:::RHMT::: Real Home Made Turbo
General Category => Engine Management => Topic started by: snm95ls on February 07, 2010, 08:37:42 PM
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Since it has been brought up, and I have one that I am supposed to tune on E85 when it gets warmer, let's discuss what should be done when using E85.
Obviously A/F ratios are different, but when using lambda, you essentially use the same targets, no?
What does the lower energy density mean as far as a tune goes.
I ASSume that burn rates are quite a bit slower as evidenced by the much higher octane rating, so much more ignition timing is needed.
JD and others, input?
Unless others get to it before me, I will try to compile some basic info so that we can have it all in one place when time allows.
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Obviously A/F ratios are different, but when using lambda, you essentially use the same targets, no?
Just use gasoline AFRs if you are more comfortable with them; while not exactly "correct" the equivalent lambda is the same.
11.5-12:1 and you should be fine.
What does the lower energy density mean as far as a tune goes.
It means you need a larger volume of E85, compared to gas, to react a given quantity or air. Otherwise the AFRs would be the same, right? :P
I ASSume that burn rates are quite a bit slower as evidenced by the much higher octane rating, so much more ignition timing is needed.
Not really. To quote directly from the bible of Sewell, E85 likes lots of part throttle timing, advancing the low rpm pre-boost timing results in a gain, but under boost keep the ignition timing similar to gasoline. He, and others he's talked to, say that the richer they run E85 the less timing it seems to like. I've only done one car so far, and it's been through the street portion of it's tune and not been to the dyno yet. So far, Tommy's steered me right.
Oh, yeah, the cold start/enrichment settings are off the hook. Remind me to get screenshots.
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Good to know about the ignition timing, JD.
I ASSume that you say use gasoline AFRs because the ratio displayed by a wideband is just a calculation from lambda?
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Personaly with fuel like that as well as high octane leaded fuels I tune in lambda settings.
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The only thing I've heard about the stuff is you need 33-36% more volume of fuel, when switching from gasoline.
Apparently it doesn't thermally load your motor at all. Ideal for a bracket car that may have to go many rounds back to back to back...
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Long info and discussion on NASIOC.
http://forums.nasioc.com/forums/showthread.php?t=803341 (http://forums.nasioc.com/forums/showthread.php?t=803341)
Just switched over to E85 today finally. running four 800 cc injectors @ 80% IDC and a fifth at ?idc and I am maxed out at 21-22 psi.... Have to re-install the damn fuel pressure guage to see if I am maxing out the Walbro.....
But at 12.5-1 AFR, 24 timing, I an not getting knock!
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I ASSume that you say use gasoline AFRs because the ratio displayed by a wideband is just a calculation from lambda?
(12/1)AFR/(14.7/1)AFR ~ .82 lambda
(8/1)AFR/(9.8/1)AFR ~ .82 lambda
When most widebands don't display other-than-gasoline AFRs it makes sense to use the familiar gasoline AFRs, even if that isn't the *real* mixture.
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I've done tons of e85 cars. Quite a few where i tuned them on gas, then switched to e85.
When i first started swapping them over from 93 to e85 i would add 30% more fuel and added 4 degrees to the whole map and it seemed to get the car dialed in pretty good. keep your AFR just like gas and your golden. Thats the easiest way to get rolling on e85 if your a beginner on e85.
Like jd said, now i usually add a bunch of timing down low and lean on the AFR during cruise. Up top i've been keeping the timing like gas. Its different from others have been doing, but has been working for me and my peoples :)
I CANT STRESS THIS ENOUGH. CHANGE YOUR FUEL FILTER AFTER SWAPPING OVER AND KEEP AN EYE ON YOUR FUEL PRESSURE. MORE THAN LIKELY THE FILTER WILL NEED TO BE CHANGED AGAIN , I RECOMMEND CHANGING IT AGAIN IN A THOUSAND MILES OR SO.
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Awesome! Thanks for the input, Tom.
:noel:
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I ASSume that you say use gasoline AFRs because the ratio displayed by a wideband is just a calculation from lambda?
(12/1)AFR/(14.7/1)AFR ~ .82 lambda
(8/1)AFR/(9.8/1)AFR ~ .82 lambda
When most widebands don't display other-than-gasoline AFRs it makes sense to use the familiar gasoline AFRs, even if that isn't the *real* mixture.
Good tid bit to know. I've turned down a few guys wanting to tune on e85 because my wideband only reads in gasoline afr's. I'm guessing 9.8:1 is the stoichiometric value for e85?
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I CANT STRESS THIS ENOUGH. CHANGE YOUR FUEL FILTER AFTER SWAPPING OVER AND KEEP AN EYE ON YOUR FUEL PRESSURE. MORE THAN LIKELY THE FILTER WILL NEED TO BE CHANGED AGAIN , I RECOMMEND CHANGING IT AGAIN IN A THOUSAND MILES OR SO.
