[Mangler]

Originally Posted by 6MTE92

Rump gas?! Say it ain't so!

nitro-methane!!! good catch.

T

[MDORPHN]

Originally Posted by Mangler

Yes *Z is the ethanol content in you pump gas.

T

Oops, missed that! Thanks.

Neil

[ErvGotti]

Originally Posted by Mangler

So if the scalar for 100% E85 is 1.4 but you are running 25% E85, is it 25% of 1.4? The table is written for percentage ethanol up to E85 not percentage E85 in the tank.

So 25% is 1.1
50% is 1.2
75% is 1.3
and 100% is 1.4?

edit: found it:

X = % of E85 added to gasoline
Y = actual % of ethanol in your E85
Z = % of ethanol in your pump gasoline

(X * Y) + ((1 - X) * Z) = overall ethanol content

So if your E85 is really 85%, and your mix is 30% E85 to gasoline, and your gasoline is 10% ethanol from the pump...

X = 30%
Y = 85%
Z = 10%

(.30 * .85) + ((1 - .30) * .10) = .325 or 32.5% ethanol

- Gary

T

Yeah it's tough to accurately predict what the Ethanol percentage is at your pump. I just got a rough estimate in my head assuming that the 93 had 10% and picked a scalar value based on my estimate. The car seems to be running better as far stft fluctuation numbers are concerned with no timing corrections. I'm sure I'll have to adjust my blend come winter time.

[raceyBMW]

Could this also be used to make a race gas map for those of us that don't want to go the E85 route?

[6MTE92]

Originally Posted by raceyBMW

Could this also be used to make a race gas map for those of us that don't want to go the E85 route?

Yes but if your not using oxygenated race gas you wouldn't/shouldn't need to adjust the fuel scalar since it has the same mean gravity as gasoline.

[ErvGotti]

Originally Posted by raceyBMW

Could this also be used to make a race gas map for those of us that don't want to go the E85 route?

Yes. With ATR you basically have access to most if not all of the parameters of the DME. I personally don't think that the tuning strategy for E85 and race gas would be the same though. With race gas you might be able to increase boost and timing with out messing with the fuel scale. I could be wrong though, so your best bet is too log and see what the car is doing. Or get a protune if you're not willing to mess with engine parameters.

[georgelb]

I was messing around looking at different mixes and ended up throwing everything in a spreadsheet, and though some of you might want a copy.


It calculates how much E85 and how much regular gas to put in for the different blends (85-10), and then lists the FSG and SV for each from the help file.


You can also specify the ethanol content for the E85 and the regular gas, if you know it, and any blends you can't hit with that will turn red. Tank capacity can be specified too.


The spreadsheet isn't locked or anything, though some fields for the calculations are hidden.

Download Here


Feel free to modify/etc. =)

[enrita]

Would be great to add conversion to liters as well

[georgelb]

Well it works off of percentages, so plugging 61 into the tank capacity field will give you the correct values in liters; however, I added a units drop down so the headers will change to liters too if you're working in liters.

Where X = Volume of E85

The formula I used for the volume of E85 for any given Final Ethanol % is:

X = ((Final Ethanol% - Gas Ethanol%)/(E85 Ethanol% - Gas Ethanol %))*Tank Capacity

The volume of Gas is then just a (Tank Capacity - X) type formula

[johej]

I was wondering....
Other car brands (Saab f.ex.) can handle any mixture of gas and ethanol.
Eg. E0-E100.

Will we see that soon in our BMW's?

[Dethsupp0rt]

Other than the fuel scalar, what else did Cobb adjust to get the extra 30 HP/TQ numbers? Could this be achieved with just an increase in timing? How much advance did they need?

[cloud_connected]

Originally Posted by Dethsupp0rt

Other than the fuel scalar, what else did Cobb adjust to get the extra 30 HP/TQ numbers? Could this be achieved with just an increase in timing? How much advance did they need?

It would be tuned in a similar manner as meth. More boost and timing.

[Dethsupp0rt]

I've been running 25% E85 with just the aggressive map and a modified fuel scalar, and the car seems happier (and a little stronger). I have an FMIC waiting, so I'd like to try to duplicate those results when I get it and go to Stage 1+. However, being a relative novice, I suppose I should let a pro do it.

