Bill Smith
Founder, 1929-2014
Speedy Bill
Since 1952
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Speedway Motors is America’s Oldest Speed Shop® and has been a trusted source for high performance parts for street rods and racing for over 60 years. Speedway Motors has built a reputation for providing friendly expert advice and superior service. Whether you are racing, building a street rod or restoring an old classic, Speedway Motors has the performance parts you need – in stock and ready to ship today.

The Difference Between Down-Flow and Cross-Flow Radiators

By Speedway Motors

  Created 2014

Radiators are offered in a number of different configurations. These varying configurations are offered to influence; coolant movement, rigidity for mounting, and/or plumbing methods. The most popular are down-flow and cross-flow. Each design carries its own advantage. The down flow radiator design the tanks are located at the top and bottom of the core. The fluid enters through the top tank and trickles down through the tubes with the help of gravity easing the work load of the water pump. On the cross flow, the tanks are located on the sides of the radiator's core, allowing the pump to push the coolant across the core from right to left. Cross-flow can allow the radiator cap to be positioned on the low-pressure (suction) side of the system, which prevents the pressure created by a high-flow water pump from forcing coolant past the radiator cap at high rpm. Cross-flow systems are also offered in a single, double, or even triple pass orientation. These orientations give the radiator the ability to cool the fluid multiple times by separating the fluid to be cooled from that which already has been

Cross-Flow Cross-Flow
Down-Flow Down-Flow
Double-Pass

The diagram to the left shows the coolant flow in a double pass radiator. One of the major benefits to this design is that temperatures run anywhere from 10 to 20 degrees cooler than a single pass radiator would with the same core size.

Related Articles:
Double-Pass
 
Featured Products
  • Speedway 1966-70 Chevelle/Impala Aluminum Radiator
    Speedway 1966-70 Chevelle/Impala Aluminum Radiator
    (Part #9175070)
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    This aluminum crossflow radiator is designed for the 1966-67 Chevy Chevelle/Malibu and 1966-70 Impala. They are all welded construction and include a built-in transmission cooler.

    • 1966-70 Impala
    • 1966-67 Chevelle/Malibu

    NOTE: Applications for reference only - measure your existing radiator for proper dimensions. Measurements listed are overall which includes radiator tanks.

    Shroud and fan assemblies available at right. 

    Learn more about how radiators work and selecting the proper radiator for your vehicle by reading our tech article. Radiator Cooling Performance.  

  • Universal Aluminum Radiator - 27 Inch Tall, Passenger Side Outlet
    Universal Aluminum Radiator - 27 Inch Tall, Passenger Side Outlet
    (Part #9175159)
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    These downflow aluminum radiators are for you guys that are building something a little different. They work great in many '30s, '40s & '50s medium width nose vehicles (be sure to measure before you order).

    • Built-in 7-plate automatic transmission cooler
    • Centered filler neck w/ hose nipple
    • 2 rows of 1" tubes
    • Trans Cooler ports:  1/2"-20 inverted flare

    Learn more about how radiators work and selecting the proper radiator for your vehicle by reading our tech article. Radiator Cooling Performance.

  • Speedway Ford-Mopar Universal Radiator
    From: $129.99
    Product Rating: 4.46 Stars
    Speedway Ford-Mopar Universal Radiator
    (Part #917348)
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                Leave it to Speedway to offer you a professional quality aluminum racing radiator at an affordable price. Check out these features: 
    • All aluminum, furnace brazed construction - NO EPOXY, NO GASKETS
    • 2 rows of 1" aluminum tubes (out cools 5 rows of copper)
    • Maximum amount of fins per inch, allows greater heat transfer
    • Billet filler neck - not stamped
    • Available in 22", 24", 26", 28" or 31" (width measurements include tanks)
    • 19" tall

    In this Ford / Mopar Application the upper hose is located on the passenger side & the lower hose is located on the driver side.

    Speedy Bill recommends using a 32 lb. or less radiator cap and to check it regularly.

    Learn more about how radiators work and selecting the proper radiator for your vehicle by reading our tech article. Radiator Cooling Performance

  • AFCO 1937-39 Ford Aluminum Radiator, Ford Engine
    AFCO 1937-39 Ford Aluminum Radiator, Ford Engine
    (Part #10681142)
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    When it comes to the cooling performance of these radiators, they are second to none. AFCO Aluminum radiators allow your car to remain at a constant temperature, which means that power delivery is more consistent. The uniformity of an all-aluminum construction radiator allows for the best pound for pound heat transfer characteristics.

    • 100% Aluminum construction (no epoxy)
    • Furnace brazed core
    • Tanks are made of .080” 3003 aluminum for strength and durability
    • TIG welded by skilled craftsmen in the USA
    • Factory pressure-tested
    • Filler necks feature screw-in bleed – won't crack or leak with age

    1937-1939 Ford Radiator Installation Instructions (PDF)

    NOTE: Due to the modified nature of these vehicles, some radiators will require a minimum of drilling, etc. to mount.

    Learn more about how radiators work and selecting the proper radiator for your vehicle by reading our tech article. Radiator Cooling Performance.