One of those items no one EVER tends to remember....
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I ASSume that you say use gasoline AFRs because the ratio displayed by a wideband is just a calculation from lambda?
(12/1)AFR/(14.7/1)AFR ~ .82 lambda
(8/1)AFR/(9.8/1)AFR ~ .82 lambda
When most widebands don't display other-than-gasoline AFRs it makes sense to use the familiar gasoline AFRs, even if that isn't the *real* mixture.
Good tid bit to know. I've turned down a few guys wanting to tune on e85 because my wideband only reads in gasoline afr's. I'm guessing 9.8:1 is the stoichiometric value for e85?
Stoich will still be 14.7 if you leave your wideband to read gasoline AFRs. All the gauge does is receive Lambda, and convert it to whatever numbers you want. So regardless, stoich is 1.00 and translated to 14.7 for you to read. In boost we have my car tuned for 11.5-12.0:1. It may vary, dependent on the season or time of year. In the winter, the mixture usually goes from 85%-15% to 70%-30% for cold start ease. The closer to summer, the more ethanol.
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I ASSume that you say use gasoline AFRs because the ratio displayed by a wideband is just a calculation from lambda?
(12/1)AFR/(14.7/1)AFR ~ .82 lambda
(8/1)AFR/(9.8/1)AFR ~ .82 lambda
When most widebands don't display other-than-gasoline AFRs it makes sense to use the familiar gasoline AFRs, even if that isn't the *real* mixture.
Good tid bit to know. I've turned down a few guys wanting to tune on e85 because my wideband only reads in gasoline afr's. I'm guessing 9.8:1 is the stoichiometric value for e85?
Stoich will still be 14.7 if you leave your wideband to read gasoline AFRs. All the gauge does is receive Lambda, and convert it to whatever numbers you want. So regardless, stoich is 1.00 and translated to 14.7 for you to read. In boost we have my car tuned for 11.5-12.0 (read in gasoline AFR).
It may vary, dependent on the season or time of year. In the winter, the mixture usually goes from 85%-15% to 70%-30% for cold start ease. The closer to summer, the more ethanol.
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Oh, yeah, the cold start/enrichment settings are off the hook. Remind me to get screenshots.
troof.
it'll start all the way down below freezing, but you have to DUMP fuel. i think i have the crank enrich as much as 300% above stock at lower temps, but the car fires right up regardless of ambient temp.
the issue is the low reid vapor pressure of ethanol. it creates much less vapor (the part that actually burns) at lower temps, so you need enough liquid to generate the vapor to saturate the mixture.
an engine requires about 2% of the charge volume to be fuel vapor in order to start at -30C (worst case scenerio). cold season E85 can do it with lots of fuel enrichment, warm season E85 cannot achieve 2% volume at such a low temperature. (Aikawa, Sakurai Hayashi; Honda R&D, 2009. SAE 2009-01-0620.)
i've been running E85 for 3 years now. it definitely likes low load timing, and does well running really lean in cruising. last road trip i managed 27mpg highway with the A/C on. i'm running 17.5-18:1 at very low load, keeping it as lean at 14:1 up to 5psi to help spool the turbo. you can pick up a significant amount of mileage by keeping the higher vac areas pretty lean as well. that way you don't start dumping fuel whenever you have to go up a hill or something.
mixing some EGR into there would up the mileage as well. 30mpg highway is definitely a possibility, despite what the anti-E85 folks seem to think.
as far as the fuel filter, i think it varies with the type of car. i've seen DSMs clog the filter in a few hundred miles. my stock toyota filter is perfectly fine after 3 years. i tore the fuel system down before putting the car in storage this winter to gauge the effects of long term exposure to my stock fuel system (hoses, regulator, cast AL rail, WRX injectors, filter) and there are no signs whatsoever of deterioration anywhere in the system. i also didn't have any varnish buildup on the injector nozzle like a lot of DSM guys seem to get. could have something to do with the WRX decapitated injector's spray pattern? dunno for sure.
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RB25DETT startup cal as provided by AEM, they tout these things in their forum as making significantly more power than stock and provide dyno sheets to back it:
(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fi256.photobucket.com%2Falbums%2Fhh166%2Fjoeymisanthropy%2FTuner%2FRB25%2520E85%2FRB25Base.png&hash=3ea03d58f4f192112160f57cd5b4267bf2df776e)
What I came up with with E85 and 1200cc injectors (I think they're 1000's, the owner just knows what he was told)
(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fi256.photobucket.com%2Falbums%2Fhh166%2Fjoeymisanthropy%2FTuner%2FRB25%2520E85%2FRB25E85.png&hash=b03adc850d79b77e55bb33759600536490c906df)
I think it needs a hair more fuel sub-30 degrees.
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Definitely have the same experience with cold start fueling with my E85 setup too.