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Author Topic: Spark Retard and Enrich Launch Control for 2.7t ME7.1 8D0907551M  (Read 19599 times)
prj
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« Reply #45 on: June 28, 2018, 01:01:16 PM »

I am after late ignition timing for a rally style bang bang antilag instead of a spark cut antilag.  Everyone keeps saying that using an ignition angle of -10* is too much but the typical rally style antilag runs timing in the -35* to -45* range.  They also employ a throttle kick to maintain airflow and enrich the mixture to cut down on egts.  (This would be in a system active, vehicle in motion, no input on throttle situation)  As far as timing that negative shutting the engine down, it doesnt make sense.  If you fire the spark when the piston has begun its down stroke it minimizes torque input but keeps the primary combustion event in the cylinder, valve, manifold area.  The spark cut versions dont fire any spark and they dont stall the engine.  They push the fuel to wherever it can find an ignition source, be it manifold, turbo, or exhaust from an alternate cylinder.  The goal is to have bang bang antilag as an option when I put the turbo restrictor in.  

How about you get some experience before stating these things. Everything you're saying is ridiculous.

40 degrees ATDC, absolutely shuts the engine down instantly. There is no power produced. I don't know where you got the idea about "rally style antilag" you sure as hell don't seem like anyone who has EVER tuned an antilag system before. My company does rally cars on standalone and I can guarantee not a single one of them has 40 deg atdc timing.
Not a single modern car has any "throttle kick", e-throttle is used for antilag and air control.

Same goes for 20 degrees ATDC.

Instead of discussing this stuff here and having opinions about shit you've never even done, how about go out and get some experience?
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woj
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« Reply #46 on: June 28, 2018, 02:14:08 PM »

Look at the KFZWMN table for your car, try to find out what it represents in terms of engine capability to accept retarded spark.

On the anti-lag I developed for the Fiat engine, 10-12 retard worked somewhat, but it was shooting like a bomb and in the opinion of everybody but the owner was too excessive (and I am 99% certain that it was not even the requested value, but effectively a limit from KFZWMN). So I was told, I have not experienced it live, though have seen a video. Also, the car has a considerably bigger turbo compared to factory.
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Cadensdad14
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« Reply #47 on: June 28, 2018, 03:58:59 PM »

I get the e throttle thing.  But all that would be required is to crack the throttle via the ecu.

Tell me where my concept is wrong.  When engine speed exceeds limits, the spark is retarded, eventually with some hysteresis, to the point where no power is produced but the charge is still used to spin the turbo.  The throttle is adjusted to an extent to allow air in.  When engine speed drops below threshold, ignition timing is restored and normal throttle function resumes.  How much boost pressure is built by the system can be controlled by wastegate duty cycle and how much the throttle opens and can be adjusted to match surface conditions. 

A retarded spark angle will not instantly stop an engine, it will just not add power.  Properly timed there would be no difference between a retarded spark and cutting dwell time on the coil to not get any spark with the exception of providing an ignition source.  I know you can slow an engine without the throttle 3 ways, spark retard, spark cut, and fuel cut.  Spark retard is going to be roughest on egts.

Im going to continue to tinker with this and figure it out.  If I blow up my engine, ill pop another one in. 

In looking at KFZWMN in the FR it makes the point that this would be the latest angle at which the combustion event would not be audibly heard.  This tells me I likely have to move beyond KFZWMN.  Also worth noting is that this is a feature that the subie guys are able to implement with the carberry Rom thats floating around.
« Last Edit: June 28, 2018, 04:02:22 PM by Cadensdad14 » Logged
prj
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« Reply #48 on: July 02, 2018, 02:59:19 AM »

Tell me where my concept is wrong.  When engine speed exceeds limits, the spark is retarded, eventually with some hysteresis, to the point where no power is produced but the charge is still used to spin the turbo.  The throttle is adjusted to an extent to allow air in.  When engine speed drops below threshold, ignition timing is restored and normal throttle function resumes.  How much boost pressure is built by the system can be controlled by wastegate duty cycle and how much the throttle opens and can be adjusted to match surface conditions.

A retarded spark angle will not instantly stop an engine, it will just not add power.  Properly timed there would be no difference between a retarded spark and cutting dwell time on the coil to not get any spark with the exception of providing an ignition source.  I know you can slow an engine without the throttle 3 ways, spark retard, spark cut, and fuel cut.  Spark retard is going to be roughest on egts.
It went wrong at the point where you said that boost is controlled by WGDC. No it's not. Boost is controlled by the amount of timing retard,WGDC is flat 100%. And the difference between retarding timing until no more power is made vs retarding timing enough that there is sufficient boost and then cutting spark as soon as you exceed the RPM threshold is the difference between molten pistons and the engine that is running.

So yeah, your "concept" is very wrong at the core.
Which is fine because you have zero experience, what is not fine is claiming you know how everything works when you don't.
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giles92
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« Reply #49 on: July 18, 2018, 03:39:07 PM »

hey prj if you wanna hate, you should go to audizine and troll there. Know what is helpful and what is toxic. Some of us aren’t professionals. You could help or do nothing instead of being an ass.
« Last Edit: July 18, 2018, 07:33:44 PM by giles92 » Logged
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