/harness, your O2 connector plugs are different and my harness didn't have O2's with it) I purchased from my local parts store and they came with the option of getting the weld on bung from the store too...just FYI really.

I just installed mine on the exhaust tube just after the header collector. Just used a step drill and welded it in. Easy peasy

 

[RootBreaker]

View of the EGR bullchit that is used on the early L18’s. If I had time I would have removed it all and sent the ECM out for tuning. While the clutch looked like new the flywheel had a few burn marks on it so I sent it out to be turned as well.

So now i have an 8.1 in my garage... everything including the vented piece comes off? Pn for egr block off?

 

[Larry]

So now i have an 8.1 in my garage... everything including the vented piece comes off? Pn for egr block off?

Sorry, was out of town for a few days. Congrats on your score!

12559976 EGR Block Off Plate
12580673 EGR Gasket

Yes sir, all that crap comes off but there isn’t a part number for the manifold block off plate. The later manifolds without EGR have the EGR port cast over. You don’t want to run the stock 8.1L manifolds anyway as they won’t fit a square body frame without hacking into the upper frame rail. Don’t be that guy that hacks.

 

[RootBreaker]

Sorry, was out of town for a few days. Congrats on your score!

12559976 EGR Block Off Plate
12580673 EGR Gasket

Yes sir, all that crap comes off but there isn’t a part number for the manifold block off plate. The later manifolds without EGR have the EGR port cast over. You don’t want to run the stock 8.1L manifolds anyway as they won’t fit a square body frame without hacking into the upper frame rail. Don’t be that guy that hacks.

thx bud... and yeah I have a set of 454 manifolds and dangit.. they have egr port so I'm hoping an exhaust shop can close that up!!!!

 

[SpeedlabDan]

Sorry, was out of town for a few days. Congrats on your score!

12559976 EGR Block Off Plate
12580673 EGR Gasket

Yes sir, all that crap comes off but there isn’t a part number for the manifold block off plate. The later manifolds without EGR have the EGR port cast over. You don’t want to run the stock 8.1L manifolds anyway as they won’t fit a square body frame without hacking into the upper frame rail. Don’t be that guy that hacks

thx bud... and yeah I have a set of 454 manifolds and dangit.. they have egr port so I'm hoping an exhaust shop can close that up!!!!

So are you keeping the 8.1L now?

 

[sweetk30]

thx bud... and yeah I have a set of 454 manifolds and dangit.. they have egr port so I'm hoping an exhaust shop can close that up!!!!

might wana verify those manifold will work . if from a 88-00 style truck you might have to notch the frame rails .

i had headers for a 350 sbc 88-95 truck and even capping off and grinding the head off the plug i had to notch the frame rail for the 02 bung port location .

 

[RootBreaker]

So are you keeping the 8.1L now?

Reality check.....

might wana verify those manifold will work . if from a 88-00 style truck you might have to notch the frame rails .

i had headers for a 350 sbc 88-95 truck and even capping off and grinding the head off the plug i had to notch the frame rail for the 02 bung port location .

checking from the guy that I got them from...

 

[RootBreaker]

@Larry - how do you get such clean 8.1's????
and whats that motor behind it in the far background....

 

[RootBreaker]

The O2 sensors I got (depending on you harness, and sometimes depending on the year motor/harness, your O2 connector plugs are different and my harness didn't have O2's with it) I purchased from my local parts store and they came with the option of getting the weld on bung from the store too...just FYI really.

I just installed mine on the exhaust tube just after the header collector. Just used a step drill and welded it in. Easy peasy

yeah its interesting. I don't know how exhaust works today but both the motor and the 454 manifolds came with the piping AFTER the collector!!!!
so I have the o2 port holes and one o2 was missing and the other smashed...and I don't see the plugs. I don't know... will see later... when I get there...

