Has Anyone Installed a Fan Control Kit on a Gen 2

[Shakazito]

Hi,
Roe Racing, among several Viper suppliers, sells a fan control unit that makes your fan come on earlier than the stock setting and acts to cool the engine after the key has been turned off. I was wondering if anyone has installed one, and if you noticed an improvement? Thanks in advance for your help!

[dave6666]

Yes. They suck. The wire taps are too cheesy for the current draw of the fan and can do heat damage at that joint. Even tried a solder joint and it overheated as well.

If you are just trying to lower the fan on temp buy an SCT and have it programmed. If you are trying to solve a cooling issue that's not electrical, like your fans aren't coming on, a fan kit does not fix overheating.

[dave6666]

Pics of the melted wire tap. The one that is supplied with the kit.

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Pic of soldered tap that eventually overheated as well. The final straw for when I completely got rid of the factory fan control relay and wire system. I retained the factory temp sensor and PCM interface.

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[Viper Red]

That is not encouraging.

[Shakazito]

Thanks Dave. This is helpful. I see that Roe has an SCT with one tune for $550 that will also turn off the skip shift feature and turn the radiator fan on 12 degrees cooler than stock. Do you have any preferences for a SCT vendor?

[ViperTony]

I've had the fan kit on my Gen2 since '07. It doesn't improve cooling. It improves nothing, really. If your engine is heat soaked after a long track day the fan may kick in for a while. Nothing really exciting about that. Otherwise open the hood after it's parked and let the heat out. It's not going to improve cooling or bring down your coolant temps while you're pucker-vortexing your seat cushion during an WOT pull. It will not fix an overheating issue as Dave mentioned. I found my radiator clogged after 16k miles even after more-than-frequent coolant changes. Once it was cleaned and re-cored I did notice my temps come down slightly. But my temps have always operated within range of the manual. I do have an SCT that turns on the fans at lower temps (Dan @ Viper Specialty). I also have a vented cowl that helps move heat out of the engine bay. Airflow is key as well as a functional cooling system.

[04BlackSRT10]

I have the Roe Racing SCT tune on my SRT10. I'm aware this is a Gen 1/2 forum, but on my 04 it made a huge difference and I'm sure it will do the same for your car as well. Not only does the fan indeed come on sooner, but the elimination of the skip shift makes the car so much more relaxing to drive slowly around town. However, the best part is the smoothness of the power delivery. There is noticeably more power --especially in the mid-range, and it's much, much easier to shift between gears with no jerkiness. With the stock tune it was genuinely difficult to shift smoothly when driving around normally. Now it's difficult to not shift perfectly smoothly every time. The whole car feels like another generation of Viper, such was the improvement. I highly recommend the Roe tune, and for 550 bucks it's a great value given all the enhancements. I paid about double that for the tune I had on my F Type and it didn't do nearly as much for the overall experience!

[dave6666]

I think Tony captured it pretty well, but unless your car has an electrical problem with the fan, having it come on sooner by changing the fan control does not help a cooling problem unless the fan control is what's broken.

Look at it this way...

SCENARIO 1 - cooling system in proper working order

Let's say the engine produces 1 million BTUs of heat, or thermal energy. No idea what that amount is but it's an easy number to use.

Now let's also say that the cooling system and all of it's components are able to remove, or cool, 1.1 million BTUs of thermal energy.

So the fan cycles on and off to regulate the temperature as the cooling system is actually capable of over cooling. This equilibrium temperature whereas the engine heat produced and the cooling system capacity to cool are matched in operation, is what the engine operates at. What you see on the cooling gauge.

SCENARIO 2 - cooling system is NOT in proper working order

Engine produces 1 million BTUs, blah blah.

But your radiator is fouled both internally (scale) and externally (bugs, leaves, drink cup bits) and you are only getting 0.9 million BTUs of cooling. So in this case the fan still comes on at whatever temp it's set to come on at, but since the cooling system can't remove all of the engine heat the temperature continues to climb. The fan won't cycle. Equilibrium temperature is higher. What you see on the gauge is higher.

What impact would having the fan come on sooner i.e. a lower temperature have on equilibrium temperature? None. Absolutely none. It may slightly delay equilibrium by a few minutes, but if you're generating 1 million BTUs of heat and removing 0.9 million BTUs of heat, it's going to overheat. Or run hotter.


BTW that same equation applies to the thermostat. If your car does not cool with the factory 192* stat, changing it to a 180* won't do anything but slightly delay your overheating by a few minutes because is has a 12 degree head start in the latter. But the equilibrium temperature remains unchanged.


If you are looking to go SCT Dan Lesser of VSP can help you as well as others like ROE. Not sure if Dan Cragin is tuning with SCT or just does PCM reflashes but he can help as well.

[Shakazito]

I have the information I need - thanks all. What a great group of contributors!