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100 octane with 93 tune?

24K views 34 replies 6 participants last post by  tjhawk 
#1 ·
Ok so I need some input, I live colorado where 91 oct is the norm and 93 is harder to find than bigfoot, so I was thinking of getting a 93 octane tune from bama and running 100 octane at the track only. Would I see any performance gains? Or would it cause trouble on a n/a setup and nitrous setup? Just trying to squeeze every hp out of the pony .
 
#2 ·
You'd lose performance actually.

It would be like using 93octane on the stock 87 tune. A friend from this fourm has recently went from a 91 tune (that they sent him by mistake) with 93octane gas to the 93 tune and he said there was a noticable difference.

When I went back to the stock tune and had a full tank of 93 octane my car was sluggish like crazy!

Maybe with the new system where you can run 87 or 93 and the computer will adjust.
 
#3 ·
Oak Lawn Chris is correct. You'll lose performance using 100 octane gas with a 93 tune, because there will be incomplete combustion.

Another option is to add 3.5 gallons of 100 octane to 12.5 gallons of 91 octane to get a 93 octane mix.
 
#4 ·
After I posted it I saw that he was running Nitrous and wasn't sure if that would change anything. Thanks ski for confirming.
 
#5 ·
Or get a 100 octane nitrous tune for the track and a 91 octane tune for the street
 
#6 ·
actually, you wont see a performance increase or decrease. a fuels octane rating is simply a rating of its resistance to pre-detonation. higher rated fuels are less like to pre-ignite or in laymans terms cause the engine to "ping". If you have a 93 tune, as long as you run 93 or better your good, but you wont get more performance with a higher octane fuel.

actually, i have dougs 91 octane torque tune and ive been running 89 in it for 3 years now unless im going to the track and know i will be pushing the car really hard. for everyday street driving i use 89 cuz its cheaper, i havent heard a single ping running 89 with the 91 tune. in the winter when its really cold, i do go back to 91 too.

simply put, as long as shes not pinging, obviously the octane rating is ok.


to debunk another common myth, higher octane fuel is not cleaner either...:winks
 
#8 ·
actually, you wont see a performance increase or decrease. a fuels octane rating is simply a rating of its resistance to pre-detonation. higher rated fuels are less like to pre-ignite or in laymans terms cause the engine to "ping". If you have a 93 tune, as long as you run 93 or better your good, but you wont get more performance with a higher octane fuel.

actually, i have dougs 91 octane torque tune and ive been running 89 in it for 3 years now unless im going to the track and know i will be pushing the car really hard. for everyday street driving i use 89 cuz its cheaper, i havent heard a single ping running 89 with the 91 tune. in the winter when its really cold, i do go back to 91 too.

simply put, as long as shes not pinging, obviously the octane rating is ok.


to debunk another common myth, higher octane fuel is not cleaner either...:winks
Actually, I think you're wrong. Speaking from personal experience, I've noticed less performance when using higer octane, as have many others. Cars run a bit more sluggish. As for you running 89 on a 91 tune, maybe the tune is conservative.

I dont have any scientific proof, just how the cars I've used have felt to me.
 
G
#7 ·
One other thing to consider also is most racing fuels are oxygenated. This means oxygen entering the combustion chamber which has not been acounted for by the MAF which could cause a lean issue.

I've been mixing my fuels for the last couple years now with no problems. Just keep a log book and update it everytime you fill up.
 
#9 ·
I stand by my post. Ive researched this before for personal knowledge. Everything I find is the same as this



From Discovery channel "How Stuff Works":

first line tells it all....


The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.
The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.







Im sorry, but I fail to see how having a fuel that can be compressed more will affect performance UNLESS you ARE compressing it more.


