Tuning: PE or spark first in SD and theory behind, and the balancing act?
08-08-2006, 05:32 PM
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Tuning: PE or spark first in SD and theory behind, and the balancing act? Been getting a lot of great over at hpt, and with all this help comes more questions that come up, lol! Figured I post this here as well since most people frequent this board. So here it is:
My VE table is looking close to perfect in all rpms, next step is spark, then MAF. My question lies with the balance of PE and Spark when tuning in SD OL w/ WBO2 before reverting back to Closed Loop Maf.
Reading many posts here and on ls1tech, and the close to perfect way to tune spark is via the afr, if goes lean as spark increased, and then stops and reverts to rich, that is the spark limit. Etc etc for reverse... I plan to do this for my whole VE and Spark table.
The problem is, some posts I read people set their PE to a guestimate to what they want, and then do spark. I'm thinking to myself, how do you know what PE is best suited to the application, any tell tale signs if your good or not?? Then I read rich for max tq, lean for max hp base off tuning many other cars.
Should I just tune for spark first through all rpms, and then go straight to PE? What's the fine balance btw these two, and any easy tell tale sign without a dyno or anything else too technical other than HPT and a WBO2? Are there any theories about the balance of spark and PE, and what affect more of one over the other up to knock retard has on power output? They both produce power obviously, but which one do you use more of?
Thanks!
My VE table is looking close to perfect in all rpms, next step is spark, then MAF. My question lies with the balance of PE and Spark when tuning in SD OL w/ WBO2 before reverting back to Closed Loop Maf.
Reading many posts here and on ls1tech, and the close to perfect way to tune spark is via the afr, if goes lean as spark increased, and then stops and reverts to rich, that is the spark limit. Etc etc for reverse... I plan to do this for my whole VE and Spark table.
The problem is, some posts I read people set their PE to a guestimate to what they want, and then do spark. I'm thinking to myself, how do you know what PE is best suited to the application, any tell tale signs if your good or not?? Then I read rich for max tq, lean for max hp base off tuning many other cars.
Should I just tune for spark first through all rpms, and then go straight to PE? What's the fine balance btw these two, and any easy tell tale sign without a dyno or anything else too technical other than HPT and a WBO2? Are there any theories about the balance of spark and PE, and what affect more of one over the other up to knock retard has on power output? They both produce power obviously, but which one do you use more of?
Thanks!
08-08-2006, 08:33 PM
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You have to start with one and it makes more sense to set your PE first.
Most engines will prefer between 12.8:1 and 13.2:1 so that's a good place to start.
Once the spark is finished you can easily go back and fine adjust your PE to see what your engine likes with your new timing curve.
Most engines will prefer between 12.8:1 and 13.2:1 so that's a good place to start.
Once the spark is finished you can easily go back and fine adjust your PE to see what your engine likes with your new timing curve.
08-09-2006, 10:32 AM
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If you had a surplus of dyno time (or street
tune instrumentation good enough to get some
consistent, quantitative performance numbers)
you could shotgun the fuel, spark space crudely,
overlay the acceleration / RWTQ curves and
pick the "top line" and its pointwise best tune
pairs (fuel, spark for best TQ@RPM) and then
stitch the best segments & smooth them in.
To large extent both have a "flat top" character
to them with degradation to the left and danger
to the right; once leaner stops mattering, once
once advanced stops helping, you can step back
and figure out where to call it safe and good
enough. If there is such a thing as good enough.
Me, I settle for high 12:1s and 2-3 degrees short
of ping (although you'll need to work with some
of the environmental spark adders to stay out
of it, when the weather gets hotter than your
tuned-to, etc., if you chose to really tighten
it up to the post).
tune instrumentation good enough to get some
consistent, quantitative performance numbers)
you could shotgun the fuel, spark space crudely,
overlay the acceleration / RWTQ curves and
pick the "top line" and its pointwise best tune
pairs (fuel, spark for best TQ@RPM) and then
stitch the best segments & smooth them in.
To large extent both have a "flat top" character
to them with degradation to the left and danger
to the right; once leaner stops mattering, once
once advanced stops helping, you can step back
and figure out where to call it safe and good
enough. If there is such a thing as good enough.
Me, I settle for high 12:1s and 2-3 degrees short
of ping (although you'll need to work with some
of the environmental spark adders to stay out
of it, when the weather gets hotter than your
tuned-to, etc., if you chose to really tighten
it up to the post).