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So for us flex fuel guys what percentage should you start retarding timing and blending with the gas tables? With Ms3 I start blending tables below 75% ethanol content. Guessing this is a bit high. Currently in SW PA ethanol content from speedway Gas stations is 80%
I agree with the above. Just like any other fuel why run more octane than your setup needs? Lower ethanol content requires less fuel system maintenance.
So for us flex fuel guys what percentage should you start retarding timing and blending with the gas tables? With Ms3 I start blending tables below 75% ethanol content. Guessing this is a bit high. Currently in SW PA ethanol content from speedway Gas stations is 80%
Depends on the setup and what the engine wants. Pretty impossible to answer without tons of info. The problem with blending tables is the effects of ethanol percentage aren't linear. So if you have a tune up on the edge, it may be completely safe at 50% and at 45% you'll knock like crazy. Assuming you don't have a radical setup, I'd bet you can run E50 on the E85 timing map. . I'd want my "pump gas" timing to be 100% in at 50% and below to be safe I guess. Then try to run it around 60% for cushion.
Another thing to consider is the "blender" fuel may be batter or worse depending on location. I'd bet its the cheapest crap the gas station can get their hands on. The "serious" blender guys I know get ethanol free 91 and E98 (or E85) at the pumps and blend themselves. Gives you a much more consistent fuel that's likely much better quality as well. (Eth. free 93 oct. would be great if it were available)
I don’t really blend fuels I just put gas in it, usually unleaded race fuel, over winter and have the ability to put pump gas in it in an emergency if I can’t find an E85 pump. Most of the time after winter is over I drain the tank and fill with ethanol. Just figured it was a good question for the thread on what content can be a safe to get the full effects of e85. I usually don’t have a problem since I have an ethanol pump with in 10 minutes in any direction that I drive. I appreciate the feed back!
So, this morning was able to get 3 nice sized datalogs, at several different loads, MPH's, RPM's, etc...
I did get the 145 amp truck alternator on yesterday, and it maintains exactly .5 volt higher than the old one, at max boost, max rpm.
E-64, according to my sensor, being read through my P01 ECM.
At highest logged boost, 16#, the injector duty cycle hit a high of 75.5%...as opposed to 97.3% duty cycle on E-76 a week ago.
Conditions same, except different alternator, and 12% less ethanol content
55* ambient, 80% humidity
17-18* of timing
180* coolant
70* IAT average, highest after 3 gear WOT "pass", was 79*
Zero knock retard, and car felt great all morning...
I also found out that my car makes anywhere from 4-6# more boost with cutout OPEN instead of closed.
Not sure if that's a wastegate issue or what?
Now, for the weird ****...Evidently, while I was removing and re-installing the bigass alternator 8 times, I somehow hit the "lock" on the accelerator cable, and all three of my extended logs, only saw a HIGH of 45% TPS...LOL.
I thought it felt funny when I got in it, but figured it was just because I hadn't driven it in a week...
It shifted fine, screamed to 6800 rpm every time I asked it to, so aside from feeling like the gas pedal was in a bowl of mashed potatoes, it did everything else fine...
Interesting that the sensor reads quite a bit different than the test vial.I heard the same from a guy who was filling his modified BMW at the station I buy from. We only have one station here.
He said it was never over 80% by his gauge. When we use the test kit, 85-87%.
So which is correct?
Non flex cars will have to set stoich based on the test kit. Flex fuel setups will use its own measurement.
Seems as though the flex fuel cars will see a slight reduction in IDC.
Not sure if TruckusDougus has a test kit? We buy from the same station.
Originally Posted by rel3rd
I run a sensor, on my car, and my daily driver truck (both converted). Truck, a knock happy 2008 Silverado, I mainly spike it with flex only when towing to Cecil...but, obviously a moot point so far this year...
Anyway, my truck reads 11% on pump 87 at either Costco or any Royal Farms stores.
My car "reads" 77%, but my test bottle, always reads 85% or higher, all through the winter, the lowest I saw was 80% on the test kit.
This is at Royal Farm store at Pulaski Highway and Ebenezer, (near White Marsh, exit 67 off of 95) and has also been the same % at the one on Boston Street, and at Route 7 and Route 24 intersection. The RoFo's seem to be really consistent with one another everywhere near me.
Interesting that the sensor reads quite a bit different than the test vial.I heard the same from a guy who was filling his modified BMW at the station I buy from. We only have one station here.
