VersaTune User Forum

Most of people have after market ignition. But how to define the new dwell ? Google didn't helped me. Most of us have D585 AC Delco.

If you have a high output coils you should do:
1000=6ms
2000=5ms
3000=4ms
4000=3,5ms
5000=3,5ms
6000=3ms
7000=3ms
8000=2,5ms
9000=2,25ms

You should notice a smoother overall pull if you lightly accelerate in 3rd gear from 25mph to 85mph
do that at best on a closed road.
also do 2-3 high load runs 1st gear to 9k 2nd gear to 9k and 3rd gear to 9k should pull nice and even.
you should log the test and try to keep an eye on engine rpm changes over the run it should be climbing very even,
if that isn't the case decrease the timing in the rpm range that the slowdown occurs by about 0,1ms.
keep also in mind that at 9000rpm your coil has max. 3,2ms charge time before it fires but don't do that if you track or race a lot cause the coils will overheat and get damaged.
Cheers

10000RPM wrote: ↑March 27th, 2020, 8:48 am
keep also in mind that at 9000rpm your coil has max. 3,2ms charge time before it fires but don't do that if you track or race a lot cause the coils will overheat and get damaged.
Cheers

Hi 10K,

i'm not sure where you're getting the max 3.2ms to charge at 9k rpm??
in 1 minute : 60.000ms
60.000ms/9000rpm =6.67ms/rpm

Or am i missing something??

Marco

il_performante wrote: ↑April 27th, 2020, 5:44 am i'm not sure where you're getting the max 3.2ms to charge at 9k rpm??
in 1 minute : 60.000ms
60.000ms/9000rpm =6.67ms/rpm

Or am i missing something??

Yeah but you're not firing the coil for the entire duration of the compression stroke, are you?

mituc wrote: ↑April 29th, 2020, 6:29 pm

il_performante wrote: ↑April 27th, 2020, 5:44 am i'm not sure where you're getting the max 3.2ms to charge at 9k rpm??
in 1 minute : 60.000ms
60.000ms/9000rpm =6.67ms/rpm

Or am i missing something??

Yeah but you're not firing the coil for the entire duration of the compression stroke, are you?

Right, so i have 6.67ms total from which i can subtract charge time + firing time (say 2ms?)
6.67 total -3.2 charge -2 fire = 1.47ms extra leftover.

something specifically that i'm missing?

thanks,

Thoughts on using the "typical" D585 dwell times?

VersaTuner caps the dwell time at 10ms, but honestly I can't see any reason to *need* the higher dwell at those crazy low voltages anyway.

I switched to the above coil dwell times (the lower half of that image) with a huge improvement in drivability & throttle response and the car definitely pulls stronger too.

Can you alter dwell for stock coils or are they already at there optimum/limit??

dieseldaz wrote: ↑November 11th, 2022, 9:18 pm Can you alter dwell for stock coils or are they already at there optimum/limit??

Better late than never. Stock coils were tested at way higher limits than they are stock, but at the same time, you'll just worn them out quicker. How quicker? Less than most aftermarket (excluding AEM and some others) that weren't initially designed for the RX8.

il_performante wrote: ↑April 29th, 2020, 10:18 pm

mituc wrote: ↑April 29th, 2020, 6:29 pm

il_performante wrote: ↑April 27th, 2020, 5:44 am i'm not sure where you're getting the max 3.2ms to charge at 9k rpm??
in 1 minute : 60.000ms
60.000ms/9000rpm =6.67ms/rpm

Or am i missing something??

Yeah but you're not firing the coil for the entire duration of the compression stroke, are you?

Right, so i have 6.67ms total from which i can subtract charge time + firing time (say 2ms?)
6.67 total -3.2 charge -2 fire = 1.47ms extra leftover.

something specifically that i'm missing?

thanks,

coil has to rest as well, duty cycle = (discharge time + charge time) / cycle time, you should never be above 80%.. on the 4t coils not even near that!!