Blank Slate: Dwelling On Keeping Things Cool

Our no holds barred autocross project car that we have anointed as “Project Blank Slate,” was in desperate need of an updated cooling system to match the mighty LS mill that we mounted in the engine bay. Going from a radiator with standard Gen 1 small-block configuration (return on the top of the driver’s side with the exit on the lower passenger side) to an LS configured radiator (return and exit on the passenger side), was a big concern for this upgrade. Plus, we need a good performing cooling system for all our track days. 

Our no holds barred autocross project car, Blank Slate.

Basically, the cards are stacked against our project car and keeping it running cool. When you take a super hot car with a fire generating engine in the stupidly hot Inland Empire weather of Southern California… cool is an illusion. We have witnessed many retromod rebuilds cooling down on the side of many Southern California highways that criss-cross the desert. Deciding not to become another roadside victim, we reached out to our “cool” friends at AFCO Racing Products.

“We’ve got just the thing,” said AFCO’s Eric Saffell. “You want a complete cooling package that will maintain a good temperature range and not get to a car show and spill coolant all over the ground and embarrass yourselves? You’re going to want our radiator, aluminum shroud and electric fan combo.”

We wanted a cooling system that was going to keep our hot classic car cool, even on the demanding SoCal highways in the middle of summer.

To Saffell’s point, anyone can build a cooling system that keeps an engine cool when it plows down the highway with tons of air flowing through the radiator. It’s a different story when you are on the Southern California highways during rush hour in the hottest part of summer. Airflow is precious at two mph in 110 degree ambient air temperature.

Radiator Specs

  • Part Number: 84251-S-DS-N
  • Overall width: 28.01″
  • Overall height: 17.75″
  • Overall thickness: 3.00″
  • Core width: 22.38″
  • Core height: 17.75″
  • Core thickness: 2.25″
  • Inlet location: Upper Right
  • Outlet location: Lower Right
  • Inlet size: 1.38″
  • Outlet size: 1.38″
  • Tube size: 1.00″
  • Tube style: Downflow
  • Radiator style: Double Pass
  • Row quantity: Dual
  • Transmission cooler: No
  • Shroud: Yes
  • Cooling fan: Double
  • Material type: Aluminum
  • Finish: Satin

Heat: A By-Product of Power

Internal combustion engines are considered inefficient as far as mechanical engineers are concerned. More heat is generated by the engine than comes out as mechanical power. The heat that enters and stays in the engine is a by-product of the combustion that must be removed. Some of the waste heat dissipates through the surrounding cooler air. Heat is also transmitted through exhaust gasses leaving the engine. The rest of the waste heat must be handled by an engine cooling system.

All engines need cooling to operate. High temperatures damage the internal engine materials and lubricants. Internal combustion engines burn fuel hotter than the melting temperature of many of the engine’s materials and hot enough to set fire to the lubricant. A well designed engine cooling system will remove heat quickly to keep temperatures low enough to make the engine survive. An over-heating engine is one that has a compromised power output and a short life.

AFCO’s Radiator, Aluminum Shroud and Electric Fan Combo

AFCO’s aluminum radiator (Part #84251-S-DS-N) is designed for 1967 through 1969 Camaro and Firebirds with an LSx engine swap. Combining this with the accompanying aluminum shroud with dual electric fans (Part #84251-F-DS-N) makes for a very efficient cooling system that stands up to the many demands of modern combustion techniques.

“Our engineers work hard to design a system that is a hundred percent bolt-in design with no modifications needed. The engineering team’s focus is on fitment with a maximum core capacity without compromising air flow,” stated Saffell. “What many people don’t realize is that there is a specific number of cooling fins per square inch that each application requires for maximum efficiency.”

Designing an efficient radiator is more than just cramming  in as much radiator core that is physically possible in the space; maintaining high airflow within that core capacity is a key to superior cooling. Saffell reminded us that, “There is a lot to consider when designing a fan shroud that supports the radiator. Airflow is critical in the cooling process. The fans and shroud have to fit the demands of the radiator as well. You must use the fan shroud designed for the radiator. For instance, if you have one of our radiator with transmission cooler combinations, the fan shroud designed to work with a radiator and trans cooler is what you need to use for maximum efficiency.”

Our radiator was delivered and we couldn't wait to check it out.

AFCO engineers believe that they have the best designed and most complete cooling packages on the market. “Our team takes a look at every aspect of the cooling package,” he said, adding,”Especially with packages that are designed for engine swaps. They have to fit correctly and do the job efficiently right out of the box.”

