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Old 03-31-2015, 11:26 PM   #101 (permalink)
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Quote:
Originally Posted by ever_green View Post
Yeah the new stratified charge lean burn Hondas might help, but the new Prius can get pretty good mileage on highway without lean burn. Therefore I personally don't see the point.
Well, lean burn is better than cooled EGR like I mentioned for attaining complete combustion. Of course, the biggest problem is getting rid of the NOx, and the current NOx traps are not a good solution.

Since you've experimented with this, do you mind sharing your fueling tables? I'm thinking about getting a BRZ and I'm super excited to fiddle with the ECU (that is, lean burn!). Just to get an idea of how lean you can go at what speed.

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Old 04-01-2015, 03:46 PM   #102 (permalink)
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Quote:
Originally Posted by serialk11r View Post
Well, lean burn is better than cooled EGR like I mentioned for attaining complete combustion. Of course, the biggest problem is getting rid of the NOx, and the current NOx traps are not a good solution.

Since you've experimented with this, do you mind sharing your fueling tables? I'm thinking about getting a BRZ and I'm super excited to fiddle with the ECU (that is, lean burn!). Just to get an idea of how lean you can go at what speed.
Standard Subaru ecu does not allow you to go leaner than 14.68 Afr or lambda 1.0 in closed loop. What you have to do is induce a fulltime open loop behavior and then have the Maf sensor underestimate airflow by reduce Maf scaling. This is a lot of work as it requires you to reduce the engine load scale across the board in ecu or else it will think there is less cylinder pressure than actually is and run too much timing (this is just one example). Also on the BRZ I highly doubt this is feasible. The direct injection and firing angle tables are extremely confusing and I wouldn't dare tinker with it.
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Old 04-01-2017, 03:37 PM   #103 (permalink)
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Old 08-29-2017, 01:19 PM   #104 (permalink)
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The reasons are as follows:
- Combustion stability is too low when running lean (engine knock and/or pre-ignition is caused)
- NOx generation is too high
- Power is decreased
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Old 08-29-2017, 06:04 PM   #105 (permalink)
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Quote:
Originally Posted by pgfpro View Post
To me, their lean burn engine looks like a direct-injection Engine judging by the diagram.

Quote:
Originally Posted by ever_green View Post
What you have to do is induce a fulltime open loop behavior and then have the Maf sensor underestimate airflow by reduce Maf scaling.
Any blog write-ups on that ?

Quote:
Originally Posted by pgfpro View Post
This is a lot of work as it requires you to reduce the engine load scale across the board in ecu or else it will think there is less cylinder pressure than actually is and run too much timing (this is just one example).
I was watching this video. They show it being done on a spreadsheet.

https://youtu.be/kBk0KudOVAg after about 4:20

Using pattern-matching algorithms, I'm really confident that this could be done in software with some type of blanket-algorithm. (True, I don't value car engines like I used to :-) )

Translated into young peoples language, "like a facebook bot? or iPhone app?" but I mean some type of spreadsheet macro or script code.

It's a good conversation, so keep going.
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Old 08-29-2017, 06:16 PM   #106 (permalink)
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Cool

NOx can react in a fuel cell to make electricity, I wonder why they don't just do that
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Old 08-29-2017, 08:09 PM   #107 (permalink)
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RMay, do you have a source for that? I just get stuff about Bloom Box, which does not mention NOx.

Google does not even bother asking "Do you mean box?"
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Old 08-31-2017, 12:10 AM   #108 (permalink)
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Quote:
Originally Posted by ar5boosted View Post
To me, their lean burn engine looks like a direct-injection Engine judging by the diagram.
The Honda one (HLSI on that diagram) is port-injected. I think part of what drove Honda to develop this was that they could keep using lean-burn after emissions standards kept them out of cars. They have a bunch of 4-stroke lean-burn outboards, for example.
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Old 08-31-2017, 12:22 AM   #109 (permalink)
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Even running lean-burn, port-injection is expected to decrease the NOx emissions compared to direct-injection. Particulate matter emissions, which plagues Diesels and has become an issue for spark-ignited direct-injection too, is another reason for some engines to retain port-injection.

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