HELLO : An Introduction to MoTech and LS Swaps

MOTECH

New member
Hello

It's good to be here. We have a lot of WAL members come through the shop so I think it's time to contribute here.

Most of you know we have been doing LS JK swaps since 2009 and I believe we are the originators of the fully functional LS JK. We work on nearly all performance upgrades for the JK including Hemi's, Superchargers, Diesels and Turbo's. TBH at the end of the day the LS is the only engine I want to drive; it is the only one that feels right in the JK chassis. Size, weight, economy, CG, torque, drivability is all there with the LS. When combined with the 6l80 no other powertrain is as well suited for the JK IMO, the 6l80(and now 8l80) are a key part of the swap.

From the beginning our design philosophy was to keep the operating systems pure. This means leave the network alone, let it do what it is designed to; problems arise when hacking or patching calibrations. In this way we have a pure GM powertrain and run pure GM calibrations which supports all emission monitors, enhanced DTC's, all Mode 6 data, manufacturer bi-directional controls and more. Of coarse this assures emissions compliance, but also has the advantage of OE level service. Our harnesses, power and ground distribution, network configuration, circuit protection mimic exactly OE. This means your vehicle can be serviced by a dealer using factory tools and procedures. There is no hacked or patched calibrations to deal with. On the flip side the Chrysler network remains pure. Engine performance codes are removed from the PCM but that is it. The Chrysler network can be serviced by a dealer like a stock JK.

The key is our MoTech module which acts as a bridge between the two networks. This allows your standard JK controls to work normally. This means AC, Cruise Control and Instrument Cluster all function normally. While the MoTech module is key it is also not required to operate the vehicle. In fact the MoTech module can be removed and you will continue to drive. We wanted reliability in tough conditions and the GM limp mode will get you home even if you have a TIPM failure.

Early on the swap was somewhat of a challenge due to the additional circuits required. We offered the swap in house or a builders kit for our installer shops. This was not a consumer level kit and required some special knowledge to install. With the release of our Gen III electronics all that has changed. The design philosophy for the Gen III kit was ease of installation. We eliminated all redundant sensors, incorporated circuits for AC, brakes, fuel pump and much more right into our main harness. This means you lay the harness out and plug it into the GM and JK sides, we do all the hard work in the harness.

This also has the advantage of a low wire count, similar to stock. The completed Gen III swap is as reliable as you can get, very clean looking due to the removal of the ugly JK engine harness. An LS3 in a JK looks small in comparison to a Pentstar which is 4 valve 4 cam engine.

Our new billet aluminum brackets have eliminated any alignment issues and puts the JK accessories right where they belong so you can run stock hoses and lines available at your dealer, no custom work required. And this is another important point, running stock calibrations, stock accessories, stock motor mounts(hydraulic) means you can gets parts at your local dealer or parts store. This was an important goal for us since we have swaps all over the world. We have swaps in Mexico, Russia, China, Australia, South Africa..... What we find is LS parts are available worldwide vs custom or Hemi parts.

We have a couple Gen V swaps in the works, both a L83 5.3 and L86 6.2. The Gen V engines have direct injection, continuous VVT, high compression and aggressive AFM. This promises a 15-20% mpg increase and TBH I don't see any other conversion technology that can match the power and efficiency of the gen V engines; and all this on regular gas. Then consider the compact size and light weight of the LS and the choice is clear for me.

Well that's a start, I tend to ramble because I live and breathe this stuff. I feel there are options out there now that are confusing things, like LS engines being run inside Chrysler OS's running Chrysler transmissions. I hope I can answer questions why we do what we do and how we do it. With over 200 conversions and well over 1 million driven miles on our swaps we have gathered a lot of information over the years. Being located in Vegas means we learned a lot about cooling systems. It's currently over 110* here and I drive high compression LS3's around with no overheating issues at all. I'll do my best to answer any questions.

