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The truth about E85 fuel

There is a lot of talk about E85 in recent years with the V8 supercars making the switch and more and more racers discovering the benefits of this “green” racing fuel so we thought we would give you some facts about what it is all about.

E85 is an alcohol based fuel that is 85% Ethanol and 15% Gasoline. E85 is a high octane fuel with an Octane rating of approximately 105-108 Octane points (depending on manufacturer). This is several octane points higher than 98 Octane premium unleaded and on par with many designated professional level race fuels.

The advantage of using a higher octane fuel is that the in-cylinder flame front travel rate of a higher octane mixture is slower than that of a lower octane mixture.

Having a higher octane rating, slows down the burn rate of the combustion cycle. This means that it is possible to increase the boost level, compression ratio, and/or  timing advance and return the mixture to a burn rate similar to that of gasoline, having a comparable level of ’safety’ in the cylinder, a similar mixture volatility, but albeit at a much higher power level.

On average it is not uncommon to see power increases of more than 30% in a turbocharged vehicle over “pump” fuel and more than 10% power increases are not uncommon over a comparable unleaded race fuel but again every application is different and there is no golden rule. The bottom line is though is it is unlikely you will ever see a car go backwards by making the switch, they will always make more power on E85.

The Mazda Motorsport RX8SP saw a substantial power gain by switching to E85

 The other by product of using alcohol based fuel is that it burns much “cooler” and in turn the whole engine will in most cases run much cooler, and therefore will in turn make even more horsepower. This generally means the turbocharger will run cooler and will be therefore be more reliable.

The next  interesting fact about E85 ethanol based fuels is that it reaches stoichiometry at an air/fuel ratio of 9.7:1 compared to an air/fuel ratio of 14.7:1 for gasoline meaning for any given application you will use as a minimum of 30% and in many cases closer to 50% more fuel to achieve the same result. Part of the reason for this that E85, and in fact any alcohol based fuel has a much lower calorific value or in simple terms the same amount of fuel contains much less “energy”

E85 on average produces around 25 Mega Joules of Energy per litre of fuel, while normal 98 Octane petrol will normally produce in excess of 33 Mega Joules of Energy per litre so for this reason alone we will always use much more E85 fuel to achieve the same result.

Because of the requirement for much higher fuel consumption it is normal practice to replace the whole fuel system in a performance application with much higher flowing components. If you required 600cc injectors and a 250litre per hour fuel pump with petrol, then it is fair to assume you will need at least 1000cc injectors and closer to 450 litre per hour fuel pump, but normally it is safer to go even bigger because as discussed earlier, you can now run even higher boost which in turn will require more fuel again. We highly recommend the Injector Dynamics brand of injector that come as a matched set.

.Click here if you need advice on component sizing.

The next thing to remember is that different brands of E85 may have different properties and certainly in race applications it would be advisable to stick with the same brand from a sealed drum every time. We stock Cheetah brand E85 and have seen exceptional results with this brand of fuel and the consistency appears spot on. The consistency of the fuel is critical in all out applications where tuning is on the edge and a bad or lower quality batch of fuel could result in total engine destruction. From what we hear this has been a problem in the US with some suppliers but we have not experienced it in Australia.

There have been many rumors going around that E85, which is biodegradable in water, can corrode a vehicle's fuel system, including the fuel tank. Although E85 is corrosive, it is not much more corrosive than regular petrol. The chemical properties of E85 are not what cause the corrosion; it is the water in E85 that may cause rust and block up the fuel system.

The other interesting fact is the different processes used to manufacture the ethanol in E85. In Australia Ethanol is made from either wheat or sugar cane. In the USA it is made from corn, in Finland  it is manufactured from bio-waste and in Ireland it is made from whey which is a by product of Cheese production.

So surely there must be a downside to this enviro friendly racing fuel? Well the reality is there is, but the positives certainly outweigh the negatives. The only real negatives are firstly as you are going to use somewhere between 30% and 50% more fuel you will need to carry more fuel for any given race distance which is more weight. Suffice to say the increased power benefits will in most cases far outweigh the extra weight. Secondly at around the $2 litre mark (in a drum) you will be spending around $3-$4 compared to every “equivalent” litre of petrol because of the extra usage rate. If you are switching from pump fuel to E85 this will effectively mean that your fuel cost will almost double every time you race the car but the first time you hit the track I’m pretty sure you will realise it was well and truly worth it. If on the other hand you are switching from a commercially available race fuel the you will probably find your fuel cost will be way less as most race fuels cost well over $5 per litre with many costing closer to $10 per litre. Lastly the only other risk with E85 is oil contamination. Some inferior oils will break down when exposed to alcohol based fuel. The solution to this is to use an extremely high quality synthetic oil such as Royal Purple and make the oil changes very regular. Apart from this, the only other downside is the setup cost with bigger injectors and pumps often costing more than their lower flowing counterparts.

The RB30 in the Advan/Hi Octane GTR is now much faster on E85 fuel

 So now bears the question....... do I set my engine up to run on E85? Well the reality it is, probably depends on what you want to do with your car. If you have a daily driver that you occasionally take to the racetrack or dragstrip, we would say certainly not, as the practicality of filling up at your local servo will far outweigh the extra power gains. If however your car is “predominantly” used at the circuit or strip then in our opinion it would be pretty much a no brainer. A cooler running engine with a fair bit more power is what most guys would be after! That and the fact is OK for the environment and that it devoid of all the toxic carcinogens that some race fuels contain are also a bonus. So the fact that you have to spend a bit extra buying the right bits just remember you will end up with probably more than 30% more power, I bet the next 30% you try and find costs an awful lot more than the E85 setup.

Click here to order Cheetah 108 Octane E85

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