Another LS Swap: L92 & 6l80e into a '94 LC

Joined
Nov 13, 2010
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92
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La Grande, OR
ENGINE INSTALLED/MOUNTED

This thread oversimplifies things a bit. This makes it sound like the engine made about two trips into the engine bay before being mounted. That's not the case. We probably had it in and out 8-10 times.

At any rate, we finally lowered it in there for the last time and bolted it up.

Transmission and transfer case breather hoses were attached.
Transmission dip stick attached
Transfer case electrical hooked up (large square plug)
 
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92
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La Grande, OR
DRIVESHAFTS ADDRESSED

My existing shaft was a custom shaft made by Woody’s with 1310 u-joints after the Slee 4” lift was installed. Took out the last of the vibrations at the time. Because I'd moved the transfer case forward 3/4" I wasn't sure if it would create a problem. I talked to Shawn at Woody’s and he instructed me to lift the truck off the ground in the rear and see if any splines were visible. If visible, the shaft should be lengthened. Fortunately, no visible splines. Good to go in the rear. Pic is of the rear shaft with the back of truck lifted by the frame and tires dangling.
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In the front, I ran into problems I hadn't anticipated. The front shaft had come as part of a Slee 4" lift kit. There were two issues...
1. It would not compress enough to meet the flange on the transfer case. Too long with the TC being moved forward ¾”.
2. The DC joint at the TC is too big around. Hits the pan edge of the transmission. I need to move it at least ½” to get the bolt holes to line up. Will need another ¼” or so for clearance. This made me pretty nervous because I didn't really see a solution. Couldn't relocate the transmission and an '80 without a front driveshaft would have been pretty worthless to me.
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Spoke with Shawn Wood at Wood’s Drive Shafts. (Those guys are fantastic to work with) He sent both a DC and single cardon shaft to if either would work. His DC shaft has a 1310 U-joint which is smaller diameter than the one from Slee (with Toyota u-joints).

By grinding about ¼” off the trans pan, I was able to get the Woody’s DC shaft to fit.

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Nov 13, 2010
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92
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POWER STEERING LINES

This was pretty simple. I bent the hard portion of the lines to accommodate the swap and they were marked to be cut and crimped. I did not have to buy any additional hose. Took them to a local shop that builds hydraulic lines and they put them together for me.
 
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92
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La Grande, OR
COOLING SYSTEM

As previously mentioned, I had read a few posts in which folks that went with electric fans struggled with overheating issues. I figured it would be nearly impossible to retrofit a mechanical fan so I decided this was the time to do it. Mechanical fan sourced from 1999 Chevy express cargo van. It’s big, metal, has nine blades and looks like it'll move a lot of air.

I picked up a radiator from Summit Racing (see parts list). Radiator fits well. I used the Toyota bracket / insulators for mounting. Used some stacked cardboard to space radiator above frame rails and behind front body piece. Welded brackets to radiator and bolted to truck.

Toyota mounting bracket on left
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Joined
Nov 13, 2010
Messages
92
Location
La Grande, OR
I decided to go with a fan clutch that had a little longer shaft as this would give me more room to deal with the intake. I bought a new fan clutch for a 2015 Sierra 2500 6.0L. It’s a little heavier duty and has a longer shaft.

Next was the shroud. Funny thing - pulling the dash was a pain and so was building the shroud. Friend of mine fought it with a TIG welder for about a week before finally giving up. Took it to another friend who welds professionally. When he was done he refused to charge me because it looked so rough. Either way it was stuck together and wasn't anything a grinding wheel couldn't fix. Must have been the aluminum alloy they made the shroud out of.

I had to cut a vertical center section (3”) out of the universal fan shroud to get it to fit the core width. Height was just right. The two halves were tig welded back together.

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The center of the shroud was then marked before it was screwed to a sheet of plywood.

Figured out the diameter of the circle by using the fan as shown here. The band was cut to size and the ends welded together.
Using a plasma cutter, I cut a circle out of it. The circle was large enough to cut the shroud in half (reason for screwing it to plywood).

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The aluminum strip (circular part around fan) was then placed into the circle and recessed such that it would just cover the fan blades when installed. This required a 1” offset from the radiator.
The whole thing was TIG welded together. Next step was to cut the shroud in half horizontally and weld tabs on it so we could get it in and out of the vehicle.

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The halves of the shroud were placed in the truck around the fan to ensure they were centered before securing them to the radiator.

Finished shroud:
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I don't have a lot to say about the radiator hoses. I ended up using 4 hoses and spent the better part of an afternoon at the parts store with two bend coat hangers scratching my head. What I bought worked. Again, see the parts list. I do recall a size difference between the bung(s) on the radiator and the engine.
 
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Joined
Nov 13, 2010
Messages
92
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La Grande, OR
AIR INTAKE

The reason many go with electric fans is because it's pretty tough to work around the fan when setting up the air intake. There just isn't a lot of room.

