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straight ethanol performance?

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Old 05-29-2011, 05:45 PM
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Originally Posted by rjwz28
I wasn't referring to tuned vehicles, just stock. I know that the tuned performance of a vehicle should increase, at least marginally, as it gets tuned for 87>91>93>E85. However, on a stock 5.3 peak power is rated on E85, with losses to be expected on 87 and no premium power rating at all. This led me to believe that there is a table to take advantage of the E85's qualities, which would make it advantageous (from a performance standpoint) to run E85 in an untuned 5.3 FlexFuel truck. However, on a 6.2 FlexFuel truck, peak power is rated at 403hp on 91 octane. Since there is no power rating on E85, and E85 is capable of supporting more power than 91, I assumed that they had no tables designed to optimize the vehicle's performance on E85 and therefore it would only produce as much power as it did on 91+ octane premium. This would mean that it is in no way a performance advantage to run E85 in an untuned 6.2 FlexFuel truck. That is all I was trying to say. I don't know anything about the actual tables in the ECM, as I have never tuned a vehicle. What I do know is that the ratings are adjusted based on the fuels being used, and this is what I'm going on.
I thought GM was still advertising the 5.3s w/87 @ 315hp? The only time I see E85 numbers on those is on the GM powertrain website where they list it as 326hp w/E85.
Old 05-30-2011, 01:04 AM
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I believe that's correct. They have two seperate ratings, the higher being on E85. There is no E85 power rating that I've found for the 6.2. Just 403hp on 91 and less on 87 (I believe I saw a 385hp on regular rating for them a few years ago). That would likely be on the low octane table referred to above. However, the point remains that the factory tuning on the 6.2 just doesn't seem to take advantage of E85 like the 5.3's tuning does.
Old 05-30-2011, 04:32 PM
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Originally Posted by 91Z28
After I get my headers/catback insalled I need to get a tune and am tempted to go for an E85 tune since I can run it no problem with 3 stations within 4 miles of my house, all on the way to work or anywhere else I would be going. My question is this: What about when you go out of town and have to run 93? How does it run on the 93 when tuned for E85?
simply put, i can not run my e85 tune on pump gas. when i do road trips, i just load up a pump gas map. you can however use the wot timing adders to build a difference between the e85 and pump gas to make it more fun on corn.

now stock for stock tune wise. pump gas runs more timing and richer wot afr. e85 doesn't have much of a timing increase over the main HO timing table, however, the wot fueling side is a whole lot leaner. {using a 14.7 base number to calculate it}
Old 06-01-2011, 05:03 PM
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Originally Posted by Area47
simply put, i can not run my e85 tune on pump gas. when i do road trips, i just load up a pump gas map. you can however use the wot timing adders to build a difference between the e85 and pump gas to make it more fun on corn.

now stock for stock tune wise. pump gas runs more timing and richer wot afr. e85 doesn't have much of a timing increase over the main HO timing table, however, the wot fueling side is a whole lot leaner. {using a 14.7 base number to calculate it}
Damn, that is what I was afraid of. Looks like I will get a 93 octane tune.
Old 06-02-2011, 06:47 PM
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Originally Posted by 91Z28
Damn, that is what I was afraid of. Looks like I will get a 93 octane tune.
every 3-6 months i flip back to pump gas for a few tanks to clean the system out, then back on e85. the power and torque difference is through out the entire powerband is so much more fun.
Old 06-03-2011, 12:02 PM
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Area47, what do you tune with?
Old 06-05-2011, 01:20 PM
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Originally Posted by rjwz28
Area47, what do you tune with?
hopes, dreams, pixie dust, and beer.




hp tuners for gm stuff
Old 06-05-2011, 05:16 PM
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Hooray BEER!
Old 06-06-2011, 11:11 AM
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Originally Posted by Area47
hopes, dreams, pixie dust, and beer.




hp tuners for gm stuff
Old 06-06-2011, 11:14 AM
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I am planning to get a BlackBear EfiLive tune and get the AutoCal so I can change it at my convenience, but I also have been talking to other guys to see what they use. I don't plan on writing my own tunes any time soon, but I am researching before I pay for anything.


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