E30 with jb4

[rpoffen]

BIG TIME! very nice juicy difference

Can’t wait!

 

[94FD3S]

Have seen discussions elsewhere but was unable to find here. Given E85's effect on octane in a mix and is common to see 91 octane used due to local availability, how much does one give up mixing E85 with 87 octane regular - assuming a "tier 1" fuel?

Have been out of the tuning scene for a (long) while, but close to pulling the trigger on a JB4 and contemplating E85 mixes as well. E85 nearby is 50cents less than 87, which is in turn $1.50 less than 93. So in addition to determining the ethanol content of a mix, any way to calculate the octane rating based on different grades of base fuel?

 

[rpoffen]

Have seen discussions elsewhere but was unable to find here. Given E85's effect on octane in a mix and is common to see 91 octane used due to local availability, how much does one give up mixing E85 with 87 octane regular - assuming a "tier 1" fuel?

Have been out of the tuning scene for a (long) while, but close to pulling the trigger on a JB4 and contemplating E85 mixes as well. E85 nearby is 50cents less than 87, which is in turn $1.50 less than 93. So in addition to determining the ethanol content of a mix, any way to calculate the octane rating based on different grades of base fuel?

There are apps to help you calculate the effective octane rating starting with the base octane, the amount of ethanol already in the pump gas, etc. The fuel-it app has a calculator on page 3.
I won’t pretend to be an expert here, but I have gleaned much information from this forum.
Using a lower octane fuel and upping the E rating just to get octane isn’t that simple in reality. The more ethanol in the fuel means that more volume of fuel is needed. The limiting factor in our cars is the HPFP, which starts to run out of steam around E30. So trying to get an octane rating for map 3 or 4 on the jb4 may require higher than E30 if you start with 87.
If you want to run higher than E30 then you need to consider CPI to supplement fuel flow. Another option is to skip the E30 idea and go with WMI, but there are other considerations with that.

 

[Scorpion24]

How you guys doing now since switching to e85 mix?

Just tried it this morning on map 2. I only put 2 gallons of e85 with 91.

 

[winjury]

Even if you fill up with more ethonal.
You’ll get worst miles per gallon vs reg 93 gas.
On avg you’ll get 25% worst on full E85 vs reg gas 10% ethonal.
There been studies done, usually worst cost benefit from E85.



I know this is an older thread but that ^^ flat out is not correct in actual application. E85 is approximately 108 octane, due to this you are getting more power throughout the rpm range so you arent pushing you car as hard to get to the same speed as pre e85 etc, thus the gas mileage will not suffer nearly what the theoretical difference of ethanol being 25% less efficient.

As someone that has used flex fuel kits (all listed were e85) with my Hellcat, N54, X5 M and my wifes wrx s208 sti I can tell you that in some cases gas mileage may even go up, i never experienced anything more then 10% drop in gas mileage for any of my current or past cars. I can also tell you that the engine will run cooler running a higher ethanol content. I will eventually dabble with e30 on this stinger, but not dumping money to get the entire fuel system to run full e85 right now.

 

[Thomby]

Octane is not power, it is knock resistance. Higher octane can enable you to make more power via higher compression or higher boost, but by itself it won't do anything.

Driving around town out of boost, you will definitely see a dip in mileage from ethanol's lower energy content, but it won't be as bad as the 25-30% flex fuel cars on straight E85 see. For E30, you can expect more like 9-10% worse mileage (basically 30% of your fuel x 30% worse mileage).

And anecdotally that's about what I see in my Stinger, a couple mpg worse. On a long road trip with cruise in the low 80s, I started out about 24-25 mpg on E30 and it gradually rose to about 28 mpg a couple tanks later as I refilled with straight 93. Around town if I switch back to 93 the computer will gradually increase my per tank range about 35-40 miles (it went up a lot more on the road trip, because I was getting highway vs. city mileage).

 

[winjury]

Octane is not power, it is knock resistance. Higher octane can enable you to make more power via higher compression or higher boost, but by itself it won't do anything.

Driving around town out of boost, you will definitely see a dip in mileage from ethanol's worse mileage, but it won't be as bad as the 25-30% flex fuel cars on straight E85 see. For E30, you can expect more like 9-10% worse mileage (basically 30% of your fuel x 30% worse mileage).

And anecdotally that's about what I see in my Stinger, a couple mpg worse. On a long road trip with cruise in the low 80s, I started out about 24-25 mpg on E30 and it gradually rose to about 28 mpg a couple tanks later as I refilled with straight 93. Around town if I switch back to 93 the computer will gradually increase my per tank range about 35-40 miles (it went up a lot more on the road trip, because I was getting highway vs. city mileage).

sorry i over simplified it, but you are correct. The higher octane allowed my tuners to get more power out of the vehicles more easily due to the higher knock resistance.

 

[TheBeginning]

Can’t wait!

Might be a dumb question, how do you communicate to the JB4 your ethanol content so it will adjust fueling? Does going to the e30 map automatically do this? Alternatively, what if you have something between e10 and e30? I have the flex fuel sensor, so will this adjust fueling?

 

[rpoffen]

Might be a dumb question, how do you communicate to the JB4 your ethanol content so it will adjust fueling? Does going to the e30 map automatically do this? Alternatively, what if you have something between e10 and e30? I have the flex fuel sensor, so will this adjust fueling?

There is a wire with the flex fuel kit that you can route to the jb4 connector, and enable the input in the app, I don’t know for sure how the jb4 uses it other than it will show in the logs and you can enable a gauge on the screen.

 

[Thomby]

Might be a dumb question, how do you communicate to the JB4 your ethanol content so it will adjust fueling? Does going to the e30 map automatically do this? Alternatively, what if you have something between e10 and e30? I have the flex fuel sensor, so will this adjust fueling?

The ECU controls fuel with feedback from the O2/lambda sensors. The optional "fuel wires" for the JB4 are really "O2 wires", which let the JB4 trick the car into varying the air/fuel ratio across the rpm range, but I don't think this has anything to do with the ethanol mix, it's just pushing it richer or leaner.

The Fuel-It kit will measure ethanol content for the JB4, but I don't think that changes the AFR, I think it's just to let it know your octane and therefore what boost to target.