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Dual Fan Setup For Radiator

hibshman25

Vendor
Joined
Sep 25, 2005
Messages
2,846
Age
40
Location
Lebanon, PA 17042
Country
USA
Snowmobile
2017 sidewinder ltx dx
2018 snoscoot
There is no fan shroud on the backside of the radiator where the fan is. Does anyone make and sell one?

Adding a fan shroud would make the fan more effective by ensuring there is good air flow across the entire radiator. In turn this would improve cooling efficiency. By no means is this concept new. Its common in the automotive industry. The SR vipers have a fan shroud, so I'm thinking about offering one for the Nytro. It would be an aluminum shroud that sandwiches between the fan mounts and radiator. Would be a very easy install.

Update: I have transitioned the shroud plate idea to a shroud that houses two fans. Will be testing it this season.
 
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Your idea is to add a shroud so only air can go through the fan body? Wouldn't that in theory make it restrict air flow when the fan is not running and cause dead spots in the corners that are farthest from the fan?
 
I like the idea but that would be my concern as well, given the relatively small size of the fan compared to the radiator.

How much airflow is there through the radiator when the sled is moving, and the fan is off? If it is significant the shroud may not be a good idea. If it isn't significant I'd like to see a dual fan setup.
 
The motor runs most efficient when its skirting the thermostat opening and closing. That said the flat plate mock up shown is incorrect, it needs to dome, away from the radiator so when the boost fan is not running you can get airflow over the fins. When you put any flat plate plate across the backside of the radiator you get stagnation. In other words you get stagnant air, its just plain caught in an opposing force situation, you push air from the front and the air pushes back from the plate and you get minimal thermal transfer. If you must go with a flat plate you need at least 1/2 the thickness of the radiator gap away from the fins and the fan must run constant to create a negative pressure on the back of the radiator to avoid stagnation.
 
The plate would not be smack up against the fins. Air will still be able to pass through. The cardboard mock up is just showing concept. I was just testing the fan to see the difference in pull through the radiator with and without a shroud.

The location of the radiator doesn't warrant itself to much airflow to begin with. I feel it more less acts as a heat sink, and doesn't efficiently dissipate heat until the fan runs. If we can get the fan to pull even more air flow through the radiator then it may possibly eliminate the overheating issues some experience.

If the shroud itself does not improve cooling enough my next thought is to couple it with a thermo switch and turn the fan on earlier than the factory ECU does. If fan starts pulling air through radiator sooner it may be able to keep ahead and never allow engine to reach overheat temps.

In any event I will be testing some of these ideas. I will be sure to post up the results.
 
Most automotive radiators are positioned in front of the engine so when the fan runs it pulls air through the radiator and across the engine. The Nytro's radiator positioning doesn't allow the fan to properly flow air across the engine and what flow there is through the radiator is to restricted. I'm not convinced a shroud would transfer heat away well enough to make a difference but the only way to know for sure would be to test the concept. I believe the best option is to add a tunnel heat exchanger so that the heat can be dissipated more efficiently with the increased coolant capacity and surface area.
 
Hoping to do some testing this week.

Anyone know off top of head what temp the fan comes on?
 
Most automotive radiators are positioned in front of the engine so when the fan runs it pulls air through the radiator and across the engine. The Nytro's radiator positioning doesn't allow the fan to properly flow air across the engine and what flow there is through the radiator is to restricted. I'm not convinced a shroud would transfer heat away well enough to make a difference but the only way to know for sure would be to test the concept. I believe the best option is to add a tunnel heat exchanger so that the heat can be dissipated more efficiently with the increased coolant capacity and surface area.

I like the idea of a tunnel cooler with a tube tucked up in each side of the tunnel with a cooler in the back , i think this would help keep that big block of ice from forming in the back
 
The idea of a fan shroud is to have the fan pull air across the entire radiator surface instead of only the area directly in front of the fan. The fan in our sleds are already right up against the radiator so adding a flat shroud would likely not increase that surface a whole lot. Looking at automotive fan setups, they are set back a bit and molded towards the fan. For something to work on our sleds, the fan would need to be set back a little and a shroud would be molded over the entire radiator to the fan.

In my experience with converting a belt driven fan to electrics, I have seen kits that had a flat panel like you are proposing and it caused overheating while cruising because it restricted natural air flow. Would it affect out sleds that much? probably not because there isn't that much air flow though it while moving. It's not like a car with a huge grill in front. Our radiators a just there for when we are idling and possibly to supplement the tunnel cooler in low snow conditions.
 
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Did a little testing today with my mock up shroud. With the sled idling I did a test with and without the shroud. With out shroud, from time the fan came on to overheat light it was 7.5 minutes. With the shroud it was 8.5 minutes. So the shroud definitely helped cool, but not dramatically.

Did a second test with two fans mounted. I mounted the stock nytro fan and also a smaller apex fan. With both fans running I was able to get 12.5 minutes of idle time before the overheat light came on. Going to continue looking into this option with a shroud to house both fans.

On the SR Vipers the fan and rad combo actually cools fast enough to never let the sled overheat at an idle. Would like to achieve same thing on nytro.
 
Had a little time today and drew up a shroud plate which will house the stock nytro fan and also an apex/vector fan. apex fans are readily available in used market so should be a rather inexpensive and simple upgrade for additional cooling.
image.jpg
 
let us know how it turns out. id also like to see a comparison of stock fan vs two fan amperage draw to see how much more strain is on the electrical system.
 
Seems to me a big part of the problem is that there is no room behind the radiator to help evacuate the hot air. Since I had the OFT relocate, I was able to build new rad mounts which moved it forward almost 3 inches. The benefit was the rad had room behind it to breathe and it seemed to help cooling significantly.

The double fan shroud would definitely help to cool the engine at idle, but at speed, you need much more air flow to keep temps in line.

OTM
 
Seems to me a big part of the problem is that there is no room behind the radiator to help evacuate the hot air. Since I had the OFT relocate, I was able to build new rad mounts which moved it forward almost 3 inches. The benefit was the rad had room behind it to breathe and it seemed to help cooling significantly.

The double fan shroud would definitely help to cool the engine at idle, but at speed, you need much more air flow to keep temps in line.

OTM

any pics of this? I also have the oft relocate and there is so much room in front of the radiator. even an ice forward would help a ton!
 


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