He said it was never over 80% by his gauge. When we use the test kit, 85-87%.
So which is correct?
Non flex cars will have to set stoich based on the test kit. Flex fuel setups will use its own measurement.
Seems as though the flex fuel cars will see a slight reduction in IDC.
Not sure if TruckusDougus has a test kit? We buy from the same station.
I have a flex fuel segment swapped operating system, so mine does adjust stoich to the content it reads...but like you've said, which % reading is right? The sensor or the tester? I don't recall mine ever reading over 80%. Locals who also go to the same station report the same higher numbers that I see with my test kit, on their actual vehicles.
I actually swapped out my sensor and saw no difference between it and the original one...both Continental brand FWIW. One from a Chevrolet dealership, reboxed as an AC Delco, and one from a parts house, reboxed as Standard brand ignition part. Both still clearly embossed as Continental on the actual sensors though.
My daily driver Silverado, also converted to sensor, seems to read dead on.
I wonder if there's a way to rescale the flex sensor reading via HPTuners?
What I’d like to see is data proving that paper is in anyway incorrect? I’ve yet to see it.
Yes, those octane numbers are correct. Of course they are! If you take those blends and test them on the same tests that pump fuel uses… those are indeed the RON/MON numbers they average out to. It’s a fact. Look it up.
Just like Methanol is only rated at 108.7 RON and 88.6MON. The fact that that there is twice as much fuel in CC at like AFR cools things down in a hurry and makes it “ACT LIKE” a much higher octane fuel. But the facts are facts the facts on that paper are correct. Nowhere do they state E50 is as good of a race fuel as E98, E85 etc…
The problem is that the amount of fuel and the cooling effect are supposed to be INCLUDED in the octane numbers, as the test circumstances for determining octane should see an immediate benefit from the cooling effect and the extra fuel and result in a higher octane rating on the test machine.
The ASTM2699/2700 had to be later revised because the test conditions specified were for gasoline type fuels only, meaning factors such as lower heating value, specific gravity, and stoich AFR weren't being considered or altered for. ISO 5164 in 2014 set out to standardize the two test methods, and determined that ethanol blends above 25% were not to be tested.
Scope
This International Standard establishes the rating of liquid spark-ignition engine fuel in terms of an arbitrary scale of octane numbers using a standard single-cylinder, four-stroke cycle, variable compression ratio, carburetted, CFR engine operated at constant speed. Research octane number (RON) provides a measure of the knock characteristics of motor fuels in automotive engines under mild conditions of operation.
This International Standard is applicable for the entire scale range from 0 RON to 120 RON, but the working range is 40 RON to 120 RON. Typical motor fuel testing is in the range of 88 RON to 101 RON.
This International Standard is applicable for oxygenate-containing fuels containing up to 4,0 % (m/m) oxygen and for gasoline containing up to 25 %(V/V) ethanol.
NOTE 1 Although 25 % (V/V) of ethanol corresponds to approximately 9 % (m/m) oxygen, full applicability of this test method for that oxygen range has only been checked for gasoline type of fuels. NOTE 2 Work is under way to check the possibility to use the method up to and including 85 %(V/V) ethanol.
It was later determined that ASTM D2699/2700 were not able to accurately measure octane of fuels containing over 25% ethanol because the specifications outlined for the type of equipment used do not allow changes to the carburetor to reach the air/fuel ratio needed fuels with a high ethanol content. The test methods were revised to clearly state within their scope:
This laboratory test method covers the quantitative determination of the knock rating of liquid spark-ignition engine fuel in terms of Research O.N., including fuels that contain up to 25 % v/v of ethanol. However, this test method may not be applicable to fuel and fuel components that are primarily oxygenates.
The RON/MON numbers determined by ASTM D2699/2700 were for testing E85 AT THE AIR FUEL RATIO OF GASOLINE, and it still managed to score better octane ratings than premium 93.
Want to see how archaic the parameters are for air/fuel ratio for the RON/MON testing?
They don't allow jetting size changes, as the jet part number used MUST BE 75985. The jet size is outlined specifically in the equipment parameters, and you determine the AFR by markings on a sight glass above the vertical jet that were determined by the amount of head pressure on the jet with that level of fluid in it. A horizontal jet is used like a float bowl, and determines the rate at which fuel can enter the bowl.
This level CANNOT be altered based on fuel type.
