OK...lets talk about high octane fuels and your car

[Two Fangs]

Yeah, I think it is time for an E85 thread. I am far from an E85 hater, but my responses in this thread may make it appear as though I am. Closing the chapter in this thread on E85 as an octane booster, I would like to say to those readers out there in internet land, please be careful using E85 in any application that does not call for it. While it is an inexpensive high octane fuel when compared to race gas, its chemical composition requires changes in the operating parameters of the engine that your car's computer may not be able to compensate for. Additionally, adding race gas, Torco, Mr.Zog's Sex Wax, or any other octane enhancing product does not mean you will produce any more power. Please do the research and ask questions before tossing anything into the tank that the powertrain calibration engineers did not specify being in there.

[FNBADAZ06]

Well said, Mr. Parker. If you don't have any desire to tune your LS7 engine, but want to maximize the anti-knock capabilities AND lean the open loop WOT operation of your engine for track use while keeping the greater BTU/lbs fuel output, I think my methodolgy has merit. I'm not sure if it works as well for the othe LS engine platforms, but the LS7 certainly seems to have responded favorably to my ideas

[Cross]

Honestly me tuning him was just because he put on a cat back and wanted to get rid of all EVAP, Cat O2 Codes and our wonderful CAGS system lol. I did play with it a little after but honestly his runs were all done originally at the stock fuel map tunes with no changes. After I saw his knock go down I was willing to tune because honestly he was over 6 at times and that scared the hell out of me for a stock car with a cat back on it on gas. But all I did was make a very minor change to his tune to which he loved. I know there is more there but I want him to have good 91 in it with no E85/E30 mix for me to look at it further. Using the E85 just added to the mix on his stock tune was where I got to watch the 8% added to compensate so the stock ECU took it like a champ. I would not mind testing it on a vehicle without crediting the vehicle to have changes made on it just logging to show how it works. His was my first to do that with but he does want to tune it some one who does not would be a better source of testing beyond what I did last night. Either way I think were having fun with our Tech Specific section...

[FNBADAZ06]

Agreed We are having fun, and a meaningful exchange of ideas.

But, I want to point out the differnce between using E85 vs racing fuel when mixing with pump gas, specifically the one's I identifed back a few post, to boost anti-knock behavior, leaning of A/F during WOT open loop operation, and the potential energy contained within the fuel mix itself.

Remember this definition....

Energy Value (for a given fuel):

Energy value is an expression of the potential energy in the fuel. This energy is measured in BTU's (British Thermal Units) per POUND, not per gallon. This data is important as Air Fuel (AF) ratio is measured in weight and not volume. This value may vary with compression ratio and engine speed.

This is where the E85 based route of mixing to achieve the goals stated above, differ (and IMHO, is inferior) to the mixing of the specific race fuel I identified earlier, when it comes to 91 pump gas.

Wiki states...

" Using E85 in a gasoline engine has the drawback of achieving lower fuel economy, as more fuel is needed per unit air (stoichiometric ratio) to run the engine in comparison with gasoline. This corresponds to a lower heating value (units of energy per unit mass) for E85 than for gasoline." In other words, ethanol as a fuel source, has less energy per mass than gasoline because of it's stoich value.

Let's compare gasoline (stoich of 14.7), straight ethanol ( stoich of 9.0), E85 (stoich of 9.6), then throw VP 109 (stoich 13.4), and GT+ (stoich 13.7) into the mix.

Gasoline base stoich 14.7 = 114,000 BTU/lbs

Ethanol (E100) stoich 9.0 = 76,100 BTU/lbs

E85 gas/ethanol mix stoich 9.6 = 81,800 BTU/lbs

VP109 stoich 13.7 = ? , but greater than E85 as it's gasoline based. The specific gravity measurements are available.

GT+ stoich 13.4 = ? , but greater than E85 as it's gasoline based. The specific gravity measurements are available for this fuel as well.

In my view and mind, this info shows a clear difference in the energy content in our competeing ideas (and which fuel mix is superior) , to achieve the stated goal. E85 has it's place, as I stated before I'm planning on moving to it at some time in the future, but it's not the proper fuel to use in boosting 91 octane pump gas when using the stock factory tune on a LS7.

Additionally, these racing fuels are "oxygenated" fuels available at some tracks that have the potential to increase power output. As the fuel burns, it releases captive oxygen and allows a fuller fuel burn and so more can be added (richer mixture)...or, leave the fuel amount the same and lean the mixture out.

