L18 8.1L swap resource thread

[-stew-]

Subbing!

 

[olive-drab]

Thanks again Larry! Have read this over a few times I had planned on the L29 TB swap, on the fence for AC relocation or delete. Any idea if a york will work with these, I don't think I can afford the air brake accessory kit!! Going to give ORD's HD crossmember a try, I know it will require some modding for my 67 but that doesn't bother me. Any preference to brand of motor mounts?

I have an Eaton HO72 with the load bolt in it and 4:10's, just looking for a Dana 60 front, going to run those with an Sm465 & NP205 as far as drive train

I will get a build thread going here soon. Have been buying body panels and tools for the last 18 months

 

[Larry]

Glad to help. If you are looking at running a compressor for the sake of air conditioning, I would definitely go with the Workhorse/Gvan/Medium Duty truck accessory brackets and run a HT6 compressor. The HT6 is one of the best compressors to ever come on a GM vehicle. If the compressor you need is more for air pressure then a York would be something to look at. I’ve never saw a York on a late model engine but with enough determination anything is possible. These days it is too easy to just install an electric air compressor and tank and be done with it.

I prefer Energy Suspension engine mounts. They are very stout without feeling the harsh engine harmonics so many other aftermarket engine mounts are known for. These require OEM mount casings then remove the OEM rubber and install the Energy insert. My truck ate two sets of Napa engine mounts before I installed the Energy mounts. No problems after that. To make these work in a ’67 you may need to install ’73-’87 frame brackets though.

Energy next to China's finest Napa mount that has been ripped to shreads

Twice (one set a year for two years straight ) the Napa engine mounts caved in driving the oil pan into the ORD xmember. Luckily, it never rubbed through

Extreme Outback air compressors are really handy. Strong and portable so it isn't committed to just one vehicle. I can carry this in the K10 one day and the Burb the next. Just don't close the lid after airing up 4 big tires. Chitz gets really hot in there

Sounds like you have the axle situation under control. Look forward to a built thread when you get around to it

 

[olive-drab]

Well I picked up the motor on Monday for 700. I plan on cleaning her up this weekend weather permitting. Know of any good sources for a service manual? It seems the chilton and haynes manuals do not cover this motor, and I don't have the extra 3$$ for the factory one right now

 

[Larry]

Nice score! She is definitely a dirty pig. You’ll want to remove that EGR valve and tubing then install the later EGR block off plate. You’ll probably end up using different exhaust manifolds or headers anyway as these stock 8.1L manifolds don’t fit old trucks without frame hacking so blocking the hole in the manifold shouldn’t be an issue. Don’t be that guy to hack up a frame for exhaust manifold or A/C clearance! Whatever tuner you use can remove the EGR function from the calibrations when they do the tuning. Also install a new crank sensor as you will not be able to get it out once you stick the engine in an old truck as well. That is the bad thing about an 8.1L in an old truck, if your crank sensor fails….the engine has to be pulled forward about 6 inches.

I use GM’s online SI2000 Service Information for everything so I don’t have experience with the aftermarket books like Chilton’s for this generation of trucks but usually avoid Chilton’s or Hayes at all possible. You’re right, the factory printed manuals are steep! I just check out ebay and they are $300 to $550! Damn!

 

[olive-drab]

Luckily we stock PB Blaster at work and lots of other goodies. I had planned on doing the EGR and crank sensor while I have it out and am cleaning it. I plan on running without AC for now so I will just be pulling the belt.

I will be buying an ECM from Howell along with a harness, planning on stock tune with egr and torque management delete. Is everything that is needed in their harness? The guys who pulled the motor hacked it pretty bad Also, do you have a part# for those workhorse fuel lines?

Gonna bug the local dealer for a login for si2000 I guess

 

[y5mgisi]

Sweet! Super jealous! One of these would move my 78 so nicely.

 

[COCHEV]

Wow! I can't believe how cheap you got that!

 

[diesel4me]

I spent most of thursday night watching those videos!...awesome trails out there and scenery,I felt like I was in the truck --going up those steep inclines with no gaurd rails must induce some severe butt clenching!....sounds like the truck had no trouble climbing those grades...I couldn't help but think how bad it'd suck to break down out there though--looked like a LONG walk if you had to hoof it to a main road from there!..

