Author Topic: Frankenstein- montero to monstero. LS swap  (Read 63 times)

tyeler18

  • Member
  • Posts: 5
Frankenstein- montero to monstero. LS swap
« on: January 13, 2021, 08:56:23 PM »
Since I get asked about a build thread frequently, I've finally started to compile my pictures. I have no intentions of this being a how-to guide to LS swaps, but hopefully some of the pictures can help people decide if they want to tackle this (simple) swap. I'd like to treat this like a standard build thread to help document the truck for myself.

1991 Montero-

Drivetrain: Gen 3 LQ4 (6.0)
Truck intake
VS Racing 78/75 turbo
VS 44mm wastegate
4" full exhaust
Hooker aerochamber muffler
2.5" intercooler piping
3"intercooler core
4 bar GM map sensor
4L80E trans
NP263 Tcase
Custom steel driveshafts

Fuel: intank walbro 450
Snake eater 1000cc injectors

Cooling: Becool 35202 radiator
Taurus dual speed fan

Suspension: KYB shocks
Cranked torsion bars
Gen 2 rear coil springs
2" body lift

Axles: Gen 2 SR 4.63 rear
Stock gen 1 4.63 front

Brakes: Gen 2 sport fronts
Gen 2 SR rear disc brakes


I've owned the truck almost 5 yeras now, bought it basically stock from a buddy. We planned to pull the 6g72 out for his mighty max and junk/sell the shell. Neither of us knew much about monteros at the time, and I had no idea how attached I would become to this thing.

His mighty max and the montero right after he bought it.

Montero build by Tyeler Andersen, on Flickr

Paid $600 for the truck because it was hit in the front. The bumper was bent and the front grill broken/bent, but it ran and drove great otherwise.

Montero build by Tyeler Andersen, on Flickr

Back at my house, you'll notice in future pictures how much that slammed 2wd mighty max changes after getting the montero. I learned low trucks really aren't fun or practical after mobbing around in the montero.

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr


First order of business was ruining the power, or lack of already, and gearing with a set of 33x12.5 deegan 38s on some old K5 steel wheels. I think this aided to the demise of the already high mileage and under powered engine, but it made the truck so much better looking and fun to drive.

Montero build by Tyeler Andersen, on Flickr

Some testing on the trails behind my house.

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

I put a bunch of miles on it like this, it eventually burnt an exhaust valve on cylinder 2 and I gimped it around for another near 10k miles on 5 cyls. Finally the waterpump began to weep and I had no intentions of putting money into a high mileage 3.0. LS swap had been on the table from the start, but it was time to get it now. I picked up a complete 6.0 LQ4 for $800. We drove my 4" lowering blocked, mono leaf spring mighty max 70 miles up the interstate to pick this up. It was frame on axle the whole drive home. Not a fun ride back, but we got it. I can't seem to find the picture but I'll post it when I find it. Next was a 4L80 and NP263 tcase, I had no intentions of dealing with the short comings of the 4L60's, the swap would be a lot easier with a 60, but having been in enough GM builds I wanted a reliable trans.

Started with a 2" body lift to make sure everything clears. This actually wasn't entirely necessary as I have a pretty decent amount of room. I plan to put 35's on so this was necessary anyways.

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

3.0 out, 6.0 test fit in

Montero build by Tyeler Andersen, on Flickr

Mocked up the trans/tcase where I wanted them and to see how much room there was. I have an LS1 swap in my e30 which required a 3lb sledge to portions of the firewall to fit. This was much easier. Minor rework of the firewall for extra clearance.

Montero build by Tyeler Andersen, on Flickr

Tcase to torsion bar crossmember clearance. I ended up pulling the engine forward in hopes of being able to remove the tcase with the engine in the truck. This ended up not being possible, my current position is farther in front of this but it was mocked up originally at this position and I will eventually move it back to this.

Montero build by Tyeler Andersen, on Flickr

I spent a lot of time determining the best route for engine mounts. After going through a bunch of different styles I decided to mimic the mounts in my C5. This allows me to use stock C5 corvette mounts, or any version of C5 aftermarkets which come in shortened height, lifted height, and varying types of materials. Stock mounts were more than adequate for what I wanted as this is a daily driver and I didn't want the vibration acquainted with poly or solid mounts. I planned to use the factory frame horns and making adapter plates off of them, but there was no nice way to do this. Executive decision was made to remove the factory frame horns and weld in frame plates. They are leveled/gusseted and they allow quite a bit of movement to change engine position both fore and aft, height can be altered easily to change pitch.

