Insight: How a 100-Year-Old Technical Paper Helped Take Acura to Rolex 24 Win

HPD President David Salters reveals his company's solution for an oil dilution dilemma in the build up to the GTP class debut...

There were a number of unknowns heading into January’s Rolex 24 at Daytona for competitors in the reborn IMSA GTP category. With brand-new prototypes running a new hybrid powertrain on new Michelin tires and with a new renewable fuel from VP Racing Fuels, there was not much that manufacturers and teams could lean on from past WeatherTech SportsCar Championship seasons.

Acura, which scored a 1-2 finish with its cutting-edge ARX-06 LMDh cars, was among those that overcame challenges in the immediate build-up to the Florida endurance classic that saw a rapid rate of development not only with the machinery but with the consumables.

One of the wrenches thrown into the mix was the introduction of an 80 percent blend of renewable fuel, to be used exclusively in the GTP class, that inadvertently led to an oil contamination issue inside the powerplants.

While each LMDh manufacturer dealt with the challenge in different ways, Honda Performance Development, Acura and Honda’s U.S.-based motorsports arm, went back into the automotive archives, with a technical paper that was written 100 years ago, to help solve a 21st century issue.

HPD President David Salters tells the tale: "The fuel supplier did a brilliant job to move heaven and earth and get the fuel here but of course we were all running late (because of supply chain challenges). We started testing the fuel in November and we found some issues with oil dilution. 

"This fuel is brand-new, it didn't really exist in the world before. What were we going to do about it? 

"We noticed that we were getting quite a lot of fuel in the oil. Normally you might expect 1 or 2 percent and this was ten times more than that. I think most people would know that fuel is not the best lubricant in the world; in fact it's about the worst lubricant. 

"So you don't really want it in your beautiful 2.4-liter highly stressed 700 horsepower racing engine. Bad things will happen if you don't look after it.

"We got some very clever measurement equipment that helped us so we could measure and understand. Then we started to sweep parameters. 

"But one of the guys who leads our development (Jason), went away to get the books out and understand what causes oil dilution. 

"These days it doesn't happen very often but it used to happen a long time ago when fuels and lubricants were very different. The quantities we get now are minuscule. In the early days of new stuff, like a new fuel now, you got quite a lot.

"We actually found a paper that was 100 years old. A group at a university had modeled the equilibrium status of how fuel and oil interact.

“So we did loads of classical sums and we were able to use a 100-year-old paper with 21st century measuring equipment and we were able to figure out how the oil and fuel would reach an equilibrium state.”

The analysis, performed over the Christmas break at HPD’s headquarters in Santa Clarita, Calif., helped to ensure that both the Meyer Shank Racing and Wayne Taylor Racing with Andretti Autosport entries got to the end of the Rolex 24 without encountering engine-related issues.

"We have libraries here [at HPD] for technical papers and they are typically archived,” Salters explains. “We found some stuff that actually modeled, depending on some of your fuel chemistry and temperatures and stuff, how much fuel you could absorb in the oil. 

"It had all been done by hand because everything was done by hand [back] then. So we had found these old models and we noticed we could correlate to, so we could start to predict mathematically the amount of fuel in the oil.

"It actually reaches an equilibrium at some point. So we looked at the things that it depended on and found a way to manage it.”

The two Acuras completed oil flushes, essentially a rapid oil change, several times during routine pit stops that helped mitigate the issue over the course of the twice-around-the-clock enduro.

"We kept it at a manageable proportion and we understood how much oil we needed to change to keep it the right way and then we've since done other things where we're able to reduce it,” Salters explains.

"At Sebring we had it all under control. We just kept learning and we're still learning. We’re now working with the oil supplier, who now knows a bit more about it on how to deal with it, and we can change some of the running conditions so we don't put as much fuel in the oil.

"We've done the engineering and now it's more-or-less under control now. We don't have to do anything special anymore."

Salters, who was one of the proponents for a switch to a renewable fuel, praised IMSA’s adoption of the new blend, even if it created some initial headaches in the critical weeks leading up to the season opener.

"The best thing you can do is empower the people,” he says. “The engineers went away, went back to basics, got the books out, and found a solution.

"We had this machine from the 21st century and a technical paper that was helping us from 100 years ago. It was good old fashioned engineering with the modern stuff.”

Photos: Mike Levitt & Rick Dole