More E85 Info - This Time From Nasioc .

[discopotato03]

This is from the North American Subaru Impreza Owners Club (NASIOC) , it gives a bit of feedback from someone Stateside that wanted to push the envelope (a little) in a noughties or post 2000 era car .

http://forums.nasioc.com/forums/showthread.php?t=803341

Enjoy , cheers A .

[Guilt-Toy]

having a read of this.. might take a different approach to my next emissions test.

http://www.skylinesaustralia.com/forums/Em...63#entry4124163

if anyone is interested

[Duncan]

very interested. but my simple question is....can I run the stuff safely in my stagea?

[GTRNUR]

If your tuned for 98 unleadded then the answer is no. You must re-tune for E85 or you will be running lean. Fuel hoses will likely require replacing to make them alcohol compatible.

Also due to E85 having a lower calorific value than unleadded you need to burn more of it to make the same power. So your fuel system (injectors and pumps) will need to flow more to make the same power you already are.

Cut from that thread... interesting....

======== stoichiometric AFR ===== max power rich AFR

Gasoline ---------- 14.7:1 -------------------12.5

100% E-85 ------- 9.73-9.8:1 ------------- ~ 9:1 - 8:1

100% fuel ethanol - 9:1 ------------------- ~ 7.2:1

And also the mentioning that E85 likes a little more ignition when on max load, and that it also tolerates a richer fuel ratio before losing power, simular to methanol.

Ive heard that E85 is available in some places in melbourne. Whats it worth per litre? It would be interesting to compare the price per litre, per KW, factoring in the fuel flow increase required to maintain the same level of power.

[Equinox]

Is it actually available in Melbourne yet? Was looking into it yesterday but could only find info about the one United in NSW selling it.

[Bond]

you would want it to be a fair bit cheaper as you use over 40% more fuel just cruising around

[discopotato03]

From memory the chemically correct ratio (burn all fuel and oxygen) for E85 is around 9.7:1 .

What everyone forgets is that petrol engines are throttled or strangled if you like and its the dynamic or effective compression ratio that becomes very important at part throttle cruise .

What high ethanol content fuels allow you to do is to advance the ignition timing up to the point where you get best torque or reach the detonation threshold . Most tuners will tell you that E85 gets you a LOT closer to BMT (best mean torque) timing that most pump ULP fuels do so the gain is more optimal cylinder pressure rise on the power strokes .

Where you light the fire and where the innitial prressure rise occurs at the beginning of the power stroke is absolutely critical to torque and specific fuel consumption .

When you can get an engine to make more efficient use of its air (oxygen) and fuel it needs less of both to make comparable torque - so it gets better fuel consumption .

I wouldn't like to say that you could get on par as far as L/100Km goes but it's the cost of fuel that concerns most people so $/100Km is probably a more practicle yardstick .

80's into early 90's OEM turbo engines may not be the ants pants for getting good squirt and reasonably good fuel consumption . The generally lower static CR that was used to help control cylinder pressure and detonation (on boost) goes against you when other ways are found to supress the detonation . Part throttle dynamic (effective) CR is pathetically low in engines like my dinosaur Subaru (7.7 static) , Turbo 280ZX's similar and VLT's . None of them had any form of intercooling and they all had to use advanced low load timing just to move from rest .

This is part of the reason why I don't agree with real low CR's and high boost to get some grunt . I prefer higher CR's (~ 9 - 9.5) and things like larger turbines and their housings (not necessarily larger compressors and their housings because with reasonable fuel octane and intercooling I believe you can get a better (almost larger NA engine like) result . It makes the turbo configuration look a bit more diesel like and like them the higher CR petrol engines can stand on their feet better before the onset of boost . More NA like drivability is a plus in my book .

A lot of the reason why turbo engines detonate is because they become restrictive on the hot side - the combustion conditions turn to shit and the cure all for detonation is to retard the ignition timing and or hose in more fuel . When it gets to that stage we are in damage control and struggling to save the engines life , fuel consumption not surprisingly goes through the roof .

In this day and age of high powered turbo endurance race cars and limited fuel stops , doing an Indy race and never dropping below 13.7:1 AFR has to say something .

Out of fingers again , cheers A .

Edited September 11, 2008 by discopotato03