 

H8ROADS

Caught the Bug
I already want to do this and my engine and transmission aren't even broken in hardly. The JK transmission is just plain terrible. It has such a hard time with shift points. Thanks for the insight.
 

dillard09

New member
Great intro! Yall are a company that has put in their time and hard work finding out what works best. I have heard nothing but great things about the product and service that Yall put out.
And my 08 jk just sits for weeks at a time while I'm at work. L86 Gen V guineas pig, I'm just throwing that out there!
 

Thegreenmachine12

New member
Awesome intro! You guys rock I should have gone to your shop from the beginning. I want to thank Robbie for talking to me and helping me with the issues on my swap. I'm going to do yall's drop in radiator upgrade for my LS3.
 

Benito

New member
You are definitely passionate about what you do! I see a lot of favor to the 6l80 Auto transmission, do you guys offer a standard option and if not how do you go about converting a standard to auto with the engine swap? Does an automatic shifter have to be bought from Chrysler?
 

boardsurfer

Caught the Bug
Please ramble more. :) that's good stuff. What's the difference with Gen III and gen V? Is that a different version of your swap kit, or are they different motors entirely?
 
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GoldenJK

New member
Ditto on the standard transmission question. What are your options for an 07 jk with the 6 speed manual? Do you have a kit for that or the T-56 manual.
 

highoctane

Caught the Bug
I like the idea of the Gen V 5.3. It makes similar power to the previous gen 6.2, and with the Gen V perks you mention. The 8L80 though is what really has me wanting the Motech LS.
 

cozdude

Guy with a Red 2-Door
Thanks for the detailed background! Looking forward to learning more about you guys and the swaps
 

kyle521

New member
Ive actually had a question about your swaps,
Say someone wanted to do an ls swap but wanted stay on small budget in the beginning, if you swap in a 6.0 ls, and then down the road want to upgrade to the 6.2 truck motor ls, would there need to be significant changes to the harness that you supply?
 

MOTECH

New member
You are definitely passionate about what you do! I see a lot of favor to the 6l80 Auto transmission, do you guys offer a standard option and if not how do you go about converting a standard to auto with the engine swap? Does an automatic shifter have to be bought from Chrysler?

Yes we do a lot of manual to auto swaps. For 2007-10 JK's you need a new main center console, sled(metal plate under shifter), automatic shifter assembly, automatic brake pedal(no need for a new pin or clip), key interlock cable and shifter cable. On the 11+ JK's it's very similar but there are more console pieces to get.

Our MoTech module handles the manual to auto signals so you will have proper neutral safety, reverse lights and ESP modes. One nice thing about the MT module is it is fully programmable so we can run a 12' shifter in a 07'-11' JK if you want Bumpshift.

One thing I will mention on the manual to auto swap is you will not have the PRNDL display on the cluster. On the early JK's the PRNDL is driven off the C4 connector of the NGC4 PCM, the manual NGC4 does not have this connector and the harness does not support it either. No big deal though the PRNDL on the shifter works fine, My wife has been driving a manual to auto swap for many years now.
 

wayoflife

Administrator
Staff member
I should note that Moby was a manual and we're now running a 6L80 automatic transmission. As mentioned, everything works great and the only thing we don't have is a PRNDL light up on the dash. No big deal being that you can see where you're at by looking at the shifter.
 

JEEPnGEO

New member
Welcome,

If I get enough scratch together to drop an LS in my Jeep then I will head your way. That has always been a head scratcher for me to think about. I am one of those who like all the lights and knobs to work. BTW... You wouldn't happen to have an LS sitting around would you...
 

MOTECH

New member
Please ramble more. :) that's good stuff. What's the difference with Gen III and gen V? Is that a different version of your swap kit, or are they different motors entirely?

We no longer support the Gen III engines, mainly because they are not emissions compliant; in addition the Gen IV engines added many desirable features.

The Gen IV engines added can driven transmission support; this means you can run the 6l80 transmission, you cannot run the 6l80 with a Gen III engine. The Gen III controller is a PCM which means it controls the engine and transmission, this works well with the old 4 speeds like the 4l65 but does lead to a lot of additional wires for the IMS, PRNDL, solenoids, etc. The can transmissions have the TCM built into the valve body making the wiring very simple, bascially can in and out, brake signal and power and ground. Can transmissions have proven very reliable and strong.

