how much variation is acceptable if you are tuned on e85? +/- %?

 

It would depend on how close to the edge you were tuned on any particular fuel.

 

So, take the E74 as an example. What options do you have if you get a batch that low, and you're tuned fairly agressively on E-85? Driving 150-200 miles until you can hopefully fill back up with the good stuff would suck. Is it possible to have 3 maps then for map switching. 93, E70, and then E85? Just trying to figure this out, because Valero is building a Corner Store with E-85 about 3 miles from my house right now, and I fully intend to be ready to use the stuff when the store opens next spring.

 

how much would AFR change if tuned on E85 and filled up with E70?

 

Sounds interesting. Hope you make a thread about it.

 

Placed an order! Cant wait to test our local station that says E85 minimum.

Thanks :-)

 

the lower the ethanol content the richer the car will run correct(say i was tuned on 85% and happen to fill up with 70-75%)? or am i backwards lol?? anyways this is the one thing i dont like about running corn. this is another reason why a wideband or logging is mandatory and should be part of the budget when people switch over...
im going to order one of the testers

 

The more ethanol content the more fuel required. so the less ethanol content the less fuel.. e85 requires 30% more fuel approx due to the ethanol content. If you're tuned on e85 and fill up with e70 you will run richer.

The difference from e85 and e70 would be a few degrees timing depending on how aggressive the cars tuned.

 

David, have you actually noticed in power limitations regarding specifically on the ethanol content?

We get E70 around here, and it's been tested to be closer to E60 and yet guys are still making great power on it. I've also hear of some guys running more like E30 with 93 octane as the base fuel and it working well.

Obviously the AFR changes if the ethanol content changes, but does how aggressive of tune you run really change at all?

 

essentially less ethanol is less octane, but e70 vs e85 i dont think theres to much difference. maybe 5octane ratings. not sure if e70 is enough to max timing or not. i get e85 here seasonal so im not a good person to ask.

 

If you go by octane alone, ethanol wouldn't do what it does.

I'm not looking for a theoretical answer though. I'm curious if other then adjusting for AFR due to the lower ethanol content, does the tune really need to be any different? I've seen on what we have that passes as E85 (really closer to E60) in 4 cylinders making over 800WHP on it. Even at 60% ethanol, it still seems sufficient to allow MBT on almost any boost level on any setup.

 

Heh are you serious? You actually talked about this a few years ago but it was kinda scraped I thought?

The main problem is the AFR swing. If you tune on E70 and set the AFR at 11:1, when the fuel suppliers switch to E85 over the months your AFR will be just over 12:1. Shane@DB Performance has nearly perfected the art of a safe 'year-round' MN E85 tune, and it has taken some years to perfect. If you're tuning on the edge, you want to know exactly what % you're tuning on, that is for damn sure.

Here in MN we see 3 blends, but from station to station it can vary what you get. They will all 'switch' to E80 or whatever Sept1 but you'll still see full E85 in some places until end of october. Then come January or Feb everyone is full E70 and start to make the switch back to E80 sometime in April, but you see it some places until May, where you're also likely to start seeing full E85 at some places. It's a damn CF and part of the reason I haven't made the switch yet.

Still, an amazing fuel! Good post dave, having a gauge is a good idea.

 

I should have one of those tunes in the next couple weeks.

I'll have to get one of those testers when I get back, I don't know when the blends change in the TN/KY area.

 

ok for one thing.. nobody can "perfect" an e85 tune seasonal. Just from personal experience running it in my car with MAF during a hot summer day vs later at night that same day the AFR jumps almost .6 points as it is (on stock ecu). what do you think its going to do when you use that summer tune in the winter? I hate false info, and there is no such thing as "perfecting" an e85 tune.. if you dont know how to tune for max power then you shouldnt be tuning period. There is no better way of tuning cars.. maybe smoothing the map better then another tuner, but the cars gonna make the same power either way with the same timing advance / AFR from any tuner.

Thats my experience with stock ECU and maf.

 

I think you get what he's trying to say. Its safe year round... he has perfected the "safe year round" tune. He didn't say that he has a perfect year round tune.

Great product. Good ideas.