Testing Different Fuel - Modern Fuel For Thought

There is a fly in the ointment though—even the most meticulously restored Pontiac still has to run on modern gasoline. There simply is no place where we can turn the calendar back and fill our ride with the gas we grew up on (or at the old price). The days of High-Test fuel on every corner have long passed and will never return.

Will my finished car run well on modern pump gas? Though not enough of a concern that it would derail someone’s plan to own a classic Pontiac, it does weigh on every hobbyist’s mind. To further complicate this, the federal government is on the verge of implementing new rules for gasoline that will mean even more changes at the pump. Talks of increased ethanol content, up to 15 percent from the current 10 percent, along with other new chemistries are all on the table with no concern of how it will impact the collector-car hobby, let alone the Pontiac community.

The opportunity to explore this concept required a test mule. HPP needed a strong-running Pontiac engine and Melvin Benzaquen of Classic Restoration Enterprises had just the right candidate. Robert J. Tomasetta and his son, Chris, own a ’73 Formula SD-455—an extremely rare car. Melvin was performing a complete restoration on the Formula and had contracted out to RaceKrafters Automotive Machine owners, Bob and Craig Wise, to rebuild and mildly tweak the Super-Duty mill.

To even a casual reader of HPP, these two shops are no strangers. Both businesses are well entrenched in the Pontiac community and respected for their ability. With the blessings of the Tomasetta family, HPP created a test protocol to examine the impact of fuel composition on one of the most respected Pontiac engines of all time.

Testing had to be done in incremental steps on RaceKrafter’s advanced and very accurate engine dyno with a Depac data acquisition system. Bob and Craig have over 30,000 dyno runs on the current data-collection system. This makes them an excellent choice for repeatable information and removing the potential of skewed results from an inexperienced operator.

As mentioned in the gasoline story, Rockett Brand Racing Fuel joined us in the endeavor. Not only did it provide the fuel, but it also performed an analysis of it to remove any possibility of corrupting the test. This is important so that there is no debate as to the validity—the variables have been removed.

In the chart above, AKI is the anti-knock index. This is a measure of the octane as derived from the method R+M/2=AKI. SG is the weight of the fuel measured as specific gravity. The amount of ethanol is listed as a function of volume, so it’s read in percentage.

Ethanol contains oxygen; it replaced MTBE as an oxygenate for a reduction in emissions. Rockett provided the amount of oxygen in each test fuel using the industry standard, a percentage of the total weight of the fuel. As ethanol is added, the octane improves slightly.