E85 bioethanol

[SteveninNI]

Hi all,

I have recently been involved with a client engine (Honda in a MK2 escort) that is running on E85 fuel. The power was good and the torque was pretty amazing for a 2.0L engine 190+lb ft.

My point is what are your experiences with this fuel both positive and negative?

I am currently thinking about a move to it for our own engines for next season. Have to keep moving forward.
thanks in advance

Steven

[Guy Croft]

I have not been asked this directly before so here, for those of you who don't know it at all - a bit of background:

The biofuel E85 is 85% ethanol and balance - gasoline. Ethanol is a biofuel produced by fermentation of crops like corn and wheat or sugarcane. It's called 'bio' because it's produced from biological material. Since 2008 UK pump gas has to have 2.5% biofuel in it and this will rise to 5% in 2013. It seems attractive mainly because it reduces dependence on fossil fuel. Combustion of pure ethanol with oxygen gives C2H5OH + 3O2 >> 2CO2 + 3H2O but of course cars don't run on pure oxygen and the combustion of ethanol in air - although cleaner than gasoline, is by no means pollutant-free, it produces a lot of the nasties that gasoline does including formaldehyde that has been firmly linked to increased ozone levels. Add to that the massive shift in many countries (eg: India, China, Mexico) of production from wheat for flour to ethanol for fuel and the impact on the food chain that has, well - you figure out why that's good because I can't. The US Government reckons that ethanol produces twice as much energy as it consumes in production so I guess that is the main driver. Interestingly you can mix pure ethanol with water (up to 50-50 mix) and it still burns, the WWII rocket, the V2 burned 25% water in ethanol and that kept the combustion temperature down. All ethanol of any % sold as a engine fuel must have some gasoline added to make it 'unpotable' ie: undrinkable because, well, just an aside ethanol neat or diluted can be dangerous if you drink it - because it's so strong in alcohol. toxic if you inbibe too much.

In terms of producing power the first thing I have to point out is that it has a much lower calorific ( = energy) value than gasoline - only 62% of gasoline's value - which means you'd have to use a lot more to get the 'same power' (so to speak) as a gasoline powered engine. In a fuel-injected engine you need to extend the injector pulse width significantly or fit bigger injectors (and maybe fuel lines too) to get more of it in and the best engines use direct - rather than port injection. It does have a higher octane rating - which means you can run a much higher CR - this naturally increases the thermal efficiency of the engine (because the two are directly related) and some reckon the thermal efficiency of the 4 stroke spark-ignition engine can approach that of a diesel and of course, as everyone who has followed a bus knows, biofuels can be used in diesel engines.


If you mod the engine to_the_limit to create a very high CR (over 15/1) to take advantage of E85 it will detonate if then run on pure gasoline of any grade. It can cause cold-start problems because of its low vapour pressure and most countries who use it extensively (Sweden, USA, Brazil for example) have what's called 'seasonal reductions' - basically doping the E100/E85 with gasoline so the engines will start at all. Secondary fuel tanks are used commonly on new production - providing a 'cold start' supply of gasloine. Unlike gasoline ethanol absorbs water - potentially causing corrosion of tank, lines, cylinders etc., so a rethink on the fuel circuit is probably needed - along with engine oil that can cope with it. In my view, if your run this stuff in an engine you could be asking for long-term trouble unless the thing is virtually redesigned.

I should be interested in any other views including Steve's.

GC

Revised after a re-think by GC 28th Nov 09

[tempra16v]

Here in Brazil we have cars that can use E25 and E100 without any modification. This configuration is made in factory cars like GM, Fiat, Honda, etc... its called Flex Fuel Engine.
The factories say that a stock car produces 1-2 hp more in E100 than in E85.

In turbocharged cars around 90% of the people use E100 in the cars.
We need to use around 7ºdegrees more in ignition and around 40% more fuel.

One advantage in using E100 instead E25 is that it doesn´t produces "sludge" in the engine.

Here exists a lot of parts(fuel pump, fuel filter, fuel injectors...) that can be used with E100 without any problem.

[SteveninNI]

maybe a little more detail will help here.

I mostly work on competition cars and the first i came across the fuel was doing some dyno work for Mountune on the ST Fiesta challenge cars. When they moved to E85 we redynoed a couple and found an average 10hp increase on these engines (just an injector change and a reflash of ECU).

