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Discussion Starter #1
To start off I have an 08 JKU L96,6.0,6L80,using the Motech kit, tons and 40's. I was driving through Death Valley over spring break, the outside temp was 95. My engine usually runs between 200-210 range. This day it got up to 230 and I was just driving down the paved road. I have a CSF radiator with CSF 20psi cap. I have not had any radiator issues in the three years after my engine swap. I am looking to see if anyone has upgraded from the stock 3.8 fan to the Pentstar or Camaro fan and was it worth the $700. I have also heard that I may need a new TIPM to control the fan. Or am I better off adding a Poison Spyder hood vent for $180 to help expel some hot air.
 

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Discussion Starter #3
Yes I am still using the stock 3.8 fan. The link you posted definitely is a better price point but also have the expense of buying a tuner. This is still in the price range of adding a Pentstar or Camaro fan that flow more CFM. I am trying to decide if dropping $700+ on a fan is worth it, or just try the vented hood and see if it works.
 

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To start off I have an 08 JKU L96,6.0,6L80,using the Motech kit, tons and 40's. I was driving through Death Valley over spring break, the outside temp was 95. My engine usually runs between 200-210 range. This day it got up to 230 and I was just driving down the paved road. I have a CSF radiator with CSF 20psi cap. I have not had any radiator issues in the three years after my engine swap. I am looking to see if anyone has upgraded from the stock 3.8 fan to the Pentstar or Camaro fan and was it worth the $700. I have also heard that I may need a new TIPM to control the fan. Or am I better off adding a Poison Spyder hood vent for $180 to help expel some hot air.
The fact that you were cruising down a paved road and the temps rose to that level would suggest an issue elsewhere.
 

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That I am not sure of. I will have to check.
The reason why I ask is because after fitting a Hemi to my 07, I juggled around a few things to get the best result that I could.
I started with the biggest 3 core unit that would fit.
I believed that an aftermarket fan was the ticket to trouble free cooling but after smoking said unit, I replaced it with the 3.8 factory unit and found it actually moved more air at high speed. The aftermarket unit was controlled by a separate thermostat and power.
What I failed to realize was, the TIPM controlled the OEM fan and since the Hemi thermostat didn't open until 203f, the fan started at 195-198 thus the fan was running full time. Once the fan started playing up, it would intermittently turn off and on, resulting in an overheat in traffic, but never on the open road.

Solution was to fit a 195f thermostat to Hemi so everything works together like the factory.

Now the Hemi will run at 197f cruising at 55 mph in 95f+ heat and I won't hear the fan until I'm back in slower traffic.
 

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Discussion Starter #8
I checked last night and the fan comes on at 210. This is the correct running temp for the LS engines. When the fan come on the temp immediately dropped to 200. I did notice that my coolant in the reservoir was empty when cold which possibly created a air bubble in the system. I topped it off and ran up to temperature and then checked again this morning when cold. The coolant reservoir wasn't empty this time. Hopefully this was my problem. I think I may still add some hood vents though to help evacuate some heat.
 

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I'm running the Pentastar fan with my L96 and have seen some extreme temps in Moab while crawling. I had some issues early on but after some good tuning with the fan settings it is back to normal operation.

This last trip to Moab, I flushed the system and went with Evan's waterless coolant. Wow, what a difference! I heard the fan twice, once on Cliff Hanger and once on Poison Spider but only for a minute then it was back to idle.
 

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I have a 2008 JK with LS3 Crate motor and 6L80E transmission. I used an RPM Extreme conversion kit and did the work myself. I recently upgraded to the RPM upgraded HD radiator and Pendstar fan. It is like night and day to the previous upgraded radiator and stock fan setup. My temps varied widely from 200-215+ when the a/c was running in the summer and would go higher if I didn't turn off the a/c. I am firmly convinced the Pendstar fan with variable speed and HD radiator are a must in LS JK's. I did some air flow testing on my own and the Jeep grille opening is just too small and ineffectively designed, and air flow becomes very turbulent at speeds above 65mph and actually flows less air as speeds increase due to the aerodynamics of the Jeep front end which actually creates a reverse air flow current effect. And that is without a large front bumper or winch in place which further complicates and disrupts the airflow. I highly encourage anyone thinking of an LS conversion to talk to Jon at RPM Extreme before buying a conversion kit. He is extremely helpful and his follow-up service is tops. I have almost 40K on my JK with LS3 with zero problems following startup. He has a superior product in my opinion and when you need advice or help he is always available.
 

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Im new to jk's and don't know if this helps but I swapped an ls into a commando and used a Taurus fan, two speed, shroud and have never had a temp problem. Do Taurus or mark viii fans fit on jk's?