 

[Kay86K5]

yeah its interesting. I don't know how exhaust works today but both the motor and the 454 manifolds came with the piping AFTER the collector!!!!
so I have the o2 port holes and one o2 was missing and the other smashed...and I don't see the plugs. I don't know... will see later... when I get there...


View attachment 277118

Those look like manifolds off a L29 Vortec 454. They had that big EGR port going off the driver manifold back up to the intake (those things freaking such to take off...had to do it on my old 96 K2500 and ended up destroying the tube, haha). Just unscrew that thing off the manifold and plug it with something like a large bolt of something like that. Then right after the collector on the exhaust tubing install some O2 bungs and be done with it

 

[RootBreaker]

Those look like manifolds off a L29 Vortec 454. They had that big EGR port going off the driver manifold back up to the intake (those things freaking such to take off...had to do it on my old 96 K2500 and ended up destroying the tube, haha). Just unscrew that thing off the manifold and plug it with something like a large bolt of something like that. Then right after the collector on the exhaust tubing install some O2 bungs and be done with it

he said not sure...
1997 he thinks...
suburban 4x4 where motor was a roller 454 with peanut heads

 

[Larry]

@Larry - how do you get such clean 8.1's????
and whats that motor behind it in the far background....

They just find me . The engine in the background is a L96 6.0L

Don’t forget, ANY GM BBC manifold or header will fit the 8.1L. That certainly makes it easier to find manifolds for them. I have 80’s 454 manifolds on my K10 and 67-91 BBC Sanderson shortly headers on my Suburban. Brand new manifolds from Napa are under $100

 

[RootBreaker]

Brand new manifolds from Napa are under $100

well crap.. paid half of new price for used.. go figure.. story of my life.. hah

do you think the upper 90s manifolds will not clear the frame? I may just flip these cheap and buy 80's ones then

 

[sweetk30]

aftermarket new is dorman china recycled crap material .

 

[Larry]

well crap.. paid half of new price for used.. go figure.. story of my life.. hah

do you think the upper 90s manifolds will not clear the frame? I may just flip these cheap and buy 80's ones then

Dunno, I never tried them on anything.

aftermarket new is dorman china recycled crap material .

Yessiree! China’s finest manifolds no doubt but I would rather run China’s finest exhaust manifold than be a hack that chops out a section of an already sketchy paper thin frame to make the wrong manifolds work. Hey, at least the metal may be recycled out of old American cars

 

[sweetk30]

Yessiree! China’s finest manifolds no doubt but I would rather run China’s finest exhaust manifold than be a hack that chops out a section of an already sketchy paper thin frame to make the wrong manifolds work. Hey, at least the metal may be recycled out of old American cars

i know . i got lucky and got a gm orignal set clean used .

and recycled metal from my heavy rust belt

 

[SpeedlabDan]

Reality check.....






checking from the guy that I got them from...

I don't know how I missed that

 

[RootBreaker]

I don't know how I missed that

More to come in that thread.. lets keep manly 8.1 beefness here

 

[SpeedlabDan]

So i got the howell harness for my build and the only issues other than some odd lengths are the knock sensor plugs. Im usingvthe knock semsors you have listed but i cant locate a pigtail to fit them. Thr connections on the harness are a small two pin utilized only one pin. The semsotd are somewhat round but with a clip spuke to pne side. Noy the typical round style. Any ideas?

 

[Larry]

So i got the howell harness for my build and the only issues other than some odd lengths are the knock sensor plugs. Im usingvthe knock semsors you have listed but i cant locate a pigtail to fit them. Thr connections on the harness are a small two pin utilized only one pin. The semsotd are somewhat round but with a clip spuke to pne side. Noy the typical round style. Any ideas?

Can you post a pic of the connectors? If they sent the wrong end connectors I'm sure you could call them and they'll send you the right ones. They're easy to back out the terminals and push them into the right connector bodies even if you have to replace the terminals. They may even make an adapter for you so you can plug and play. They did that for me on a different project with the TPS.