Dwell time coils????
10-02-2010, 06:26 PM
#2
The values are on a dwell time table in the GM software. The values are from 0-8000 RPM down & 0-26v across. Dwell times range from less than 3ms through 26ms depending on where you are on the table. If you have tuning software, can open the tuning repository files listed as "stickies" @ the top of the tuning section page on this site. In the tuning file, open spark, then general & then spark dwell time. The table will pop up.
If no software, then you are probably looking for the rates from 11-14v @ 0-7000 RPM. There's too many to list 'em all, but generally, @ 11volts, the dwell times go from 6.13ms @ 0 RPM down to 4.16ms @ 8000 RPM. @ 12volts, 5.3ms @ 0 RPM down to 4.16ms @ 8000 RPM. @ 13 volts 4.6 ms @ 0 RPM down to 3.5ms @ 8000 RPM. 14v are 4.2ms down to 3.6ms.
10-02-2010, 06:44 PM
#3
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Thanks for the reply, the reason I ask, we have a prototype FI/data log system on my bro. Outlaw 10.5 car. Put the D585 coils on and we are getting some misfire and no ability to climb rpms over 7000. we are at 2.7ms right now, but we are also pretty fat on the fuel. we spin the motor aroung 8500. BBC twin 94s on alcohol. thank Shawn
10-02-2010, 10:25 PM
#5
Thanks for the reply, the reason I ask, we have a prototype FI/data log system on my bro. Outlaw 10.5 car. Put the D585 coils on and we are getting some misfire and no ability to climb rpms over 7000. we are at 2.7ms right now, but we are also pretty fat on the fuel. we spin the motor aroung 8500. BBC twin 94s on alcohol. thank Shawn
2.7 seems way low. Does the info I posted get you where you need to be? Generally, you can go between 3.5 & 6.4 ms depending on where you are in the RPM range. I can understand how 2.7ms may not be enough. Can also see, from your set up, where if you get too much dwell, she'll get too hot.
The best thing to do is to maybe change the dwell a bit to get closer to what we've discussed here & then test it & post this discussion in the forced induction section. If you don't get better info there, the tuning section would be next. What has been noted here is all that I can offer. Have no experience w/ how too much or too little dwell effects a forced induction engine. As noted though, it does appear that your dwell is too short based on the stock GM dwell times.
