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RpmExtreme Official GEN4 LS Swap Thread 2007-2011 JK

83K views 389 replies 37 participants last post by  0lllllll0 RPMEXTREME 
#1 ·
We know alot of people have questions when it comes to installing a LS engine in their JK. We are opening an official tech thread for anyone running a LS engine or planning on running an LS engine.
We know there are several kit options in the marketplace and we can only speak for our own in this thread, but we will try to be helpful no matter what kit you are using. With that being said most of the info posted here will be related to the RpmExtreme swap kits for 2007 - 2011 Jeep JKs and may not apply to other kits.

We know doing a LS Swap is a big investment and there are many many options to sort out before you pull the trigger.
We will try to lay out the most common options and concerns in the next few posts and will field questions after that.

Please keep the posting to technical questions and things of that nature.

Here are some common terms to make sure everyone is on the same page.
GEN3 refers to earlier 2002-2006 engines
GEN4 refers to 2007-2013 engines
6L80e and 6L90e refer to a 6 speed automatic transmission commonly used with the GEN4 swaps
4L60e, 4l65e and 4L80e refer to a 4 speed automatic commonly used with a GEN3 swap
DBW refers to drive by wire. This would be a system where you don't have a throttle cable. This is the preferred system for an LS JK swap
TAC Module refers to the DBW module used with GEN3 engines
APP refers to the accelerator pedal (gas pedal)
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#2 ·
Gen4 conversions use a 07-13 GM LS based engine. All are DBW drive by wire. They can be had in either cast iron or aluminum blocks and sizes ranging from 5.3L - 6.2L 58X

LH6 5.3L vin code “M” is an aluminum block engine producing 315HP and 338lb ft of torque.

LY5 5.3L vin code “J” is a cast iron block engine producing 320HP and 340lb ft of torque.

LMG 5.3L vin code “O” is a flex fuel version of the LY5 making the same power.

LC9 5.3L vin code “3or 7: is an aluminum block engine producing 320HP and 335b ft or torque.

L92 6.2L vin code “ “ is an aluminum block engine with VVT (variable valve timing) producing 403HP and 417lb ft of torque.
L9H 6.2L vin code “ “ is a flex fuel version of the L92 making the same power

L94 6.2L vin code “ “ is the same as a L9H but with added AFM (active fuel management)

Applications:
• 2007-2013 Cadillac Escalade (L9H for MY 2009, L94 for MY 2010-2013)
• 2009 Chevrolet Tahoe
• 2007-2013 GMC Yukon Denali/Denali XL
• 2007-2013 GMC Sierra Denali
• 2008-2009 Hummer H2
• 2009-2013 Chevrolet Silverado 1500 (as RPO code L9H)
• 2009-2013 GMC Sierra 1500 (as RPO code L9H)

LS3 6.2L was introduced as the Corvette's new base engine for the 2008 model year. It produces 430 bhp at 5900 rpm and 424 lb·ft at 4600 rpm. Look for engines from a 2010 - 2014 camaro with a manual transmission

L99 6.2L is derived from the LS3 with reduced output but adds AFM (Active Fuel Management) and VVT (variable valve timing). Look for engines from a 2010- 2014 camaro with a Auto transmission.

LS3 Crate engines:

LS3 crate engines come semi complete from oil pan to the ignition system. It also includes the EFI intake manifold assembly with injectors and throttle body, exhaust manifolds, corvette water pump & balancer and 14-inch automatic-transmission flexplate. You will still need to source an accessory drive i.e.: alternator, power steering, AC and brackets. We typically try to use a 2010 camaro accessory drive with a truck style AC compressor. You will also need to change over to a Camaro or Truck balancer and water pump. A complete parts list can be provided and will be on our website to help guide you in choosing the correct parts.

430HP 6.2L
480HP 6.2L
525HP 6.2L
 
#3 ·
With the Gen4 engine swaps we use a GM 6l80E 6 speed automatic transmission. A transfer case adapter allows us to use the stock Jeep JK 241J transfer case. The Rubicon transfer case will not work because no one that we know of makes a 32 spline input shaft for it.

The 6L80 features a generously deep first gear for an automatic, making for favorably powerful starts from a standing stop. It also features two overdrive gears. The gearing spread is a very capable 6.04, with ratios in each gear as follows: compared to your stock JK auto transmission you can see a 6L80e has a much better 1st and second gear along with 2 overdrives.
First: 4.02, JK 3.00
Second: 2.36, JK 1.67
Third: 1.53, JK 1.00
Fourth: 1.15, JK .75
Fifth: .085,
Sixth: 0.67,
Reverse: 3.06 JK 3.00

The 6L80 has a maximum RPM limit of 6500 RPM.

