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  1. #1
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    Over 12 AFR - dicey??

    Am I the only one here who think's its a bit dicey to bring the AFR above 12? I like to keep mine in the 11.2-11.8 range then maybe stretch it out to 12.2 up top.. or am I just being a pussy?

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    It's a valid concern but what fuel for that AFR, how much boost, etc.? I'd be more concerned about going lean at 500+ whp than with just a tune.

    Stage 2 or 2.5 E9X M3 S65 V8 supercharger kit for sale
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    Running e30, single turbo.

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    I think you are ok but I'm not a tuner and would need to see your AFR graph.

    I think the N54 with ethanol shouldn't cause any problems hitting 12.0.

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    I really wish we could embed these damn logs.

    Stage 2 or 2.5 E9X M3 S65 V8 supercharger kit for sale
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I really wish we could embed these damn logs.
    iframes

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    Click here to enlarge Originally Posted by aflatau Click here to enlarge
    iframes
    It should work like embedding a youtube video where if you post the link to the chart it automatically embeds it in.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    It should work like embedding a youtube video where if you post the link to the chart it automatically embeds it in.
    use a preg_match and search for the datazap string, replace w embed iframe with the url.

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    Click here to enlarge Originally Posted by aflatau Click here to enlarge
    use a preg_match and search for the datazap string, replace w embed iframe with the url.
    You are a fairly bright fellow. Yes, this could be done.

    However, since I have an automated embedding system in place for so many different content types with a little work it could be adjusted to work with Datazap.

    Stage 2 or 2.5 E9X M3 S65 V8 supercharger kit for sale
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    I like 11's for turbos max...that was where people wanted to stay for Subarus and Audis...

    Both run/ran high 10s stock - at least close to redline...sometimes a little leaner down low.

    I have zero specific knowledge of the E30...especially with turbo.

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    Click here to enlarge Originally Posted by singletrack Click here to enlarge
    I like 11's for turbos max...that was where people wanted to stay for Subarus and Audis...

    Both run/ran high 10s stock - at least close to redline...sometimes a little leaner down low.

    I have zero specific knowledge of the E30...especially with turbo.
    Yes those are for port injection cars tho, we got the DI.

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    Click here to enlarge Originally Posted by aflatau Click here to enlarge
    Yes those are for port injection cars tho, we got the DI.
    Ah - clearly I missed some critical facts : )

    Also have no experience with DI! Good luck!

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    We do know this is DI right?
    No, targeting say 12.5:1 up top is perfectly fine assuming you have the fuel. Pump gas that’s a bit lean, but hardly “$#@!’s gunna melt” lean. If you run with ethanol in the tank, that is absolutely fine. I target about 12.3-5:1 up top for E50 without meth right now. OTS E30 fuel targets more like 12.2-4:1 from what I’ve seen, pump gas Cobb maps seem to target closer to 11.5-12:1.

    Now port injection, Houston we have a problem once you clear 12:1 or so. But not the case here, OP you are fine.

    We’ve all seen piggyback only logs with LEAN conditions. The type of targets you are talking about are good to go.
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    If you target leaner than 10.5:1 with a suby motor at any point in the tune you're gonna have a bad time. That's what you get when you build a motor out of glass. Gotta try to drown the horsepowers with fuel if you wanna push more than factory boost through them.

    For any normal car it's kinda like this: gasoline E10 max power rich is around 12.3:1, max power lean is around 13.2:1, but those values may be unsafe depending on your conditions, and you may get more power richer if you can run more timing... but timing being equal, that's generally peak power AFR's. 100% E85 max power rich is around 10.5:1, max power lean is around 12.6:1 (converted to gasoline AFR's for comparison purposes).

    E85 has a wider range of ideal AFR but they are at a bit lower lambda's then gasoline because the fuel is oxygenated. And there you have it.

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    With the single turbo at higher boost levels richer is better if you can support it. But supporting richer air/fuel ratios is difficult with the current fueling situation. With E85 it's almost impossible. I'd draw the line around 12.2:1 if over 20psi personally.
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    Thank for the info guys

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    Adam?
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    yes?

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    Click here to enlarge Originally Posted by 135pats Click here to enlarge
    We do know this is DI right?
    No, targeting say 12.5:1 up top is perfectly fine assuming you have the fuel. Pump gas that’s a bit lean, but hardly “$#@!’s gunna melt” lean. If you run with ethanol in the tank, that is absolutely fine. I target about 12.3-5:1 up top for E50 without meth right now. OTS E30 fuel targets more like 12.2-4:1 from what I’ve seen, pump gas Cobb maps seem to target closer to 11.5-12:1.

    Now port injection, Houston we have a problem once you clear 12:1 or so. But not the case here, OP you are fine.

    We’ve all seen piggyback only logs with LEAN conditions. The type of targets you are talking about are good to go.
    Can you please explain to me why 12.5 is a bit lean for pump gas and perfectly fine for ethanol? The only way that statement is true is if you experience lean related knock with pump gas. As far as lean conditions are concerned lambda is lambda is lambda. Regardless of the fuel in the tank the lambda is the same and the valve is converted to a gas afr. Everyones target afr is personal preference, but that target should be the same regardless of the fuel used.

