Volume I, Issue 3, Page 21


How These Fuels Affect The Drag Racer

Q: With today’s methanol prices appearing more attractive compared to racing gasoline, what are the advantages and disadvantages of switching a drag race car to methanol?

A: There are advantages and disadvantages to each type of fuel. Of course, methanol is consumed at approximately twice the volume of racing fuel. Also, methanol absorbs

moisture from the atmosphere, which can be to the detriment of the cylinder walls, combustion chambers, valve gear, as well as the lubricating oil if regular maintenance is not performed. In addition, not only will oil changes be required on a more frequent basis but also engine rebuilds will become more regular. However, methanol will produce more torque than its gasoline counterpart. It will also perform more consistently and the engine will run cooler due to the greater consumption of fuel, which is an advantage during hotter months.

Q: Is it true that the engine will produce more power when tuned for methanol?
A: The chemical formula for gasoline is C8H18; for methanol the formula is CH3OH. Notice the methanol formula contains the letter “O” (oxygen). Therefore, since methanol contains more air than gasoline, it has the potential to produce more torque and horsepower.

Q: What kind of fuel system is required to run methanol?
A: Since the volume of methanol consumed is almost twice that of gasoline, the carburetor requires varying fuel pressures and volumes between idle and full throttle. This is best accomplished by using a belt-driven fuel pump and a diaphragm bypassing fuel pressure regulator. The belt-drive pump facilitates lower fuel pressures (2 to 4 PSI) and volume at idle and higher pressures (9 to 11 PSI) and volume at fully open throttle. The regulator controls the fuel pressure to the carburetor and bypasses the unused fuel to the fuel cell.

Use a diaphragm bypass or a pill-and-poppet style regulator with a belt-driven fuel pump. Having an adjustable fuel log simplifies connections, accommodates a fuel pressure gauge and the NHRA-mandatory fuel safety shut-off valve, and provides an additional fuel reservoir. A separate mounting kit is required to install the belt-driven pump.

Q: Why do racers using methanol seem to run more consistent times than those using race fuel?
A: Because the air-fuel ratio of an engine running on alcohol is about half (approximately 6:1) compared with an engine on race gas (approximately 12:1), some racers believe that the alcohol engine is not so affected by weather changes. However, it’s more likely that the consistency of the alcohol engine is derived from the cooling effects of its fuel.

Q: What is the best way to tune an engine on methanol?
A: There are many ways of tuning an engine. But adjusting the ignition timing to that recommended by the engine builder and jetting and tuning for your highest speed (mph) is still the most effective. Gasoline engines produce more power when tuned slightly toward leanness; however, methanol engines generally produce more power when tuned slightly toward richness. Once you determine where your car runs best, use a Lambda meter (a wide-band oxygen sensor for measuring air-fuel ratios) and an EGT Pyrometer (for measuring exhaust gas temperatures) for further tuning.

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