[benzy89]

Originally Posted by Dethsupp0rt

Other than the fuel scalar, what else did Cobb adjust to get the extra 30 HP/TQ numbers? Could this be achieved with just an increase in timing? How much advance did they need?

Timing is the biggest factor for that bump in HP ---- PM Jake@PTF if you have some questions & want some very intelligent insight on E85 tuning with COBB

[Dethsupp0rt]

So perhaps increasing load targets slightly in the 2500-5000 RPM range, and bumping the timing 1-2 degrees at max. load in that RPM range as well would be a reasonable place to start?

[cloud_connected]

Originally Posted by Dethsupp0rt

So perhaps increasing load targets slightly in the 2500-5000 RPM range, and bumping the timing 1-2 degrees at max. load in that RPM range as well would be a reasonable place to start?

That would be a good place to start. Remember that you need to increase the timing where the actual load trace is, not just where the requested load is.

[Mike@N54Tuning.com]

Originally Posted by Dethsupp0rt

So perhaps increasing load targets slightly in the 2500-5000 RPM range, and bumping the timing 1-2 degrees at max. load in that RPM range as well would be a reasonable place to start?

With E85 there isn't much of a need for a pro tune. Just add 40% E85, use the S2+ aggressive map and copy the 120 load timing values to columns130-180, change the fuel scalar on bank1 and bank2 to say 1.2, and enjoy a lot more power than their off the shelf maps. You could also lean the air/fuel ratio out if you wanted every last horsepower but the gains there are minimal. The timing curve and fuel scalar are the main things you need to address.

Mike

[harry$]

Originally Posted by Mike@N54Tuning.com

With E85 there isn't much of a need for a pro tune. Just add 40% E85, use the S2+ aggressive map and copy the 120 load timing values to columns130-180, change the fuel scalar on bank1 and bank2 to say 1.2, and enjoy a lot more power than their off the shelf maps. You could also lean the air/fuel ratio out if you wanted every last horsepower but the gains there are minimal. The timing curve and fuel scalar are the main things you need to address.

Mike

Mike, If one were to use VP MS 109 would the same timing curve apply? and leaving the fuel scalar were it is originally?

[eamon]

What wheels are those on the 5 series?

[cloud_connected]

Originally Posted by harry$

Mike, If one were to use VP MS 109 would the same timing curve apply? and leaving the fuel scalar were it is originally?

The timing curve mike suggested is fairly aggressive and i would suggest starting a little more conservative and working your way up using datalogs to be sure the car likes it.

[harry$]

Originally Posted by cloud_connected

The timing curve mike suggested is fairly aggressive and i would suggest starting a little more conservative and working your way up using datalogs to be sure the car likes it.

The key here is octain , with mikes 40% mix of e85 with say 91/93 octain pump,
what octain are we left with?

What is e85 rated at?

VP MS 109 is rated at 105

Will this mix equal or better VP MS 109?

[dfv2]

Originally Posted by harry$

The key here is octain [sic] , with mikes 40% mix of e85 with say 91/93 octain pump,
what octain are we left with?

What is e85 rated at? ...

Here's something I wrote about e85 octane for another forum:

Originally Posted by DFv2

The Renewable Fuels Foundation states in its Changes in Gasoline IV manual, "There is no requirement to post octane on an E85 dispenser. If a retailer chooses to post octane, they should be aware that the often cited 105 octane is incorrect. This number was derived by using ethanol’s blending octane value in gasoline. This is not the proper way to calculate the octane of E85. Ethanol’s true octane value should be used to calculate E85’s octane value. This results in an (AKI) octane range of 94-96 using (R+M)/2. These calculations have been confirmed by actual octane engine tests."

It is widely accepted that E85’s knock resistance is very high, but its resistance to pre-ignition is nothing special. E85 has a RON of 102-105, but a MON of only 85-87 which pulls the AKI octane rating down to 94-96. Even 91 octane gasoline scores 87-88 per MON.

http://en.wikipedia.org/wiki/Octane_rating

So pulling it all together, is pre-ignition an issue for our N54 DI engine? Not that I’m aware of, and nothing like it is for a PI engine. Then is E85’s AKI of 94-96 meaningful if the calculation includes less-relevant (MON) values? You decide. Bottom line - E85’s observed octane in the N54 is pretty gosh darn high.