e85 + 3.0 + megasquirt - whats needed

[Sundance 6g72]

So ive been doing alot of thinking lately about e85 when i should really be thinking about how im going to get my motor back in the car before the weather gets really nice.

Im curious about e85 and whats needed to run it.

From my understanding, for my car to do 350whp, my walbro 255 that i have to install, 42# injectors (stock fuel pressure regulator), stock fuel lines, will be enough.

My first setback is how to actually tune e85. I know it burns at different air fuel ratios but the lambda values are the same?

so 14.7afr for pure 93 octane is 1 lambda but for e85 1 lambda is 9.7. I get this.

my first problem with that was that my wideband only goes to 10:1 BUTT i kept reading and found that my wideband is for gasoline and it really reads lambda values and then converts them to gasoline AFR values. So when im tuning for cruise with e85 i want the wideband to read 14.7 afr because that means the sensor is reading 1 lamda and i happen to really be at 9.7 afr but the gauge says 14.7 because it dosnt know that im not running gasoline anymore?

if this is true, tuning WOT to 12:1 AFR would actually mean my afr is around 8.5 due to the car burning e85 (or close to that?)


i guess what im getting at is do i tune the car as if its on gas? do i tune so my cruising afr is 15:1 and my WOT is 12:1 and not worry about what the real afr is because it should be the same because its the same lamda values

makes my head spin

i found this too




comments, suggestions, questions?

[c2xejk]

I think for the MS you just need to change the fuel setting to be e85. May have to change the AFR table. You should not mess with the VE table.

Not sure about your wideband, but I believe my innovate can be configured to read for e85. Remember that the wideband is reading excess O2 in the exhaust stream. It then maps that back to the AFR.

[Sundance 6g72]

the wideband should be reading in lambda though. so 1 lamda for gas is 14.7afr but for e85 its 9.7

i think my gauge will read 14.7 because thats how my wideband is setup to read.. so im thinking just tune to gas afr numbers. What i want to find out is this, does the prosport controller send lamda data to the megasquirt or does it convert it to AFR first and then send it to the megasquirt.

i have not looked at the MS settings yet but i figued i would just change settings, not ve values.

[Sundance 6g72]

so i just comfirmed that my current wideband is okay. once you understand how it all works you start to understand it. ill be tuning so my AFR values look correct for that of a gas engine and ignore the fact that the real afr is much "richer"

http://www.hptuners.com/forum/showthread.php?t=22372

[RoadWarrior222]

Yes, O2 sensor is an electrical cell activated by the presence of O2, it has 2 sides to it, backside and in the pipe, 2 cells, where the backside one is the reference as to how much O2 is actually in the air, and the inside one is how much is actually in the exhaust. So these are biased to give a value for how much O2 is remaining out of how much was there in the first place.

[Sundance 6g72]

yeah i get that. And now i understand that my gauge will distplay the same GAS afr and thats how i should tune the car

so im shooting for 15.5 gas afr during cruise and 12:1 gas afr during boost. Evo guys are talking about getting knock in the low 11 and 10 gas afr areas and leaning out to high 11s and mid 12s helps alot and usually eliminates it. they also say that they can run any timing they want and wont knock so they have to be extra carefull not to go past the MBT timing (timing where they see max TQ)


so im thinking 12:1 afr and maybe a few more degrees of timing in the boosted areas. Reason for this thinking is that my restrictive manifold, 13:1 afr spike and "high timing" only damaged one piston on 93 pump. I wont touch timing after that until i get knock detection figured out.

[Ondonti]

Evo guys are also using knock sensors that are probably worthless at those power levels. More likely they are suffering spark blowout when they run richer. It is well known that Alky can make better power compared to gas when run lean. This means you can be safer and not suffer as much power loss. Rich mixtures are hard to light. Thats why huge amounts of meth injection is hard to light off for me.

[Sundance 6g72]

i was thinking about that

if 14.7 gas afr is really 9.xxx e85 AFR then 10.9:1 gas afr is INSANE for e85. its funny reading threads that DSM guys post when making the switch, wondering why their car runs like --- when they have it tuned to the mid 10:1 gas AFR while running e85.

[c2xejk]

In a lot of ways, Lambda is probably a better way to read the AFR. I haven't switched because AFR is so ingrained in my head.

Some peoples confusion problably comes from a lack of understanding of what the number represents. AFR is the actual ratio of the Air to the mass of the fuel. That assumes a particular BTU/lbs of the fuel. Alcohol has a lower BTU and to further complicate thing, alcohol also brings oxygen with it. Thus max power for e85 comes when you add more fuel than just the BTU rating would suggest... As you might guess, you can make more power with e85 even with all else (ie. spark advance) being equal...

[TainterRacing]

The turbo you are running I dont think its going to help much you need to get a larger turbo to realy get advanteds with the E85.

