[SacTownN54]

Hey fellas I've read quite a bit on running e85 mixed with 91/93 octane and the results look great. I have access to 100 octane gas and I was wondering if there would be any benefit to mixing the 100 octane with a few gallons of e85. I'm not looking to go over 30% e85. The only mods I have on the car are the jb4 G5 ISO, DCI, and occ. I'm not planning on running e85 often, nor do I want to pay for 100 octane all the time, but I have a family showdown coming up between my 335i and my dads stock 2014 stock 550i. So for the best power gain in the 335, should I use pure 100, 100/e85 mix, or 91/e85 mix? I'm in Cali so I can't get 93.

[zeel]

I'd say 100/e85 with about 40% e85.

[Randomaccess335]

I guessing u'll destroy ur dad on 93 alone

But what I do when I go the track 50/50 E85/93 and when I get to the track I put a few gallons of 100oct to water down the E85, To keep Oct up and prevents throwing codes
R

[Infamy]

Just jb4 and 93 you got him, but throw 100oct in and you will destroy him. GL

[Mit_Boost]

True E85 offers similar performance to a VP Import or C16 (VERY high octane), but offers additional benefits those fuels cannot, specifically the cooling effect of ethanol when it burns and that it's not leaded (so you don't kill your cats or o2 sensors).


Either way, unless you have a backend flash you're not really going to be able to capitalize on the benefits of 100 octane or E85 because you won't be able to make adjustments to the Ignition Tables, VANOS, or Fueling. I honestly believe it'll be a lot closer than other people in this thread believe. The F1x 5-Series all come with the 8-speed trans, which means the car is kept more in it's powerband. Here's a video of an FBO 335 (Bren Tune/18 psi midrange) on Pump Gas vs. a 550xi (so heavier) running the BMS Stage 1 Tune that only adds 2-3 psi (about 30 WHP).

Yes, the FBO 335 easily pulls away, but it's also running custom flash software (a LOT more Ignition Timing, Boost and VANOS adjustments than your JB4/DCI setup) and it's also an Xi.



End of the day, there's only one way to find out how you two stack up

[stanlalee]

This is what your looking at:

e30 mixing 91 octane (e10)/e85 (105 octane)= 94.8 octane
e30 mixing 100 octane (no ethanol)/e85= 101.8 octane
obviously 100 octane race = 100 octane


Right away e30 is likely going to be too mild for the cooling effects to make up for the 5 octane minimum disadvantage from using pure race or race/e85 mix so I'd rule that out.

e30 using race gas and e85= 6 gallons e85/10 gallon race gas(with no ethanol) = $88/tank and 101.8 octane

straight 100 race gas= $112 and 100 octane

I'm using $3/gallon for e85 (what it cost here) and $7/gallon for race gas

So e30 from e85/100 race gas mix is going to be cheaper, have higher octane and the added cooling effects of ethanol vs straight race gas.

Sure you don't want to add ($100) Walbro,(free) backend flash and use e50 for your race? You'd get almost 99 octane, the cooling effects of ethanol and it would only cost $52/tank (using $3.60/gallon for 91 octane e10). if you filled up twice with race gas you've already spent Walbro money in the gas price difference. You would use 9 gallons e85/7 gallons 91 oct e10 which works out to E52, 98..9 octane. Then there is also the poor gas mileage of ethanol when factoring in cost lol but for one race or occasional use shouldn't matter.

[Mit_Boost]

It's been widely confirmed that E85s true octane rating cannot be confirmed or compared to a "MS109", etc. If you speak with any knowledgeable tuner, it is very difficult to have a motor "knock" while tuning with E85, more than likely you will hit a fueling (requires an additional 30% fuel vs. traditional gas) or physical component (rods, pistons, etc) limitation first.


Eddie Bello tunes off E85 with his 1300 WHP 964, and he can run a much more aggressive Timing Curve than the UGR guys can run with VP Import (C16+). One of the reasons why his car can do this:

Peak Power ≠ Faster Car. Power Under the Curve is the most important part of tuning when building a car for the street or high speed, roll racing.

[Killerfish2012]

Originally Posted by stanlalee

This is what your looking at:
e30 mixing 91 octane (e10)/e85 (105 octane)= 94.8 octane

The octane value of E85 is NOT 105. It's actually 94-96 depending on the season.