Radiator Shroud Specs:

  • Part #: 84251-F-DS-N
  • Overall width: 22.25″
  • Overall height: 17.75″
  • Overall thickness: 3.25″
  • Depth: .75″
  • Cooling fan: Double
  • Hole diameter: 12.00″
  • Material thickness: .080″
  • Material type: Aluminum
  • Finish: Satin
  • Hardware included: Yes

TIG welded mounting brackets, 1.38-inch inlet and outlets define this radiator unit as one of the toughest available while maintaining the stock size upper and lower hoses for LS engines.

 Other Considerations

A bolt-in unit for an engine combination that did not come stock from the factory used to be a rare item. Because of the LS engine’s popularity and the sheer number of enthusiasts that are jumping at the chance to upgrade their classic with a modern engine, manufacturer’s like AFCO Racing take the time to engineer a perfect fit component. “It’s crucial that we take a look at the whole picture and get everything right. Things like the placement of the inlets and outlets. The engine requirements for an LS engine are different than the Gen I engine requirements,” said Saffell. “There are different sized inlets and outlets too. We want our customers to spend their time enjoying their parts, not standing at the parts store trying to get a hose that fits.”

The original Gen I small-block required a radiator with the upper hose (radiator inlet) on the drivers side of the car. The lower hose (radiator outlet) was located on the passenger side of the car. LS engines, typically those using multiple pass radiators, have both the inlet and outlet on the passenger side of the car. Swapping a newer GM LS style engine in place of the original Gen I small-block GM engine requires this change in plumbing for your coolant system.

Even the blades on the fans in this kit are held to a higher standard. Able to withstand almost unlimited number of hot and cold cycles without degradation.

The quality of the complete kit goes beyond the work that AFCO physically puts into the system. “Anything that we outsource, like the fan units, have to meet our specifications. We searched for fan units that were made with a composite of materials that would stand up to continuous duty over many years. We wanted to know that the blades wouldn’t become brittle over time and would perform well for our customers for years to come,” added Saffell. “Fan blades can become weakened after several hot and cold cycles. We tested fans until we were satisfied with the quality.”

Not only do the fans have to stand up to the test of time, Saffell also explained the most important factor in electrical fan selection, “We required a set of electrical fans that operated with a low amp draw but had high output. These fans helped to make our cooling system a complete efficient cooling package.”

Dwell On This 

Dwell time refers to the amount of time spent in the same area or time spent in a stage or process. In the case of our project car’s cooling system, dwell time is the amount of time that engine coolant stays in the radiator being cooled by the air flow. “The coolant is forced to circle through the radiator because of a baffle that is welded in the core. This baffle forces the coolant flow across the core for a second time which helps lower the temperature of the coolant,” Saffell said as he explained AFCO’s double pass radiator design.

When asked how much more a double pass radiator will cool, Saffell stated, “we will say 10-20 degrees depending on several variables within the cooling system.”

We wanted to go one-step further and make some hard lines for our supply and return coolant lines. Using polished aluminum tubing from Vibrant Performance, we TIG welded new lines.

AFCO Racing took great care to engineer the radiator to fill the needs of an LS engine swap with the inlet and outlet on the passenger side of the car. Both inlet and outlet tubing size is the standard 1.38-inch LS size for ease of locating and replacing the hoses. A quick run to the local part’s store for an LS coolant hose is all that is required. We wanted to go one step further and install a hard line. Understanding that not everyone has a TIG welder or the skills to pull off a neat trick like this, we still wanted to show what could be done with a little time and the right parts and tools.

Using two 1.5-inch O.D. 180 degree bend aluminum tubes (Part #2863) and one 1.5-inch O.D. 18-inch straight aluminum tube (Part #2171) from Vibrant Performance, we fabricated our own set of hard lines. These aluminum tubes are manufactured from T6061 aluminum and are 1.5mm thick.

Speaking strictly from an aesthetic perspective, manufacturing custom hard lines for your cooling system is going for the gold ring in looks but it may not always fit your budget or fabrication ability.

True to the instructions, the radiator assembly dropped into place and bolted in without any modification at all.

Putting It All Together

Installing the AFCO radiator and shroud package couldn’t have been more simple. Because the components came together as a single unit, it was simply a matter of dropping the assembly into the engine bay and bolting it down. We found out that Saffell was correct. The radiator assembly was a true bolt-in unit without any modification needed. Hood clearance was not an issue because the radiator is purpose-built for this make and model with an LS engine swap. All the difficulty has been engineered out.

The fitment was perfect with the top of the radiator core slightly below the stock radiator support. With our custom lines in place, we felt good about our cooling upgrade.

After we dropped the radiator unit in, tightened the four original mounting bolts and installed our newly constructed hard lines on the upper inlet and lower outlet mounts, we were ready to check the system for leaks. Currently there is no wiring in the car at all and our electric fans will have to wait to be wired into the system, which means that you will want to be on the lookout for our next update on this classic project car build.

Article Sources

About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
Read My Articles

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