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

Here's where things began to snowball. Decided to pick up a turbo setup because why not. 76mm 76/65 with a 44mm wastegate was purchased.

Montero build by Tyeler Andersen, on Flickr

Oh a whim huron-speed had their silverado turbo log manifold on sale. Hoping it would fit I grabbed it, fitment was even better than expected. Like it was made for the truck

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr






tyeler18

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  • Posts: 5
Re: Frankenstein- montero to monstero. LS swap
« Reply #1 on: January 13, 2021, 09:18:29 PM »
My e30 uses a 35202 radiator, after some test fitting with it it was as perfect fit for the montero too. I didn't want to cut up the core support, so I notched the frame. I ended up cutting the top of the core support anyways so this was kind of a waste. The radiator sits low at least.

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

This was a plated for strength. Core support was trimmed for the radiator.

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

Crossover for the exhaust built along with the down pipe

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Intercooler was next. Frame notched, core support hole sawed for the piping. This was a chore since I kept a/c and wanted to ensure I had room for the condenser and high side hoses.

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

I wanted to stay drive by wire as I wanted cruise control and easy idle control when this engine gets cammed. This meant wiring up the TAC module to control the throttle pedal as well as mounting a throttle pedal. The GM pedal damn near bolts in with some minor cutting/rework of the pedal arm. This was very satisfying how easy this was.

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Now that the engine was situated it was time to set the driveline. I grabbed a stock silverado trans mount for a 4L80 and made a bolt on plate extension to the factory trans crossmember. Very easy, I can adjust output shaft angle up/down with shims from here.

Montero build by Tyeler Andersen, on Flickr

Driveshaft measurements made. I bought this pinion flange that converts to a 1310 GM u-joint. It's actually for a samurai but the center hole is the exact same bore as a montero. Just need a minor re-drill of the pinion flange and it bolts right on. Driveshaft built with 1310 joints and a stock GM slip yolk.

Montero build by Tyeler Andersen, on Flickr

Montero build by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Lokar supplied the shift cable. I was hell bent on using my stock shifter. Still could use some minor adjustments to be perfect but it works well enough I'm not concerned with changing things.

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr



tyeler18

  • Member
  • Posts: 5
Re: Frankenstein- montero to monstero. LS swap
« Reply #2 on: January 13, 2021, 09:20:09 PM »
Got a little side tracked here with interior improvements. Evo 8 steering wheel and a touchscreen stereo install to make the cabin nicer. The wheel is such a nice upgrade over the big truck wheel.

Montero build by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

I won't go too indepth into engine wiring since it varies from year to year too much, but it's very easy. All my gauges, speedo (cable) aside work like stock. The temp gauge uses the montero sender with an adapter in an open port of the LS passenger head. Oil pressure comes from the oil cooler adapter with a montero sender. I kept the LS digital sender so I can log real oil pressure through the LS computer as well. Being drive by wire cruise was an easy addition. The montero switch works opposite of the GM switches (normally open vs normally closed) nothing a couple of relays couldn't solve. I added in a stealthy "trans brake" to the cruise set switch for launching the truck. Cruise operates under normal conditions just like stock, flip a switch near the fog lights and the cruise set turns into a spool valve button which locks the trans in 3rd gear. This allows me to foot brake the truck up into boost and launch. Release the button and it power down shifts into 1st with full boost pressure.

Air conditioner all operates like stock through the LS pcm. DBW is nice as it controls idle very well with the A/C and fans kicking on/off. I bought a universal 134a condenser mounted up front, then built new hoses to mate the montero evaporator to the LS truck compressor. It was 110F at the time of this picture.

Untitled by Tyeler Andersen, on Flickr

Couple of pictures post swap, pre accident. The truck was hit september 2020 by a drunk driver outside my house. My next post will be on the repair and upgrades done post accident.

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Had friends in town from portland so we explored the desert.

Untitled by Tyeler Andersen, on Flickr

4lb wastegate spring wasn't cutting it. Turned it up to 6lbs, this turbo is way to small. It spools instantly on the 6.0, 78mm should help with that

Untitled by Tyeler Andersen, on Flickr

8x11? Trans cooler, keeps the trans nice and cool.