This also explains the biggest reason why diesel fuel wont burn in a gasoline engine, a regular gas engine cant compress the fuel the required 25.1 ratio to ignite it.



on another note, if your buying any of that s--ty 10% ethanol crap that some stations are selling, your gasoline engine doesnt have enough compression to ignite that either, which means 10% of the fuel you pump is just going out the exhaust, which is why i wont put that crap in my car. .:nono: (not too mention my father whos been in auto parts for 30 years says he is selling more fuel pumps than ever since that stuff hit the market. He says its eating away at all the pumps internal seals)



EDIT: the only exception i can think of is if you put in a really high octane like 105 or higher, then your engine would have a harder time igniting it. but any fuel 87 - 93 octane should still be well within the range for igintion. if performance did decrease, I seriously doubt it would be a measurable amount.
 
#10 ·
I stand by mine as well. I'm speaking from my experience with my cars now. From everything I've read online, they say some engines can have less performance and some it wont really effect.

To the OP, I would say do NOT use the 100 octane on a 93 tune! There is no benefit and it CAN actually hurt. Not saying it will, but it can. I noticed using 93 on the stock tune that my car was more sluggish. Maybe it was in my head, but I had no preconcieved ideas about it at the time.

You said you wanted to squeeze every HP out of it, have them change the tune for the racing fuel. Is this an option?

You can always swap out the jets and run a 125 shot too!:winks
 
#12 ·
To the OP, I would say do NOT use the 100 octane on a 93 tune! There is no benefit and it CAN actually hurt.

ahh, at least we have found some common ground. I totally agree with you on that one, sir.:winks definately no benefit.


main thing that gets on my nerves is the gas companies market premium fuel so that misinformed people think that it is cleaner and will get better performance or economy from simply pumping it in their gas tank. there is nothing "premium" about it. Its just higher octane.

bottom line - premium fuel is a fuel for performance engines that require it. It is NOT a performance fuel.:winks
 
#11 ·
Below is an interesting article on regular vs. premium gas.
Please take note of the quote from Lewis Gibbs, consulting engineer and 45-year veteran at Chevron Oil Company, and chairman of Technical Committee 7 on Fuels, part of the Society of Automotive Engineers (SAE) Fuels & Lubricants Council:
"Premium, in fact, sometimes is worse fuel than regular. It resists knock because it's harder to ignite than lower-octane fuels. As a result, some engines won't start as quickly, or run as smoothly on premium."
USATODAY.com - Why use premium gas when regular will do?

Also, E10 is a mixture of ethanol and regular gasoline in ratios that are designed to equal the octane ratings listed at the pump.
Thus, an engine designed to operate with a specific octane gasoline should not have any problems with incomplete combustion if the correct E10 octane is selected.
However, I agree that E10 is crappy fuel, not only because it can damage critical fuel system parts, but it also reduces gas mileage due to ethanol's lower energy content per unit volume, and it has a short shelf life which causes it to easily gum up fuel systems, e.g., my lawnmower.
 
#13 ·
Also, E10 is a mixture of ethanol and regular gasoline in ratios that are designed to equal the octane ratings listed at the pump.
Thus, an engine designed to operate with a specific octane gasoline should not have any problems with incomplete combustion if the correct E10 octane is selected.
However, I agree that E10 is crappy fuel, not only because it can damage critical fuel system parts, but it also reduces gas mileage due to ethanol's lower energy content per unit volume, and it has a short shelf life which causes it to easily gum up fuel systems, e.g., my lawnmower.

my thinking exactly. 10% ethanol means 10% reduced fuel economy. if you do the math, that nickel you saved at the pump wont be worth it.


and that is an interesting article
 
#14 ·
I was actually addressing your inaccurate comment that a gasoline engine does not have sufficient compression to ignite E10.

Also, I'm retracting my comment in my initial post "You'll lose performance using 100 octane gas with a 93 tune, because there will be incomplete combustion", and modifying it to "You may lose performance using 100 octane gas with a 93 tune, because there may be incomplete combustion".
 
#15 ·
I was actually addressing your inaccurate comment that a gasoline engine does not have sufficient compression to ignite E10.

actually, i said it doesnt have enough to ignite ethanol. Not ethanol in gasoline. (E10) E10 will burn, just not completely. if you pump pure ethanol in your tank, you wont go nowhere. in other words, the 10% ethonal in E10 wont burn completely, and not at a temp to provide any power to the engine, there for is basically 10% waste. you need COMPLETE combustion for optimal performance.

i also will retract my statement on the performance decrease with the higher octane and agree with you on your statement that "you may lose performance." it sure wont increase.
 
