Summary

00:00 - Cody has asked, what's a good air/fuel ratio to aim for on ethanol since you have to use more fuel? OK so this again is a question that seems on face value pretty simple but there's a couple of complexities around it.
00:12 First of all, just to mention though, yes we will need to inject more fuel on ethanol or E85 compared to what we would use on pump gas.
00:21 On E85 typically around about 35% to 40% more fuel.
00:25 But that additional fuel will actually give us the same effective air fuel ratio, so that's just important to understand there, that's just to get us back to the same air/fuel ratio.
00:35 The more difficult aspect here that I do need to explain is there are two ways of representing the fuel delivery of our engine.
00:42 We've talked today about air/fuel ratio, the other way of representing the fuel delivery is using the lambda scale.
00:49 Now most tuners that I've seen out there, particularly those across the U.S. market, will tune using air/fuel ratio numbers which is absolutely fine.
00:58 The complexity is that in order to represent a true air/fuel ratio or an accurate air/fuel ratio, we need to actually set the stoichiometric air/fuel ratio of the fuel we're tuning on, inside our wideband meter.
01:11 Now of course as we know, for pump gas this is 14.7:1 and then once we've got that set it's going to represent an accurate air/fuel ratio.
01:19 The tricky bit is on E85 for example, our stoichiometric air/fuel ratio actually becomes 9.8:1.
01:26 So technically to be truely accurate we would need to adjust our wideband stoich setting to 9.8:1 Then it would represent true air fuel ratios for our E85 fuel.
01:37 Now most tuners don't do that.
01:39 They leave the wideband set to the stoich setting for pump gas and then the air/fuel ratio meter is going to represent air/fuel ratio targets that are actually innacurate technically for ethanol so we may be seeing numbers such as 11.5:1, 12.5:1, these are pump gas numbers.
01:56 So because most people do it like that, I just wanted to mention that this technically isn't accurate.
02:02 But on the stoich setting for pump gas, we actually find that ethanol, E85, responds to very similar air/fuel ratio targets to what pump gas does.
02:12 Now to take all of that confusion out, because I know what I've just talked about is a little bit complex, I prefer to tune on the lambda scale.
02:19 And on lambda scale, regardless what fuel we're running on, pump gas, E85, methanol, diesel even, the stoichiometric air/fuel ratio of that fuel is always lambda 1.
02:30 So what this means is we know that when we're running at lambda 1.0, we are always at the stoich setting for that particular fuel.
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