Higher horses, higher revs & even higher torque, a streetable LJ engine swap

Apparition said:

Understood, just figured it was worth the ask.

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Good question and you're not the first to ask! I've even mulled over that question myself.

toximus said:

I stumbled across something interesting!!! I'm not going to be the first one to tuck the 6L transmission on an LJ! I sent him a message and the transmission pan doesn't hang below the frame either. It's a bit of a relief to see that it tucks nicely and the amount of cutting required appears to be acceptable.

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@mrblaine Have you found that there's any real world benefit to have a skid with a narrow lower center (such as the Savvy skid) causing less drag than a flat skid? Much like a rub rail only contacts on a small point vs no rub rail. The trade off in this theory is that the lower center would contact more often due to hanging lower. Obviously the ground/rocks/obstacles aren't flat either so maybe in reality the ground would create a narrower point of contact?

I settled on an LS3 430hp (basically the production engine) with a 6L80e in the connect and cruise package. I don't know enough if the hot cam in the 480 will be an issue or not and I'd rather go the easy route for now and stick with what I know will work. If I get bored in the future and want to invite trouble I can always do the cam swap myself. I caught wind that the wiring harnesses for the connect and cruise are drying up since that GM facility is having issue making them due to COVID. On that note I decided to place my order now instead of waiting for the transfer case to be ready.

Here's my updated shopping list:

1. Radiator fan: Spal 16" brushless PWM
2. Water pump + tensioner: I will buy OEM (must fit above radiator and be truck or f-body offset) also need a thermostat?
3. Harmonic Balancer with correct offset: F-Body offset: ACDelco (OEM) 12553118, Truck offset: ACDelco (OEM) 19300488. Replace TTY bolt.
4. AC bracket: Holley low-profile or Dave's Customs high mount. I'll get the engine in before deciding which will fit.
5. Transmission shifter: I'd like a 6 position. I'm undecided between a Winters + tap or using an OEM tap shifter. It'll probably come down to what fits best.
6. Engine oil pan: Kevko or Tilden/Pacific.
7. Oil filter relocation kit: Wait on pan.
8. Radiator coolant: Decide between G05 (HOAT) or Dexcool (OAT).
9. Dash gauges: Maybe Autometer for essentials + Torque app for other stuff? I don't love how Autometer gauges look.
10. Exhaust headers: CTS-V + heat shields (waiting to order until I have a visual on how the engine fits)
11. Engine oil: 5w30 synthetic Amsoil (leftover from the Jeep 4.0). Driven Racing 5w30 Break in oil first (optional, but not a bad idea).
12. Air filter: I'm waiting to see what space I have left to fit it in.
13. Starter + heat shield
14. 6L80e shallow pan

Ordered:

1. Radiator: Superior Radiator - I've heard this one lasts longer than others do. (http://rover.ebay.com/rover/1/711-5...0001&campid=5337789113&icep_item=164219718305)
2. Accessory brackets: I'll be going with GoatBuilt's driver's side brackets for the alternator and PSC CBR pump (truck or f-body offset)
3. Power steering pump: I'll be reusing my CBR pump off the TJ 4.0 and bought a 6" pulley offset for the LS.
4. Alternator: Mechman high output alternator (probably overkill but 180a at idle will be awesome for heavy winching).
5. Transfer case: Atlas 2 speed 3:1
6. Transfer case fluid: Comes with Atlas.
7. Ignition switch: Retain the stock keyed ignition on the steering column.
8. Spark plug boot pliers
9. Engine mounts: There's no mounting kits that will work for me so I'll use universal style brackets and make my own.
10. Trans/TC mounts: AutoFab bushings
11. A ton of bolts for attaching enginey parts to the engine.
12. LS3 430 + 6L80e Connect and Cruise
13. Transmission fluid: Dexron VI
14. 4 corner steam vent kit

I asked Jon at RPM Extreme about their PWM fan controller compatibility with the SPAL brushless fan and he mentioned that he isn't sure if their module would work with the connect and cruise harness/ECU but would work fine with the fan. After discussing his experience integrating with the LS electronics some more, it turns out that the connect and cruise setup may be limited in functionality. Instead, he'll be making me a custom harness with support for the LS3 and 6L80e with all of the features I want and providing a GM E38 ECU for my swap.

