THE QUESTION OF FUEL                                                     Printer-friendly format
PART 5 -
Testing For Performance And Legality

By John Copeland

In the previous four segments of this series, we've discussed the specific factors that influence fuel performance, commonly used fuel tech procedures, and the subject of oxygenators and other additives. Hopefully we've laid the groundwork for this month's subject: the actual test results. We've tested fuels and additives, both for performance and for legality.

Before we get to the subject of additives, a few words about the current state of fuel legality. As we discussed earlier, the oil companies have been reformulating their products in the effort to improve fuel mileage and reduce tailpipe emissions. In most cases, this reformulation has involved adding Ethers like MTBE or ETBE, and the federal government has dictated that only reformulated gasoline may be sold in major metropolitan areas. To check this out and to determine if karters buying their fuel in major cities might be at risk, legality-wise, we obtained samples of nine pump gasolines from Chicago area gas stations. We then obtained samples of the same nine pump gasolines from stations here in Lafayette, Ind. In addition, we also tested samples of six racing gasolines from several geographical sources. We mixed each of these gasoline samples with Burns oil at a ratio of 20:1, mixing 4 ounces of Burris Castor and 2 ounces of Burris Blend per gallon of gasoline. All fuel samples were tested at 55 degrees Fahrenheit and, of course, the Digatron meter was calibrated to -55 with Cyclohexane. (See chart #I for the results:)

Two things are pretty obvious here. First of all, fuel legality is highly variable, both from manufacturer to manufacturer and from grade to grade. Secondly, obviously the composition of the fuels sold in the Chicago area are not the same as those sold in the Lafayette area, at least not at the time these samples were purchased. As we've said before, race gas is much less subject to changing composition. You should expect that any of the race gases listed here will test approximately the same as our results here.

Chart #1

Octane Meter Reading
Shell Premium (Chicago) 93   -8
Shell Premium (Lafayette) 93 -36
Shell Plus (Chicago) 89 -14
Shell Plus (Lafayette) 89  -39
Shell Regular (Chicago)


Shell Regular (Lafayette)  87 -41
Amoco Ultimate (Chicago)  93 -22
Amoco Ultimate (Lafayette) 93 -40
Amoco Silver (Chicago) 89 -8
Amoco Silver (Lafayette) 89 -44
Amoco Regular (Chicago) 87 +83
Amoco Regular (Lafayette) 87 -39
Phillips Premium (Chicago) 92 +82
Phillips Premium (Lafayette) 92 -45
Phillips Midgrade (Chicago) 89 +71
Phillips Midgrade (Lafayette) 89  -42
Phillips Regular (Chicago) 87 +69
Phillips Regular (Lafayette) 87 -40
Unocal Race Gas 110 -46
Cam 2 Purple 114 4
Cam 2 Blue 116 -20
Phillips B32 Race Gas 108 -43
ERC Purple 110 -36
ERC Blue/Green  114 -14

Now on to the additives. In order to minimize non-addictive variances, we mixed all additives with a base fuel of Shell Premium, 93 octane, purchased in Lafayette. This base fuel was then mixed with Burris oil at 20:1, as outlined above. That resulting fuel read ?36 on the Digatron meter, just as before.

The test procedure was as follows: the Digatron meter probe was immersed in a measured quantity of base fuel. Then the additive being tested was slowly added to the base sample until the meter reading exceeded 0.00 or until it became apparent that the testing would not exceed the 0.00 mark. At that point, the percentage by volume of the additive being tested was calculated to determine the threshold of legality for that particular additive. Here are the results:

Chart #2

Percent by Volume

Meter Reading
Propylene Oxide 1.75% +1
Nitro Methane 0.80% +1
Nitro Propan 0.20% +6
Ethyl Ether 0.73% +1
Toluene 59.00% -8
Xylene 58.00% -8
1,4 Dioxane 70.00% -26
Hi-Rev 3:1 30.00% -28
Klotz Coxoc 40.00% -30

To help you interpret these results, 1.00 percent by volume is 1.28 ounces per gallon, or about one tablespoon of additive per gallon. From these results we can determine that it is extremely unlikely that a fuel mixture could pass the meter and contain enough Propylene Oxide, Nitro Methane, Nitro Propane, or Ethyl Ether to accomplish any measurable performance gain. It is also apparent that the Digatron test is insufficient to detect significant quantities of the other flue additives tested. Obviously, other testing procedures will be required to detect these.