The part of the trail where that giant round Mesa is in the background,looks like a perfect place for a giant UFO to land on!...I'd love to get to see that area of the country and the grand canyon someday...

 

[Larry]

I spent most of thursday night watching those videos!...awesome trails out there and scenery,I felt like I was in the truck --going up those steep inclines with no gaurd rails must induce some severe butt clenching!....sounds like the truck had no trouble climbing those grades...I couldn't help but think how bad it'd suck to break down out there though--looked like a LONG walk if you had to hoof it to a main road from there!..

The part of the trail where that giant round Mesa is in the background,looks like a perfect place for a giant UFO to land on!...I'd love to get to see that area of the country and the grand canyon someday...

Cool! Glad to hear someone else enjoyed the past trip videos. When I travel for work and live in hotels I love to sit and wear my headphones and watch past trip videos. Nothing warms you up more like sipping a few beers and watching videos of a 112 degree day in Canyonlands when you are sitting in a hotel in Detroit when it is below zero. Headphones really bring out the sound of everything just like you are there in real time. If you poke a second set of headphones up your nose you can smell the sweet smell of the desert with a layer of big block exhaust fumes over it.

Canyonlands in Northern Arizona and Southern Utah offers the some of the most remote pristine terrain in the lower 48. You can be out there for days or even weeks at a time and never see a sole or anything man made other than planes flying overhead. Forget about your cell phone working out there so if you want people at home to know you are still alive you need to carry something like a SPOT GPS unit. The trails are not always the most difficult but there are many technical areas where there is no room for error just due to the remote location of it all. If you break something or break down, you are screwed and have a long walk out. You must have a solid vehicle, carry spare parts and know how to fix your junk. In the summer that can be a death sentence….walking out is not always an option. We usually make those trips in July when my buddy has time off from the school business. The hottest we saw was a 122 at the Hite Marina while fueling up before heading into Canyonlands in 2010.

Most of the places we go in Canyonlands get 5 to 8 hours deep into an area at 5 mph from the nearest paved road and the nearest paved road is usually 150 miles way from an actual town, which is usually Moab, UT, St. George, UT, Kanab, UT or Colorado City, AZ. Death Valley is more traveled and populated than Canyonlands.

Speaking of UFO’s..the first time I saw the space station fly over was at Ekker Butte in Cayonlands. It is so dark out there you can see satalites flyover every half hour or so in a crisscross pattern overhead. The space station sighting was really cool as it was very low on the horizon (much lower than I ever expected it to be) and moved very fast and smooth. Other than that, you don’t see anything or hear anything. Not even coyotes…there isn’t anything for them to eat! We haven’t seen any creatures out there, not even a snake. Too hot and too dry in July but this year we are going back to roam around in May for 3 days after the Overland Expo. That could be a different ball of wax being it could be cooler and wetter. We’ll see! Although we have ran into wild horses in Northern AZ and Southwestern CO as well has heard wild donkeys in the night on the Hole In The Rock trail in Southern Utah.

Some pictures of past trips..

2009: Toroweep (Grand Canyon area, AZ/Hole In The Rock trail, UT)

2010: Canyonlands

2011: Canyonlands - Top of the World & White Rim Trail

2012: Southern Utah/Western CO Nick with his famous Cummins powered '72 Suburban was along for that trip (Mosesburb)

2012: Overland Expo/Northern AZ/Southern UT

2013: Mohave Rd/Death Valley, California and some Utah Canyonlands

2013: Overland Expo

After watching the videos you will probably figure out which pictures go along with which video.