Maximum engine power: "555 bhp ( 414 kW )"

Maximum engine torque: "550 lb-ft ( 746 Nm )"

The 6L90 transmission is slightly longer and taller than a comparable configuration 6L80 due to it's beefier internals. GM states, ". It is a heavy-duty version of the 6L80 six-speed automatic, with a strengthened input gearset which has two additional pinion gears for six total, and a strengthened output gearset, that uses wider gears than the 6L80. The 6L90 flexibilty extends to the clutches where the 6L90 has one more clutch plate than the 6L80 in each clutch for heavy duty applications. "

The 6L90 case is about 1.4" (35mm) longer than the 6L80 case.

Our electronics and adapters will support a 6L80e or 6L90e but with a 6L90e you may need to modify the trans bracket to accommodate the extra length and driveshaft modifications are a must.

AWD/4WD Transmission-bellhousing to end of output shaft (bellhousing to end of case)
4L70: 26.875" (22.25")
6L80: 27.125" (23.3")
6L90: 28.625" (24.7")
4L80: 29" (26")

6L80 weight
Transmission weight:258mm converter: Wet: 94-96kg ( 207-211lb )
Transmission weight:300mm converter: Wet: 102-104kg ( 225-229lb )

6L90 weight
Transmission weight: w/ 300mm converter
Wet: 109kg ( 240lb ) estimated

4L60 weight
Wet: 74 - 88.5 kg (163.2 - 195.0 lb)

4L80 weight
Wet: 115 kg (254 lb)

The Engine Control Modules (ECM) that communicates with the 6L80/90 Transmission Control Module (TCM) is programmed to only recognize Gen IV LSx engines. Specifically the 58X crankshaft reluctor ring, the 4x cam shaft sprocket. The pre-2007 model year Gen III and Gen IV motors (LS2 Corvette notwithstanding) operate with a 24x crankshaft reluctor ring, a 1x camshaft sprocket are not compatible with this transmission.


Our kits offer fully functional TAP shift capabilities allowing you to fully control your shifts along with TOW HAUL mode utilizing your factory buttons. No adding a toggle switch or modifying your shifter.
Your PRNDL display will indicate the correct chosen gear 1,2,3,4,5,6 right on your factory dash. This makes it very easy to tell what gear you have selected.
This transmission is truly the unsung hero of the LS swap. Silky smooth shifts and very generous overdrives allow for less gearing and better fuel mileage. No more hunting for gears every time you come to a hill.
 
#4 ·
LS Engine Conversion Kit for 2007-2013 GEN IV GM Engines : Click here to see the kit JK-LS-GEN4-Engine-Conversion-Kit-07-11

This engine conversion kit is for 2007-2011 Jeep Wrangler JK when installing a GM LS GEN IV series engine 2007-2013 5.3 6.0 6.2 and 6L80E 6 Speed automatic transmission. The overwhelming amount of GM LS series V8 engines at great prices it makes this swap a home run.
We know it can seem daunting to try and wrap your head around so many options, we try and make it a no brainer. To get your Jeep up and running, our harness comes complete and is 100% brand new. No need to send in your old harness or modify anything and with only a few wires to splice into the existing Jeep its extremely easy to be up and running. We also incorporate a state of the art CanBus module to take care of all the data, that means you get a factory style fully integrated GM engine running in your Jeep JK with all the factory bells and whistles.
Our harness integrates the Jeep and GM side harnesses into one single harness. The engine harness routes directly to the ECU with a factory plug at the factory firewall connector. The bulk of the harness routes behind the engine and under the fuel rails which is visually appealing and allows for factory engine covers to be used. Our under dash harness incorporates the GM accelerator pedal, ALDL, GM fuses-Relays and EZ CanBus module all while plugging directly into the main harness.
The final result is a harness that features improved aesthetics and versatility, easier to install and offers premium quality and durability.

Technology:

There is a big difference in our conversion compared to others is technology. The Jeep JK is a full CanBus vehicle, what that means is everything is run by a computer speaking it's own language to all the other modules on the CanBus. GM also uses a CanBus on their GEN IV engines and vehicles, however, the GM and Jeep system don't speak the same language. What our EZ CanBus system does is take the GM CanBus and Jeep CanBus and run them through our EZCanBus module, it will then translate the language between the 2 systems and allow us to send messages between each one. We are able to take the GM tachometer signal and send it to the Jeep gauges without using an add on reluctor ring and extra wires, this saves you a lot of time on the install and this is much more reliable. We are also using the GM coolant temp signal and sending it to the Jeep gauge, again saving you time and money by not having to install an extra coolant temp sensor in the engine. Some other cool things we are able to do is have a 100% functioning PRDNL display on the dash with 1-6 gears indicated during TAP shifts. We are also able to use the factory Jeep cruise control switch to control not only the cruise control but also the GM TAP shifting with the added benefit of not having to modify your shifter or instrument cluster. The cruise light and check engine light will function as normal thanks to the EZ CanBus module. We are also able to incorporate is GM TOW-HAUL mode, by pressing you OD off button it will put the system into TOW-HAUL mode. We have many other features built into the EZ CanBus system and it is fully upgradable as we add new items.

