D585 coils - necessity of changing dwell tables?
07-16-2010, 05:45 AM
#21
I put on the truck coils and if memory serves me I think I just bumped my table by 5-10% which still puts the dwell lower than the truck settings. Right now I'm in the middle of a head cam swap, so I can't test anything, but after I get everything back together and get the tune squared away, I'll try bumping the dwell a little more to see what difference it'll make. I saw a solid 15-30 miles per tank increase with just swapping the coils which translates to a 1-2mpg gain average as well as better throttle response.
To the disbelievers, there has to be a reason why GM went with stronger coils as the ls motors have evolved. If they thought the original ls1 coils were good enough, they never would have bumped up their capacity and gone with stronger coils as the motors made more power. I know, it's not dyno data, but it's empirical data that you can extrapolate a good enough reason to drop $200 and swap out yours if you've got the money.
To the disbelievers, there has to be a reason why GM went with stronger coils as the ls motors have evolved. If they thought the original ls1 coils were good enough, they never would have bumped up their capacity and gone with stronger coils as the motors made more power. I know, it's not dyno data, but it's empirical data that you can extrapolate a good enough reason to drop $200 and swap out yours if you've got the money.
Last edited by The Alchemist; 07-16-2010 at 05:51 AM.
06-08-2012, 10:53 AM
#27
You could go with the argument that GM's engineers set the dwell tables up for maximum longevity, and you'd probably have a pretty decent argument if that's what you chose to believe. The D585 and LS1 coil dwell tables are definitely different...see below.
I went off of that Megasquirt link I posted above where they found that the maximum dwell time for the D585 type of coil was around 5.0ms @ 14V - any more dwell didn't generate any more spark energy, so it would probably just heat up the coil (although they do have heat sinks, so they might handle it better). I just massaged the table for mine so that the maximum value was 5.5ms @ 12V, 5.0ms @ 14V, and so on (as seen in the table in that link I mentioned), and whatever it took to get there, I just added to the rest of the values all across that row. A little linear interpolation, and you get the randomness that is my current dwell table. It might be a little high on dwell in the upper RPMs, but I'm not sure...after all, I could ask it to charge for a lot longer, but it will only charge as long as it can before it has to fire under those conditions.
Stock LS1 coil dwell table:
Stock D585 coil dwell table:
And what I currently run:
I went off of that Megasquirt link I posted above where they found that the maximum dwell time for the D585 type of coil was around 5.0ms @ 14V - any more dwell didn't generate any more spark energy, so it would probably just heat up the coil (although they do have heat sinks, so they might handle it better). I just massaged the table for mine so that the maximum value was 5.5ms @ 12V, 5.0ms @ 14V, and so on (as seen in the table in that link I mentioned), and whatever it took to get there, I just added to the rest of the values all across that row. A little linear interpolation, and you get the randomness that is my current dwell table. It might be a little high on dwell in the upper RPMs, but I'm not sure...after all, I could ask it to charge for a lot longer, but it will only charge as long as it can before it has to fire under those conditions.
Stock LS1 coil dwell table:
Stock D585 coil dwell table:
And what I currently run:
06-08-2012, 10:20 PM
#29
I got hptuners in today, and i updated the dwell tables with the stock d585 tables from a 2002 tahoe. It could be some sort of placebo effect, but i must say the car seems a little bit more "crisp". I think my 02s are taking a dump, so it's been a little weird maintaining the afr, but despite that the car ran great today.
I'm going to fix what i need first, but i'm going to try the table MeentSS02 posted and see how i like that, just in case anyone looking here is curious on a wider array of experimentation.