Interesting, by the way, as nitrous does the same thing but at a much greater mass of oxygen release as it burns

By ther way, all my comments are based on my opinion, without direct hands on experieince with tuning a car.

The science seems sound....my drag times seem to back it up...but after all is said and done, it's just an educated guess on my part

[Jon]

Well shoot. Now that I know I can datalog and not mess up my warranty, it's time for a wideband and some experimenting. Maybe Victor can volunteer to be the test driver at the track? I can't drag race a stick shift to save my life. I have fun, but I know I'm not getting the most out of it.

[Cross]

But what about the fact that the actual stoich Lean Max HP is below 14.7 its 13.23 I believe. It means that while you can lean it further your not making more power off it at that point however you are gaining fuel economy. Now when comparing BTU's were comparing the same (Lets make it easy and say 200ml) of 91/E10 vs a true E85 mix. 200ml to 200ml yes one will contain more BTU's. However one will also contain a higher octane rating, cylinder temp cooling abilities as well as other features. To achieve the same output at 200ml of E10/91 you will need more E85 and this would be a number I should actually take the time to look up just for fun... but I would pref to go down to the fridge and get a beer lol. Its been a birthday weekend for the little man and I need to relax of all the party fun so to speak lol. Now when you use E85 though as a boosting agent in the scenario I mentioned it compensates by adding more fuel which evens the playing fields and the end loss is just gas mileage with the gains of lower cyl. temps and higher octane. Yes you will have better gas mileage on Race gas but as you pointed out when using it your pushing it anyway so gas mileage is not really you main concern. If 4 gallons in a C6 full fuel system only causes an 8% long term fuel trim adjustment then I would say its not only safe but you could even go further if you really wanted but this is where someone willing to test comes in and we up it half a gallon at a time testing it until we find the safe max and then we can take that and test the actual results of just what Exx rating it becomes and what the Octane level would be at that point. Either way though, lots of fun and this is my take on it through playing with it. I am an aspiring engineer but I do not hold that piece of paper yet so I can only play with things hands on and see how my speculation, reading and thoughts come into play. Many have more knowledge than I do but I like to speak up and engage in the conversation, how else can you learn something or test out something new?

[FNBADAZ06]

Well shoot. Now that I know I can datalog and not mess up my warranty, it's time for a wideband and some experimenting. Maybe Victor can volunteer to be the test driver at the track? I can't drag race a stick shift to save my life. I have fun, but I know I'm not getting the most out of it.

That's the ticket !!!

I'm always very leary about driving someone else's car on a race track but I'll definetly give you help and tips on how you might be able to get the car down the track. It takes seat time and intimate knowledge of your car, but I'm betting you'll get the hang of it with a little help and some experience

[FNBADAZ06]

But what about the fact that the actual stoich Lean Max HP is below 14.7 its 13.23 I believe. It means that while you can lean it further your not making more power off it at that point however you are gaining fuel economy.

Now when comparing BTU's were comparing the same (Lets make it easy and say 200ml) of 91/E10 vs a true E85 mix. 200ml to 200ml yes one will contain more BTU's.

However one will also contain a higher octane rating, cylinder temp cooling abilities as well as other features. To achieve the same output at 200ml of E10/91 you will need more E85 and this would be a number I should actually take the time to look up just for fun... but I would pref to go down to the fridge and get a beer lol. Its been a birthday weekend for the little man and I need to relax of all the party fun so to speak lol.

Now when you use E85 though as a boosting the the scenario I mentioned it compensates by adding more fuel which evens the playing fields and the end loss is just gas mileage with the gains of lower cyl. temps and higher octane. Yes you will have better gas mileage on Race gas but as you pointed out when using it your pushing it anyway so gas mileage is not really you main concern.

If 4 gallons in a C6 full fuel system only causes an 8% long term fuel trim adjustment then I would say its not only safe but you could even go further if you really wanted but this is where someone willing to test comes in and we up it half a gallon at a time testing it until we find the safe max and then we can take that and test the actual results of just what Exx rating it becomes and what the Octane level would be at that point.

Either way though, lots of fun and this is my take on it through playing with it. I am an aspiring engineer but I do not hold that piece of paper yet so I can only play with things hands on and see how my speculation, reading and thoughts come into play. Many have more knowledge than I do but I like to speak up and engage in the conversation, how else can you learn something or test out something new?