Current features:
* 100% New harness
* EZ CanBus system
* PRNDL display with 1-6 gears in manual mode indicated on the dash
* GM TAP shifting using your factory Jeep cruise switch
* Fully functional cruise control using your factory Jeep cruise switch
* GM TOW_HAUL mode using your factory OD off button
* Factory AC control with evaporator temp monitoring
* Factory Jeep remote start functional
* Full GM Emissions compatible
* GM VVT and AFM-DOD compatible

What is in the basic kit:
* LS conversion harness
* EZ CanBus module
* Weld in motor mount plates
* Transmission mounting bracket
* Transfer case adapter 6L80E to Jeep 241J (non Rubicon)
* Transmission mount
* Transmission shifter cable bracket
* Transfer case shifter cable bracket
* Accelerator pedal bracket
* Plug n play fuel line adapter
* Jeep computer reprogramming
GM computer reprogramming
TIPM Reprograming

The basic kit comes with everything you need to get the engine into the Jeep, wired up, and running. This kit is for the guys that have experience with engine swaps and want to build their own exhaust, air intake, AC hoses, and radiator as well as all the miscellaneous parts needed.
If you're looking for a little more complete kit we offer some add on items to the base kit.

Optional or add on items:

* High flow aluminum radiator: Inlets and outlets are made to fit a LS engine and give extra room for the intake tube. This radiator also will accept the factory JK fan and condenser as a direct bolt in.
* AC hoses: Pre-made AC hoses made to fit either GM accessory or Jeep accessory drives.
* Exhaust manifolds: The same manifolds we use in house and guaranteed to fit.
* Driveshafts: We can supply you with custom driveshaft to fit with the LS conversion.
* Air intake kit: A custom made composite air intake using a K&N filter
* Jeep accessory brackets: A set of custom brackets that will allow you to reuse your 3.8 Jeep accessories.
* GM ECU Computer. We can supply a brand new E38 computer programmed to your application.
* Primary exhaust kit (engine to muffler). we can supply you with the same exact components we use to build out forward exhaust sections in the shop. It will have 2 high flow catalytic converters, o2 sensor bungs, mandrel bent pipe sections, Y style collector and stainless steel band clamps. Cutting and welding required.
* More items will be added as we build them.
 
#8 ·
One of the most detailed thread for LS conversion well done great effort.

Few questions
1. Can you post some pics of your Gen4 kit PRNDL, harness, EZ Canbus
2. With Manual JKs how do you propose PRNDL shifter and Dash Display
3. Can the GM accessories be used like Alternator, AC, and PS Pump?
4. Your wiring Harness is it genuine GM wiring harness modified or complete custom
5. What opitions are there to upgrade to your harness from other vendors already running LS engines?


GM Performance now offers complete GM genuine LS system connect and drive but do you know why they only offer the connect and drive sytem in 4L80e trans mated to LSA and LS3 etc and NOT 6L80 e or 90e
 
#11 ·
One of the most detailed thread for LS conversion well done great effort.

Few questions
1. Can you post some pics of your Gen4 kit PRNDL, harness, EZ Canbus

I will work on some pictures of the harness and such. Are you asking for a picture of the PRNDL simply on the dash? We don't use a separate PRNDL box.

2. With Manual JKs how do you propose PRNDL shifter and Dash Display

Our CAN bus module will do all the hard work and send out the correct PRNDL messages even if your Jeep was a manual. Everything will work even the BTSI shifter.

3. Can the GM accessories be used like Alternator, AC, and PS Pump?

YES. We prefer GM accessories. Another bonus is our CAN bus module takes place of the factory GM BCM and will control the GM alternator voltage so your not stuck with a set 13.6 volts. We have verified The GM truck accessories and camaro accessories will fit without modification and we offer AC hoses and adapter for them. We recommend running the GM truck AC compressor that is fixed displacement. We stay away from corvette and CTSV assessors because the AC compressor fittings are rotated to the rear and point right into the frame. We also offer a nice set of brackets if you want to reuse your factoryJK stuff, but we recommend having the alternator converted to self exciting so you don't rely on the Jeep ECU to control it.