My poor old K10 never leaves the house unless it is going on nothing less than a 500 mile off-road journey The truck (and the 8.1L) have racked up almost 20,000 miles in the last few years riding the backroads of the Southwest. It is the most well maintained vehicle in our fleet just because it gets shaken, flexed, frozen, baked, dusted and beaten every time it leaves the house plus it flies down the interstate at 85 MPH at 8 hours at a time like any new truck can. Just leave the credit card on the dash for quicker fillups

 

[gonefishin]

great thread! I just bought a 2001 8.1 with harness, complete exhaust system, harness, computer, pedal, and radiator for 700.

it is going in my 91 c1500 that originally had a tbi v6. I am planning on using the 62 psi pump in my stock sending unit inside the tank.

anyway what did you do with the evap line that went to the original tank on the 2001? I have the 3 lines that almost go all the way back to the tank from the donor truck.

also has anyone used the tune from lt1swap.com? I want something on the cheaper side with a decent tune for now. I would like to be close to 375 hp and 500 ft lbs... later I plan on a rebuild and cam/springs/adjustable rockers so I would get a better tune done then.

also would there be any benefit to keeping the egr if I have room?
thanks for any help

 

[Larry]

great thread! I just bought a 2001 8.1 with harness, complete exhaust system, harness, computer, pedal, and radiator for 700.

it is going in my 91 c1500 that originally had a tbi v6. I am planning on using the 62 psi pump in my stock sending unit inside the tank.

anyway what did you do with the evap line that went to the original tank on the 2001? I have the 3 lines that almost go all the way back to the tank from the donor truck.

also has anyone used the tune from lt1swap.com? I want something on the cheaper side with a decent tune for now. I would like to be close to 375 hp and 500 ft lbs... later I plan on a rebuild and cam/springs/adjustable rockers so I would get a better tune done then.

also would there be any benefit to keeping the egr if I have room?
thanks for any help

That’s a great deal! Personally, I would not even mess with the original harness and throttle pedal. A mechanical throttle body is much more easy to deal with and more reliable. My preference is a stand-alone harness and a L29 7.4L mechanical throttle body. That said, it is a tough nut to swallow to buy $700 harness when the entire engine only cost $700.

Ah, that will be sweet! It’s a lot of work though. If you never done a 4.3L to a V8 swap in a GMT400 truck it is a lot of work as you must drop the front control arms to gain access to the engine mount nuts in order to replace them with V8 mounts. I recently did a 4.3L to TBI 7.4L swap in my FIL’s ’93 C1500. I’ll NEVER do a TBI project EVER again. Phuck TBI! An 8.1L will really scoot that little C1500 though . An AC Delco EP381 will work in your existing fuel sending unit and will run the 8.1L with no problem. That pump has plenty of snot to even bump the fuel pressure up to about 68 psi for some added power.

I am not running any EVAP lines. The EVAP purge sensor on my engine is not hooked up but I don’t see why you couldn’t use it. That would be a good question for whoever you use for tuning.

As far as a tune goes, there are a lot of good tuners out there when it comes to OBDII tuning on LS engines and 8.1Ls running the P59 ECM. 375 hp and 500 ft lbs is no problem in stock form. Back when I did my 8.1L in 2008 Howell claimed their hot tune was dyno’d at 425 HP / 555 lb ft of torque on a stock engine. Mine’s never been on a dyno but it feels strong. It made a barber pole out of the little rear driveshaft on one of the first test drives. As I mentioned a few times, all I've done to my engine is bump the fuel pressure up to 68 psi which made a noticeable difference in power with the Howell tune I run.

There is no benefit of keeping EGR. It just gets in the way and adds nothing to performance. Grab a 2004 and later EGR block off plate and have your tuner tune out the EGR function. 8.1L engines after 2003 did not use EGR.

 

[gonefishin]

Thanks for the info. I did a 350 tbi swap into the truck about 10 years ago... it still wasn't enough power though.

I am still undecided on what trans to run. Either nv3500 or nv4500. I like the ratio of the nv3500 better, but I don't think it would last long. I am going to call howell and find out more on their tune. I like your power numbers lol.

 

[Larry]

Thanks for the info. I did a 350 tbi swap into the truck about 10 years ago... it still wasn't enough power though.

I am still undecided on what trans to run. Either nv3500 or nv4500. I like the ratio of the nv3500 better, but I don't think it would last long. I am going to call howell and find out more on their tune. I like your power numbers lol.