#17 ·
and this one says E10 gets 1% less....

E10 ethanol achieves only 1% less fuel economy than E5: study : Biofuels Digest


and this one a member on some forum did and got 7.8% less with E10 over regular


E10 vs E0 MPG study - Bob Is The Oil Guy

here is another that says 1.5% drop

Energy Answers: ACE Study shows minimal mileage drop for E10

point being my friend, is that we could debate this all day long, as i ran across just as many "studies" that showed E10 made no difference.

its for this exact reason that E10 fuel usage has been in debate all over the country and in fact the world since its introduction.

you pretty much just have to decide what you believe.



for me, mileage isnt the real reason i dont use it anyway.

fuel pumps are expensive! not too mention a PITA to change.
 
#18 ·
funny, you said:

it also reduces gas mileage due to ethanol's lower energy content per unit volume


I said:

the 10% ethanol in E10 wont burn completely, and not at a temp to provide any power to the engine, there for is basically 10% waste


we are so busy debating, we failed to realize we are debating something we already previously agreed on.:heha:


To the OP - sorry man, i didnt mean to turn this into an E10 thread
 
#19 ·
I believe we have what's called a proverbial apples and oranges situation.

I'm referring to the % combustion of E10 vs regular gasoline, and you appear to be referring to the mpg of E10 vs regular gasoline.
The article I linked indicates that E10 burns more completely than regular gasoline, and your linked articles indicate E10 gets less mpg than regular gasoline.

However, the reduced mpg of E10 is due to its lower energy content than regular gasoline. Not because it combusts less efficiently.
 
#20 ·
Ok so I am here to tell you guys all about Ethynol. I have many E-85 stations all over my area and love it to death. Sure it has some drawbacks namely decreased ecomony but its over a dollar cheaper and that 10-15% ecomomy loss still saves me money in the end. Lets do some math. I have a 2004 Explorer Sport Trac which on regular gas costs me $87 to fill 24 gallon tank at $3.65 a gal. Now I can get maybe 400 miles for that money if I drive all highway with the cruise set. Now I can get for that same $87 dollars a full tank of Ethyl and still fill three additional 5 gal cans for the same price. Now for that $87 dollars I can go 575 miles! While my MPG is less my dollars spent per mile is less which in the end is money saved. Also when I change my oil after 5,000 miles(yeah you read it right) the oil comes out just as clean as it went in. I had a Cat oil analysis done once and they found no impurities what so ever. Now more about how you said a tank of Ethyl wont run in your car. You are so wrong!
Alcohol is flamable and will burn. It may not burn well and your car may run pretty bad due to programming issues but it will none the less burn. The only exception is trying to run it in the winter you may have starting problems in a non flex vehicle...lol. I ran it in my Jeep Cherokee for an entire summer once to prove the guys in my Jeep Club wrong. I think that this fuel is misunderstood and full of myths started by the oil companies who dont want you to change your ways and keep you under their thumb paying their prices etc. Still dont believe me? Here is a link for a study some guys did a while back.

YouTube - ‪E85 Ethanol Does not harm Non-FlexFueled Engines‬‏. Sorry about the poor sound quality.

I really like E-85 because it has 105 octane and with the right tuning you can make it work in just about any vehicle and have the benefits of high octane without paying the race gas prices.

BTW the reason you cannot find 93 octane in Colorado is because the altitude is so high and the air is so thin that your ressistance to detonation is greater naturally. Thats why everywhere else in low elevation has 87 octane for the regular and you guys have 85 octane.
 
