Pros & Cons of E85 fuelDue to popular* demand, The following is a summary of the pros and cons of running E85 fuel in my experience.
[* one forum member asking me via PM]
I've been running E85 since about April 2017. Full-time E85 (not flex fuel) because United petrol stations are fairly local. I own 3x20L jerry cans as a precaution against shortages and to have an option for long trips.
Pros of E85-20% more power across the rev range. See the two dyno lines pre and post E85 (ignore the dip from the slipping gearbox):-
- Great responsiveness for regular driving on account of the ignition advance and extra torque - even off boost (I have the VF46 small/med turbo). My particular tune is an economy/power Jekyll/Hyde tune, so the car can really lug along at low revs on account of the knock-resistance when I'm not driving "sportingly".
Specifically, you get better cylinder cooling, much better knock-protection (allowing ideal timing) and a longer power stroke (if you have variable exhaust cam timing - tune for exhaust valve closed longer). Chemistry and tuning boffins can probably say more about this.
- clean upper engine (no need for Upper Engine Cleaner);
- cleaner oil between changes;
- arguable environmental differences I won't get into.
Cons of E85- cost of physical upgrades to run it (bigger injectors, some fuel lines, usually a fuel pump, possibly some other things, flex fuel gear if applicable, labour to fit, cost of tune)
- Even rubber vacuum lines controlling the wastegate are not immune (replace with silicone). If you want a wild adventure, try "no effective boost control because the wastegate vacuum lines have swelled"
- Massive increase in water vapour in the crank case - especially in cool seasons/climates. 2x catch cans and regular emptying becomes essential. The car ceases to be a "nip down to the shops & back" convenient vehicle because you want to get the oil up to temp every time you drive it to boil off the water. Probably more manageable with flex fuel if you save the ethanol for spirited weekends.
[Head breathers catch can contents on the left, crank case catch can on the right. Collected over a longish period. Probably on the previous "foam forming" oil]
- can be fussy with oil selection. "E85 friendly or not" per the packet is not the key factor if you change often enough (I do 5000km intervals - longer than that and the manufacturer's specs on E85 suitability become important). Watching funny yellow foam formation in the crank case is a factor. I switched oil types to stop this. Currently running Penrite "Ten Tenths" 10W40 oil with no issues.
- wear & tear on the drivetrain with all the extra torque. The E85 tune sent my already-slipping auto box into full-on "rebuild time". Accelerated need to replace other drivetrain components.
- rumoured greater wear & tear on cylinders due to reduced lubricity of ethanol (apparently solvable with some fuel conditioners, but then the cost per tank goes up higher).
- rumoured issues with injectors jamming if the car is left sitting too long (flex fuel would address). Mine is daily-driven so no issues.
- fuel conditioner products being very vague on their packet as to what they are claiming to actually do. I don't use them.
- cost of fuel. United gouge Brisbane people about $1.80 a litre at the moment.
- 30%+ greater fuel consumption at minimum. Worse if you hammer the car often (E85 responds well to adding richness). I get about 15.6 litres per 100km for urban commuting.
- bad cold-start in cold climates (depending on tune). Not a south-east Qld problem, although starting takes longer than on petrol, and it's good form to switch to "on" for a few seconds to let the fuel pump pressurise the lines before hitting the starter.
- possibly others I have forgotten.
In summary, the value of E85 (or upgrading to flex fuel) will depend on your circumstances and what you're prepared to deal with. Thanks for reading.