200 Proof Ethanol

Most pump E85 is not truly 85% ethanol — it can range from E50–E75, especially in winter. This inconsistency kills performance for tuned engines that rely on E85’s high octane and oxygen content.

✅ Solution: Ethanol Topping

  • Use 200 proof ethanol to “top off” your tank and bring the ethanol content closer to true E85 (85% ethanol).


Adding food-grade 200 proof ethanol is a smart move when:

  • You're dealing with unreliable pump E85

  • You want to DIY a race blend without paying $12+/gallon

  • You're looking for more knock resistance, cooler temps, and safer tuning

 

Food-grade 200 proof ethanol (100% ethanol with no water content) can enhance race fuel in a few ways — especially when blended with gasoline or used as a base for custom formulations. Here's how it helps:

✅ High Octane Rating

Ethanol has a high octane rating (typically 108–115 RON), which:

  • Helps prevent engine knock (pre-detonation)

  • Allows for higher compression ratios

  • Supports more aggressive ignition timing in tuned engines

This means more power and efficiency when used properly.

✅ Oxygen Content

Ethanol is oxygenated — it brings additional oxygen into the combustion process, which:

  • Enhances combustion efficiency

  • Increases cylinder pressure

  • Can improve throttle response and horsepower

✅ Cooling Effect

Ethanol evaporates quickly and absorbs a lot of heat, which:

  • Lowers intake air temperatures

  • Reduces the chance of detonation

  • Acts as a chemical intercooler (especially helpful in turbo/supercharged setups)

✅ Cleaner Burning

Food-grade ethanol burns cleaner than gasoline:

  • Reduces carbon deposits

  • Lowers emissions

  • Keeps valves and injectors cleaner over time

⚠️ Things to Watch Out For

  • Corrosiveness: Ethanol can be corrosive to certain metals and rubbers. Use ethanol-compatible fuel system components.

  • Water Absorption: Ethanol is hygroscopic (it absorbs water), which can be a problem over time if exposed to moisture.

  • Lower Energy Content: Ethanol has less energy per gallon than gasoline, which can reduce mileage. However, in race applications, power is often prioritized over fuel economy.

When to Use It

  • As a component in E85 or custom blends

  • In high-compression naturally aspirated or forced-induction engines

  • When running in classes that allow oxygenated fuels

  • When you need to push your tune to the edge safely