Only one other customer has run it- We did a Pinto engine on it and car was mixing it with Millingtons and won national championship by miles. The engine has been stripped and found to be perfect inside and has subsequently been reassembled and sold on.
This recent engine is a 2.0L Honda and never has a 2.0L engine produced more than 182-4lbft on our dyno yet this Honda was producing 190 repeatedly and the engine spec isnt that wild.
forged pistons/ rods/ cams and throttle bodies and dry sump. thats it. Head is Standard as it wasnt within budget. Engine has 8 injectors and I spent a long time mapping for this fuel as well as mapping the cam timing (variable)/ vtec crossovers and the blending of the staged injectors and the sequential injection. Yes it uses a LOT of fuel compared to petrol but the engine runs cooler produces more power and has now done several rallies (outright winner in 1)

I take your points above, only problems we have come across are use of rubber fuel lines in the fiestas but they didnt reappear when changed to proper hosing. My question was mainly about engine longevity. We have only stripped and assessed one engine so far and thats not enough to make a very clear discision.
The fuel in the summer months may well be E85 but may be E65 in the winter due to adding more petrol to the mix to help cold starting. This however would totally throw the AFR int he engine mapping.
GM now produce a fuel flex vehicle which uses an ethanol sensor to measure the ethanol content and output a voltage dependant on this in order to adjust the AFR. DTA are ahead of the game in this as they have a calibration to account for this sensor. It will keep your mixture where you map it. As far as availablility- its sold as 105 octane in South but not in North and for those of us who are bound to compete on pump fuel, maybe this is a gain?

Let me know your thoughts- but so far from what i have seen (which isnt enough to be conclusive) but there does seem to be a power gain.


Steven

[tempra16v]

take a look at this thread: viewtopic.php?f=13&t=1468&start=0

look the posts from "dfom" he is my friend and have a better english and knowledgement.

sorry for not giving more datails but my English isn't great so I can't write all that I know.

What I can say is that here the factories are using this technology and we don't see any reduction in the engine longetivity.

[Guy Croft]

Thanks for your reply Steve.

The only possible explanations I can think are:
a) that occasional detonation events in the Honda are now not happening at all on E85, and with the Pinto engine on gasoline the tendency (and I only mean 'tendency')to detonate would be higher as it has a cast-iron head but far less so on E85
and
b) superior fuel homogeneity (ie: air-fuel mixing) and better burn (??)

I must admit I'm struggling slightly with this one!

If anyone can offer a more cogent explanation I'm 'all ears'..

POSTSCRIPT: maybe c) engine running cooler, less conductive heat to inlet air and higher charge density?


G

[PersonaGrata]

I plan to swap to E85 but can't get the figures to add up:

If you take values taken from internet you get a calculation like this:
Petrol E85
Specific Calorific value 100% 67%
AFR (Rich) 12.5 6.975
Kg Fuel / Kg Air 0.08 0.14
Chemical Energy / charge 0.08 0.10
Increase due to switch to E85 20.07%

Implying up to 20% increase - but this doesn't tie up with peoples experience (usually 10% increase max)

I can't figure out where the calcs fall down.

[Guy Croft]

Do you know I never thought of looking at it that way. You've hit on I guess. I drew up a table based on your idea, see att

Sorry - I graduated so long ago I've forgotten more than I've remembered. Well, it is Friday..

G

[PersonaGrata]

That's pretty much how I came up with the 20% figure - but that was for E85 where I think yours is for pure ethanol?

The problem is that even though the chemical energy is so much more people still don't seem to get these sort of benefits.

Perhaps the engine needs to be physically configured to get the most out the fuel. For example the CR can be raised to 12, 13:1 (or more??). Combustion chambers could be redesigned because detonation in squish areas would be less likely.

Having the compression ratio raised would make the exhaust valve size less important, so inlet valves could disproportionately large?

Just a few ideas.

[tempra16v]

Here the flex fuel cars have 13:1 CR and we can use E100 or E25 without any modification.

[Guy Croft]

the 20% figure - but that was for E85 where I think yours is for pure ethanol

yes, I couldn't find the energy figure I needed, feel free to edit and upload if you do.

Gasoline exhibits dissociation at high temperatures and doesn't release the energy it should, don't know if high % ethanol fuels suffer from this?

G

[ace124]

Has anyone run any sort of biofuel thru a carburetored set up?
Aside from obvious changes in jetting, are there any other challenges?
How about the longevity of Fiat TC valve seats, if used in an 8V for example? My thinking concludes they may be ok, given that combustion will run cooler due to more fuel thru richer jetting, but how about valve and seat lubricating properties?

[Guy Croft]

I know of a Virtual 4T simulation on E85 vs gasoline and the E85 only showed power gain when the engine was equipped with much higher (typically) 15/1CR - which is unachieveable on most engines except very narrow angle multivalve units without totally wrecking the burn rate with a massive intruder volume on the piston.

Steve- did you get drum E85 or pump? Worth checking it's the right stuff.

G

[SteveninNI]

it was pump but the ethanol sensor in DTA accounts for varying %. it was summer grade fuel so was in region of 75-79% according to the GM sensor i had fitted

Both cars won rallies outright..

http://www.irish-rallying.com/article.p ... 302/200438

I also ran several simulations on a known setup and found similiar but i also like to try things in practice too. So far we are finding it working but will be doing some back to back tests in new year.

Steven

[Guy Croft]

Results - Well done indeed!

I must confess I'm still none the wiser as to where the power gain comes from!

I would urge you to get a sample analysis and find out exactly how much methanol was indisputably in there..

What do you actually think?

G