Ethanol in 4 and 6 Cylinder Engines?

If it is true that Ethanol provides a higher octane rating than premuim gasoline, then how can ethanol be run in 4 and 6 cylinder engines? Will they have lower octane ratings available for these engines? And if so, won't those be slightly higher than the gasoline counterparts?

This is probably a stupid question, but I don't care. :shrug:

Not sure what you're asking, but I don't believe a higher octane will hurt a 4 or 6 cyl. Only problem w/ octane that I'm aware of is too low an octane in a higher compression engine could expose it to detonation.

I guess that 4 and 6 cyl engines dont use high octane gas? News to me.
I wonder what kind of effect E85 gas will have with a direct injected motor like the 2.0T in the Kappa's?

If I put 91 in my car, it would run like ****, like most other v6 and 4 cylinders that require 87 or 89. It's like you guys running low octane, we can't run higher.

Um, yes you can? If you run a low grade octane gas in a high compression engine, you will develop detonation, but I have never heard of any problems if you run high octage in a low compression engine. You need AT LEAST that rating of octane, not that EXACT rating.

Maybe it's the quality of gas you're getting, not the octane. I got Racetrack one time....neeeever again! It knocked like hell running super in my old Formula. At least it was trying to before the computer dumbed down the timing to account for it. Terrible quality stuff, thats probably why it was so cheap :D

I had a 2001 Z24 Cavalier and it could run on any of the 3 octanes. Had more power with 89 and 93 but got better mpg with 87. Odd to say the least. It was running 10:1 compression stock.

Well I'm quite confused. I've always been told you can't run premium in most V6's unless it says to.

Well, needless to say, I don''t think my 3.4 will run any better with 89 or 91.

Sorry for the waste of a thread, lol. I'm just excited about ethanol.

the number of pistons has nothing to do with the required octane rating. what matters is compression, whether it is by the natural compression ratio made by the shape/position of the pistons and volume of the head or if it is caused by some form of boost, you only need higher octane with higher compression. it also allows for more spark advance.

if the engine is not meant to run on the higher grades then use the lower ones. it isnt a quality thing. your engine should run best at the point where anything lower will hurt it.

Understand that a higher octane rating actually means that the fuel burns slower and therefore allows higher compression and more aggressive timing...and therefore more power.

You'll actually get higher dyno numbers with lower octane fuels...but in the real world, detonation is your enemy and bigger, more powerful engines need the protection offered by higher octane fuels.

Normal 4 & 6 cylinder engines are programmed to use a lower octane rating because they are meant to be workhorse, economy motors. Using high octane fuels is just a waste..but I doubt that they actually run worse...it's just that you were probably expecting more.

Sorry for the waste of a thread, lol. I'm just excited about ethanol.


Why?

Other than the fact it takes about twice the ethanol to do what gasoline does....I don't see what the party is about.

Bring me biodiesel anyday...

Understand that a higher octane rating actually means that the fuel burns slower and therefore allows higher compression and more aggressive timing...and therefore more power.

It's not that high octane fuel burns slower; it's that it is harder to ignite and therefore more resistant to pre-ignition and knock. That is what allows for higher compression / more aggressive timing.

Higher octane does actually burn slightly slower and some people claim this as a reason not to use higher octane in an engine not designed for it. But in the real world its slightly slower burn rate is a non-issue.

Putting premium in a car designed for regular causes carbon build up though... While it may not make an immediate noticeable difference, its not good for the engine.

Im sure someone could find a work around of what you are talking about if it is a legitimate concern.

I can imagine the outrage when people are given the choice between $2.00 E60 for their Civic and $1.25 E85 for a Z/28 :lol:

Vehicles designed for use with E85 adjust the fuel AND timing accordingly; therefore, if the manufacturer says that a vehicle can run E85, it can. I don't understand the mystery here.

The reason that few smaller engines have been equipped to run E85 is because the whole reason behind flex-fuel vehicles is to gain a CAFE break (there's a HUGE bump in the economy figures that are used for the fleet average calculation), and that's why the attention is being put on getting larger vehicles to be compatable with ethanol.

Well I'm quite confused. I've always been told you can't run premium in most V6's unless it says to.

Well, needless to say, I don''t think my 3.4 will run any better with 89 or 91.

Sorry for the waste of a thread, lol. I'm just excited about ethanol.

The 3.5L OHV V6 in the Impala can run on Ethanol.

As long as the engine is tuned fo E85 there are no problems. Ford sells 1.6L FlexFuel cars in Brazil.

Why?

Other than the fact it takes about twice the ethanol to do what gasoline does....I don't see what the party is about.

Bring me biodiesel anyday...

Party is that it's something that can be done within the short term to remove our dependence on foreign oil. Brazil this year is now totally self supporting with E85 and domestic oil production.

I’ll be filling up my truck with B20 on Sunday with my trip through Ft.Worth. :D

I had a 2001 Z24 Cavalier and it could run on any of the 3 octanes. Had more power with 89 and 93 but got better mpg with 87. Odd to say the least. It was running 10:1 compression stock.

I believe a lot of cars are this way nowadays - the ECM makes adjustments based on the type of fuel being run. If you put regular in they will retard the timing to prevent knock - resulting in a reduction in power but preventing engine damage, but on premium they will make their full power.