Gen IV and V operating systems use a separate TCM and ECM, they are not PCM's like with the Gen III powertrains. If you were to run a Gen IV engine with a non can transmission like a 4l65 you would need to add a T42 TCM to the network. The T42 would talk to the ECM over the can bus and control the transmission like in the old days.

IMO the Gen III engines are not worth running in a JK, they are good engines just old technology. The Gen III engines are close in price to the Gen IV engines now; in 2008 Gen IV engines were rare and expensive, but now the General built millions of them so they are at rock bottom prices.

Some differences between the Gen III and Gen IV series LS engines:

Gen III does not support the 6 speed automatic
Gen IV added VVT on many engines
Gen IV added DOD/AFM on many engines-4cly mode
Gen IV has a 58x crank trigger wheel vs the Gen III 24. This allows more precise fuel and spark management
Gen IV engines use ultra fast O2 and knock sensors for better fuel and spark control

If you look at the Gen III engine performance calibration it is about 200kb, the Gen IV ECM alone is 2MB showing the magnitude difference in control. The Gen III engines used fuel tables with 0-256 block cells like we did since the 1980's. With the Gen IV engines it became clear more control was required so they did away with the old fuel tables and went with a coefficient based fuel strategy. This means dozens of coefficients are multiplied many times a second to determine fuel and spark delivery.

In the old days you would have a fuel table then a modifier. So if you were in a certain block cell and IAT rose, or you put it in 4WD the cell number would be modified. By going to a coefficient based virtual table dozens of variables can be taken into account with minimal guessing. GM is really at the forefront of this technology.

For example GM uses a cold emissions start up mode on Gen IV engines. Using ultra fast O2 sensors your Gen IV can be in closed loop with the O2's switching in under 10seconds. GM went to an expanded ECT scale under 100 degrees F for precise cold start emissions. The coolant temp signal is divided into two scales, one for below 100 degrees F and the other above. This posed programming challenges to detect the switch point since it runs off internal timers.

Like the Gen III to the Gen IV engines the Gen V engines are evolutionary, not revolutionary. Gen V engines add contentious VVT, this means the cam is not just parked and open, it can be phased wherever it is commanded; this allows more power and efficiency. most importantly gen V engines add Direct Injection. DI allows higher compression which means higher cylinder pressures, higher cylinder pressures mean more power and efficiency. The key is injecting the fuel directly into the chamber rather than behind the valve, this allows better combustion. Gen V engines also stepped up the AFM or 4 cylinder mode. Running in 4 cylinder mode reduces pumping losses but can pose some issues. Noise and vibration has always been a problem with multiple displacement engines all the way back to the Cadillac 4-6-8 engine. The Gen V engine run a new hydraulic motor mount we are gearing up for, it is designed to handle the additional vibrations. Modern AFM engines control the throttle for you so you don't have to step on the gas when you go from a 8 to a 4. Also the ECM drops and brings in cylinders one at a time so the trnasition is not abrupt. Overall AFM can help mpg a little but it won't help a heavy JK too much because it only operates under a light load.
 

Ddays

Caught the Bug
What an education. Thanks for taking the time to do so. Man how much can you get selling plasma these days? I'm drooling at this...
 

MOTECH

New member
Ditto on the standard transmission question. What are your options for an 07 jk with the 6 speed manual? Do you have a kit for that or the T-56 manual.

With a 5.3 engine we can support the stock JK NSG370 6 speed manual transmission, that's about all it can handle.

GM did not offer the gen IV V8 trucks with manual transmissions so we do not support OE cruise control with the manual transmission. We do offer an aftermarket CC which works OK.

On larger engines we can offer a NVG 4500 or a custom Tremec 4WD manual, both add to the cost of the build.

Personally I like the 6l80 with the manual mode. The 6l80 is low friction, low heat, 4:1 first gear and .6 OD. GM rates the 6l80 the similar to a manuals in MPG. The 6l80 has RPM match shifting so when it shifts between gears it is very smooth and keeps wheel speed constant. So if you were climbing a rock and went from 1st to 2cd you would maintain constant wheel speed with no lurch since the TCM anticipates the shift and the ECM blips the throttle for you. It is actually the BCM that controls the shift.