[SacTownN54]

Originally Posted by stanlalee

This is what your looking at:

e30 mixing 91 octane (e10)/e85 (105 octane)= 94.8 octane
e30 mixing 100 octane (no ethanol)/e85= 101.8 octane
obviously 100 octane race = 100 octane


Right away e30 is likely going to be too mild for the cooling effects to make up for the 5 octane minimum disadvantage from using pure race or race/e85 mix so I'd rule that out.

e30 using race gas and e85= 6 gallons e85/10 gallon race gas(with no ethanol) = $88/tank and 101.8 octane

straight 100 race gas= $112 and 100 octane

I'm using $3/gallon for e85 (what it cost here) and $7/gallon for race gas

So e30 from e85/100 race gas mix is going to be cheaper, have higher octane and the added cooling effects of ethanol vs straight race gas.

Sure you don't want to add ($100) Walbro,(free) backend flash and use e50 for your race? You'd get almost 99 octane, the cooling effects of ethanol and it would only cost $52/tank (using $3.60/gallon for 91 octane e10). if you filled up twice with race gas you've already spent Walbro money in the gas price difference. You would use 9 gallons e85/7 gallons 91 oct e10 which works out to E52, 98..9 octane. Then there is also the poor gas mileage of ethanol when factoring in cost lol but for one race or occasional use shouldn't matter.

Yeah I would consider adding a pump in the future, but I would want to upgrade the down pipes and get a BT tool for the flash first. I know the BT tool vin locks for coding and troubleshooting, but would I be able to borrow someone else's for the sole purpose of uploading the BMS flash or do I need an unlocked BT tool for that?

Originally Posted by Killerfish2012

The octane value of E85 is NOT 105. It's actually 94-96 depending on the season.

Yeah I've heard different octane numbers from different people. I'm in a pretty warm part of the country so I don't think the e85 differs from season to season. Not 100% sure on that though.

Ok, so is the use of e85 just a cheaper way of boosting the octane higher in regular pump gas or are there other characteristics that allow the motor to produce higher output that I would be missing out on if I used straight 100 octane? I need more POWA!

[Mit_Boost]

Originally Posted by Killerfish2012

The octane value of E85 is NOT 105. It's actually 94-96 depending on the season.

Can you find me a dyno or 60-130 times that supports your claim? Could be ANY car that shows it makes more power/goes faster on 100-116 octane then on straight E85?

[stanlalee]

Well its kind of contradictory isn't it? On the one hand e85 works so well timing can be advanced to ridiculous levels without knock. On the other hand everybody says the true octane rating isn't 105 like pumps suggest. I don't know the protocol for pump octane ratings but if you base its knock resistance (isn't that what octane rating is for) on what you can do with timing and boost it most certainly is effectively every bit of 105 octane.

[Mit_Boost]

Here's why traditional "octane ratings" applied to E85 is misleading:

Ethanol AND methanol can NOT be properly rate by regular

"octane rating methods"

If you look up how gasoline is rated for octane you will understand.

The scientists have a special one cylinder engine , that just does this one job.

It is a lengthy process run under strict observation.

It is a very complex process, and I am not going to explain it.

Also, ethanol (and methanol) has a very high latent heat evaporation rate,

this means as the ethanol is made into tiny droplets ,

the methanol basically sucks the heat out of the air.

This drops the intake temp like a prom dress.

This process helps prevent detonation, therefore you can use

more timing, compression, etc to build more cylinder

pressure, hence more horsepower (actually more torque).

It is kinda involved, but that should give you an idea.

If anybody tells you that E-85 has an "X" octane rating,

they do not know what they are talking about or

are trying to blow smoke up your ass.

[SacTownN54]

So back to my original question. Which fuel would be best for making power in my car? Straight 100 octane OR 100+e85 mix OR 91+e85 mix. Both e85 mixes would be right around 30%.

If this hasn't been tested out before I'd be happy to be the guinea pig. I assume that the 100+e85 will outperform the 91+e85 for obvious reasons, but I don't want to "water down" the 100 octane if the only reason for adding e85 to regular pump gas is to raise the octane level to the high 90's. Is there something else that the e85 has to offer that will give me additional gains over straight 100 gas? Is the cooling effect enough to justify mixing with 100?

[stanlalee]

I get that 100% but why does the means to the end matter?

[Mit_Boost]

Originally Posted by SacTownN54

So back to my original question. Which fuel would be best for making power in my car? Straight 100 octane OR 100+e85 mix OR 91+e85 mix. Both e85 mixes would be right around 30%. ?