Untitled by Tyeler Andersen, on Flickr



tyeler18

  • Member
  • Posts: 5
Re: Frankenstein- montero to monstero. LS swap
« Reply #3 on: January 13, 2021, 09:24:05 PM »
Fuel upgrades involved swapping what appears to be the original factory pump with a walbro 450. The sock on this pump was non-existent, im mildy suprised it even still worked. All the rubber had turned to goo.

Untitled by Tyeler Andersen, on Flickr

by Tyeler Andersen, on Flickr

by Tyeler Andersen, on Flickr

by Tyeler Andersen, on Flickr

Catching up to current, the truck was hit by a drunk driver while parked in front of my house at night. The rear axle was shoved into the front of the wheel well, trailing arm mount ripped off the frame, axle bent, suspension bent, and amazingly very minimal damage to the body. The rear bumper end was bent in and there was some small impact areas on the body, but the wide tires actually saved most of the truck.

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

As of this post I still haven't settled with insurance on this. While the truck is down it was time for some upgrades. The 76/65 turbo i've been using is way too small for a 6.0, I've been wanting a 78/75 since the start of the build. Christmas this year the gen 2.5 billet 78/75 went on sale, so I grabbed one. Going from a .80 A/R turbo to a 1.25 A/R will greatly help as well as gaining 10mm of turbine wheel size. This turbo has made over 900whp on multiple 6.0 setups as it is, which is more than I plan on making.

by Tyeler Andersen, on Flickr

by Tyeler Andersen, on Flickr

Out with the old, the compressors look similar since ones 76mm and the new 78mm. The exhaust housing is signifacantly larger.

by Tyeler Andersen, on Flickr

by Tyeler Andersen, on Flickr

by Tyeler Andersen, on Flickr

I ended up trading the old turbo for a 5.3L swap for a buddies international traveall. I sold it with the 44mm wastegate planning to upgrade to a 50mm instead. I wasn't expecting the size difference of the 50mm to the 44mm. Space was already a concern and the height difference wouldn't allow me to fit this and close the hood easily, so I ordered a new 44mm gate and will be welding this to the new turbo hotside just like the previous turbo. 44mm left, 50mm center, tial BOV right.

by Tyeler Andersen, on Flickr

Next was to fix the rear diff. Mine was beyond what I wanted to spend on saving, I wanted disc brakes ideally too. Gen 2 montero's are normally fairly common in the local yard, naturally when I need something there's none to be found. I contemplated buying a full truck just for the diff and any other upgrades I could scavenge. After some research it seemed the montero sport diff had potential to work, we pulled a 9.5" sport rear axle with 4.63LSD only to figure out why they wont work. The montero trailing arm mounts toe inwards as the trailing arms mount on the inside of the frame rails, the sport mounts have zero toe as the arms mount under the frame. There's enough difference that it won't bolt in, looks like the mighty max gets a coil spring rear upgrade and a 9.5" LSD. Over christmas I found a salvage yard in Colorado with a 96 SR being parted. 9.5" rear, disc brakes, 4.63 gears and a factory air locker, perfect for my truck. I paid just under $600 shipped and they included the e-brake cables, track bar, and gen 2 trailing arms to upgrade from my gen 1's.

Untitled by Tyeler Andersen, on Flickr

We swapped the diff in over New years, now I'm just waiting to fix the trailing arm mount. I'm building a new 4" exhaust as the 3" that I built for the old turbo is too restrictive. 3" was a big enough pain to fit, this 4" is going to be even more fun. Luckily I made accomodations while building the 3" for up to a 5" exhaust so I have some work cut out for me.

tyeler18

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  • Posts: 5
Re: Frankenstein- montero to monstero. LS swap
« Reply #4 on: January 15, 2021, 12:59:08 PM »
Had some free time at work today so I started prepping my exhaust housing. Wastegate hole drilled, burred, and ready for welding.

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Housing is cast, the flange is stainless, luckily these weld nice and easily. Pre-heated the housing to 350F before welding.

Untitled by Tyeler Andersen, on Flickr

Untitled by Tyeler Andersen, on Flickr

Wastegate mounted. Wish I had remembered to bring my downpipe to work, I would've merged the wastegate dump back into the downpipe if I had it. Maybe a weekend project now.

Untitled by Tyeler Andersen, on Flickr