The 6l80 is also fully programmable, we are working on 2cd and 3rd gear launches and more.
 

jesse3638

Caught the Bug
We no longer support the Gen III engines, mainly because they are not emissions compliant; in addition the Gen IV engines added many desirable features.

The Gen IV engines added can driven transmission support; this means you can run the 6l80 transmission, you cannot run the 6l80 with a Gen III engine. The Gen III controller is a PCM which means it controls the engine and transmission, this works well with the old 4 speeds like the 4l65 but does lead to a lot of additional wires for the IMS, PRNDL, solenoids, etc. The can transmissions have the TCM built into the valve body making the wiring very simple, bascially can in and out, brake signal and power and ground. Can transmissions have proven very reliable and strong.

Gen IV and V operating systems use a separate TCM and ECM, they are not PCM's like with the Gen III powertrains. If you were to run a Gen IV engine with a non can transmission like a 4l65 you would need to add a T42 TCM to the network. The T42 would talk to the ECM over the can bus and control the transmission like in the old days.

IMO the Gen III engines are not worth running in a JK, they are good engines just old technology. The Gen III engines are close in price to the Gen IV engines now; in 2008 Gen IV engines were rare and expensive, but now the General built millions of them so they are at rock bottom prices.

Some differences between the Gen III and Gen IV series LS engines:

Gen III does not support the 6 speed automatic
Gen IV added VVT on many engines
Gen IV added DOD/AFM on many engines-4cly mode
Gen IV has a 58x crank trigger wheel vs the Gen III 24. This allows more precise fuel and spark management
Gen IV engines use ultra fast O2 and knock sensors for better fuel and spark control

If you look at the Gen III engine performance calibration it is about 200kb, the Gen IV ECM alone is 2MB showing the magnitude difference in control. The Gen III engines used fuel tables with 0-256 block cells like we did since the 1980's. With the Gen IV engines it became clear more control was required so they did away with the old fuel tables and went with a coefficient based fuel strategy. This means dozens of coefficients are multiplied many times a second to determine fuel and spark delivery.

In the old days you would have a fuel table then a modifier. So if you were in a certain block cell and IAT rose, or you put it in 4WD the cell number would be modified. By going to a coefficient based virtual table dozens of variables can be taken into account with minimal guessing. GM is really at the forefront of this technology.

For example GM uses a cold emissions start up mode on Gen IV engines. Using ultra fast O2 sensors your Gen IV can be in closed loop with the O2's switching in under 10seconds. GM went to an expanded ECT scale under 100 degrees F for precise cold start emissions. The coolant temp signal is divided into two scales, one for below 100 degrees F and the other above. This posed programming challenges to detect the switch point since it runs off internal timers.

Like the Gen III to the Gen IV engines the Gen V engines are evolutionary, not revolutionary. Gen V engines add contentious VVT, this means the cam is not just parked and open, it can be phased wherever it is commanded; this allows more power and efficiency. most importantly gen V engines add Direct Injection. DI allows higher compression which means higher cylinder pressures, higher cylinder pressures mean more power and efficiency. The key is injecting the fuel directly into the chamber rather than behind the valve, this allows better combustion. Gen V engines also stepped up the AFM or 4 cylinder mode. Running in 4 cylinder mode reduces pumping losses but can pose some issues. Noise and vibration has always been a problem with multiple displacement engines all the way back to the Cadillac 4-6-8 engine. The Gen V engine run a new hydraulic motor mount we are gearing up for, it is designed to handle the additional vibrations. Modern AFM engines control the throttle for you so you don't have to step on the gas when you go from a 8 to a 4. Also the ECM drops and brings in cylinders one at a time so the trnasition is not abrupt. Overall AFM can help mpg a little but it won't help a heavy JK too much because it only operates under a light load.

Mind Blown!...haha. Great information and if I have enough pennies and my 3.6 takes a turn for the worst I know where I'm going. Plus you are only a few hours away!
 
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