Tuning on e70 how lean with e85?

alaskablkmach

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If I get tuned on e70 in late winter early spring how lean will it be on e85 in summer? Will it matter that much? I know e70 makes it a tad but richer going from e85, so I assume it will be leaner. Thanks
 

04sleeper

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All you really need to figure out is the difference in Stoich and divide.

E85 Stoich = 9.8526. E70 Stoich is 10.6975.

So 9.8526/10.6975 = .9210189 Essentially 8% leaner.

Hope this helps.
 

bigmoose

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You best bet is just to get a tune for both. Your tuner should be able to dial in on e70 then adjust for e85. Come summer, just watch your STFTs, when they start going above a few percent after a fillup then switch to your e85 tune.
 

ctgreddy

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You best bet is just to get a tune for both. Your tuner should be able to dial in on e70 then adjust for e85. Come summer, just watch your STFTs, when they start going above a few percent after a fillup then switch to your e85 tune.

This. When I switched to e85 I dialed it all in on that then made another tune for e75 which I've found a few times, and all I needed to do to make a second tune was switch the stoich value and it was almost spot on.
 

Brades44

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This. When I switched to e85 I dialed it all in on that then made another tune for e75 which I've found a few times, and all I needed to do to make a second tune was switch the stoich value and it was almost spot on.

So I just picked up my Terminator after converting to e85 and having it tuned accordingly. If that is the only tune on the car and e85 isn't available in my area until May, should I not drive the car until then or is there a workaround? I am BRAND new to this, so I apologize in advance for sounding like an idiot.
 

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