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| 4.9L Cadillac Information (Page 10/11) |
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lou_dias
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AUG 25, 11:13 AM
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If you look at my A/F graph, they tuned me down to 13:1 at around 3600 where as I personally kept asking for 14:1. It should have broke 200rwhp @14:1. E85 doesn't ping like regular gas so it's ok to tune it leaner and meaner. These 'classic' tuners haven't gotten around that in their heads yet...
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FieroWannaBe
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AUG 25, 06:30 PM
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| quote | Originally posted by lou_dias:
If you look at my A/F graph, they tuned me down to 13:1 at around 3600 where as I personally kept asking for 14:1. It should have broke 200rwhp @14:1. E85 doesn't ping like regular gas so it's ok to tune it leaner and meaner. These 'classic' tuners haven't gotten around that in their heads yet... |
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I had always been under the impression Rich Best Torque wasn't affected much by E85, so if peak power is at 12:1 or 12.5:1, AKA Lambda of .85-.82, you tune to achieve the same AFR reading on the dyno. Almost all tuners do not rescale their graphs for fuel types (stoich on Gas is 14.7, on E85 it is 9.76) Oxygen sensors are blind to fuel type, they report voltage vs lambda, the numbers reported are scaled typically for the fuel type i.e. gasoline. The benefit of E85, is its octane rating, allowing for more timing, at the cost of EGT's since the flam front propagation is slower.
The textbook chart for a "typical" relationship of Lamba. It will vary based of efficiency of design and flame front speeds, which is affected by a laundry list of variables.
Correct me if I am wrong.
*edit: I believe this chart is in % Mass ratio 6.8% mass ratio is stoich for gasoline[This message has been edited by FieroWannaBe (edited 08-25-2020).]
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pmbrunelle
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AUG 25, 07:32 PM
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| quote | Originally posted by lou_dias:
If you look at my A/F graph, they tuned me down to 13:1 at around 3600 where as I personally kept asking for 14:1. |
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Well you can't ask someone to tune your car, and then tell them how to do it...
For me at least, when I'm told to do something, I want to do it my way!
Normally, if I'm really picky about something, I'll do it myself rather than try to micromanage someone else.
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lou_dias
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AUG 25, 07:46 PM
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| quote | Originally posted by FieroWannaBe:
I had always been under the impression Rich Best Torque wasn't affected much by E85, so if peak power is at 12:1 or 12.5:1, AKA Lambda of .85-.82, you tune to achieve the same AFR reading on the dyno. Almost all tuners do not rescale their graphs for fuel types (stoich on Gas is 14.7, on E85 it is 9.76) Oxygen sensors are blind to fuel type, they report voltage vs lambda, the numbers reported are scaled typically for the fuel type i.e. gasoline. The benefit of E85, is its octane rating, allowing for more timing, at the cost of EGT's since the flam front propagation is slower.
The textbook chart for a "typical" relationship of Lamba. It will vary based of efficiency of design and flame front speeds, which is affected by a laundry list of variables.
Correct me if I am wrong.
*edit: I believe this chart is in % Mass ratio 6.8% mass ratio is stoich for gasoline
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Isn't it funny that 14.7 - 34% = 9.702 ... It's all in what "scale" you want to report on. Yes we added a bit more timing... But the bottom line is no matter how you scale it, if your injectors ECM/PCM can supply fuel fast enough, running a little rich only helps with snap throttle acceleration, not WOT. Leaner is meaner. When you are at WOT for more than a second you are losing power by being rich. You can prove this to yourself on any dyno...which I've done year after year after year. When I switched to E85 and fixed my engine code, I was running at 19:1 for a month. It didn't blow up. I tuned it and it made more power being closer to stoich. For what it's worth, the E85 pump I gas up from typically tests closer to E66...but typically, engine PCM's designed to run a variety of fuels have a fuel sensor which tells the PCM how scale and adjust the fueling.
If I was the one running the tuning software, I would have left with 14.0 a/f across the board. Early on we got it to 14.5 but it was pinging...so they richened it (too hell if you ask me)... My v6 with heavier wheels left there with 178 rwhp...and yes, it's only a 3.4L...and yes, I tuned it to 14.0:1 on E85(66)...
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lou_dias
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AUG 25, 07:51 PM
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| quote | Originally posted by pmbrunelle:
Well you can't ask someone to tune your car, and then tell them how to do it...
For me at least, when I'm told to do something, I want to do it my way!
Normally, if I'm really picky about something, I'll do it myself rather than try to micromanage someone else. |
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I told them what I wanted. They are like "no, trust us...we don't want you to blow up your motor". This is just the classic old-school mentality of tuners. The car ran at 19:1 for a month. NEWSFLASH - it didn't blow up.
