criptballer

iTrader: (3)

so I recently decided to get a set of DW 1000 cc's and switch over to e85. I decided to start doing some research on the properties of e85 compared to that of gasoline and found some interesting stuff. but when it came down to actually getting a plan together for tuning it, I could't seem to find straight answers. So I'm writing this in hope of it being useful to somebody like me that has questions as to what "afr" they should tune to.

Whenever i have a question about cars i turn to my buddy J.R. this was not an exception. i asked him what the stoich afr of e85 was and he mentioned about 9.0. so i said cool. then i started doing some research on the forums and found that some gurus were running different numbers than these. the more i read the more i got confused. some people were running 6.0 others 11's and others even 16's! well to my shock they could all be right or wrong. i did more in depth research and even ended up talking to guys at aem. turns out that the AEM widebands have a little "nob" that can be adjusted with a flat head screw driver and it gives you different readings for different purposes. now not a lot of people know this apparently, at least people i talk to. So i started thinking, those forums of the gurus never mentioned changing their calibration of the AEM wideband.

If you have a new wideband, I would highly recommend tuning with and to lambda and forget about afr's period. afr's mean nothing. i can have a perfectly stoich car at 30 afr's if i want to, all i would need to do is change the equation that the AEM wideband reads with. Interestingly enough, after reading the "how to" install article provided by AEM i found that the equation the Wideband comes with from the factory is (lambda x 14.7 = AFR) which makes sense because most people use it to tune their gasoline powered vehicles. so what does this mean excatly?.... this chart should help



so, since i bought my wideband used, i don't have the different face plates that they come with new (which should include a lambda face plate). but not to worry, it doesn't matter. the wideband is dumb. it doesn't know what fuel you're feeding the car nor does it care. all it cares is about lambda! and what do we know, we know that 1 lambda will always be stoich! in any fuel! it doens't matter. hence the equation, lambda x 14.7= afr. so this means that if i put e85 in my car and log it with my AEM gasoline calibrated wideband, i should still tune for 14.7 stoich!! the difference comes from the best power ratio of e85 to gas. gas is 12.5 (varies a little depending on car obviously) and i believe e85's is .7 lambda which equates to about 11.2-11.5. now as to how safe that actually is, i don't know. so i'm going to shoot for 10.8 and go from there. sorry for the quick and sloppy write up but i thought i'd share my thoughts and findings and hopefully someone benefits from it.

cfdfireman1

iTrader: (11)

Good place to do some more research. http://www.innovatemotorsports.com/forums/index.php

goofygrin

iTrader: (5)

As I posted in your other thread on the other site:

Assuming you're using the 14.7 gas range, 10.8 is rich even on gas... 11.5 is typical for EvoX's and near 12 for E85. That's what I've seen in my reading/tuning.


There is a wealth of information already on EvoM: https://www.evolutionm.net/forums/alternative-fuel-225/

criptballer

iTrader: (3)

replied to on other thread

TTP Engineering

iTrader: (465)

Gasoline calibrated widebands can be tuned on different fuels if you know what you are doing.

criptballer

iTrader: (3)

^+1

mrfred

iTrader: (50)

I wouldn't say there's any misconceptions about tuning E85. There could be some potential confusion though about how people are reporting AFR. On EvoM, pretty much everyone reports E85 AFRs using widebands set to gasoline calibration. Once that is understood, I think you'll find that there is broad concensus that the optimum AFR is somewhere between 11.5 and 12.5:1.

criptballer

iTrader: (3)

same as gasoline? how can that be? it doesn't chemically make sense... how can peak hp burn be the same as stoich or even a little leaner.... that would be like saying gasoline makes the best power during wot at 15.3...

mrfred

iTrader: (50)

A gasoline AFR of 12:1 represents a lambda of 0.82. E85 has a max power lean lambda of 0.88 and a max power rich lambda of 0.71, so 12:1 gasoline calibration falls within the optimum lambda range for E85. Its slightly to the lean side of the range because in practice, knock is reduced at leaner AFRs with E85. It truly is amazing stuff for forced induction motors.

criptballer

iTrader: (3)

wow ok. i'm learning something here. so where in gasoline the max power rich side is less prone to knock, the opposite holds true with e85? meaning the richer max power lambda is more prone to knock than the lean side? oh yeah, and referring back to the chart i posted, isn't .82 lambda more towards 11.6 afr in a gasoline calibrated wideband, according to AEM?

edit: never mind i was looking at volts not lambda on that last part. disregard that.

mrfred

iTrader: (50)

Going lean on E85 is definitely counterintuitive, and can get a person if trouble if they don't recognize what's happening. Knock goes away pretty much entirely, so knock can no longer be used as a tool to setting the maximum best timing. Instead, timing has to be tuned based on power. On the rich side of optimum, there is an increased tendency for mild knock across the rpm range. I haven't seen any examples of sharp knock like what can be seen when pushing gasoline too lean.

scorke

iTrader: (18)

Knock should never be used as a tool to set MBT. If a car is octane limited the knock threshold usually occurs close to MBT for that particular car, but even still the only way to do that properly is on a dyno.

The "add timing till it knocks then remove a degree" attitude is like going to a barber shop that uses a hedge trimmer instead of scissors.

I had a great learning experience when I was tuning a car that continued to make more and more power as timing was increased, even though more signifigant knock was occurring as the timing was being added. Anybody want to guess what was causing that to happen?

Took me a while to figure it out


Scorke

criptballer

iTrader: (3)

Tell us tell us ....

crcain

When you say "more significant knock" were you simply relying on the ECU's knock sum? Or where you monitoring the engine with det cans?

crcain

To the OP.. using lambda is nice, but you have to remember any AFR number for a specific fuel has a lambda number equivalent, so they are just different ways of expressing lambda.

If someone says they tune E85 to 12:1 gasoline AFR, it may not be sematically correct, but it gets the point across just fine. What they should say is the lambda equivalent of 12:1 gasoline afr. But most widebands read in gas afr, most people are used to the numbers, so people use it, and it works just fine.