G
#21 ·
I really like E-85 because it has 105 octane and with the right tuning you can make it work in just about any vehicle and have the benefits of high octane without paying the race gas prices.
I agree with your thoughts toward E85 but here is part of the misinformation. The octane rating is not 105 as this number was derived by non-industry accepted methods. The "105" stickers have been removed from the vast majority of the pumps. Its resistence to preignition comes from its high latent heat of vaporization value. In other words it does a great job of pulling heat out of the combustion chamber when it vaporizes. This allows for increases in compression or ignition timing. For this same reason (charge cooling affect) you need to increase the percentage of gasoline to reduce the cold start problems.

Also, without a proper tune to account for the necessary increase in fuel volume at WOT you could create a lean condition and burn holes in your pistons.

E85 is a great alternative to reace fuel for high compression/high boost applications.
 
#22 ·
"...Also, without a proper tune to account for the necessary increase in fuel volume at WOT you could create a lean condition and burn holes in your pistons."

I have never seen holes burned in pistons of ANY car with working knock sensors.(minus the car that was running nitrus and forgot to fill his 2nd fuel tank that was strictly for the nitrus..lol) I have seen many pistions detonated in carbie cars and older TBI units. Once pinging is detected within a few seconds timing starts getting pulled out at 2 degree incroments each time a pink is detected. Programming is the key ingredient in running E-85 fuel. If you could look at your oxy sensor on E-85 it is showing nearly no voltage (tells computer to go rich). Since the computer only knows what to do within its perameters it can only add so much fuel before it reaches its MAX RICH LIMIT end of the scale. On my Jeep it has a higher limit in the programming because its made to go anywhere in the world and run on just about anything that the world can throw at it.
 
G
#26 ·
"...Also, without a proper tune to account for the necessary increase in fuel volume at WOT you could create a lean condition and burn holes in your pistons."

I have never seen holes burned in pistons of ANY car with working knock sensors.(minus the car that was running nitrus and forgot to fill his 2nd fuel tank that was strictly for the nitrus..lol) I have seen many pistions detonated in carbie cars and older TBI units. Once pinging is detected within a few seconds timing starts getting pulled out at 2 degree incroments each time a pink is detected. Programming is the key ingredient in running E-85 fuel. If you could look at your oxy sensor on E-85 it is showing nearly no voltage (tells computer to go rich). Since the computer only knows what to do within its perameters it can only add so much fuel before it reaches its MAX RICH LIMIT end of the scale. On my Jeep it has a higher limit in the programming because its made to go anywhere in the world and run on just about anything that the world can throw at it.
You can be lean without suffering preignition (commonly and incorrectly refered to as detontation). For example, as I previously said, most race fuels are oxygenated. They have high octane levels and are resistant to preignition. These fuels introduce more oxygen molecules into the combustion chamber which are not "seen" by the MAF. If not accounted for in the tune it can cause a lean condition.

For purposes of this discussion, there are a couple of factors at work here which you have already stated as reasons to use ethanol such as the "105" octane. Even if there is insuffecient fuel, ethanol in a relatively stock application is not likely to preignite due to its higher autoignition temp and its ability to remove more heat from the combustion chamber compared to gasoline. Check this chart out and you can see:

http://www.afdc.energy.gov/afdc/pdfs/fueltable.pdf

You are correct in the fact that cruising around in closed loop will allow the O2 sensors to make adjustments to fuel;however, at WOT these sensors are not used. You are relying on preset fuel tables from your tune.

With that said, lets look back at the table. You can see gasoline has a stoich of 14.7:1 where as ethanol is 9:1. This is what was used to develop the gasoline tune and is what is behind the need for higher volumes of ethanol. Running ethanol on a gasoline tune at WOT leaves more oxygen molecules available which creates more heat. At the top of fourth gear running down the track or freeway or whatever, you can in essence create an oxygen torch.

Point being...although you can run your engine on other fuels it is always best to tune for your specific fuel.
 
#23 ·
I did the math, and your numbers do not add up.

E85 has 82K BTU's/gal., or approx. 28% less than gasoline's 114K BTU's/gal.
Vehicle testing has shown mpg drops 25%-30% with E85 vs gasoline.
Your mpg numbers show a decrease of only 12% with E85 vs gasoline.
Your numbers have a 52%-60% error compared to the results from numerous tests. And no amount of programming is going to make up for that large of a % gap.