Tuning was done with TunerCat. I don't feel like spending money on it. I am somewhat amazed no one has made a proper TunerPro .xdf file for the 4.9 yet... If someone did, I would be tuning it myself...
It wasn't worth arguing over a few rwhp when I already gained 20 over the dyno from years ago... Only trolls will crap on the dyno...and I don't care about them.[This message has been edited by lou_dias (edited 08-25-2020).]
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FieroWannaBe
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AUG 25, 08:16 PM
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| quote | Originally posted by lou_dias:
Isn't it funny that 14.7 - 34% = 9.702 ... |
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34% less energy density pretty much translates to 34% less available carbon and hydrogen atoms per unit of air.
Its been a long while since I have had to balance a molecular combustion equation, but it sort plays out that way.
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Will
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AUG 26, 08:51 AM
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| quote | Originally posted by FieroWannaBe:
I had always been under the impression Rich Best Torque wasn't affected much by E85, so if peak power is at 12:1 or 12.5:1, AKA Lambda of .85-.82, you tune to achieve the same AFR reading on the dyno. Almost all tuners do not rescale their graphs for fuel types (stoich on Gas is 14.7, on E85 it is 9.76) Oxygen sensors are blind to fuel type, they report voltage vs lambda, the numbers reported are scaled typically for the fuel type i.e. gasoline. The benefit of E85, is its octane rating, allowing for more timing, at the cost of EGT's since the flam front propagation is slower.
The textbook chart for a "typical" relationship of Lamba. It will vary based of efficiency of design and flame front speeds, which is affected by a laundry list of variables.
Correct me if I am wrong.
*edit: I believe this chart is in % Mass ratio 6.8% mass ratio is stoich for gasoline
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Let's play "How many scales can we fit on the same graph?"!
Snazzy plot... what book is it from?
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FieroWannaBe
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AUG 26, 10:46 AM
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| quote | Originally posted by Will:
Let's play "How many scales can we fit on the same graph?"!
Snazzy plot... what book is it from? |
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Figure 3-1. Representative Effect of Fuel/Air Ratio on Cylinder Head Temperature, Power and Specific Fuel Consumption at Constant RPM and Manifold Pressure in Cruise Range Operation, from Operator’s Manual Lycoming O-360, HO-360, IO-360, AIO-360, HIO-360 & TIO-360 Series, 8th Edition, Part No. 60297-12, dated October 2005. Page 3-7
https://i.stack.imgur.com/tJAao.png
That took some time to track down. I first saw it and similar plots during my ICE course as handouts from the Proff.
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FieroWannaBe
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AUG 26, 11:02 AM
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| quote | Originally posted by lou_dias:
running a little rich only helps with snap throttle acceleration, not WOT. Leaner is meaner. When you are at WOT for more than a second you are losing power by being rich. You can prove this to yourself on any dyno...which I've done year after year after year. . |
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I would argue this is patently false. I dare say many professional engine builders or tuners would agree with me here. Unless, of course, those nerds who does this all day are just wrong. There is no Universal number, but universally there is a richer than stoich. point where best BMEP is achieved. It may not be lambda .8 or .9, but its probably not 1.0, since no fuel injected engine will safely burn 100% of its potential charge during the duration of the expansion and combustion process at normal engine speeds. However, there are many engines that run lean of stoich, and they require careful consideration to avoid pre-ignition.[This message has been edited by FieroWannaBe (edited 08-26-2020).]
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pmbrunelle
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AUG 26, 12:17 PM
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| quote | Originally posted by lou_dias:
I told them what I wanted. They are like "no, trust us...we don't want you to blow up your motor". This is just the classic old-school mentality of tuners. The car ran at 19:1 for a month. NEWSFLASH - it didn't blow up.
Tuning was done with TunerCat. I don't feel like spending money on it. I am somewhat amazed no one has made a proper TunerPro .xdf file for the 4.9 yet... If someone did, I would be tuning it myself...
It wasn't worth arguing over a few rwhp when I already gained 20 over the dyno from years ago... Only trolls will crap on the dyno...and I don't care about them.
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You could always dilute your E85 with gasoline, then have the A/F retuned by these folks to 13 or whatever.
Then, after you leave, you run straight E85, bringing you to 14.
If there's still easy-to-get power left on the table, it makes sense to go get it. Retuning is cheaper than changing hard parts.
It just seems like a shame to not fully exploit a hardware setup because of imperfect programming.
| quote | Originally posted by FieroWannaBe:
there is a richer than stoich. point where best BMEP is achieved. It may not be lambda .8 or .9, but its probably not 1.0
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Lou wants to run an (I assume) gasoline-equivalent 14 AFR, so lambda 0.95. Still rich of stoich.[This message has been edited by pmbrunelle (edited 08-26-2020).]
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