AFR What you should know.... LONG

i'm back to ask another question.

So when i was tuned, using mostly sunoco 93 in the tank, maybe a bit of ultra 94, all "up to 10% ethanol" my a/f was left at 11.7ish. back home when i am racing, using only ultra 94 "with up to 10% ethanol" i have datalogged my a/f at just over 12, sometimes 12.2, but can vary each race from 11.6-12.2 during a sinlge pass, and some passes it stays below 12 on the same night.

basically what i'm asking is should i be worried, or re-tuning for a bit lower of an a/f?

Sean
 
91 Probe GT said:
What all would a guy have to do to convert and run e85? anything special a guy needs or is it just a matter of pumping more fuel in to compensate for the extra ethonal? Our pumps claim 91 octane with the e10. I have a predator tuner, and my maf extender is only on number 2 right now. I think I have 50lb injectors running a 2.3l kb. Can a guy make more power with a good tune on e 85? I would assume so beings it has a higher octane rating.
Click to expand...

All I do is pump more fuel. In fact, I had my tuner set my Mafia on setting #3 on the pump gas tune. When I put in the E-85 I change the setting to #2 and it runs pretty well like that. My pump gas tune is near 11.0 and the E-85 tune is high 12's to low 13's.
I haven't had a change to strap it back on the dyno to see what the before and after is. However, I have seen turbo cars pick up 10% more power with the E-85 conversion, with the timing and target AFR the SAME! (600 whp 2.0L on 110 to 660 whp on E85).
That being said, if you are comparing the max safe power on pump gas with the max safe power on E85, then yes you can make alot more power. At the least, compare the E85 to leaded race fuels for a power comparison. More boost, timing, and a leaner AFR all means more power and is very dooable on E85.
 
lightning25 said:
i'm back to ask another question.

So when i was tuned, using mostly sunoco 93 in the tank, maybe a bit of ultra 94, all "up to 10% ethanol" my a/f was left at 11.7ish. back home when i am racing, using only ultra 94 "with up to 10% ethanol" i have datalogged my a/f at just over 12, sometimes 12.2, but can vary each race from 11.6-12.2 during a sinlge pass, and some passes it stays below 12 on the same night.

basically what i'm asking is should i be worried, or re-tuning for a bit lower of an a/f?

Sean
Click to expand...
It all depends on boost, compression, and timing. As long as you are not detonating, then you will be fine. I suggest you pull the plugs after a full quarter and see how they look. If they are not any specks on them, then you should be fine.
 
Don 95Vert said:
Great discussion! I do have a couple things to add that may make everyone's life a little easier.

It's really, really wise to get a wideband that also reads Lambda. That way you don't ever have to worry about doing some kind of conversion. Because no matter what fuel you are running, the stoich point will always be Lambda 1.0 - and you'll always know that your target lambda will be right. For instance if you are targeting an 11.5 A/F ratio and you want the equivalent A/F ratio with an alcohol fuel, all you do is log Lambda on the meter and look for around 0.79 Lambda and all will be good. As mentioned the 02 sensor doesn't 'care' about A/F ratio - putting it simply it's 'native' language is lambda. The A/F readings you see are based on internal calculations done within the wideband which you a reading for gasoline.

The other thing to consider is, as mentioned, E85, ain't always E85 - in fact here in Ohio, it varies by season, so you may get E60, E70 or maybe E92 sometimes. You never know. And virtually ALL gas nowadays is at least E10, sometimes it's posted on the pump, sometimes it's not.

To be really sure, and on a vehicle tuned on the edge, I always use Zeitronix's new nifty tool - an Ethanol content analyzer - you have to also buy a flex fuel sensor, but it works really well and is a must here up north.

Hope this helps,

Don LaSota
Click to expand...