For once in my life I was actually thankful to have an order get caught up in the fraud department which allowed me time to cancel my connect and cruise order and order only the LS3 430 engine (19370416).

The transmission is the confusing bit... RPM Extreme has only confirmed their harness to work with the production 2011-2013 Chevy Silverado 6L80e. I talked to several dealers and they are only able to program a new production or performance transmission if it's installed in a Chevy truck with a Chevy VIN. After a few phone calls to aftermarket transmission builders, I talked to Zero Gravity Performance. And that guy really seems to know his stuff! He said he actually worked for Chevy until 2013(iirc) and had worked on the Performance 6L80e design for them. He also can reflash any of the TCMs to be any other TCM and be programmed to work with any of the ECUs (not even limited to GM). And he could help me if I buy the Chevy Performance transmission or one of his. I gave him the specs of my Jeep and what I'm planning to do with it and he'll be getting back to me with a quote for one of his built 6L80e transmissions — he mentioned it'll probably be somewhere between his stage 1 and stage 2 transmissions.

I'll now need to pick out an accelerator pedal too.

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The custom harness from RPM Extreme will include:

PWM Fan Controlers

One controller for the main radiator up front and a second controller if I end up running a second transmission cooler with fan. He can add up to 4 fan controllers per harness, after that you have to use multi-speed brushed fans.

This will allow for PWM brushless variable speed fans to work. These fans tend to have longer lasting motors and can slow down or speed up the rotation of the fan based on ECU factors such as radiator temp, if the throttle is above a certain percentage, or if the AC is turned on. It should be less sensitive to stalling so hope it'll fair better if I forget to turn it off during a deep water crossing.

Alternator Voltage Bump

Without, the alternator will fall back to 13.2v. Their module will output the alternator request signal to the GM E38 ECU and command the alternator to 14v which is perfect for the EGM batteries we use.

Reverse Lights

Add an output wire for the reverse lights using the CAN signal from the 6L80e.

Tap Shift

So I can manually select gears. The connect and cruise also has this available.

Tow/Haul Mode

Since my Jeep really isn't set up to do any towing I can use this mode as an alternate shift table. I'm not sure that I'll use it, but it doesn't hurt to have the provision available.

AC Signal

Lets the ECU know when the AC is turned on. This allows for things like RPM bump at idle and turning on the radiator fan when the AC is running.

sjalkian said:

I ordered a 2 Speed Atlas back on 6/29. I know they said 7-8 weeks. I saw a pending charge a day later and then a couple days after that it dropped from pending. Did you experience the same? I wasn't going to call them until next week just to be sure I'm still in line.

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I had placed my order over the phone because an option I needed wasn't available online, and the guy I talked to suggested they call me to collect payment 2 weeks before they start so I wouldn't have a pending charge sitting on my CC.

Yesterday I checked in with Advance Adapters on the status of my transfer case and I just made the cut of what parts they have available to assemble them. My order was placed on June 25th and supposed to ship on August 21st. All orders now are 9 weeks out IF they get the parts in to make them. All of the parts for mine are thankfully on the shelf and allocated to my Atlas. Hopefully your order made the cut too!

gaabbee said:

Nice catch on the harness/ecu tuning. Now you get a built trans out of it and some nice features!

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Thanks. It's taken me weeks of researching and on phone calls to figure just that bit out.

gaabbee said:

Did you mean AGM battery?

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Yes. Good catch!

gaabbee said:

Wait so he can make a 6l80e tcm work with a jeep ecu? Who wants to make an adapter for the auto guys?