The true answer is none, because without a flash tune you're not going to be able to make the necessary changes to the Ignition Timing, VANOS & Fueling Tables that it will make significant increases in power. All the JB4 and Map 7 (Race Map?) will do is run a lot more boost then if you were running the pump gas map, but you'll be running nearly the same Ignition Timing Curve

[SacTownN54]

Originally Posted by Mit_Boost

The true answer is none, because without a flash tune you're not going to be able to make the necessary changes to the Ignition Timing, VANOS & Fueling Tables that it will make significant increases in power. All the JB4 and Map 7 (Race Map?) will do is run a lot more boost then if you were running the pump gas map, but you'll be running nearly the same Ignition Timing Curve

Ok so in order to maximize my gains I should have a flash tune, but are you saying that I won't see any gain from using different fuels with only the jb4?

Also, do I need an unlocked BT cable to upload the BB flash or can I borrow a cable to do this?

[chili36]

Originally Posted by SacTownN54

Ok so in order to maximize my gains I should have a flash tune, but are you saying that I won't see any gain from using different fuels with only the jb4?

Also, do I need an unlocked BT cable to upload the BB flash or can I borrow a cable to do this?

With the right octane you are able to run a more aggressive map. But to maximize performance a back end flash is best.

You do not need a unlocked BT cable.

[chili36]

Originally Posted by Killerfish2012

The octane value of E85 is NOT 105. It's actually 94-96 depending on the season.

Originally Posted by Mit_Boost

Can you find me a dyno or 60-130 times that supports your claim? Could be ANY car that shows it makes more power/goes faster on 100-116 octane then on straight E85?

E85 is NOT always 85% Ethanol, there for the octane can vary.
Only way of knowing ethanol content is to test the ethanol content in the fuel before pumping it into your tank.

[biz77]

Originally Posted by SacTownN54

So back to my original question. Which fuel would be best for making power in my car? Straight 100 octane OR 100+e85 mix OR 91+e85 mix. Both e85 mixes would be right around 30%.

If this hasn't been tested out before I'd be happy to be the guinea pig. I assume that the 100+e85 will outperform the 91+e85 for obvious reasons, but I don't want to "water down" the 100 octane if the only reason for adding e85 to regular pump gas is to raise the octane level to the high 90's. Is there something else that the e85 has to offer that will give me additional gains over straight 100 gas? Is the cooling effect enough to justify mixing with 100?

You can't really compare the octane values of E85 and gasoline. As already mentioned, E85 tunes more like a 116 octane oxygenated gasoline. Look at what Cobb does on their 100-octane maps and their E30 maps. They utilize the same timing advance, load request etc. That means a low mix (30%) of ethanol gives equivalent performance to straight 100-octane.

Here is what you do...

Mix up a 30% concentration of ethanol. put your JB4 on the correct map to run this mixture. Run it for a bit and give the car and JB4 time to adapt to the mixture. Go out and do some hard pulls logging ignition timing correction. If you have no ignition correction, then you won't gain anything by adding 100 octane gasoline. Simple.

[chili36]

Originally Posted by SacTownN54

So back to my original question. Which fuel would be best for making power in my car? Straight 100 octane OR 100+e85 mix OR 91+e85 mix. Both e85 mixes would be right around 30%.

If this hasn't been tested out before I'd be happy to be the guinea pig. I assume that the 100+e85 will outperform the 91+e85 for obvious reasons, but I don't want to "water down" the 100 octane if the only reason for adding e85 to regular pump gas is to raise the octane level to the high 90's. Is there something else that the e85 has to offer that will give me additional gains over straight 100 gas? Is the cooling effect enough to justify mixing with 100?

E30 blend is approximately 94octane not 100.

[stanlalee]

Originally Posted by chili36

E30 blend is approximately 94octane not 100.

Using 91 octane e10 its 94.8 but that formula is computed assuming the e85 has an 105 octane rating. If you believed e85 only has a true octane rating of 94-95 as some here do e30 would only bump 91 octane pump gas to about 92 octane. What he is saying is its EFFECTIVELY 100 octane as you can tune timing and boost as if you were using 100 octane petrol which is what Cobb is doing with its e30 tune.

Originally Posted by chili36

E85 is NOT always 85% Ethanol, there for the octane can vary.

The 105 octane posted is the minimum octane rating based on e85's minimum content of 70% ethanol. Real 85% ethanol should be higher.

[chili36]

Originally Posted by stanlalee

Using 91 octane e10 its 94.8 but that formula is computed assuming the e85 has an 105 octane rating. If you believed e85 only has a true octane rating of 94-95 as some here do e30 would only bump 91 octane pump gas to about 92 octane.

I'm not following you. Are you telling me that E30 is not 94 octane?

E85 has a 105 octane rating only if the ethanol content is 85% and this is not always the case for some regions