4. Your wiring Harness is it genuine GM wiring harness modified or complete custom

Our harness is 100% brand new and is plug and play. Its has provisions for the full GM side AFM,VVT etc along with the Jeep stuff built right in. It lays out very nice and tidy and can be routed out of site for a nice clean look. The under dash harness is prewired and plugs right into our under hood harness, easy peezy.

5. What opitions are there to upgrade to your harness from other vendors already running LS engines?

We currently don't sell the harness seperate


GM Performance now offers complete GM genuine LS system connect and drive but do you know why they only offer the connect and drive sytem in 4L80e trans mated to LSA and LS3 etc and NOT 6L80 e or 90e
Im not exactly sure, I have wondered about that myself. Probably has something to do with the ECU the use and the fact that you usually need a BCM to make all the functions work on the 6L80E. We can build a standalone LS3 harness with the EZcanbus module for the hot rod guys. But for a JK a stand alone GM harness just doesn't make sense. Yes it would run the engine but the Jeep side is what runs the starter, AC,fans etc... without the CANbus working between the two it would function.

Here is how the display will look while commanding 6th gear
 
#20 ·
Witha 6L90E you would still use our standard adapter and a stock 241J transfer case. Or you could go with a atlas and have them build it for the 6l90e.


We run either Truck or Camaro water pumps mainly because they work on the same "belt line"

You can run a electric water pump as long as you account for the correct accessories and such. If you come up with something else that works post up and we will pass it along for others.

Be sure to address the fact that you need to run a "truck" style AC compressor. GM part #25891791 or 10S17F in the aftermarket world.
 
#19 ·
its approximately 4x4x1.5" with metal mounting feet at 4.5 apart.
We usually mount them under the dash.

Operating temperature is -40 to 185Âş F

We have a IP53 environmental rating on this particular module.
We do not recommend mounting this unit under the hood or where it would be exposed to water.

This unit is manufactured to OEM type standards, ISO 9001 and more recently ISO 14001. This is not a "home made" unit.
 
#13 ·
The importance of matching the TCM to the ECM

The importance of matching the TCM to the ECM

As a general guideline you will want to match the ECU to the TCM. The easiest way to describe it is if you have a 6L80E that came out of a 2009 silverado you would want to match it up with a 2009 engine calibration E38 ECU part number 12625455. Its far easier to program a engine computer than program a transmission computer as they are built into the valve body. We do have the capability to reflash a TCM with our bench top harness but it would require you to remove the TCM and send it to us along with the ECM.

A 2007 TCM should be matched up with a 2007 ECM #19210738
A 2008 TCM should be matched up with a 2008 ECM #12612384
A 2009 TCM should be matched up with a 2009 ECM #12625455
2010 - 2015 TCMs can be reflashed to any year between 2010 and 2013 for our application, We would match this up with a 2010-2013 ECM #12633238

A 2010 and newer transmission is the most desirable due to the fact that it will work with all the engine calibrations from 2010 and newer.


A camaro 6l80e will work with a few mods. You will need to trim the output shaft down, Add a seal and 2 pipe plugs. You should also reprogram it to a truck calibration

A 2wd 6l80E will work after you cut down the shaft and add the seals. We have a 2wd to 4wd conversion kit on our website so you don't have to hunt down seals and plugs. The kit also will come with instructions.
 
#14 ·
Manual to Auto LS swap info

Manual to Auto LS swap info

When doing a LS swap on a JK that was originally a manual you will need some extra pieces.
Despite what the internet may say the 6 speed center console is not as wide as a auto console. You can't just slap on a upper trim panel and call it a day.

Here is a list of the main parts for a 07-10 Grey console
shifter 52060162AE
Low bracket 52060490AE
cable 52060164AD
Nut 06104716AA x10
Consol base 1FG73BD5AB
Auto upper panel 1CG44XDVAB


All the ones that we have seen have the harness built into the jeep and all you have to do is plug them in and everything will work including the BTSI Brake transmission shift interlock.

You can also get the cable the runs up to the ignition lock cylinder but we usually don't do this extra step. I think it just keeps you from turning the key all the way off with the vehicle in gear.
 
#15 ·
I have a couple questions:
Robbie provided my lc9 5.3 (into 2010 jkur auto) from a 2012 silverado. He sent a crate trans. When the local shop installed it, there was no trans programming. They had to get the snap on guy to lend a programmer. I have tap shift. It works but I do not get engine braking. Not like a stock chev with column mounted shifter. It will drop the gear but allow rpm to rise and no compression braking.
Any ideas on the fix?

I asked motech to remove the torque management because I had done the steering wheel dance anyway. I was never bothered with the esp/bas light. My wife has started driving it more and is not 100% happy with how easy it spins the rubber when it rains.
Possible to get more nanny action? I can always use the wire cut with a switch.
Edit- possible to deactivate dash light for esp bas?