[Sundance 6g72]

edit: i agree completly. if we learned on lamda, it would make more sense though i have no problem pretending its the same as gas. not like you can tune it wrong. pop e85 in and your gas tune will sudenly be very lean... add fuel and BAM your back to your gas AFR right where you want them.

i talked to DIY,they suggest just adding fuel via the VE table and changing no other settings. i like this idea because it will be easy to import and export VE and spark tables. Also have the option of the external switch that will change the spark and ve table for you with the table switching setting.



Tainter, I agree but here is my thoughts. e85 will help any car really, but with my turbo i cant take my motor as far as brent did with his e85 motor. If i go bigger turbo (IF) then itl come with regrind cams, and ill make a full 3inch downpipe (now 2.5.... :/ )

but this thread is about 3.0 + e85 in general, not just my car.

[RoadWarrior222]

. pop e85 in and your gas tune will sudenly be very lean...

Apparently this works rather well on older N/A cars with stupider 'pooters, i.e. pre-OBD2 mostly, the trick being to use about half and half with regular, can improve gas mileage quite a bit (Though dunno if it does much for power)

[c2xejk]

edit: i agree completly. if we learned on lamda, it would make more sense though i have no problem pretending its the same as gas. not like you can tune it wrong. pop e85 in and your gas tune will sudenly be very lean... add fuel and BAM your back to your gas AFR right where you want them.

i talked to DIY,they suggest just adding fuel via the VE table and changing no other settings. i like this idea because it will be easy to import and export VE and spark tables. Also have the option of the external switch that will change the spark and ve table for you with the table switching setting.

While you can do that, I think it is a very KLUDGED way of dealing with the issue. VE is the volumetric efficiency of the engine, that does NOT change with a change in fuel. Also, if you make a change to the engine that does legitimately change the VE table, you have to tune it in two or more tables...

I would think a better solution would be to change the injector sizing...

Even better would be software support for fuel type (straight gasoline, e5, e10, e15, e20, ..., e85) I think during drag week we were getting different ethanol levels in some of the fuel and that was messing with the VE tables causing us to have to retune them when we would likely have been better off saying, we just added e10 to a 1/4 tank of straight gasoline so set the MS for e7.5. (maybe tweak that slightly) and not have to be constantly changing the all the entries in the VE table.

[Sundance 6g72]

hard to say if it helps power without knowing whats going on. from what im reading e85 makes best power between 11.5 - 12.5AFR. they tune for 12:1. This being the evo guys that i have been reading up on.

i can see a car cruising around at 13.5afr running 50% e85 and 50 straight pump would lean out a bit as long as the ecu does not compensate. Only problem with that is the injector pulse width is prolly the same and the leanning out is just an effect of whats going on.. still same amount of fuel being dumped. know what i mean?

thats why a normal modern car would go TOO LEAN and have to be tuned back to where it was by adding more fuel and thats where the bad mpg comes from.

[TainterRacing]

This is info by a guy From another page I go to. Dealing with what you are talking about. He realy knows what he is talking about. He runs a small company making MS hardware and also as done some of the programming for MS.

OK, lots of guys have moved to E85, nothing new there. I think if you read and learn from what they've done the biggest issue they have is having to keep re-tuning, sometimes daily. That's because E85 is rarely E85 in your tank. E85 becomes E70 in the winter months so for a while each spring and fall its not even E85 or E70 in the stations that sell it but something in between. That same constant mixing and dilution happens in your gas tank and messes with your tune. Having AFR targets and a wide band helps because lambda is lambda whether you're running straight gas or straight alcohol so if your fuel trim is flexible enough it can take care of smaller variations. That's what the government is saying when they announced last week that late model cars can handle E15 without problem, the trim is wide enough to adapt. But there is a way better solution, GM and Ford both supply them:



The flex fuel sensor, it constantly measures the refractive index and temperature of the fuel which indicates the ethanol concentration and reports it to the ECU. These are getting common in the junkyards now and on ebay where you can pick up a new one for about $300 or a used one for $100 or so.

So, what good is it unless you have a GM or Ford ECU? Hah! Megasquirt is already set up to read and run one! You do need an MS-2 processor as the MS-1 is already maxed out with features and has no room left.



You can program a linear fuel addition based on frequency output from the sensor (ethanol concentration) AND a linear spark angle or advance addition. You can or need to run more advance with increasing ethanol concentration as it burns slower. Adding this to an MS-2 is cheap too, less than a buck for the resistor and wiring required.



I mounted my flex fuel sensor on the drivers side fender, it needs to be part of the fuel circuit so I've got mine post-fuel rail in the return line. The fuel line is rated for ethanol so that's not going to be an issue but the flex line from the pump to the steel factory fuel line may suffer, I plan on replacing that with the same braided flex line I used from the factory steel fuel line to the fuel rail. Since I was installing the MPI system it was pretty easy to install but I think putting one on a TBI would be straightforward as well. Hopefully this thing will be running shortly and I can report how it all works.

[Sundance 6g72]

edit : i want to look into flex fuel sensor, my biggest holed up is how to get the outputs setup on the MS box its self. All my wires are used up (unless the flex fuel sensor will run on my idle valve wires. I dont use those, got through the winter just fine without it and the car was flawless all last summer)

While you can do that, I think it is a very KLUDGED way of dealing with the issue. VE is the volumetric efficiency of the engine, that does NOT change with a change in fuel. Also, if you make a change to the engine that does legitimately change the VE table, you have to tune it in two or more tables...

