Synthetic oil and proper cooling can help Dirt Late Models run more efficiently
Words Dan Hodgdon
Dirt Late Model engines run hot. While this certainly isn’t news to those who have spent significant time around the track, advances in oil and cooling systems provide an easy way to reduce temperature.
Most Dirt Late Models use deck-mounted oil coolers for ease of placement and to avoid flying rocks and mud balls. However, airflow is not very efficient in this area, which allows temperatures to rise higher than most engine builders like. Most of these engines will see oil temperatures around 300 degrees, especially at heavier and bigger tracks (think Eldora, for instance) when conditions require drivers to be on the gas harder and longer.
Advancements in suspension technology have also contributed to increased oil temperatures. It wasn’t that long ago when most chassis makers used three-link rear suspensions and Monroe shocks. However, in the past five years, chassis builders have made major engineering gains and shocks have gotten exponentially better, while cooling options have remained largely the same. Better suspension and shocks equates to more grip, thus letting drivers be on the gas harder and longer. This, in turn, raises oil temperatures.
“For every 20 degrees over 220 degrees that engines are run, it shortens the life of the oil by 25 percent,” says Driven Racing Oil’s Scott Diehl. “So, if you have an oil that is good for 500 laps, if you run at 300 degrees you shorten the life to 160 laps.”
If racers invest a little more time and money in lowering oil temperatures, it will not only make the engine happier, but also save them money in the long run.
While oil alone is important, teams can also save money on repairs by using the correct radiator and oil cooler on the front end. Herb Engelhart of C&R Racing points out that many teams are not doing so in an attempt to skimp on cost, leading to later, more expensive problems. He explains that with the nose down tight to the track and no grille openings, Dirt Late Models have very limited air flow, meaning they rely almost exclusively on a radiator’s mechanical fan. This is exacerbated by the fact that due to engine advancements in recent years, many of these vehicles are capable of making 850 to 900 hp, which creates more heat. Yet they still rely on inadequate cooling systems.
“Water and oil run hand in hand; if the radiator isn’t working well enough, it’ll drag the oil temp up and vice versa,” Engelhart says. “I believe the quality and performance of today’s oils is the only reason Dirt Late Model teams don’t have more engine issues. I really feel like the lubricants today are really saving their bacon, so to speak. But their bacon is pretty crispy most of the time, and there are solutions out there like we have here at C&R.”
One solution from the company is a new stacker design which puts the radiator and oil cooler, stacked one in front of the other, in the nose of the car.
“I can’t think of a better spot for the oil cooler to be than right in front of the fan on a Dirt Late Model,” Engelhart says.
The oil cooler utilizes an efficient tube-and-fin design vs. plate and fin, or as Engelhart is fond of saying, “a real oil cooler” core like his company uses in NASCAR and other applications.
This package sells for $1,995, which is a higher price point than most teams are used to, but it has been proven time and again both in asphalt racing and by Best Motorsports in the Dirt Late Model world, with crew chief Randall Edwards and star driver Brandon Sheppard. Instead of the typical 50-plus degree splits between water and oil temperatures, the Best team is seeing only 25-35 degrees of split. They usually are running 210 to 225 degrees on water and 235-260 on oil, depending on track and ambient temperature. This is a far cry from the 300-degree oil temperatures and 250-degree water temps often seen with deck-mount coolers.
In addition, Engelhart notes many racers believe there might be an issue with their radiator and water temperature when, in fact, the problem is with the oil temperature. To combat this problem, C&R also produces a standalone oil cooler that is run by most Dirt Late Model teams and costs just under $600. Engelhart says when it’s mounted in the right spot, it will get the job done by getting just enough air to cool properly.
Many teams will put $40,000 to $50,000 on an engine, and then spend less than $200 on a radiator and oil cooler, so it’s important to consider what companies like C&R can offer. Quite simply, there are not many options, if any, that can properly cool 900 hp with limited airflow.
Luckily for racers, synthetic oils can provide better cooling even when racers have not invested in an improved cooling system. Lubricants are asked to not only lubricate, but also to help cool engine parts. Synthetic oils have a higher specific heat than conventional options, which allows them to absorb more heat from the engine parts. It can then be released through the various cooling mechanisms of the oiling system, such as the cooler and oil pan.
“The thicker the oil is, the bigger the molecules are,” Diehl explains. “When you try to force the bigger molecules through tight orifices, they rub up against each other. This causes parasitic friction that raises temperatures.”
A properly formulated full synthetic 10W- 40, like Driven’s XP9, offers shear stability with a high viscosity index. Viscosity index is a measurement of an oil’s resistance to thinning with temperature. The higher the index, the less the fluid thins out and the better the protection. Thus, XP9 will have the same bearing film strength and same oil pressure as most conventional 20W-50s at higher oil temperatures, like 250 degrees.
“If we get oil temperature down by using better oils and a better cooler, it will allow the use of a lighter oil which makes everything better,” Diehl says.
Most teams are good about heating the water before they fire the engines, but many don’t take time to heat the oil. When engines are started with a 20W-50 that is cold, they don’t flow very well thanks to the fluid’s thickness. This is when most cold start wear is most common. Utilizing a full-synthetic 10W-40 will flow much better at colder temperatures and eliminate most cold start wear.
Thinner oils are not always better, but rather it is important to match an oil’s viscosity with the requirements of the engine. Not all oils are formulated equally, meaning that even though two different 10W-40 oils from two different companies may have the same viscosity ratings, they may behave differently inside the engine. One may not be as shear stable, or it might have a different viscosity index rating.
Using a good synthetic oil will always provide added protection. Using a good cooling system will, too. Asphalt racers understand the importance of cooling because it allows them to run more tape on the front of the nose, thereby creating downforce. On the other hand, many Dirt Late Model teams will spend money on high-end engine parts, trick shocks, tires, and anything they believe will make the car go faster, but they often overlook the importance of cooling. Here is where many Dirt Late Models with proper cooling may find an advantage.
Driven Racing Oil