Last question for now is can you program out the side air bags?
Thanks much.
 
#18 ·
I have a couple questions:
Robbie provided my lc9 5.3 (into 2010 jkur auto) from a 2012 silverado. He sent a crate trans. When the local shop installed it, there was no trans programming. They had to get the snap on guy to lend a programmer. I have tap shift. It works but I do not get engine braking. Not like a stock chev with column mounted shifter. It will drop the gear but allow rpm to rise and no compression braking.
Any ideas on the fix?

It probably has something to do with the fact your running a stock program in the transmission. When we build them in house we modify the TCM tune to match tires size and gears, then we go completely thru the tune and adjust shift points, TM, pressures etc to match the Jeep not they way GM built it for the original truck. This is a huge improvement over the "stock" TCM tune.

I asked motech to remove the torque management because I had done the steering wheel dance anyway. I was never bothered with the esp/bas light. My wife has started driving it more and is not 100% happy with how easy it spins the rubber when it rains.
Possible to get more nanny action? I can always use the wire cut with a switch.
Edit- possible to deactivate dash light for esp bas?

Your talking really about two different things. The Torque management on the engine and the Jeep's ESP system. Originally the Jeep ESP system could reduce the throttle when it saw wheel slip, now that you have a LS engine the Jeep ESP cannot reduce the throttle. There are a few ways of tackling this wheel spin issue. The easiest would be to retune the engine adding back in some torque management, reworking the timing and throttle tables to remove some of the "punch" off the line. This will make it smoother and help with wheel spin. The negative side is it will feel more "doggy" on low end.

Yes we can turn off the ESP light. You should not have any lights on the dash with a proper LS swap.

Last question for now is can you program out the side air bags?
Thanks much.

Yes we can turn them off but for liability reasons we don't mess with ABS or SIR air bags. Its pretty easy to add 2 resistors to the circuit and the system will think the airbags are still in place and the light will turn off.
Reply above
 
#17 ·
I don't really know of a good manual transmission that will bolt up, have 4wd and fit thru the stock shifter hole. Thats why we only really support the 6l80E 6 speed auto.

Its not to hard to convert from a manual JK to a LS auto combo.
 
#21 ·
Airflow Airflow Airflow

Airflow Airflow Airflow

That big warn power plant you have on your front bumper. That thing is killing the airflow across the radiator.

Something to think about before you do a LS swap or any V8 for that matter is how much airflow am I loosing because of my Winch-Bumper combo. Im not talking about "hey it doesn't look like it block much" I'm talking going down the highway at 70MPH and having all the air flow up and over the hood and not thru the radiator. Think aerodynamics, real wind tunnel type of crap. Most of us don't have a wind tunnel in our backyard so we do the next best thing. Go borrow some yarn from grandma, grab some tape and your Go Pro and head out to the Jeep. Take the yarn and cut your self pieces about a foot long and start attaching them all over the front of the bumper, stinger, winch, radiator openings, top of hood etc.... Set up the Go Pro off to the side so you can the whole mess of yarn and go hit the highway. Record what the yarn does at different speeds. You will probably see that the air will stop flowing into the radiator and go up over the hood at some point, some may even see the air coming out of the radiator. Now comes the fun part, you need to determine what is the main cause of the messed up flow. We have seen big changes from something as simple as removing a light bar that was attached to the fairlead. This is something you will need to determine on your own and by trial and error.

At idle and low speeds this doesn't really come into play. If your running hot at idle or low speeds you have other issues.

We usually only start to see issues like this at 70MPH + on really hot days. If your running the AC your compounding the issue, your basically putting 250Âş air in front of the radiator. So if she starts to run hot shut off the AC.

Another thing to try is an air dam. Most vehicles especially sports cars with small grill openings will have one. This will cause a low pressure area under the engine and will effectively "pull" air thru the radiator.
True story, back when I was a kid I had a 88 TransAm GTA. One day it started overheating while going down the road. If I stopped the temps would come back down to normal. I tried everything to fix it from water pump to head gaskets. Nothing seemed to fix it. Then one day a much wiser shade tree mechanic said " Kid you tore off your air dam, thats why she is running hot" I went to the dealer bought a new air dam and the problem was fixed. I know on most Jeeps its hard to fab up an air dam but give it a try even if its temporary to see if it helps you out.
 
#22 ·
Air dam like the stock plastic one that ripped off first day out?
Thought about fabbing an aluminum one to replace it but heard they restricted flow at crawl speeds and would be a mud sstorage shelf.
 
#23 ·
Pretty much. But I would think of it more like my old TransAM, a flat piece of plastic the hangs down below the radiator. This would cause a low pressure area to develop behind it.