39 gallons of E85 for $87 would cost $2.23/gal., or 39% less than the $3.65/gal. for gasoline in your area.
That is almost twice the max 21% differential between E85 & gasoline in Appleton, WI over the past month.
E85 Prices » Wisconsin

Also, the video would be more credible if the vehicle had been donated by someone other than the president of a company that builds ethanol producing facilities.
 
#24 ·
Well thats what it is and thats what I am doing. Its like Ripleys you can believe it or not. I am not gonna get in a pissing match over something that works for me. I think I only loose like 3-5 MPG with E-85 but the bottom line is that its cheaper than gas. MPG and BTU's are stupid to compare as they are two different things. Compare MPG to dollars per mile you drive. Alot of people are using E-85 and hopefully soon gas will just get replaced all together.
 
#25 ·
No pissing match intended.
Just stating facts, and giving my observations based on your statements.

Let's look at the E85 cost issue another way.
If the price difference between E85 and gasoline in your area is less than 28%, then you're most likely not saving any $ using E85.

On the contrary, BTU is directly related to mpg.
BTU is energy.
Energy is required to move an object against a force, whether it's inertia, mechanical friction, tire friction, air resistance, etc.
An automotive vehicle gets its energy to move from the fuel it uses. The fewer BTU's available in each gallon of fuel, the fewer mpg the vehicle gets.
Simple.

I've already compared $/mile using current prices for E85 and actual E85 test results, and gasoline is less expensive at this point in time.

Replacing gasoline with E85 would be a huge mistake because it would cause a negative energy situation, i.e., the amount of energy required to produce a gallon of ethanol and transport it to the pump is greater than the amount of energy available from a gallon of ethanol.
 
#27 ·
If I could quote myself I would...... I remember saying earlier that tuning is required for ethyl but a gas tune will work with E-85, just not as well.

As for the BTU comparision....if all engines had the same crappy compression say 8.0 to 1(think most 70's and 80's cars) gas would be the only thing that would work. But lets raise the compression to just 11 to 1. Since compressing air creates heat and heat can cause gas to pre ignite without the help of the spark plug, you need to run a higher octane fuel. Since ethyl has the ability to resist ignition(IE has a higher octane rating) it would be a great fuel and probably not need as much of its own BTU's because the added compression is helping with that. Now that said I am thinking that the reason that my 9.5 to 1 compression, 4.0 liter is able to run so well on E-85 is because in the tune, the timing curve is changed so that the ignition occurs sooner so that when the piston is at maximum quench the flame front is already moving in a relative direction. This is just a guess but its the only way I can imagine that this can be done in a flex engine. BTW it knows when to change tunes because it has an optical eye in the fuel line that is able to "see" the different fuels and adjusts accordingly.
 
G
#28 ·
Increasing cylinder compression and retarding your timing (which is what you are referencing) are contradictions. To increase pressure you advance the timing which allows the piston to compress the air/fuel mix more. This will cause a faster more powerful and more complete ignition up to MBTT. You still must allow time for the combustion process to be completed. If you do not set spark at the right degree pre-TDC, the combustion will be completed to far ATDC and you lose power. Biggest thing preventing maximum advance is the fuel. We have already established that E85 can handle the increase in pressure (i.e. more ignition advance, compression or boost).

This is similar to the old firecracker analogy. Hold a firecracker in the palm of your hand and it will burn a your hand little. Now make a fist and you will lose your fingers.

What year is your Jeep? If you have an "optical eye" (which is normally called a flex fuel sensor) and different tunes which are adjusted by what the sensor is telling the PCM, I assume it is a newer flex fuel vehicle. It works because the tune makes adjustments to fuel tables and ignition. The same thing can be done in a non-flex fuel vehicle but a hand held programmer will need to be maintained in the car to swap between regular gas and ethanol, however you will have to test the ethanol percentage to ensure best performance.
 