Ordered a piece of 4” aluminum pipe with a 120 degree bend. Another problem to solve. The mechanical fan hits the intake – by a lot. Probably interferes by at least an inch. Can’t do with this intake tube. There is a “cobra” style that may work, but the criticism of this style is that it will collapse under vacuum. Not worth it.
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Ordered 90 degree Spectre elbow. Cleared the truck (longer fan clutch shaft) fan without issue. Will have to cut the aluminum and weld it together to reach my air cleaner box. You can see the longer fan clutch shaft in this picture.
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One customer review on this 90 degree elbow said that it can collapse under hard acceleration. For this reason, it was reinforced with an aluminum strut. You’ll have to see the picture to understand what I did. The 4” aluminum pipe was cut up and welded together to make a straight shot toward where the intake box will sit.
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Joined
Nov 13, 2010
Messages
92
Location
La Grande, OR
Next was to build an air intake box. Made sure the hood was able to be opened / closed so I wouldn’t have to worry about clearance (might sound silly until you see how close it is to the side of the hood). Also had to take into account the PS hood strut. The Box houses a K&N RF1020 Filter.

The 1FZFE pulled air from the PS fender. Seemed reasonable to me so I did the same thing with this box. First was to build a tube that would fit the fender cutout. Using a piece of 2" pipe, I split it into fourths. I then welded them to pieces of sheet metal to make a tube that would just slide into the wheelwell cutout.
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I didn't take pictures of the box as I built it. You'll have to work with me a little on the picture below. In the top right you can see the aluminum intake coming into the filter. The square metal flange is one side of the box. The bottom of the box is mounted to the PS wheel well. At the very bottom of the photograph you can see the rectangular tube structure slid into the the fender where it will pull air. This was eventually shortened to about a 2" tube because I didn't need it to be long. I made the top of the box with plexiglass but don't have a picture of the completed box by itself.
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fountainhead

SILVER Star
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Apr 17, 2009
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Absolutely amazing write-up here. Your willingness to document your research, work, and lessons learned in detail is remarkable.

Well done!
 
Joined
Nov 13, 2010
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92
Location
La Grande, OR
I don't think mine has ever locked up. At first i thought it was broken and replaced the original (used from junkyard) with a new one. Then discovered it's supposed to lock at about 220 or 230 degrees (Can't remember the exact number) I've never seen my Coolant temp get above about 207 degrees.
 
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Messages
92
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La Grande, OR
GEAR RANGE SELECTOR

There isn't provision in the 6l80e to send any signal to the dash to illuminate the shift lever position. There also isn't provision to light up the reverse lights. Guys have wrestled with this problem when doing this swap and I just wasn't totally satisfied with any of the solutions I found.

I started by soldering up a Gear Range Selector as described in this post:
Couldn't figure out why it wouldn't work for me and ultimately discovered that it will not work with an E38.

Kind of liked this guy's idea but couldn't see how it would work for all shift gates:

Here's what I did...
Using a '92 shifter (again, the '94 was one shift gate short of what the 6l80e has) I disassembled it.
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I then took a 1" schedule 40 steel nipple and cut the threads off the ends. Shortened what was left to 6". I then split the pipe in half longitudinally and welded half of it to the shift arm:

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Next step was to mount microswitches with 6-32 allthread between two additional brackets. (Yes, this will all fit under the plastic cover when done)
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I then used small pieces of a large paperclip and JB weld to secure them to the steel nipple. A dremmel was used to fine tune the size and contour of the bumps that triggered the switches. The picture below is a little misleading. I ended up adding one more switch / bump to what is pictured. I separated the switches by using 1/4" distribution tubing designed for a drip irrigation system.
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This system did take a lot of fussing with but once it was working, it's been consistently displaying the correct shift gate on the dash ever since. The one that lights up the R on the dash also triggers a relay to run the reverse lights.

7 wires will be wires to the dash gear indicator, 1 is power to the shift assembly. The wires on the switches coalesce into an 8-prong plug at the shifter. The other end of the plug goes to IH2 pins 4-8, IH1 pin 3 (this is R), and the wire from the ECT plug (since it was worthless at this point) that lights up "pwr" on the dash.

The dash on the '94 displays 6 positions: P R N D 2 1. The '92 shifter (and 6l80e) has 7 positions: P R N D 3 2 1. After the transmission tune (discussed later), I wired the dash to display the following: P R N D Dpwr 2 1. The green "pwr" light that used to light up when you pushed the ECT button now comes on when I select the gate below D. That gate puts the transmission into tow/sport mode and enables tap shifting.

I have a short video of the shifter moving through the gears triggering the switches in mp4 format. I'll post it if someone can tell me how to.

This was about as clean as I could make it by myself. It does transluminate when backlit.
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Joined
Jan 8, 2012
Messages
1,108
FIT THE ENGINE TO THE ENGINE BAY

HKR8051 manifolds work. They fit between the frame rails without any trouble

There is definitely a sweet spot in which the PS pump & AC compressor fit evenly spaced btw the frame rails. There is a tubular horizontal frame support that limits how low the engine can go. With about 3/8” to ½” clearance at each of these, the motor fits. Hood will clear and the truck intake cover can go on. The hood insulation touches the intake over when closed, but it’s not resting on it.

