vtraudt
09-06-2015, 11:51 AM
There is pump gas (lets call it E10, since in most states, 10% ethanol is mixed in)
Then there is E85 (in the summer)
And E70 (have seen in winter).
I want to make my own E50!
Background: My injectors are at 50% duty cycle, so I have some "room" there.
Assumption: I can't swap to E85, would need injectors (and pump) (1/3 more flow needed, plus whatever additional net power gain comes out of it. Say 15%. Total extra fuel: 1.33 * 1.15 = 50%).
But: Mixing 9.3 gal of E10 (87 octane pump gas) and 10.7 gal of E85 (20 gal tank) should result in E50.
Or: 10 gal 87 and 10 gal E85 = E42.
The long term fuel trim should 'adjust' over time to the new mix by increasing the duty cycle of the injectors (as long as it is within the +/- 20 points control range).
Please comment if the above is basically feasible?
If so, i could setup a pump gas tune dialed in with a slight slight 'rich' bias (i.e. long term fuel trim values are pulling fuel out (IIRC: positive fuel trim numbers shown in block 032).
And also dial in a bit of timing pull (say 5 degrees?).
Then once in a while go to the E85 pump and mix it up (to an E30 to E50 for example). LTFT should adjust quickly, and ECU should give some timing back (due to the higher octane of the mix). EGT should be lower, too.
Then there is E85 (in the summer)
And E70 (have seen in winter).
I want to make my own E50!
Background: My injectors are at 50% duty cycle, so I have some "room" there.
Assumption: I can't swap to E85, would need injectors (and pump) (1/3 more flow needed, plus whatever additional net power gain comes out of it. Say 15%. Total extra fuel: 1.33 * 1.15 = 50%).
But: Mixing 9.3 gal of E10 (87 octane pump gas) and 10.7 gal of E85 (20 gal tank) should result in E50.
Or: 10 gal 87 and 10 gal E85 = E42.
The long term fuel trim should 'adjust' over time to the new mix by increasing the duty cycle of the injectors (as long as it is within the +/- 20 points control range).
Please comment if the above is basically feasible?
If so, i could setup a pump gas tune dialed in with a slight slight 'rich' bias (i.e. long term fuel trim values are pulling fuel out (IIRC: positive fuel trim numbers shown in block 032).
And also dial in a bit of timing pull (say 5 degrees?).
Then once in a while go to the E85 pump and mix it up (to an E30 to E50 for example). LTFT should adjust quickly, and ECU should give some timing back (due to the higher octane of the mix). EGT should be lower, too.