Sent from my iPhone using Tapatalk Pro
 

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I have a 2008 JK with LS3 Crate motor and 6L80E transmission. I used an RPM Extreme conversion kit and did the work myself. I recently upgraded to the RPM upgraded HD radiator and Pendstar fan. It is like night and day to the previous upgraded radiator and stock fan setup. My temps varied widely from 200-215+ when the a/c was running in the summer and would go higher if I didn't turn off the a/c. I am firmly convinced the Pendstar fan with variable speed and HD radiator are a must in LS JK's. I did some air flow testing on my own and the Jeep grille opening is just too small and ineffectively designed, and air flow becomes very turbulent at speeds above 65mph and actually flows less air as speeds increase due to the aerodynamics of the Jeep front end which actually creates a reverse air flow current effect. And that is without a large front bumper or winch in place which further complicates and disrupts the airflow. I highly encourage anyone thinking of an LS conversion to talk to Jon at RPM Extreme before buying a conversion kit. He is extremely helpful and his follow-up service is tops. I have almost 40K on my JK with LS3 with zero problems following startup. He has a superior product in my opinion and when you need advice or help he is always available.
Hey Reddog thanks for posting this. Did you have to do anything to your 2008 TIPM to get the pentastar fan to work? Also, is the pentastar fan shallower than the 3.8 and does it fit the same way onto the radiator? Thanks again.
 
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Hey Reddog thanks for posting this. Did you have to do anything to your 2008 TIPM to get the pentastar fan to work? Also, is the pentastar fan shallower than the 3.8 and does it fit the same way onto the radiator? Thanks again.
The Pentastar fan is shorter compared to the 3.8 fan and it uses the same mounting tabs.

You will need to have the TIPM reprogramed if you want it to run the pentastar fan. 2008-2011 seem to work great, the 2007 TIPMs don't usually support the newer PWM fan.

You will also need your Jeep ECU programed to send the correct signal to the TIPM or the fan will not work. This will depend on who's kit your using and if the Jeep ECU is still in play.

You will more than likely need a PWM fan harness. RpmExtreme PWM Fan Harness for Penatstar Fan :: RPM Extreme



Our conversions fully support the PWM pentastar fan for 2007-2011 without having to flash the TIPM and come with the fan harness making it plug and play.


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The Pentastar fan is shorter compared to the 3.8 fan and it uses the same mounting tabs.

You will need to have the TIPM reprogramed if you want it to run the pentastar fan. 2008-2011 seem to work great, the 2007 TIPMs don't usually support the newer PWM fan.

You will also need your Jeep ECU programed to send the correct signal to the TIPM or the fan will not work. This will depend on who's kit your using and if the Jeep ECU is still in play.

You will more than likely need a PWM fan harness. RpmExtreme PWM Fan Harness for Penatstar Fan :: RPM Extreme



Our conversions fully support the PWM pentastar fan for 2007-2011 without having to flash the TIPM and come with the fan harness making it plug and play.


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Awesome. Thanks for helping out; wish I'd gone with one of your engine swap kits. May be purchasing your harness in the near future. All I have to do is make sure the fan fits in this pig (vvt truck hemi), and get a newer PCM, fan, reprogram...
 

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Hey Reddog thanks for posting this. Did you have to do anything to your 2008 TIPM to get the pentastar fan to work? Also, is the pentastar fan shallower than the 3.8 and does it fit the same way onto the radiator? Thanks again.
RPM modified the TIPPIN for me but I believe they figured out a way to do it without the TIPPIN now. Jon at RPM is extremely knowledgeable about this stuff and he can help you out quickly. The Pendstar fan with the 52mm radiator (HD) is slightly thicker/deeper than with stock fan. It works but the top radiator hose is in a slight bind where it comes out of the water pump (I have Camaro access drive). I cut off about 1/4 inch of the spigot and it works fine. There is a significant difference between the stock fan and Pendastar fan in terms of performance though and it's worth the cost. Call Jon and he will fix you up with all the right stuff and explain just what needs to be done.
 
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Awesome. Thanks for helping out; wish I'd gone with one of your engine swap kits. May be purchasing your harness in the near future. All I have to do is make sure the fan fits in this pig (vvt truck hemi), and get a newer PCM, fan, reprogram...
Im not sure that you will need a new Jeep PCM. It should be able to be reprogramed for the PWM fan....... I don't mess with a lot of Hemi swaps so I'm not 100%


I have been toying with the idea of a small can box that would take the stock coolant temp message and output a signal for a PWM fan. This would make it easy and wouldn't require any programing.
 

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Get the pentastar fan and dont look back. You can score it in the $300 range brand new on ebay. Its not even in the same ballpark as the stock 3.8 fan.
 

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Whoops sorry, meant to say a newer TIPM. AEV says on their page that the '09 TIPM (04692289AE/AF) is req'd but I'm not sure if that's for their procal reprogram to work or not. I have TIPM #04692236AI, possibly one of the last that can't be reprogrammed (EDIT 8/27/2019: I can confirm that the TIPM (part number 04692236AI) works well with the AEV Procal and the Pentastar fan swap). Seems like the reprogram wouldn't be much more than selecting "PWM" for fan control using HP Tuners, but not sure.

I'll forge ahead with the pentastar fan route, possibly conjur up some of my ghetto wizardry to make it fit, pick up a TIPM if mine wont work. Thanks again!
Im not sure that you will need a new Jeep PCM. It should be able to be reprogramed for the PWM fan....... I don't mess with a lot of Hemi swaps so I'm not 100%


I have been toying with the idea of a small can box that would take the stock coolant temp message and output a signal for a PWM fan. This would make it easy and wouldn't require any programing.
 
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