Frequently Asked Questions

Down Flow / Shrouds

Our down flows typically use a 16” fan or two smaller fans. We recommend allowing an additional ¼” when using our mounting brackets and not using shrouds with a pusher fan. Shrouds are used to position the fan ⅞” closer to the water pump. Below the fan motor you will need approximately 2 inches between the water pump and core for room to mount the fan.

Pusher Fans

It is important to know that pusher fans with straight blades must be spaced out ¼” from core or fan mount fans. If a pusher fan attaches onto AC condensers should be attached with plastic ties that are cut off at the condenser. You should never put plastic ties through the radiator because it could cause the radiator to leak.

Pusher fans should be the same diameter or smaller than the air conditioning condenser. A larger fan can cause air to pass through the open area. Although you can use two small fans, one large fan 14” – 16” typically works better. If you are able to use two pusher fans, 12″ or larger, two fans generally work better than using only one large fan. When the pusher fan is a helper, one 11″ or larger fan will work best. You can use two 10″ or smaller fans if you have room. When a pusher fan is the only fan being used, select a fan or fans that will cover up as much of the core as possible.

Fan Switches

When selecting a fan switch for your fan, our switch kit is the perfect product for you. Follow the guidelines below to find the perfect switch for your thermostat:

• 160º thermostat – 185º or 195º switch
• 180º thermostat – 195º switch
• 195º thermostat – 210º switch

If running 2 fans with 13 amps or lower, use a 30-amp circuit breaker instead of a fuse, otherwise the fuse might blow. If you’re using two fans that require 14+ amps, use 2 relays with only 1 thermal switch.

Mounting Kits

Use our fan mount kit, use part FMK for installing electric fans. Avoid plastic push ties that can damage the radiator.

Cross Flow / Shrouds

Before ordering, you must know the core size. It is important to remember that most cross flows will be between 15” and 21” tall. If your cross flow is smaller than 21” in length, one larger fan will work best for a puller fan.

For the best cooling efficiency, use a fan that is 3 ⅜” wide when there is room. If core is larger than 22”, then two small 11” or larger can be used with a shroud. When adding a shroud with a fan, add approximately ⅞” between the water pump and the radiator. Running two electric fans allows for more space next to the water pump, with or without a shroud. Cores larger than 24″ in length can use two fans (12″, 13″ or 14″) depending on size of core.

Flapper Valves / Shrouds

Flapper valves are added to the shrouds when needed to allow excess air from high speed driving to exit fan shroud. Without flapper valves, too much air enters into the shroud causing the air to go around the radiator instead of through it, resulting in the car overheating. If a pusher fan is the only fan used, cover as much of the radiator core as possible. Remember, shrouds cannot be used on pushers. Fan shrouds need a way to mount to the radiator. The radiator is needed in order to make mounts for the fan shroud. Fax a drawing of your radiator to Mattson’s Inc. at (714) 893-4933 if you want a quote from us to build you a custom shroud made that will fit your mounts.

Car Dimensions

Ford Cars

Ford Trucks

Chevrolet

Important: Need core sizes and distance from core to water pump.