In the second installment of this series (December 1994) we outlined a test using a combination of water absorption and the Digatron meter. In this test, two fuel samples are taken and, to one sample, an equal volume of water is added and the mixture gently agitated. When the agitated sample mixture is allowed to settle, the fuel portion of the mixture will be separated from the water portion, with the fuel portion on top. Digatron meter readings are taken from the fuel-only sample and from the fuel portion of the fuel-water sample. The readings should be the same. In the event, however, that an additive or additives are present that are more soluble in water than in gasoline, the relative meter readings will be different from one another. Allowing for some minor variances, any deviation of more than five points on the Digatron meter would indicate the presence of something in the fuel other than what the manufacturer put there. In this test, the base fuel was Unocal race gas, again mixed 20:1 with Burris oil. To each sample we added 10 percent by volume of each additive to be tested, then the test was performed. (See Chart #3 for results:)

Chart #3

Percent By Volume Fuel Only Reading Fuel/Water


No additives

0% -46 -46

Propylene Oxide

10% +55 +36
Nitro Methane 10% +15 +7
Nitro Propane 10% +120 +251
Ethyl Ether 10% -12 +10
Toluene 10% -36 -19
Xylene 10% -37 -22
1,4 Dioxane 10% -40 -47
Hi-Rev 3:1 10% -42 -40
Klotz Coxoc 10% -41 -30

What we see here is that this test detects the same additives as the Digatron test, but also picks up Toluene, Xylene, 1,4 Dioxane, and Klotz Coxoc quite conclusively. 


There is a third test worthy of consideration that has come to our attention since the second segment of this series was written. We are indebted to Art Verlengiere of RLV and Mark Weaverling, the highly regarded West Coast karting innovator, for sharing their experience with this test with us. The testing procedure is relatively simple, although it requires more accurate measurements and a careful procedure.

Exactly equal amounts of the sample fuel, water and straight methanol are combined in a graduated cylinder or other accurately calibrated container. The methanol will completely dissolve in the water, but the fuel will separate and rise to the top. Once the fuel has separated from the water and methanol solution, the line of separation should be exactly at a point two-thirds up from the bottom of the container.

The use of an accurate graduated cylinder of at least 100ml capacity is recommended, allowing use of 30ml samples of each item. In this case, the separation line between the fuel portion of the mixture and the water/methanol portion should be exactly at 60ml from the bottom, leaving the fuel portion at exactly the 30ml that were originally added. Any reduction of this 30ml volume would indicate the presence of some additive that has left the fuel and gone into solution in the water/methanol solution. For our test, we again used Unocal race gas as the base fuel and used 20 percent of each additive being tested. (See chart #4 for results:)

Chart #4

Percent by Volume

Resulting Fuel Volume
No Additives 0% 30ml
Propylene Oxide 20% 25ml
Nitro Methane 20% 29ml
Nitro Propane 20% 22ml
Ethyl Ether 20% 30ml
Toluene 20% 28ml
Xylene 20% 30ml
1,4 Dioxane 20% 22ml
Hi-Rev 20% 31ml
Klotz Coxoc 20% 25ml

As you can see, this test does a good job of picking up some of these additives, particularly the Nitro Propane, 1,4 Dioxane and Klotz Coxoc. While it's a little more difficult to do this test, it's another valuable weapon in the tech man's arsenal and its occasional use should help deter fuel tampering.

As this is written, we are in contact with tech officials at the National Hot Rod Association, International Hot Rod Association, and the U.S. Powerboat Association, all exchanging information about gasoline tech inspection and sharing ideas to help police this area. We'll pass along any new developments as they become available.

We've pretty well used up our space for this month, but don't despair. Next month we'll have specific test results on the performance of using the various additives we've discussed here. We'll give you actual dyno results from using each of these products, vs. unadulterated race gas. Hopefully we'll see just what you can expect to gain from using these additives. But you'll have to wait until next month for that. See you then.

The Question of Fuel - Part 6


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