I may dig into this some more and see if i can find some examples.
 
#24 ·
Shifter Display

Shifter Display and TAP Shift Display

Here is how your shifter display will look. Remember all this is done without modifying or even removing your cluster or shifter. Just plug up the harness and it will function. As far as I know we are the only one offering a fully functional dash display with 1-6 displaying current selected gear. We can go all the way up to 9 on the display so we will be able to support the new 8 speed GM transmission in the display.

PARK

REVERSE

NEUTRAL

DRIVE

TAP 6

TAP 5

TAP 4

TAP 3

TAP 2

TAP 1

Check Engine light on

Cruise Light on

Check engine and Cruise Light on
 
#25 ·
2011+ cruise switch

Here is a picture of our optional cruise-TAP switch for the 2011+ LS conversions.






With this switch you can control your TAP shift right from the steering wheel. No need to hack up your dash to bolt in a toggle switch or grind out your shifter.
 
#26 ·
Here is a picture of our optional cruise-TAP switch for the 2011+ LS conversions.






With this switch you can control your TAP shift right from the steering wheel. No need to hack up your dash to bolt in a toggle switch or grind out your shifter.
Damn it, you didn't include a before picture. I had to run out to the garage to look. Sure enough, blank plastic from the factory.

That is really a sweet set up. No need to take your hands off the wheel to shift manually. VERY NICE!!!!!!!!!!!!
 
#31 ·
Ok I figured it was time for a few updates.

We have been doing a lot of R&D testing lately and have some really cool new features and engine-transmission calibrations in the works. Ill go over a few of them.

First it has been hot as heck here in Alabama so we took advantage if it. Our 500HP 6.2 is the perfect vehicle to test cooling systems so we strapped on a trailer and proceeded to blast it up and down the highway while monitoring several parameters. What we found led me on a quest for more cooling, both engine and transmission.

The first thing that jumped out was the transmission temps. They were running much higher than I like to see. We reworked our trans cooler setup and that helped a little bit but the real gains we done once I went in and tweaked the transmission calibration. For some reason GM programs the torque converter clutch to slip when its engaged. By tweaking the calibration and lowering the slip to 0 we were able to lower the heat that was generated in the torque converter. We didn't stop there. We also adjusted when and how much pressure is applied to lock and unlock the TCC. This allowed us to lock it up much smother and with a little more force to compensate for the weight and tire size of the big JK. By doing all these things we saw a 50Âş drop in trans temps and a 1-2 MPG increase in fuel economy.


We also have several Jeeps running our Pentastar Fan upgrade. We have full control of the Pentastar fan from either the GM side or the Jeep side. We chose to used the Jeep side to control the fan. By using the Jeep side your running the fan the way Chrysler intended it to run. The TIPM was designed to run this fan and it makes it very easy to add to earlier JKs. By using the Jeep side you can monitor fan speeds and even control them with a scan tool plugged into the Jeep OBD2 port. With our EzCANbus module we can run this fan at variable speed based on engine temp, AC pressures, trans temp and pretty much any other parameter we want to monitor. Whats nice is we vary how fast the fan is based on AC pressures so when AC pressure is lower we run the fan at a quiet lower speed, but if its real hot outside and the pressures are up we will run the fan up to a higher speed and keep the airflow thru the condenser high. This gives us a much more consistent AC outlet temp and by keeping the pressures down yields less drag on the engine because it doesn't have to turn the compressor as hard.

Using the slim Pentastar fan has opened up some extra room between the radiator and the water pump. This has allowed us to develop a few new radiators. In addition to our current high flow aluminum radiator we will be releasing a HD aluminum radiator and an Extreme Duty aluminum radiator. All will still be a direct plug and play radiator that will accept the JK condenser and both types of fans. As we start pushing these JKs past 500HP cooling really becomes a concern in hot climates.

I have yet to test it but I'm confident that we could install the pentastar fan in any earlier JK and program it to work like factory. So guys with superchargers and big winches that want extra cooling or are just tired of the crappy stock fan failing every time you get mud in it give us a call. We may come out with a upgrade kit.

This goes for the HEMI guys also. As long as your Jeep ECU isn't locked we can help you out too because we know you need more cooling.


During our offroad testing we came up with a few new tweaks.
We now have 2nd gear start based on shifter position. There were times when I wanted a little more control offroad and by adding 2nd gear start I was able to power thru some areas without slipping the tires. This would also come in real handy in snow and sand, similar to how a lot of european vehicles have a winter mode.

