E85 Lambda targets?

[TXEnginerd]

I'm getting ready to switch from 93 to E85 and am tuning myself with SCT PRP. I know I have to re-dial in my MTF since I'm changing my injectors but I know how to do that. My questions are specific to using E85 as a fuel vs gasoline.

1) To change to E85 fuel, do I just need to change my stoichiometric scalar value to 9.765 in the tune and in my wideband settings? (I already tune with my wideband configured to display lambda)

2) In my base fuel table, do my target lambdas stay the same assuming I've changed the stoichiometric fuel setting or are there different targets for E85?
E.g., Target 0.773 Lambda at WOT/High Load for both 93 and E85?

3) How do I handle variations in ethanol content once the tune is dialed in on E85? Just have a separate tune with the stoichiometric scalar set to match the fuel I filled up with?
E.g., E85 = 9.765 & E70 = 10.7xx

 

[Noisy Crickett]

You need to change your stoich scalar, just as you said. You do not have to do it in your wideband settings as it measures lambse. So if you're used to looking at gasoline stoich, sometimes it's easier to relate as your already acclimated with those numbers. I did have to do some adjusting on my MAF Transfer also, but most get away with out that. Variations in ethanol content will be tricky. You will have check manually, or with a device like zeitronix has. And adjust your tune accordingly. I don't know that I would keep changing stoich, Usually means reducing timing, which is the whole reason you switch to E85 is for more time without knock. Be careful though. E85 doesn't knock until it's too late, somewhere around 780 degrees. Best way to tune on E85, in my opinion is the old fashion way... Plugs. But then again,, I know nothing and I can prove it.

 

[TXEnginerd]

Thanks for your response.

The Innovate MTX-L allows users to change the fuel type so that the AFR scale reads correctly, but you're right.. if I've already set it up to display in Lambda then the AFR scale setting doesn't matter.


I did some research outside of svtp and found the corvette guys like to target around 0.78 lambda for E85 under boost which is pretty much the same as the safe value you would target with gasoline.

Then I guess I need to have a tune with lower timing and slightly leaner base fuel table for an E70 mix.

 

[Noisy Crickett]

My thought, I would not mess with the base fuel table. Leave it at 11.5 (.78) under WOT, I only say that number because you did. Everyone has their own opinion... 11.2, 11.8.. I would just pull time if you determine the E content is low. Texas doesn't have as much of an issue because it doesn't stay that cold here, but I know that the further north you go,, the E content can swing quite a bit from one season to the next. Can't hurt your car from having your timing set up for E70, and then find yourself in E85.. but the other way around....... $$$ BTW.. austin valero E85 is usually lower content,, but the HEB has the best E85 in town.. There's a stripes in burnet that was E87.

 

[TXEnginerd]

My thought, I would not mess with the base fuel table. Leave it at 11.5 (.78) under WOT, I only say that number because you did. Everyone has their own opinion... 11.2, 11.8.. I would just pull time if you determine the E content is low. Texas doesn't have as much of an issue because it doesn't stay that cold here, but I know that the further north you go,, the E content can swing quite a bit from one season to the next. Can't hurt your car from having your timing set up for E70, and then find yourself in E85.. but the other way around....... $$$ BTW.. austin valero E85 is usually lower content,, but the HEB has the best E85 in town.. There's a stripes in burnet that was E87.

Cool, thanks for the info. There is an HEB with E85 on my way to/from work and my parents just moved to Burnet