Party is that it's something that can be done within the short term to remove our dependence on foreign oil. Brazil this year is now totally self supporting with E85 and domestic oil production.

I’ll be filling up my truck with B20 on Sunday with my trip through Ft.Worth. :D

Exactly, and even though the MPG are worse, you'll still be saving money because it's cheaper.

Higher octane does actually burn slightly slower and some people claim this as a reason not to use higher octane in an engine not designed for it. But in the real world its slightly slower burn rate is a non-issue.

Race cars that spin to 15,000 RPM do not seem to have any issues with the "slower" burning rate of high octane. And they run HIGH octaine.

That argument makes no sense.

I believe a lot of cars are this way nowadays - the ECM makes adjustments based on the type of fuel being run. If you put regular in they will retard the timing to prevent knock - resulting in a reduction in power but preventing engine damage, but on premium they will make their full power.


This happens provided the cars are designed to run on octane higher than 87.

If the engine is made for 87, putting 89 or 91 or 93 will not add any benefits to the engine since it already runs at full power on 87. In Theory anyways.

Although I did shave off 2 tenths and gained 1 mph in the 1/4 mi when I ran my Z28. It was already filled up with 94 octane, and i just added octane boost (3 bottles of it). On an engine that is designed to take advantage of 91 octane, no more. Go figure.

Although I did shave off 2 tenths and gained 1 mph in the 1/4 mi when I ran my Z28. It was already filled up with 94 octane, and i just added octane boost (3 bottles of it). On an engine that is designed to take advantage of 91 octane, no more. Go figure.

I would say that is coincidence then, because the LS1 only has two timing tables that I am aware of, one for its recommended octane gas, and one for low grade stuff.

Required octane rating largely has to due with the engines effective dynamic compression ratio, something that doesn't seemed to get talked about a lot. I don't know where the slower burn myth seems to have come from, but higher octane rating on a gas simply describes its tendency to resist autoigniton from heat and pressure; nothing more.

Race cars that spin to 15,000 RPM do not seem to have any issues with the "slower" burning rate of high octane. And they run HIGH octaine.

That argument makes no sense.
Those 15K RPM motors are designed and built with adjustments to allow them to achieve more power from the higher octane fuels. Remember Octane has a lot of energy locked in its 7 C-C and 24 C-H bonds but more bonds to break requires more engery to get the bonds broken, therefore more ignition and pressure is required to take advantage of it. Also remember how Octane is calculated, it is on the pumps afterall, it is the lowest octane number in the batch plus the highest octane number in the batch divided by the mean or average of the bunch. So Octane requires more energy to break the bonds and more engery has to be delivered in such a way that it breaks the bonds. Lets also remember that the required amount of oxygen must be present or you will get an incomplete reaction.

Your "argument" ignores the reactions and the things nessicary to get those reactions going. Also if you have more bonds to break then it takes more time, lets remember diesel which has MUCH more energery than most gas or ethanol based fuels but requires MUCH more energy and O2 to be added before it can be combusted properly.

Those 15K RPM motors are designed


Talk about getting owned, lol. :D :cool:

I would say that is coincidence then, because the LS1 only has two timing tables that I am aware of, one for its recommended octane gas, and one for low grade stuff.

Required octane rating largely has to due with the engines effective dynamic compression ratio, something that doesn't seemed to get talked about a lot. I don't know where the slower burn myth seems to have come from, but higher octane rating on a gas simply describes its tendency to resist autoigniton from heat and pressure; nothing more.

The only explanation I have is that before the additives, the engine stayed at the timing table for 87 octane, and only switched to higher octane table after.

Reagrding the calculation, it is based on the 'equivalent' mixture of n-heptane (with a score of zero for preignition resistance) and 2,2,4-trimethylpentane (with a score of 100). Gas with octane rating of 93 would be like 93% 2,2,4-trimethylpentane mixed with 7% n-heptane. Technically, what is displayed on the pump is '(R+M) / 2', which is the average of the research and motor calculations of octane for that fuel.

I don't know where the slower burn myth seems to have come from, but higher octane rating on a gas simply describes its tendency to resist autoigniton from heat and pressure; nothing more.
That myth comes from the fact that the flame front does move slower through the 93 octane that you will buy at the gas station as opposed to the 87. Octane rating does not quantify this (nor is it meant to), but it is a real effect.

Why?

Other than the fact it takes about twice the ethanol to do what gasoline does....I don't see what the party is about.

Bring me biodiesel anyday...
Speaking of biodiesel... did anyone catch Mythbusters last night? They took a Mercedes diesel and ran it on filtered used cooking oil and the dang thing ran without a hitch. The only noticable difference was that it got 33mpg on diesel and 30mpg on used cooking oil.

:eek:

I can see it now... pull in to a McDonald's, "I'll have a quarter pounder with cheese, large fries and 15 gallons of fry-oil please." ;)

Even better than that, you might be able to get McDonald's to pay you for the waste disposal.

More discussion - fuel for the fire so to speak, on how E85 is more than viable as a next generation performance fuel as well hellping American farmers and the environment.

http://forums.corvetteforum.com/showthread.php?t=1389042