Our EzCANbus module also allows us to send the 4WD low signal from the Jeep side to the GM side. If you have a LS powered Jeep you may notice it shifts funny or hits the speed limiter in 4wd low. Thats because with the gear reduction the GM side thinks it running 90mph when your going 20 and the shift patters are based on throttle % and vehicle speed. We are able to send the correct signal to the GM side and when in 4wd low it will adjust the speed based on Tcase ratio and move over to a different shift speed calibration and throttle settings among other things. This allows us to setup a totally different shift schedule for offroad. we can tailer it for offroad use and maximum traction, the last thing you want is the dam thing to kick down and bust the tires loose when your climbing the side of a mountain.

For engines with larger camshafts affecting the engine vacuum at idle and causing the brakes to feel hard. We are able to control an aux Brake Vacuum pump. We can have it commanded on based on engine vacuum or only when the brakes are applied in 4wd. Granted with proper tuning a 500 HP engine usually has enough vacuum for the brakes but at times offroad and in 4 low you could use a little extra braking.

AC idle bump. up until now any one instilling a LS into a non newer GM vehicle with AC could not send the proper message to the GM ECU telling it that AC was requested. Not a huge deal but it did cause some issues. Originally the GM ECU would see an AC request from the heater controls, it would then look at some parameters bump up the idle, crank up the fan and then turn the compressor on. By bumping the idle before it turned on the fan or compressor the engine RPM stayed very steady and you wouldn't feel the Ac kicking in and out. When someone does an LS swap in the past there was no good way to send the Ac request signal to the GM ECU so when you turn the AC on the engine speed drops down the then the GM side will try to compensate for it. It also doesn't know that you requested AC and will never turn the fan on accordingly as well as high rpm and throttle cutouts. With our EzCAnbus module we are able to handle the high and low pressure cutouts, high or low RPM cutouts, high throttle cutouts and fan settings. We also add in if the engine temp reaches a certain temp it will disable the AC. We can now send the AC request signal to the GM ECU and get the idle bump. A lot of stock engines may never feel the AC kick in and thats fine but if you do have one that dips we can help out.


We are also testing a high idle winch setting.
Basically it will be a setting where once engaged will raise the idle to a high set point currently 1150 RPMs. This will allow you to winch much more efficiently and keep the battery charge rate up.

Im still working on the specific sequence to engage the high idle mode. It will be something like in 4wd, in Park, turn on cruise and apply the parking brake.

If there are any other cool features you guys can think of send me a PM and maybe we can get them added at some point. :grin2:
 
#32 ·
Wow that sounds like some great progress... How much torque is that 500up LS you're testing with putting out? Would you care to share any info on that engine; block, heads, intake, rough can specs (duration, lobe seperation) compression ration?

I have a odd idea for an LS swap in my '12 JK 2dr; junkyard L96, rebuild with 3.90" stroker crank, 10-10.2:1, aftermarket VVT cam. Then possibly back out with a 6L90e. It's not wild but should pack some power and be a durable setup.
 
#35 ·
It started as a L92 6.2 truck engine 6L80E. We did a full rebuild and a DoD delete. We are running a Mast Motorsports VVT camshaft with upgraded springs and such. Off the top of my head I can't remember the specs, not too wild. Stock L92 compression ratio and heads so we could still run 87. Ceramic coated headers and a nice free flowing exhaust. We have yet to put it on the dyno and get an exact HP and TQ # but estimates put the power up close to 500 depending on what fuel & tune we have in it. My 87 octane tune easily makes 450 and will bark 37's in 2nd and 3rd gear.

For marketing purposes the 500HP decal on the side just plain looks cooler than 450. LoL

Either way 400+ HP in a JK is plenty and is a blast to drive.
 
#33 ·
So, your saying that us with the earlier installs can do the ezcanbus switch over and then have access to all these benefits? I am seeing a lot of what you are talking about in my setup now. If and when I get my current state taking care of looks like some up grades are in order!
 
#34 ·
Yes most of the benefits could be implemented. There are a few upgrade paths to add a EZcanbus to our older GEN4 kits. If your looking for just the pentastar fan, I think we can add it to yours the way it sits and make it work. I will be testing that on our GEN3 shop Jeep.

I should be able to add a pentastar fan to a stock 07-11 JK using all stock computers, no canbus stuff needed there.

AC idle bump and winch mode are both in the testing phase and showing promise. I won't add them to the kit until they are fully tested. Once approved a simple reflash of the EZcanbus will add these features for customers currently running our canbus equipped kits.
 
#42 ·
Jon, this has absolutely turned into a VERY informative thread. I'm a 68 y.o. long time Jeep owner who first thought that the guys in Vegas were the only route. I live just outside of Nashville so we aren't that far away. I'll be stopping by your shop one day on the way down I-65, and check out your operation. I can see a 6.2 LS swap in my future. I've got a '16 JK 2 door and one day, I'd like to see it pop. Thanks for what your doing in the industry!
 