#29 ·
Seriously can you read anything right? I beleive I said advance the timing to get the flame front going in the right direction BEFORE max quench. This is my exact quote......

"....Now that said I am thinking that the reason that my 9.5 to 1 compression, 4.0 liter is able to run so well on E-85 is because in the tune, the timing curve is changed so that the ignition occurs sooner so that when the piston is at maximum quench the flame front is already moving in a relative direction. "

The key word here is SOONER not later. I dont mind a good debate but you need to get facts from the other guy right before spouting off an incorrect answer.

The Jeep is a non flex 1993 with 196k on it. Its been three years since my summer of E-85( remember 4.25 a gal?)The flex vehicle in question is my 2004 Explorer Sport trac. The Jeep ran fine on E-85 once it warmed up outside to ambient temp above 70. Below 70 it ran skippy until the engine warmed up to about 100 or so and ran fine after that. It never really complained after that warm up peroid. I almost would say it felt like it ran smoother. The optical eye is supposedly just that an eye. It reads the wave length of light reflected back and if it reads one length its gas if it reads another its ethyl. I priced one out once and it was like a five hundred bucks.
 
G
#30 ·
Seriously can you read anything right? I beleive I said advance the timing to get the flame front going in the right direction BEFORE max quench. This is my exact quote......

"....Now that said I am thinking that the reason that my 9.5 to 1 compression, 4.0 liter is able to run so well on E-85 is because in the tune, the timing curve is changed so that the ignition occurs sooner so that when the piston is at maximum quench the flame front is already moving in a relative direction. "

The key word here is SOONER not later. I dont mind a good debate but you need to get facts from the other guy right before spouting off an incorrect answer.

The Jeep is a non flex 1993 with 196k on it. Its been three years since my summer of E-85( remember 4.25 a gal?)The flex vehicle in question is my 2004 Explorer Sport trac. The Jeep ran fine on E-85 once it warmed up outside to ambient temp above 70. Below 70 it ran skippy until the engine warmed up to about 100 or so and ran fine after that. It never really complained after that warm up peroid. I almost would say it felt like it ran smoother. The optical eye is supposedly just that an eye. It reads the wave length of light reflected back and if it reads one length its gas if it reads another its ethyl. I priced one out once and it was like a five hundred bucks.

My apologies. I did misread you....better yet I think I go tmy advance and retard backwards...always comes down to the retard:winks
 
#31 ·
Increasing the CR of an engine in an E85 vehicle will increase its mpg, but it's a only by a mere 20% according to the following technical paper:
http://delphi.com/pdf/techpapers/2010-01-0619.pdf

Thus, if a flex fuel vehicle with a standard CR engine gets 28% less mpg than a regular gas vehicle, then that difference would improve to only 22.4% less mpg for a FF vehicle with a high CR engine.
And using E85 would still be more expensive than using regular gasoline for most areas of the US where E85 is currently available.
 
#32 ·
Yep this proves my info about getting 14-15 with E-85 and 20 with gas. 14 MPG falls right into that area of 28% loss with stock compression. For whatever reason it just seems to PULL better with E-85 vs. gas. Maybe its just my imagination but on E-85 I sometimes forget my 3500 lb boat is back there..:laughlitt
 
#34 ·
I'd like to agree with you. However, 20 mpg on regular gas is not what you originally stated you get.

"I have a 2004 Explorer Sport Trac which on regular gas costs me $87 to fill 24 gallon tank at $3.65 a gal. Now I can get maybe 400 miles for that money if I drive all highway with the cruise set."

That calculates to only 16.7 mpg.
 
#35 ·
HMMMM. Something is skewed here on my MPG then. I recently went on a trip going 65-70 all highway miles and got 20 MPG which is what Ford says I should get. Ironically the window sticker was actually correct. Lol. I must have not calculated something in my original post correctly. In anycase I talked to a tuner guy the other day and he said while he has done E-85 programs for Mustangs he said in my case with the whipple blower I would have to change my injectors to 60 lb/hr injectors so I guess there goes my hopes of trying a dyno pull on E-85.:sadcry
 
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