8.28 Fuel-air ratio For all sample fuels and primary reference fuels, the fuel-air ratio (a function of the effective fuel level in the vertical jet of the standard carburettor assembly) shall be adjusted to maximize knock intensity. When the carburettor sight glasses are used as the indication of mixture strength, the maximum knock condition shall occur when the fuel level in the sight glass is between 17,8 mm (0,7 in) and 45,2 mm (1,7 in), a condition that is dependent on selecting the proper carburettor horizontal jet. 12.4.1 Fixed Horizontal Jet–Variable Fuel Level System— Fuel level adjustments are made by raising or lowering the float reservoir in incremental steps. Selection of a horizontal jet having the appropriate hole size establishes the fuel level at which a typical sample fuel achieves maximum knock. 10.3.18.1 Fuel-air ratio is a function of the effective fuel level in the vertical jet of the standard carburetor assembly and is typically indicated as the fuel level in the appropriate carburetor sight glass.
So no, the octane ratings in that paper are not correct, and the test methods used have been deemed incapable of testing ethanol based fuels.
P.S. I'm drunk and probably F*cked some of that up.
Last edited by AwesomeAuto; 04-26-2020 at 10:54 PM.
@RonSSNova i dont have a test kit but I do have FF sensors on both the malibu and the truck and they usually agree Jay's garage/Sequential is right about 80% alky
The problem is that the amount of fuel and the cooling effect are supposed to be INCLUDED in the octane numbers, as the test circumstances for determining octane should see an immediate benefit from the cooling effect and the extra fuel and result in a higher octane rating on the test machine.
The ASTM2699/2700 had to be later revised because the test conditions specified were for gasoline type fuels only, meaning factors such as lower heating value, specific gravity, and stoich AFR weren't being considered or altered for. ISO 5164 in 2014 set out to standardize the two test methods, and determined that ethanol blends above 25% were not to be tested.
It was later determined that ASTM D2699/2700 were not able to accurately measure octane of fuels containing over 25% ethanol because the specifications outlined for the type of equipment used do not allow changes to the carburetor to reach the air/fuel ratio needed fuels with a high ethanol content. The test methods were revised to clearly state within their scope:
The RON/MON numbers determined by ASTM D2699/2700 were for testing E85 AT THE AIR FUEL RATIO OF GASOLINE, and it still managed to score better octane ratings than premium 93.
Want to see how archaic the parameters are for air/fuel ratio for the RON/MON testing?
They don't allow jetting size changes, as the jet part number used MUST BE 75985. The jet size is outlined specifically in the equipment parameters, and you determine the AFR by markings on a sight glass above the vertical jet that were determined by the amount of head pressure on the jet with that level of fluid in it. A horizontal jet is used like a float bowl, and determines the rate at which fuel can enter the bowl.
This level CANNOT be altered based on fuel type.
So no, the octane ratings in that paper are not correct, and the test methods used have been deemed incapable of testing ethanol based fuels.
P.S. I'm drunk and probably F*cked some of that up.
Wish I could see those doc's.. None of the links work for me.
But regardless, what does how someone else tested the fuel have to do with how the test we are talking about here was done?
They tested at the correct stoich AF ratio's based on the blend used. It's specifically states this in the report and on the graph pictured. I'm sure more knock suppression could be attained by testing at peak power air fuel ratios. But the non linear octane knock suppression would follow the same trend. Teh test is accurate and clearly shows there is not much knock benefit beyond 50% blends in the ranges they tested.
No, this was not a performance/race driven test... But it does clearly apply and is still useful and accurate information. MANY of us are using much lower blends with great success these days. Where originally every one was sweating over the 70% winter blends thinking their engines would suddenly knock to death. Which is clearly not the case for the vast majority of builds. I won't say there's no benefit to say 100% ethanol over E50. But for practicality on basic street hot rods E50 will suffice for many.
I’m not flex I use the test kit. Currently I always run 50 percent by diluting with 93 octane. When ever I’ve changed percentage I calculate the stoich and change only the stoich in my tune and my fueling has always been dead on doing this. I’d say the test kit is accurate.
I’m not flex I use the test kit. Currently I always run 50 percent by diluting with 93 octane. When ever I’ve changed percentage I calculate the stoich and change only the stoich in my tune and my fueling has always been dead on doing this. I’d say the test kit is accurate.
Ditto. Although I dropped and busted my test kit...….of course.