Thanks for helping make my point. The reason I say to tune your wideband to the same as your gasoline tune is because most people understand 11.8 AFR not .8 lambda.
 
lightningkylej said:
It all depends on boost, compression, and timing. As long as you are not detonating, then you will be fine. I suggest you pull the plugs after a full quarter and see how they look. If they are not any specks on them, then you should be fine.
Click to expand...

so i have another question then.
when i hooked up my a/f ratio gauge, and when i was tuned, the air fuel gauge was never changed for the fuel i was using, the "up to 10% ethanol" ultra 94. we just hooked it up and changed the configuration in the computer and went for a few test runs to obtain an a/f of 11.7.
so would my a/f have been wrong from the start and will me tune be off then?
i'm sure this was already stated, but how do i go about making sure i have the right a/f reading on my gauge for the fuel i am using.

Sean
 
lightning25 said:
so i have another question then.
when i hooked up my a/f ratio gauge, and when i was tuned, the air fuel gauge was never changed for the fuel i was using, the "up to 10% ethanol" ultra 94. we just hooked it up and changed the configuration in the computer and went for a few test runs to obtain an a/f of 11.7.
so would my a/f have been wrong from the start and will me tune be off then?
i'm sure this was already stated, but how do i go about making sure i have the right a/f reading on my gauge for the fuel i am using.

Sean
Click to expand...

Tune your wideband to the SAME AFR no matter the type of fuel.
 
Different fuels have different A/F, but there all tuned for the same lambda.

Wayne
 
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The wideband reads in Lambda then converts to a A/F number.

Let's say you tune for .775 Lambda. What you do is take the Lambda times that by the stoich of the fuel you run, let's say regular fuel 14.64 and you come up with your A/F number which would be 11.346.

Now let's do the same with E10 fuel with a stoich value of 14.08. .775 times 14.08 is 10.912.

Get it now?
 
lightningkylej said:
All I do is pump more fuel. In fact, I had my tuner set my Mafia on setting #3 on the pump gas tune. When I put in the E-85 I change the setting to #2 and it runs pretty well like that. My pump gas tune is near 11.0 and the E-85 tune is high 12's to low 13's.
I haven't had a change to strap it back on the dyno to see what the before and after is. However, I have seen turbo cars pick up 10% more power with the E-85 conversion, with the timing and target AFR the SAME! (600 whp 2.0L on 110 to 660 whp on E85).
That being said, if you are comparing the max safe power on pump gas with the max safe power on E85, then yes you can make alot more power. At the least, compare the E85 to leaded race fuels for a power comparison. More boost, timing, and a leaner AFR all means more power and is very dooable on E85.
Click to expand...

So ur saying that having the mafia on #2 pumps more fuel than having it on #3? i would have thought it would be the other way around? I modified my own tune from the really rich tune that it had. spent about 2 hours on the dyno trying to make it scream on 91 octane. there isn't a good tuner near me and the dyno operator here basically just let me have free reign to adjust my tune.
 
My custom tune is set to #3. So I am going from #3 to #2. That is where I get the extra fuel. The higher the number on the mafia, the leaner the tune (except I believe #6 which is stock plus 5 or 10%). Contraversly, the lower the number the richer the tune.
 
I got retuned for the E85 finally. With 16* of timing ramping to 19* on the stock eaton, 8lb lower, sbtb, patriot stage 2 heads, comp stage 2 cams, and built shortblock. I made 475 HP and 570 TQ. The rest of the tuning will be done at the track. Even with the lower timing, I was able to pass my previous best mph 112.45 to 112.83 on the 1/4 while being in 30* warmer temperatures. The ET's only slightly got better because of the 60ft. Went from a previous best of 12.32 with a 1.78 60' to a 12.29 with a 1.86 60'. And it was 84 degrees out side with high humidity this time compared to mid to low 50's last fall when I did my previous best. My tuner will be going to the track with me in a couple weeks to get it dialed in. I'll post up after that.
 
lightningkylej said:
Tune your wideband to the SAME AFR no matter the type of fuel.
Click to expand...

If I may ask . . .

If i was tuned to 11.712 (0.8 lambda) on unleaded gas, and switched to E10 93 octane, would it mean that i should continue to tune for 11.712 AFR with the E10? (i.e 11.712 divided by 14.08 = 0.832 lambda)
 
Nice Sticky!

I got a simple dumb question:

If i plug the WB sensor on driver side and my injector on cylinder # 4(passenger side) miss, my read will be corrupt on the wideband?

Should we have 2 WB for safty?
 
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