DIYEFI.org Forum

So I've heard various things about the LS coil pack dwell numbers, like never go over 5ms, etc. So I decided to check a tune file of a oem chevy ecu for a corvette. 2002 chevy ls corvette. What I found goes aganist what the internet says so far that I've found. You can see in this picture that they run the coils up very high dwell numbers at low voltage.

Great stuff, Hentai! Typical misinformation from the usual source mythbusted again?

Can you get more data points from other older/newer/different LS engine and chassis types?

I would love to see someone methodically test some different coil variants against various voltages and dwells. I bet the protection is smart about saturation, and not a hard-coded time at all.

Fred.

To be fair, I don't think anyone would even consider dwell times below 12 volts, except for dwell while cranking. If you're hearing advice for nothing above 5ms, those folks are probably assuming 12-15 volts?

6 and 7 Volt columns are reachable during worstcase cranking conditions. 8V col is clearly a legit set of values, too. 8V contains close to 10ms, which invalidates internet BS by itself. But yes, sounds like a context-less statement made as an absolute truth rather than @ X Volts.

Ben, the advice was "self limits (fires plug early) @ 8ms" if you try to go longer.

http://www.yellowbullet.com/forum/showt ... 602&page=4
http://www.efi101.com/forum/viewtopic.p ... 3653c817dc

Some of that discussion is highly dubious typical inet pecking order bullshit. I'd like to see some variants tested from 6v to 16v and 2ms - 12ms in a 10x10 (or even 5x5) grid, for each type. Then you'd KNOW.

OEM Chevy ECU calibration doesn't necessarily go against what was said about the coil self limiting at 8ms. That could be true of the coil even if the calibration assumes otherwise. x2 on test = knowledge.

Ok so remember there is many different coils that are used with the LS engines now, I've show Fred a pic showing atleast 4 or 5 different ones not including the ones with the heatsink.

So for the 2002 corvette this is the coil referenced on autozone.com

Now I checked the 2005 corvette which uses the E40 ecu and I found different figures including a map that is for understanding the expected tempature of the coil

Tune data
spark dwell followed by the mod table




coils for 2005 corvette which don't match the other coil design physically.