What is the afr for a E50 blend of fuel? I would like to use this blend in my engine.

That is uncharted fuel

I noticed that. I can't find much on the web either. Surely someone knows.

Set your O2 setup to Lambda if it's capable, then it won't matter what fuel. I find .83-.85 usually works for E fuels.

No such luck. Now what do I do?

Why bother with e50? That sounds like alot of work to mix e85 with 93 if perfect portion for that.


Just run e85, enjoy cooler water temps, more power, and cheaper fuel prices.

Blender pump. Does it for you.

I still don't see the benefit. E85 is cheaper, you can buy it at a pump and pump it directly in a car, plus you get all the benefits of an alcohol based fuel.

Not much cheaper, 5 cents, but is cheaper. E50 comes from the same pump as E85, hence the blender pump, and pump it directly into your car. About the same octane as e85.

I wouldn't waste my time on trying to learn how to tune that, how can less alcholol content have the same octane, or almost as much octane as E85 I run straight pump E85 in my high compression(14.5 to 1 ) bracket motor If E98 was availble locally I would race with that

The AFR for E50 is 11.9. Max power would be AFR 10.2

I agree it's easier to use Lambda, but for initial settings you may need the AFR for calculations.

Here is complete info for you:

Octane is irrelevant with ethanol based fuel.

Why is that?

Lets say you run E-50 fuel, what adjustments, IFR, IAB, MAB, boosters, or any other drilling needing to make it work?

You can't use those numbers unless the AFR gauge is calibrated for the stoich of the fuel. In other words a gas scaled AFR gauge is calibrated for 14.7 as stoich for the fuel. The easiest way to use a gas gauge is to divide the observed number on the gauge by 14.7, that will give you the Lambda number. On a gas scale shoot for 12.2-12.5 as a starting point, jet for best performance from there.

Mark,
12.2-12.5 is for max power right? What would be used for idle and cruise?
Ed

x2. If you're using a wideband that can't be set to lambda, it's likely that a/f ratio can't be set for different stoich points either, so you'll be stuck using the gasoline scale.

The Lambda sensor measures the contents of the exhaust gases and when the combustion is optimal all oxygen is used in the combustion process. This is Lambda=1. Then for those people who want to use the old AFR value, you have to program in the stoiciometric value for your type of fuel. Based on the Lambda value measured, the AFR value is then computed based on the stoiciometric value programmed, and displayed if so chosen.
A Lambda sensor (AFR gauge) is calibrated in free air, not with any relation to the fuel type used.

Pump gas was sooooo easy for me but now with alcohol I'm still trying to learn it. I ran (2) 6.10@112mph yesterday and a 9.66 and 9.65@137mph after leaning out my alcohol 850 carb from 154 jets to 150 jets. My racepak is switched over to the alcohol scale and I'm STILL reading 4.90-5.10 on the O2 reading during a pass. Hard to believe I'm still rich.

Jet and tune for max MPH in the 1/4 mile, correct? The spark plug and time slip will tell you what your combination likes and wants

Here is an example from today:
I'm using a wood burning stove to heat my house. The same Innovate MTX-L AFR gauge is used both with the stove and with alcohol and gas powered engines.
- The Innovate MTX-L doesn't know it's reading the exhaust gases from burning wood, all it cares about is the contents of the gases in the exhaust. When it measures Lambda=1, all is well, doesn't matter if you are burning wood, ethanol, gas, nitro or whatever.

Why make things complicated with AFR?

I don't need to know the stoichiometric value for burning wood, I don't need to know it for ethanol, I don't need to know it for gas...all I care about is Lambda, and that's what the AFR gauges with oxygen sensors are measuring. If interested, one (or the gauge) can then compute the AFR...

With an Innovate or some others that's correct, however if his O2 system is set for typical gas stoich at 14.7 your table has no value. Sensor calibration is done in free air, however the gauge calibrations if set and unchangeable at 14.7 (equaling a 1.0 Lambda) will suggest a starting point reading around 12.2 to 12.5, which translates to .83 to .85 Lambda. Those are safe starting numbers, jet from there as needed for best performance.

I agree the 12.2 can be used as a starting point, but with E50 it will be lean, and even more so with 12.5.

As far as I can see the table I published is correct:
- Stoich for E100 = 9.0
- Stoich for pure gasoline (E0) is 14.7

With a 50% mix (E50) the stoich (Lambda=1) will be (14.7-0.5(14.7-9)=11.85, shown as 11.9 in the table.

For max performance with E50 we aim at Lambda = 0.85, which gives us roughly AFR = 10.1 with E50, shown as 10.2 in the table (Lambda target unknown for WOT in the table).

So in my opinion the table is correct, and an AFR gauge set to stoich 14.7 for pure gasoline, should display AFR = 10.1 for max power at WOT with an E50 mix. For ideal combustion (Lambda = 1) it should show AFR = 11.9

The table is correct, however... it would only show an AFR = 11.9 at stoich if the meter can be rescaled to represent E50. Mark is assuming the meter can only read on the gasoline scale. If it is, the meter is going to be reading 14.7 at stoich regardless of what fuel you're using if you do not have the ability to adjust the AFR scale.

Especially with an oddball fuel like E50, I would suggest buying a meter that can be set to lambda, it'll be much easier to comprehend instead of trying to back calculate AFR targets when it's not displaying the correct scale.

Correct, his gauge can't read Lambda, so the assumption that it is fixed at 14.7. With E50 it should actually run leaner than with E85, the higher percentage of gas will need less fuel. Straight gas will be anywhere from 12.8 to 13.2 depending on vaporization properties of the gas and the distribution ability of the engine. A very efficient engine can even run well up into the high 13 range. 12.5 will be more than safe with E50, what it wants in the end is up to the engine. The AFR in the 10 range will only work if the gauge can be calibrated to register a stoich value of 11.9.

Yes, you are right, I (finally) see the point with the non-programmable scale...