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piggy back module for boost control.

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Old 11-21-2003, 04:50 PM
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Default piggy back module for boost control.

Hi guys,

Can anybody recommend a suitable module for low turbo boost applications, Something simple would be nice. I'd like to retain stock ecu functionability with retard under boost conditions.

Thanks, Mike.
Old 11-21-2003, 05:32 PM
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Since the stock timing table is scaled vs. g/cyl you will actually be able to meter cylinder loads that you only see in boost conditions (greater than 0.7-0.8 or so). other than that I am not aware of anything other than going to a nice DFI setup.
Old 11-22-2003, 03:46 PM
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Originally Posted by ChrisB
Since the stock timing table is scaled vs. g/cyl you will actually be able to meter cylinder loads that you only see in boost conditions (greater than 0.7-0.8 or so). other than that I am not aware of anything other than going to a nice DFI setup.
Chris, thanks for the reply but I don't understand your terminology, g/cylinder? .7-.8, bar? Can you clarify what you mean please. Are you suggesting the stock pcm can make the adjustments? Thanks, Mike.
Old 11-22-2003, 04:11 PM
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Yep, the timing table on the ls1 isn't scaled by RPM vs. MAP (what is more commong) - it is scaled by RPM an grams/cylinder.

So a 2 bar map wouldn't make a difference in timing - as the table isn't scaled directly by it.

G/cyl - "Grams of Air / Cylinder Intake stroke" - esentially the grams of air that go into the cylinder during an intake event. You can calculate it as

MAF flow rate (g/sec) * 15 / RPM = g/cyl

No in a FI setup you are going to get much more air per cylinder event than you would otherwise - though the actual amount depends on your VE/manifold pressure. Typically NA you won't see much higher than 0.7 g/cyl or so - while a FI setup will go up to the top of the table (1.2 - 1.5g/cyl depending on your year, etc).

Best bet is to set all the timing conservative (say 14 degrees or so on a LS1), watch the fueling, and log a run - see what kind of g/cyl values you are getting, and tune from there.

For fueling you will have to add in extra fueling once the MAF maxes out via the PE vs. RPM table.
Old 11-23-2003, 02:24 PM
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Chris,

many thanks for your explanation! Quite onboard with all of that




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