I would think a better solution would be to change the injector sizing...

Well think of it like this. does VE of an engine change just because you tuned it from 13.2afr to 12.5? The VE would increase even though you did nothing to improve VE.

point being that the ve table should just be called the fuel trim table or something like that (in my opinion) because its not an exact representation of volumetric efficiency.

Injector sizes would stay the same in most cases. for me, i would just tune my gas tune on my 42-46# that i plan on getting and then fill up with e85 and make a second ve table for the e85. the only variable changing would be the type of fuel used. both tables will have the same injectors.

Even better would be software support for fuel type (straight gasoline, e5, e10, e15, e20, ..., e85) I think during drag week we were getting different ethanol levels in some of the fuel and that was messing with the VE tables causing us to have to retune them when we would likely have been better off saying, we just added e10 to a 1/4 tank of straight gasoline so set the MS for e7.5. (maybe tweak that slightly) and not have to be constantly changing the all the entries in the VE table.

we do have the option to run a flex fuel sensor. Im curious if the big block guys running MS had this happening? i think it was something different but its worth looking into.

[c2xejk]

Well think of it like this. does VE of an engine change just because you tuned it from 13.2afr to 12.5? The VE would increase even though you did nothing to improve VE.

VE does NOT change because you change the AFR. Power may change, but not VE. To change the AFR at a particular operating point, you change the AFR table NOT the VE table...

point being that the ve table should just be called the fuel trim table or something like that (in my opinion) because its not an exact representation of volumetric efficiency.

Actually it is a representation of volumetric efficiency of the engine. The problem is that to tune it properly, you need a motoring dyno so that you can hold an operating point long enough to factor out the dynamic effects so you can set the static VE for that operating point.

Injector sizes would stay the same in most cases. for me, i would just tune my gas tune on my 42-46# that i plan on getting and then fill up with e85 and make a second ve table for the e85. the only variable changing would be the type of fuel used. both tables will have the same injectors.

Changing the injector sizing would be a more accurate way of dealing with the problem (and quicker) than monkeying with the VE table. That said, I think I need to dig into the flex fuel sensor. That may help stablize the tune...

Anybody have an idea how accurate the sensor is in the 0-20% ethanol range? (common non-e85 fuel alcohol content levels) More research to do

[Sundance 6g72]

VE does NOT change because you change the AFR. Power may change, but not VE. To change the AFR at a particular operating point, you change the AFR table NOT the VE table...

huh? you just lost me..

if im cruising at 35mph at 2000rpms taking in 35kpa and going steady. Im at an air fuel ratio of 13.9:1. To rich for cruise. My afr table would be saying 15:1. I could let the closed loop settings lean it out for me but id like to get it closer to 15 before i turn closed loop on. I take the laptop and i lower the VE value of 2000rpms x 35kpa until i get close to 15:1, then i call it good.

i dont see how changing the 2000rpm x 35kpa cell in the afr table would do anything to change the tune other than telling the closed loop settings what you want the car to be at.. even then the closed loop settings change the ve cells until they get you close to your afr target.


as for changing the injector sizing, you mean lying to the MS and saying your injectors are different even though you really didnt change them? that could work too.

[TainterRacing]

Anybody have an idea how accurate the sensor is in the 0-20% ethanol range? (common non-e85 fuel alcohol content levels) More research to do

Flex Fuel Sensor Technical Specification
Measuring range: 0…100% Alcohol (ethanol) in fuel mixtures
Sensor Accuracy: ±5% of the mixture ratio
Output characteristic: Linear
Operating temperature: Environment ‐40°C… +125°C, Fuel ‐40°C… +90°C
Maximum fuel pressure: 10 bar, (145 psi)
Maximum pressure drop: 0.1 bar, (1.45 psi)
Maximum flow: 200 l/h
Supply voltage: 6…18 VDC
Sensor Temperature error: <± 1.5%
Response time: < 250 ms after power on at any temperature

[Sundance 6g72]

one thing i want to say. If fuel companies are putting 10% ethenol into pump gas, it should change our WOT tune on the stock ecu sense that is not tuned by the ecu

I never noticed any difference when going WOT with the sbecII. I had ran normal gas, premium gas, and 100% gas no E added.. always had a 13.2 AFR no matter what as long as i was WOT. Makes me want to say that the 0-10% added to some of the gas did not effect the tune much at all.

So going from e80 to e85 and then to e70, i am not worried much. Another cool thing is that motors dont tent to detinate with e85. so if you tune e85 to 11.8:1 afr and the next day your running e95, your tune will lean out a little but not enough to cause problems as far as damage to the engine goes. same goes for e70, you would richen up but still have power. I too would like to have a perfect tune when going from e70 to e85 or even higher, so the flex fuel sensor would be nice. but from a durability of the engine standpoint, im not worried.