    As for what afr to run, I have had .8-.82 (12-11.8 gas afr) lambda work well in the past.
    Last edited by andy_divers; 05-02-2014 at 11:28 AM.

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    Click here to enlarge Originally Posted by andy_divers Click here to enlarge
    Can you please explain to me why 12.5 is a bit lean for pump gas and perfectly fine for ethanol? The only way that statement is true is if you experience lean related knock with pump gas. As far as lean conditions are concerned lambda is lambda is lambda. Regardless of the fuel in the tank the lambda is the same and the valve is converted to a gas afr. Everyones target afr is personal preference, but that target should be the same regardless of the fuel used.

    As for what afr to run, I have had .8-.82 (12-11.8 gas afr) lambda work well in the past.
    I explained myself poorly, lambda = lambda regardless as you noted. Muh bad Click here to enlarge

    Bottom line point was that on this platform, target AFRs of say 12.3:1 are not "unsafe" per se.
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    Click here to enlarge Originally Posted by andy_divers Click here to enlarge
    Can you please explain to me why 12.5 is a bit lean for pump gas and perfectly fine for ethanol? The only way that statement is true is if you experience lean related knock with pump gas. As far as lean conditions are concerned lambda is lambda is lambda. Regardless of the fuel in the tank the lambda is the same and the valve is converted to a gas afr. Everyones target afr is personal preference, but that target should be the same regardless of the fuel used.

    As for what afr to run, I have had .8-.82 (12-11.8 gas afr) lambda work well in the past.
    Gas max power lambda is .84 to .9

    E85 max power lambda is .71 to .87

    There are catches, however. Richer OR leaner lambda will slow flame speed, which is fastest around the max power lambda's. So, if you are targeting max power lambda's and have high advance, you will have a faster flame speed and higher cylinder pressures. This could induce knock.

    Also, since richer lambda's increase cooling, leaner lambda's to the point of max power lamdba's may not cool the charge enough to prevent knock at such high cylinder pressures encountered with the higher flame speed as well, inducing knock.

    With gasoline, this is a problem, because the octane is 93 (in DI vs PFI it's effective octane is much higher, but still meh)

    With E85 or race gase, due to higher Octane (and with E85, octane and fuel volume), you are not limited by detonation, thus you can increase timing and lean to a max power lambda. Due to our fuel system, with E85 we just happen to be forced to run at max power lean lambda for the fuel because we cannot run at max power rich for the fuel. It's fine because of the nature of the fuel. If we could support a .71 lambda with E85, you wouldn't need an intercooler.

    Target lambda should not be the same regardless. We target rich lambda/AFR (in relation to max power) for gasoline because of it's characteristics. We target a comparatively LEAN afr/lambda for E85 due to its characteristics and our fuel system limitations. Just because it works great to target .8-.82 lambda for both fuels, don't misconstrue the reasons why.

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    @ Very well put, thank you for clearing it up.

    Also good point RE: energy density in Ethanol. I hadn't brought that up but it's a good thing to remember.
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    Click here to enlarge Originally Posted by V8Bait Click here to enlarge
    Gas max power lambda is .84 to .9

    E85 max power lambda is .71 to .87

    There are catches, however. Richer OR leaner lambda will slow flame speed, which is fastest around the max power lambda's. So, if you are targeting max power lambda's and have high advance, you will have a faster flame speed and higher cylinder pressures. This could induce knock.

    Also, since richer lambda's increase cooling, leaner lambda's to the point of max power lamdba's may not cool the charge enough to prevent knock at such high cylinder pressures encountered with the higher flame speed as well, inducing knock.

    With gasoline, this is a problem, because the octane is 93 (in DI vs PFI it's effective octane is much higher, but still meh)

    With E85 or race gase, due to higher Octane (and with E85, octane and fuel volume), you are not limited by detonation, thus you can increase timing and lean to a max power lambda. Due to our fuel system, with E85 we just happen to be forced to run at max power lean lambda for the fuel because we cannot run at max power rich for the fuel. It's fine because of the nature of the fuel. If we could support a .71 lambda with E85, you wouldn't need an intercooler.

    Target lambda should not be the same regardless. We target rich lambda/AFR (in relation to max power) for gasoline because of it's characteristics. We target a comparatively LEAN afr/lambda for E85 due to its characteristics and our fuel system limitations. Just because it works great to target .8-.82 lambda for both fuels, don't misconstrue the reasons why.
    Thats a hell of a break down, but you are likely wasting your energy typing it. Me and the diver went back and forth one evening on the N54 enthusiast fb page, he's pretty dead set on only acknowledging his own opinions.
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    1 out of 1 members liked this post. Yes Reputation No
    There's some total $#@!s on that N5x page. I lasted there 2 days. I'd rather type things here, maybe people will learn, maybe I'll learn, that happens often here actually.

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