#43 ·
Thanks Guys. We try very hard to make the best product available and want all of our customers to be educated before they pull the trigger on a build.
We are all Jeepers at RpmExtreme. We drive our Jeeps every day. Go off roading, camping, trade shows and are active in our local Jeep Clubs. We know what it is to be in the Jeep brotherhood and try very hard to make sure everyone is happy with their purchase and take the time to answer questions pretty much any day and hour. If you have a issue with an install some Saturday evening or are running low on beer, call me, I will walk you thru it. If its 2AM you will probably get my voicemail and you will owe me a case of beer. :grin2:

Behind the scenes I have been hard at work adding new features to our GEN4 EZcanbus Kit. Most of these will be backwards compatible for our current customers free of charge.

We have some amazing custom tunes for the 5.3, 6.0, 6.2 truck and 6.2 430-480HP as well as transmission tuning for the 6L80E. We have been doing tuning for a very long time and really have these LS engines dialed in for the JK. I have seen a lot of improvement in drivability, power and fuel economy. If your running a bone stock GM calibration in your engine and transmission your not getting the real benefit of the swap. Gm developed the stock calibration for the vehicle it was originally installed in, Your Jeep is a much different beast and likely has larger tires and gears, weights more and has the aerodynamic properties of a school buss. It is possible to "remote tune" a vehicle but the best bet is to bring it to us and let me dial it in. Ill spend a few days with it correcting everything from highway driving to 4wd low crawling. If we do your install in house this is all included, I want you to have the best performing Jeep we can give you.

Im testing a new radiator design that has 25% more cooling capacity over our high flow aluminum. As we build more and more power extra cooling is needed and not to mention its has been dam hot across the US this year. I would say our high flow aluminum radiator would be excellent up to 400HP and our HD version would be for higher HP setups, towing or extremely hot climates. Both fans are plug and play and can be used with our pentastar fan upgrade for even more cooling power.

We have our GEN4 2012+ kit on the near horizon and will be a great addition to our product line.

We also have our GEN5 conversion kit scheduled as a future product. We have been working with the new GEN5 L83, L86, LV3 engines for over a year. Both 6 speed and 8 speed auto transmissions. These engines are proving to be a great choice and as more hit the wrecking yards the prices will be coming down.

Something else I have been seeing on the forums. Don't be afraid of a 5.3!
The 5.3 is a great engine and is MUCH cheaper compared to a 6.2. My personal Jeep has had 5 different engines in it so I know how each one drives first hand.
My Jeep. 4 door, armor, bumpers, winch etc.. 37's MTRs 4.56 gears. I have had 2 different 5.3s and loved them. Power was fine even when pulling my camper. Fuel mileage was pretty good around 16mpg probably better on the highway. The low end power was just fine and offroad power was MORE than enough. I even had a 6.2 installed that was sold and went back to a 5.3 while my new 6.2 was being built. The only real thing I felt was the 6.2 pulled harder on the top end and had a little more grunt. But overall I wasn't disappointed with the 5.3 at all. So if your in the market for a LS swap don't shy away from a good deal on a 5.3, it will be light years better then the 3.8 and if you ever want to upgrade down the road our harness will work with the 6.2 so just swap in a 6.2 and reflash the computer.

The 6.2 430 and 480 HP crate engines run really good and pull like fright trains on top end. My personal recommendation is if your in the market for a crate engine to go with the 430HP. It has better low end power and is a much smother idling engine compared to the 480 that has a larger camshaft. I know your saying the 480HP is only a few hundred bucks more than the 430 and I want the "big" one. Ask yourself what you will be doing with the Jeep? Will my wife be driving it? Will she be pissed when I fire it up in the garage and the pictures shake off the wall? The 480HP is a great engine and we have done several of them. They have some tradeoffs to achieve the higher horse power numbers. The first one is Idle quality. With the larger camshaft the idle will suffer and it will require a really good custom tune. No way you would be happy running this engine on a stock truck tune. With the choppy idle your vacuum brakes will suffer and it may be harder to stop especially offroad in 4wd low. This can be helped with a good tune, vacuum brake pump or raising the idle. By raising the idle you will need an aftermarket higher stall torque converter to match. The positives to the 480 are huge power on top and the idle sound will make your buddies jealous.
The 430HP engine will idle like stock,. Brakes will work great as the vacuum is there at idle. You can actually go thru a drive through and order a bigmac without having to shut the Jeep off. The wife can drive it and actually enjoy the drive....just make sure you get the keys back or she may keep it. Its an excellent engine and will produce a great exhaust note that everyone will notice. Needless to say I love the 430 and I think it has better power down low compared to the 480.
 
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