Byprodriver

I thought E85 is 15% alcohol but I have not paid much attention since I believe the best fuel available is the most economical to use.

No HTwo O

It's 85% denatured alcohol.

BiteEmNBeatEm

here in texas its hard to find eth. free fuel but the good thing is we have 93oct. at evey pump. whats even better is im here is san antonio and this is where VP fuel is so I can always try some 96 or 101 octaine...LOL

my buddy has a Z-06with fully built motor supercharged and runs only E-85 and dynos 706 at the rear wheels. So i guess ethanol cant be that bad.. haha

03996

1.....Yes, as they all do.

2....No, just as a question on whether the engine has been found to run better seeing as the energy contained in Ethanol is lower than straight gas.

03996

Just make sure the racing fuel is lead free, otherwise big problems with the cat converter.

rpm's S2

I have found that the ethanol-free pumps in my area are mostly older stations. The risk of contaminants in old gas tanks is perhaps as much a threat to your engine as ethanol. So buyer beware and ask questions before you pump gas from old tanks.

Macster

While there is more energy in a gallon of gasoline vs. a gallon of gas/ethanol blend, a blend up gas/ethanol up to say 10% ethanol (my info is while the pump notices state the gas can contain up to 10% ethanol refiners have been keeping the ethanol in the 7% to 8% range) the biggest gain is to be had by running the proper octane of gasoline.

With the proper octane grade the DME can advance the ignition timing to its optimum point and start the air/fuel mixture burning at a much earlier time.

Now you might think this occurs at WOT but this is not the way it works. Max. timing advance occurs at part throttle/high load conditions under which passenger vehicles find themselves in very very often.

Thus anything that allows for advanced ignition timing to occur -- sans any detonation -- under part throttle is good.

The result of advanced ignition timing is the air/fuel mixture is burning very well at the most opportune time when the piston/rod/et al is positioned to create mechanical energy from chemical energy.

An added benefit of running the right octane grade of gasoline is the exhaust gas temps are kept lower.

With lower octane gasoline the engine's ignition timing is retarded -- to lower max pressure in the chamber and prevent detonation (it is the signs of detonation that the knock sensors detect and which when this is signaled to the DME results in the timing being retarded to save the engine from the ravages of detonation) -- and thus the air/fuel mixture burns later in the power stroke.

This heat/pressure is wasted heat/pressure that simply heats up the later stages of combustion with the result exhaust gas temps are higher than they would be otherwise.

Sincerely,

Macster.

03996

All very true, but, with Ethanol, the burn is slower and so part of the advantage of being able to advance timing is lost due to the slower total burn and also less pressure being developed. It's a compromise I know but running pure gas, and so more inherent energy being available, should in theory provide better performance.......both in actual power and torque.

I see some listers have mentioned improved economy with pue gas. Not surprising if more energy is produced and so lighter throttle being required.

Macster

If the choice is between say 93 octane ethanol free gasoline vs. 93 octane gasoline without ethanol I'd go with the ethanol free gasoline.

However, I do not recall coming across areas where two gasolines identical in octane ratings but differing in their ethanol content were available, readily available. By readily available I mean that when I pull in to fuel up the car, the pump island pump can dispense identical octane gasoline, one gasoline without ethanol and the other with ethanol.

Since I do not live in an area that sells > 91 octane gasoline and does not sell gasoline sans ethanol when I encounter > 91 octane gasoline it is during a road trip and I am almost always (always in fact, so far) in unfamiliar territory and usually in a hurry so when I stop to gas up the car, the steps are stop, gas and then go. No time to search out those stations that sell -- if any do -- ethanol free gasoline.

Now, if the choice is between say 90 octane ethanol free gasoline vs. 91 or higher octane gasoline with 10% (in reality containing approx. 7 to 8 percent ethanol) I believe the best choice would be the higher octane gasoline, even though it has some ethanol in it.

As I touched upon in an earlier post, there is considerable benefit from the DME being able to run the ignition timing advance near its optimum which has the timing advanced in some cases to just short of incipient detonation.

That the engine runs with the designers intended ignition advance will almost result in the engine feeling "better", this just adding icing to the cake.

Sincerely,

Macster.