Most of you know we offer HD cooling system components. Soon we will offer a cooling system solution for tough builds like 6.4 Hemi's at high altitude, blown JK's and JK's that tow.
During this diligence I have looked at almost everything that is out there. My opinion is OE fan assemblies outperform aftermarket fans for the most part. Special needs like running in mud requires a sealed motor which is not what I'm concerned with, my concern is the ability to cool the engine and transmission.
Most of you know the early JK fan is okay, not great, but it does outperform most universal 16" fans by a wide margin. The stock fan blade is about 17" in diameter. The stock fan motor is a standard single wound DC motor that has been used for decades. Two speeds are achieved by using a voltage divider to lower low speed voltage to about 8 volts. This is a cheap solution when compared to dual wound or variable speed fans but we're use to cheap in our JK's. It is common for the low speed portion of the voltage divider to burn out leaving your JK with high speed operation only. You may notice erratic AC operation and odd high speed fan behavior if your divider goes out. We replaced 3 dividers in JK's just in the last two months. If your fan motor ingests mud, contaminated water or debris it will consume more amps resulting in the failure of the divider and melting the high speed relay contacts. If this happens replace the motor and divider(Chrysler calls it the fan harness).
I was surprised when I ordered my guy to gut a Pentstar fan motor($600��. He came to me and said I've never seen tis before. He would if he was into RC. The Pentstar fan motor is an outrunner, the outside bell rotates rather than the inner rotor. This means more torque to turn the 18.5" blade. Like a model motor the module contains 3 main drives and while I did not count about 22 poles(may be less I took a quick look).
I believe the unit is made by Johnson Electric and it is very heavy(dense) for it's size. The unit contains an electronic speed control and interface for the TIPM. The fan is listed as PWM but when I observed the pattern on a lab scope it was not a standard PWM signal; it was more akin to a step ladder voltage signal based on % fan requested.
I find the fan to be compact(due to the outrunner design) and powerful and give Chrysler credit for fitting it. I find the control and software lacking though. The TIPM controls the fan and it seems illogical. I see Pentstars run in the high 230's before the fan comes on and AC pressure exceeding 400 psi before the fan steps up. Once the fan spins up it seems to idle at 10% which I like to keep some air moving. At 100% it moves a lot of air but I notice it rarely goes above 75%, even if the engine is hot, like it is limited. I know motors of this design can have synch issues the high rpm.
As much as I would like to use the Pentstar fan on the early JK it is cost prohibitive and control is a problem. I do not trust variable speed controllers with software in extreme conditions.
We can get similar or better performance with old fashioned DC motors and high capacity relays along with lower cost, simplicity and reliability. So for now while I admire the Pentstar fan assembly we're going the KISS route.
During this diligence I have looked at almost everything that is out there. My opinion is OE fan assemblies outperform aftermarket fans for the most part. Special needs like running in mud requires a sealed motor which is not what I'm concerned with, my concern is the ability to cool the engine and transmission.
Most of you know the early JK fan is okay, not great, but it does outperform most universal 16" fans by a wide margin. The stock fan blade is about 17" in diameter. The stock fan motor is a standard single wound DC motor that has been used for decades. Two speeds are achieved by using a voltage divider to lower low speed voltage to about 8 volts. This is a cheap solution when compared to dual wound or variable speed fans but we're use to cheap in our JK's. It is common for the low speed portion of the voltage divider to burn out leaving your JK with high speed operation only. You may notice erratic AC operation and odd high speed fan behavior if your divider goes out. We replaced 3 dividers in JK's just in the last two months. If your fan motor ingests mud, contaminated water or debris it will consume more amps resulting in the failure of the divider and melting the high speed relay contacts. If this happens replace the motor and divider(Chrysler calls it the fan harness).
I was surprised when I ordered my guy to gut a Pentstar fan motor($600��. He came to me and said I've never seen tis before. He would if he was into RC. The Pentstar fan motor is an outrunner, the outside bell rotates rather than the inner rotor. This means more torque to turn the 18.5" blade. Like a model motor the module contains 3 main drives and while I did not count about 22 poles(may be less I took a quick look).
I believe the unit is made by Johnson Electric and it is very heavy(dense) for it's size. The unit contains an electronic speed control and interface for the TIPM. The fan is listed as PWM but when I observed the pattern on a lab scope it was not a standard PWM signal; it was more akin to a step ladder voltage signal based on % fan requested.
I find the fan to be compact(due to the outrunner design) and powerful and give Chrysler credit for fitting it. I find the control and software lacking though. The TIPM controls the fan and it seems illogical. I see Pentstars run in the high 230's before the fan comes on and AC pressure exceeding 400 psi before the fan steps up. Once the fan spins up it seems to idle at 10% which I like to keep some air moving. At 100% it moves a lot of air but I notice it rarely goes above 75%, even if the engine is hot, like it is limited. I know motors of this design can have synch issues the high rpm.
As much as I would like to use the Pentstar fan on the early JK it is cost prohibitive and control is a problem. I do not trust variable speed controllers with software in extreme conditions.
We can get similar or better performance with old fashioned DC motors and high capacity relays along with lower cost, simplicity and reliability. So for now while I admire the Pentstar fan assembly we're going the KISS route.