Pump Gas Difference Tested — Does Brand Matter For Horsepower?

The term “pump gas” can mean different things to different people. However, the generally accepted commonality is that the fuel comes from a commercial gas station pump. Because we know that humans inherently form attachments to familiar things, that can lead to people having strong feelings about the brand of gasoline they use. The question is, is there really a difference?

Additive packages aside, whether or not 91-octane fuel from gas station brand A performs differently than brand B is a valid question. Luckily, Total Seal’s Lake Speed, Jr. wanted to know, and when he’s curious about something, you know he’s going to do some testing to get an answer for himself. Tapping long-time partner Shaver Specialties (and his partner-in-crime “Dyno Don” McAskill), Speed set out to get some answers.

Additionally, the duo sets out to see how California 91-octane pump fuel, which they have had some well-documented consistency issues with, compares to VP Racing Fuel’s unleaded C20 95-octane gasoline. That part is less about answering the primary question, as it is just comparing it, since Shaver will be switching to C20 for all of the testing with that dyno-mule engine going forward, due to the California gas-quality issues.

In a previous test at Shaver’s Speed and McAskill found a huge difference between winter and summer blends of the same 91-octane pump gas from the same station.

“We know there is a difference between winter blends and summer blends,” says Speed. “But, we’ve always used fuel from the same location. However, last time, they were closed, so we went somewhere else. That made us wonder, is there really a difference between brand A and brand B?” The initial tests on the dyno between the two were fairly conclusive. However, the real test was seeing what the engine would do with the C20 with no timing changes from the 91-octane pump gas.

Both Speed and McAskill call the two different brands of 91-octane gasoline from the pumps a wash as far as power-making ability.

“First, we’ll run it at the established baseline, and then do some timing sweeps to see what it likes,” explains Speed. McAskill expands on that, saying, “Once we find that new sweet spot on with the C20, all future testing of this engine will be done with that timing with this fuel.”

“We only raised the octane from 91 to 95, so not much,” McAskill explains. “Because of that, power-wise, the numbers weren’t hugely different. But what we did find out, is that we are going to be so much more consistent with the C20 now.” Speed continues. “Once we started to adjust the timing, then we started to see differences.” This once again reinforces that simply adding better fuel to your combination without tuning for it does nothing for your engine’s output.

However, McAskill’s main point about the C20’s benefit isn’t so much that it makes power, but that there are no summer-to-winter deviations, and you know that no matter where you acquire their C20, you know it will perform exactly the same as the last batch. The C20 was also much less affected by engine temperature than the pump 91-octane. That kind of consistency is absolutely critical in a testing environment, as well as a performance one.

Once some timing was added to the C20 fuel, some additional power up top was realized. However, the results of the testing prove that A) Octane alone doesn’t make more power and B) C20 is a close analog to 91-octane pump gas for their testing, but with incredibly improved year-round consistency and batch-to-batch quality.

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Greg Acosta

Greg has spent nineteen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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