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You could ask, but like you said you would have to figure out how to bolt that sucker up. It sounds like he can control the valve body independently.

sjalkian said:

I'll give them a ring and see where I am in line.

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Post an update once you find out! Best of luck!

sjalkian said:

He ended using the TJ cluster and did some wiring wizardry.

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We've talked about doing that on mine. And I think the end look is super clean keeping the dash stock. I opted to avoid the wizardry (doubling up on sensors and running signal converters) due to reliability concerns.

I'll probably run an AIM digital dash instead which has a good durability track record and can speak GM. The idea being that I can display only what I need (RPM, gear, and MPH on the street) and nothing I don't (water temp, battery voltage, etc). If anything goes out of bounds (ie. water temp is too high) it'll be able to pop up a warning message and I can switch views to display all of the gauges. Something I'm exploring anyway...

gaabbee said:

Wait so he can make a 6l80e tcm work with a jeep ecu? Who wants to make an adapter for the auto guys?

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"The TCM-2650 will allow you to adapt the GM 6L45E, 6L50E, 6L80E and 6L90E transmission to practically any engine. We have successfully used these on numerous engines, such as Cummins Diesels. These kits come with all the necessary hardware to get the transmission to function All that is needed are a throttle position and engine RPM signal."

http://www.zerogravityperformance.c...6l90e-transmission-to-practically-any-engine/
http://www.zerogravityperformance.c...ic-transmission-controller-6l80e-6l90e-6l50e/

fixmysix said:

Did you look at the Lingenfelter version? It pulls data straight off the CAN BUS from what I understand. Is that the unreliable one? I'm debating between something like that and straight aftermarket OBD-II gauges.

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I have not seen that one yet. I'm just at the beginning stages of looking into gauges.

Here's the transmission options I'm considering:

Chevy Performance 6L80e: $3185 shipped ($4145 MSRP).

• New manufacture
• 2400-2800k stall
• Ready to ship
• 24 months or 50,000 mile warranty.
• I'm not sure how good Chevy support is.

Zero Gravity 6L80e: $4700 shipped.

• Added extra clutch plate. Raybestos High energy GPZ Clutches. Tig weld some internal drums.
• Reman with new pumps and computer ($1000 more for all new)
• 2800-3000 Stall (can be sold without)
• 24 months or 24,000 miles warranty.
• 1.5 to 2 weeks lead time
• The guy running the company seems like he's more than knowledgeable if there are issues.

Based on my previous research the converter stall speed is on the high end for my application. Another option is buying the Zero Gravity transmission without and going with the Circle-D 278mm 2600-2800 stall converter I mentioned a few weeks ago.

The price difference is nothing to sneeze at. But if the benefits for my uses outweighs the price difference I can make it work.

For the wiring harness I had to decide how I want to do tap shifting and thus what shifter assembly I want.

Gear position I plan to display on the dash so it that wasn't a factor for me when choosing a shifter.

I had narrowed it down to 3 different options:

GM car style shifter
https://paceperformance.com/i-23836...-shifter-assembly-with-tap-shift-control.html

I think this shifter looks super clean in the TJ console as seen in this thread: https://www.cj-8.com/threads/projec...th-linked-suspension.45890/page-6#post-375452



(Source: mysunnshine)

Lokar Sport Shifter

This one would be easy to install no matter what I have to do to the transmission tunnel since it can be surface mounted and covered up with a boot.



Winters/Art Carr

This is the tried and true shifter of buggies everywhere. And I can cut the gate to allow a quick shift from drive (or tap shift) into reverse for those "Oops" moments. The down side is that it's got a lot to the assembly that needs to be hidden requiring a deep mount.

RadDesigns makes a tap shift switches for this shifter:


http://www.radesignsproducts.com/winters-elec.-control-kits.html

Although it'll be a pain to find a place to mount it, I decided on the Winters shifter for my build because I can modify the gate how I need.