After the widespread use of E20 petrol (20% ethanol blended) started in India, the debate in the automobile world has intensified. Many videos and posts on social media are claiming that the engines of old cars will get damaged, there will be a huge drop in mileage and the fuel system will get damaged. But are these claims true? The answer is – it is not completely correct, but some problems have definitely arisen!
The purpose of E20 is to reduce oil imports, increase farmers' income and reduce pollution. Ethanol acts as an oxygenate, which keeps the combustion clean. However, questions are being raised on the compatibility of the fuel system in pre-2022 (especially pre-BS4) vehicles. In this article we will try to know the whole truth on the basis of scientific facts, engineering principles and workshop experience.
What is ethanol and why is it added to fuel?
Ethanol is an alcohol mainly produced from sugarcane or corn. The main reason for mixing it in petrol is to increase oxygen, which helps in better combustion of the fuel. This reduces harmful emissions and reduces dependence on fossil fuels.
Ethanol is preferred in motorsport because it has a higher octane rating, lower combustion temperatures and easier tuning. E10 was being used in India for a long time, now E20 has become standard.
How does the engine work?
Every engine has a perfect air-fuel ratio (AFR). For pure petrol (E0) it is 14.7:1. For pure ethanol it is about 9:1. The AFR changes in the E20 blend, causing the ECU to slightly increase the amount of fuel. If the ECU does not adjust, the engine may lean (run on less fuel), causing temperatures to rise. But modern vehicles are capable of dealing with this problem.
BS4 or newer petrol cars have closed-loop fueling, oxygen sensors and an ECU that can adjust the injector pulse. Most ECUs make fuel corrections up to ±20%. E20 comes easily in this range. For example, in Brazil, E25-E27 have been running in common cars for years without any major problems.
BS4 standard had already made preparations for E10. Features ethanol-resistant hoses, seals and pumps. Headroom is always kept in engineering, so most BS4+ cars can be considered safe for E20.
Is 20% more fuel injected than E20?
no way. Pure ethanol contains about 34% less energy than petrol. E20 requires 6-7% more fuel than E0 (only 2-3% more than E10). The ECU handles this easily. The claims of 30-50% mileage drop are simply wrong. The actual decline may be around 2-3%.
Myth of Melting Rubber Fuel Line
Ethanol can affect old natural rubber or cheap hoses. But after 2010, most companies use resistant materials like FKM or NBR. BS4 has strengthened these changes. Due to engineering tolerances, E20 or even E30 is safe in most cases, unless your car is an older carbureted car.
Problem of clogged injectors
Deposits build up slowly in the injectors. These can malfunction due to bad fuel, short drives or carelessness. E20 also has a cleaning effect, which dissolves varnish and carbon. It works the same way as expensive fuel system cleaners. In poorly maintained vehicles, old deposits can loosen and cause temporary problems, but in regularly maintained vehicles this is beneficial.
Water separation: the real problem
Ethanol is hygroscopic, that is, it absorbs moisture. Phase separation in E20 can occur at 0.4% water, but it takes 3-5 weeks. This problem can occur in an unused, humid and empty vehicle. Fuel keeps circulating in daily running vehicles, hence the problem is less.
What problems can arise?
- Slight 2-3% drop in mileage.
- Slight problem in cold start in very cold weather.
The case of BS3 and carbureted cars
The material in BS3 vehicles is less tolerant. Hoses, seals and pumps can wear out rapidly over a long period of time. Carbureted engines run lean due to fixed jets, which can cause hesitation, poor starting and overheating. There is a high risk of corrosion in storage.
What to do BS3 Honors?
- Install ethanol-resistant hoses/seals (FKM/NBR).
- Richer re-jet the carb.
- Check/replace pump diaphragm and seals.
- Use stabilizer in storage, do not keep E20 for long periods.
- Clean jets/injectors regularly.
- Keep an eye on drivability.
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