No worries....exchange of ideas and knowledge is always good

My suggesting are related to WOT operation (open loop opeation) when going down the track...on a stock tune, with maximum pressure from the combustion of the air-fuel mix (energy released), and the absolute max timing allowed by the high octane table (for the given air mass readings coming from the MAF).

Fuel trims, gas mileage, lower cylinder temps ,lower cost, etc. don't play into my scenario above. We're only talking about open loop WOT operation for 12 second burst at a time, where you're aiming for the greatest amount of energy release per cylinder at high RPM, while using only the stock values in the GM tune.

For extended high load, high RPM operation, a high quality race fuel may still be the better performer but it's cost prohibitive for most of us. This is where E85 has the distinct advantage.....value per performance dollar per gallon.

I'll leave the E85 discussion stuff in our E85 thread.

[FNBADAZ06]

Another idea on why I get KR on 91 pump gas when WOT at the track......oil vapors. I don't run a catch can on my car (yet), but maybe oil making it into the intake manifold or the airflow via the lines coming from my dry sump tank are contaminating the air-fuel mixture prior to making it to the combustion chamber. I'm pretty sure motor oil drops the octane level of the air-fuel mixture when introduced into the combustion process ?

[Cross]

On the advice of the former owner of AZPS I removed the whole PCV system and run a breather... very happy that way now too. I have been drinking so I will revisit this... been an interesting few days.

[FNBADAZ06]

OK....just starting to understnd how to data log with HP Tuners that Jon has loaned me.

Screen capture of HP Tuner scan with what was left of my Sunoco GT+/91 pump gas mix...this was my max load/MPH capture of this scan....

.

I saw a very brief KR of .9, but other than that 0 KR detection during WOT, or cruise load during this entire run

I was on vapors after this test, so I pulled into the local Shell station and added 2 gallons of 91 octane to what was left of the GT+/91 in my tank. Not a straight up 91 octane fuel load, but I figured I'd get another scan.

Hmmm...don't know if this shows anything conclusive yet, as ECT were higher during this scan. Here's a screen capture of the max load/MPH of the scan I did...

I saw a max of .6* timing pulled at the same general RPM/load I saw on the .9* KR on GT+ mix screen capture...interesting...a trend, maybe ?

I also occasional KR at times while cruising, with a high of 1.8 KR at one point...

Not smart enough to make complete sense of anything yet, but interesting I saw NO KR at all with the GT+ mix, with the exception of the very brief blurb I posted above...yet I saw some very limited instances of 1.8* KR during cruise when I diluted my leftover race mix with an additional 2 gallons of Shell 91 pump gas. THe additional ECT temps might be the answer here, but I'm not sure.

Interesting......

[Jon]

You can adjust the range for RPM on the chart. That way the line isn't right up against the top. I think I put mine at 7500rpm max.

[FNBADAZ06]

You can adjust the range for RPM on the chart. That way the line isn't right up against the top. I think I put mine at 7500rpm max.

Is there a quick area I need to go to , to make that adjustment ?

[Two Fangs]

You can adjust the range for RPM on the chart. That way the line isn't right up against the top. I think I put mine at 7500rpm max.

Is there a quick area I need to go to , to make that adjustment ?

Right click on the graph. You will see a menu pop up. Select "Chart Settings" from that menu. Open the drop down in Chart 1, (They are labeled one through five in groups of four from top to bottom, every group of four is a "chart"). Left click RPM, and on the far right, you can adjust the scale.

Hope this helps.

PS, proud of you, bro. Good job....

[FNBADAZ06]

You can adjust the range for RPM on the chart. That way the line isn't right up against the top. I think I put mine at 7500rpm max.

Is there a quick area I need to go to , to make that adjustment ?

Right click on the graph. You will see a menu pop up. Select "Chart Settings" from that menu. Open the drop down in Chart 1, (They are labeled one through five in groups of four from top to bottom, every group of four is a "chart"). Left click RPM, and on the far right, you can adjust the scale.

Hope this helps.

PS, proud of you, bro. Good job....