I would concur with the posts on IH8MUD that say the engine has to go forward and to the PS ¾” or so. The side to side movement is determined by the frame rail clearance. The forward movement is to get the PS head to clear the firewall. I did have to trim a corner off the PS heat shield (on the firewall) to keep the valve cover from touching.

Moved the trans mount forward and to the PS by 3/4'” each direction. Did this by drilling two new holes in the crossmember for the trans.
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Motor put in and mounts tacked in place. Removed motor and burned them in. I went ahead and gusseted the mounts with 3/16” plate just because it makes me feel a little better about it.
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Hey was wondering, in your your opinion, would the extra 1 3/8” of length you get with the 6l90 negate the need for modifying the trans mount, and put the engine in the sweet spot?
 
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Messages
92
Location
La Grande, OR
Not sure. You'd still be drilling new holes in the crossmember to move it sideways. I think you have to cut some off the output shaft of a 6l90 to get it to fit Mark's adapter.
 
Joined
Jan 8, 2012
Messages
1,108
Not sure. You'd still be drilling new holes in the crossmember to move it sideways. I think you have to cut some off the output shaft of a 6l90 to get it to fit Mark's adapter.
I think you have to swap the output shaft, since the 6l90 has a different spline count. Length might be different between 2 and 4wd. Oh n can’t remember.
 
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Messages
92
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La Grande, OR
OIL LEVEL SENSOR

Both the 1FZFE and the L92 have a float in the oil pan the turns an idiot light on when the level gets too low. I figured I'd retain this feature. Both sensors are looking for a ground to activate the idiot light. I simply cut the plug off the Toyota harness and added the GM plug to it. One wire goes to the gauge cluster and the other goes to ground. Sorry - looks like I didn't take any pictures of this.

I'm going to throw a question out there... The only issue I haven't been able to overcome has to do with this light. When the RPM are consistently up (on the freeway or descending and letting the motor hold me back), this light comes on. Oil pressure never drops. I've continued to add oil and am now running 7.5 quarts with no change. There are guys running up to 8 qts but if I remember correctly, they're launching their rigs on a track. There is a good posting of the F-body pan with marks on the side of the pan corresponding to different volumes of oil. Not sure I want to go much more than 7.5. Anyway, just curious if anyone else has run into this. Recommended capacity for this pan is 5.5 qts.

At 7 qts, I did shorten the dipstick so it reads in the normal range. Pretty easy to do. Tap out the pin holding the metal shaft in the yellow plastic handle, cut to length, drill a hole for the pin and put it back together.
 
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Joined
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92
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La Grande, OR
TRANSMISSION COOLER LINES

Been a while, but I believe when I disassembled it, we discovered that Toyota had run ATF not only through their ATF cooler but also a portion of the radiator. I decided to retain the LC cooler but did not run ATF through the radiator.

I used only a short segment of the trans cooler lines that came with the 6l80e. They were cut as soon as they crossed midline and pointed forward.
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In this picture, the original cooler lines come in from the right. The AN fittings are there only so I could add the temp sender.
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I used 4’ x 3/8” hard lines from local auto parts store and coupled them with inverse flare nuts. At the coupling, added a “T” for the Toyota ATF idiot light. An AN-6 “T” (AN6 to 16 x 1.50) was used for the ATF temp sensor. The anodizing on the AN fittings was enough of an insulator that it had to be brushed off (brass brush in a Dremmel) to get the sensor to ground.
 
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Messages
92
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La Grande, OR
Lines were bent in parallel over the front pumpkin and to the front DS corner. They were anchored at the PS to the crossmember tube between the front frame rails. The first pic below is looking rearward. You can see the lines going up and over the pumpkin.
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Unfortunately, I discovered that the Russell adapters from -6AN to flare nut do not seal. The female threads are not cut deep enough to seat the flare. I overcame this by using a hand file and taking the last couple of threads off the flare nuts. Kind of a pain. This had to be done to the fuel line fittings too.
 
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Messages
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AIR CONDITIONING

Low Side:
The c-loop of the Toyota line that is against the firewall will not fit (interferes with PS head). The c-loop was removed at the next junction. That then bolted into the female firewall fitting. This left a short straight section coming out of the firewall.

The GM side has a “Y” in it. When bolted to the compressor, one limb of the Y headed toward the firewall. The bracket was cut from this and the aluminum end of the Toyota line was cut to length. This actually slipped inside the GM aluminum arm and they were welded together

The other limb of the Y was used for the service port which had been cut off the Toyota line.

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High side:
Used a piece from the GM side to plug into the compressor and cut the rubber portion off. I then shortened the metal pipe portion such that it would line up with the rubber hose headed to the condenser/radiator. Problem with this approach is that I had to lose the service fitting.

The service Toyota service fitting was saved. I made a Carrel patch of sorts to make welding the aluminum service port onto the GM portion simpler.
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EXHAUST

It was just too narrow to get 3” exhaust tubing with reducers next to the engine / transmission. This problem was solved by running 2 ¼ pipe from the manifold flanges through the first bend. This ended up being about 12” on each side. Not ideal, but the output diameter of the manifold is 2 ¼” so it didn’t really narrow anything down.

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Ran the DS pipe over the TC output to join the PS where the old muffler used to be.
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