Meh, for a 2wd probably a 4L80E would be best. I am actually in the middle of removing the Getrag 5 (similar to the NV3500) speed from my little C1500 project in favor of an automatic. The gear spacing of this trans just doesn’t work well behind big block torque with 3:42 gears and stock tires. First gear is too low and second gear is too high for launching. My FIL already fried clutch in just 13 months and with him being in his 70's driving a manual trans isn’t as easy for him anymore anyway. Plus the fact getting a TBI 454 tuned properly to run behind a manual trans was another good reason to go with an auto. I am DONE with messing with eccentric tuners trying to get this stupid manual trans 7.4L to run without idle flares and dying at rolling stops. I would have preferred to gone with a 4L80E but I got too good of deal on a low mileage GM SERTA 4L60E so I’ll run this until it drops

 

[Ten_Bucks]

I'm glad I found this thread. Larry, thanks for all the info you've provided. I'm planning on swapping a L18 into my '88 K5 soon and this thread and similar threads that I've read on other forums is what made me decide on the L18.

Scott

 

[gonefishin]

ok so I am a little further along in my swap and I have another question. the part number you listed for the flywheel 12582964 comes up as 1965 and up when I type it into different gm parts websites.

has anyone confirmed for sure that this is the same as earlier 2 piece rear seal internally balanced flywheels? I also cross referenced o'reilly's website and it list the same flywheel for virtually everything from 1965 to 1985. But it don't list a flywheel for the 8.1.

I read about guys using 2 piece small block flywheels and it working, but I hate to waste the mone for the wrong flywheel.

I am using a early style nv4500 and clutch also if that matters.

 

[Larry]

ok so I am a little further along in my swap and I have another question. the part number you listed for the flywheel 12582964 comes up as 1965 and up when I type it into different gm parts websites.

has anyone confirmed for sure that this is the same as earlier 2 piece rear seal internally balanced flywheels? I also cross referenced o'reilly's website and it list the same flywheel for virtually everything from 1965 to 1985. But it don't list a flywheel for the 8.1.

I read about guys using 2 piece small block flywheels and it working, but I hate to waste the mone for the wrong flywheel.

I am using a early style nv4500 and clutch also if that matters.

Cool! Anxious to see it when it is all done. You’ll love it!

Yep, that is the right flywheel part number guaranteed. What I posted is definitely correct

12582964 Flywheel
12563485 Flywheel bolts

Not sure where the confusion is at? I see this is an 8.1L specific flywheel (internally balanced) that also fits the internally balanced 427 and 572 GM Performance Parts big blocks. It is not common with 454’s because they are externally balanced.

Don't forget you will need to remove the dowel pins from the flywheel (not sure I ever even mentioned they need to be removed actually ). Then you can use any ole GM truck 10 spline clutch on it.

 

[gonefishin]

Ok thanks. I am just trying to buy the flywheel at O'Reilly for $83 instead of 160 at the dealership. And also i have a $50 credit to O'Reilly.

 

[Larry]

You know, I wouldn’t be surprised if an internally balanced 1 piece rear seal 5.7L flywheel would work on an 8.1L just fine. I’ve never had one laying around to test fitment on the 8.1L. The only real difference I recall noticing on the 8.1L flywheel vs. the typical 350 flywheels was the 8.1L used large metric holes for larger bolts to fasten the pressure plate to the flywheel as well as the dowel pins to center the pressure plate. Those two things may be what make an 8.1L flywheel a specific part number. You would need to hog out the holes in the pressure plate to fit the 8.1L pressure plate bolts and the dowel pins need to be removed in order to use an older clutch anyway. It might be worth trying a 5.7L flywheel. That would save me money in a few months too as I could reuse the 5.7L flywheel in my Burb when I do the 8.1L swap in it. If you go that route, let us know!

I remember in the old days my dad used a 350 flywheel on an internally balanced 396 big block then later on an internally balanced 427. He ran that setup for decades. Maybe we'll get lucky with these modern engines too

 

[-stew-]

So I got a line on a L18 G-van. 120,000 miles and a million hours. Motor runs great, strong. Burns a little oil. It sounds a little piston slappy. 4L80e is toast. What should I pay for this thing? $1000?