Thanks, bud

I found the online tutorisl video's.....those are pretty helpful for newbies like me

[Two Fangs]

When (if) you buy it, I have some goodies I'll share that will get you off on the right foot

[HOXXOH]

I just finished reading this entire thread, which was interesting, but the premise seemed to be a stretch from the title. No problem, as the story in the first post narrowed the subject from "your car" to "your stock tuned car" real quickly. One detail I found missing throughout, was the method of mixing fuels. At one point, CROSS mentioned filling a C5 with 4 gal. of E85 and topping it off with 91 (essentially E10) on a car that already had a half tank of fuel. Now I don't claim to know much about C5s, but if the tanks work like the C6, then the right (passenger side) tank had about 40% ethanol by the time it had thoroughly mixed. In the meantime, the left (driver side) tank had no change (remaining E10)and anything done to the tune to utilize the expected mixture would create a bigger problem after the right tank was used up. Any mixing needs to be done, either prior to filling the car, or in the correct proportions per tank being filled. If it were all one big tank, the mixing proceedure wouldn't matter.

[Two Fangs]

Good point. Thanks for reading and adding constructive input and advice.

[FNBADAZ06]

I just finished reading this entire thread, which was interesting, but the premise seemed to be a stretch from the title. No problem, as the story in the first post narrowed the subject from "your car" to "your stock tuned car" real quickly.

One detail I found missing throughout, was the method of mixing fuels. At one point, CROSS mentioned filling a C5 with 4 gal. of E85 and topping it off with 91 (essentially E10) on a car that already had a half tank of fuel. Now I don't claim to know much about C5s, but if the tanks work like the C6, then the right (passenger side) tank had about 40% ethanol by the time it had thoroughly mixed. In the meantime, the left (driver side) tank had no change (remaining E10)and anything done to the tune to utilize the expected mixture would create a bigger problem after the right tank was used up.

Any mixing needs to be done, either prior to filling the car, or in the correct proportions per tank being filled. If it were all one big tank, the mixing proceedure wouldn't matter.

Yep, I agree with you on the idea.

My mixing is done on an empty tank (low fuel indicator),which is roughly two gallons of reserve fuel, which I understand is contained fully in the driver side tank on a C6. Adding the 2 gallons of GT+ will go into the driver's tank, as there's not enough quantity in the driver side tank to reach the cross over tube.

[HOXXOH]

I just finished reading this entire thread, which was interesting, but the premise seemed to be a stretch from the title. No problem, as the story in the first post narrowed the subject from "your car" to "your stock tuned car" real quickly.

One detail I found missing throughout, was the method of mixing fuels. At one point, CROSS mentioned filling a C5 with 4 gal. of E85 and topping it off with 91 (essentially E10) on a car that already had a half tank of fuel. Now I don't claim to know much about C5s, but if the tanks work like the C6, then the right (passenger side) tank had about 40% ethanol by the time it had thoroughly mixed. In the meantime, the left (driver side) tank had no change (remaining E10)and anything done to the tune to utilize the expected mixture would create a bigger problem after the right tank was used up.

Any mixing needs to be done, either prior to filling the car, or in the correct proportions per tank being filled. If it were all one big tank, the mixing proceedure wouldn't matter.

Yep, I agree with you on the idea.

My mixing is done on an empty tank (low fuel indicator),which is roughly two gallons of reserve fuel, which I understand is contained fully in the driver side tank on a C6. Adding the 2 gallons of GT+ will go into the driver's tank, as there's not enough quantity in the driver side tank to reach the cross over tube.

Yep! I knew how you did it, but my post was meant for all the future readers of this thread.

[FNBADAZ06]

I remember a recent thread on the big board about people mixing fuel in the tank instead of pre-mixing in gas cans.

[HOXXOH]

I remember a recent thread on the big board about people mixing fuel in the tank instead of pre-mixing in gas cans.

Yep! I posted the same warning/concern there too. Amazing how we overlook some of the critical details when our focus is elsewhere.

[FNBADAZ06]

Tom, can't remember....do you run a pump/race gas mix at the track ? I know that MikeG does for his LS2 car.

[HOXXOH]

Tom, can't remember....do you run a pump/race gas mix at the track ?

I know that MikeG does for his LS2 car.

Yes, if I'm testing something and need to assure consistancy, and then only if a run log shows KR.

Other than that I don't bother 'cause I'm just having fun.

[FNBADAZ06]

LPM ran FNBADAZ06 on the dyno today, complete with wideband O2 monitoring and HP Tuners data logging 3 runs with standard Shell 91 pump gas. 3 runs with approximately 50/50 mix of Sunoco GT+ (R+M/2 = 104) and Shell 91 octane pump gas (R+M/2 = 91). I want to look over the logs before I post all the information, but on the surface, my suspicion was confirmed....I'm getting the boost I felt I was getting