If, a big IF, we get to race this year I plan to turn mine up to 26psi or so. I've not yet tried mixing the fuel down. How hard do you run yours?
Wish I could see those doc's.. None of the links work for me.
But regardless, what does how someone else tested the fuel have to do with how the test we are talking about here was done?
They tested at the correct stoich AF ratio's based on the blend used. It's specifically states this in the report and on the graph pictured. I'm sure more knock suppression could be attained by testing at peak power air fuel ratios. But the non linear octane knock suppression would follow the same trend. Teh test is accurate and clearly shows there is not much knock benefit beyond 50% blends in the ranges they tested.
No, this was not a performance/race driven test... But it does clearly apply and is still useful and accurate information. MANY of us are using much lower blends with great success these days. Where originally every one was sweating over the 70% winter blends thinking their engines would suddenly knock to death. Which is clearly not the case for the vast majority of builds. I won't say there's no benefit to say 100% ethanol over E50. But for practicality on basic street hot rods E50 will suffice for many.
Most of the results from that chart aren't from the test they were posted on. Those were pre-determined values.
The octane wasn't determined during that test, the number was taken from the SAE database using the ASTM test methods that the SAE themselves have since claimed are inaccurate and cannot be used.
Like I said, that test was from 2010 and the data on the chart is even older. The ASTM has revised the scope of the methods used SIX times since then, mostly due to the inaccuracies of testing fuels other than gasoline.
This wasn't "someone else'. This was literally the same groups of people that designed the test methods and conducted them now claiming them as unfit to test ethanol.
Its hard to see the benefits over 50% in the test that chart was taken from because they didn't experience knock at 50% ethanol, so obviously a benefit at 85% isn't going to be seen.
There was ONE instance of knock with E50 in the test conducted, and E85 didn't see any knock with FOUR MORE DEGREES OF TIMING.
People seem to largely misinterpret both the reason for the test and the data pre-provided and collected.
That "test" everyone seems to be barking about that couldn't provide benefits for E85 compared to E50 needs to be taken with a grain of salt.
The results were INCREDIBLY circumstantial and the internet caught a glimpse of a chart from that test and spread it like wildfire.
I mean cmon, do you really believe the E85 only has an octane rating of 95?
The ethanol blend percents were calculated because they were using 2 sets of injectors, one with E85 and one with gasoline.
The octane numbers in the table were not the octane numbers for the fuel, but the octane numbers give by that specific test.
They were also using much more ignition timing with E85 compared to E50, such as the 2000 RPM loaded test for 12.78:1 compression ratio where they used 15 degrees of advance with E50 and seen knock, but did not get any knock at 19 degrees with E85.
Even if the octane difference between E50 and E85 really was insignificant (its not), there would still be benefits with E85 from thermal capacity increases and the fuel cooling effect.
I'm sorry but you need to get your facts straight
That Delphi study was excellent and I am looking at it right now
The low RPM high compression is ideal to test the knock threshold
Your claimed 2500/12.78 wot test both achieved MBT timing..... Without knock...... They just took diffent ignition lead to achieve
There is not a single operation that e50 or e85 was knock limited from achieving MBT
That study is amazing. You can see the BSFC differences in the fuel and the mean cylinder pressures (tq) of each
Each fuel was attempted to be run at MBT on all load configurations and fuel
Ditto. Although I dropped and busted my test kit...….of course.
If, a big IF, we get to race this year I plan to turn mine up to 26psi or so. I've not yet tried mixing the fuel down. How hard do you run yours?
The local track just outside city limits is open this Friday. It's going to be nuts so I'm skipping this weekend. I should have my new ET street R's next week and hope to go the following Friday for street car night. I only have about 350 miles on it since I built the motor. I wouldn't say I run it hard, but I don't baby it. It gets spun to 6800 rpm at least once every time it leaves the garage now. No 4th gear to wide open down shifts to 2nd blowing the tires off hitting the limiter immediately type of abuse though...LOL.
Calculation for determining stoich based upon alcohol percentage:
[(9 X alcohol percentage) + (14.68 X gas percentage)] / 2 = Stoich
They were also using much more ignition timing with E85 compared to E50, such as the 2000 RPM loaded test for 12.78:1 compression ratio where they used 15 degrees of advance with E50 and seen knock, but did not get any knock at 19 degrees with E85.
04-24-2020, 02:14 PM
