MSD 8222 coil in a 84-89 Carrera?

[john walker's workshop]

Anyone ever try an 8222 MSD coil in a Carrera?

[peppy]

https://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=MSD-PN8222

I put this one in my 88 this spring.

[Tad240]

Pretty sure that’s exactly what is in mine (86 3.2). No problems / working well.

[john walker's workshop]

Didn't want to kill the computer, so good, it should work. Not getting much of a spark from the coil wire with 2 stock coils, not much more than maybe 7-8mm jumping to the fan housing. We'll see if it improves.

[dtwa]

I’ve been running a MSD 8222 in my basically stock 85 for about 2 years with no problems. —Dave


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[AndrewCologne]

@John

Could be Risky.
I guess the electronics in the DME use a dwell time of 2ms for saturation of the coil. As 3ms @ 6500 is the whole time between each spark and 2ms are at least needed for saturating the coil.

So with 12.5 volts at the Coil ....
Original BOSCH IDI Coil comes with 0.7 ohms and 3.6 mH and with 2ms dwell --> this results in 5.77ampere and 60 mj at the spark
MSD 8222 Comes with 0.7 ohms but with 8.0 mH and with 2ms dwell --> this results in 2.87 a and only 33 mj at the spark

So it depends on how or even if the DME varies the time of dwell. And even if it would seem like it works without problems, it "could" result in a non optimal ignition of the mixture. As IIRC at least 40 to 60 mj are needed to fully ignite the mixture in an optimal way. And here also the compression ratio counts (i.E. up to 10.3:1 with an Euro 3.2 engine and 231hp).
---> BUT if 33 mj are enough (I guess not), then ... trust on luck and even less amperes/heat are needed to be handled by the DME.
See also discussion here:
https://forums.pelicanparts.com/porsche-911-technical-forum/1151696-ignition-question-71t-s.html
And here:
https://nineelevenheaven.wordpress.com/the-ignition-of-the-911-3-0-and-3-2/

[mysocal911]

Originally Posted by AndrewCologne

@John

Could be Risky.
I guess the electronics in the DME use a dwell time of 2ms for saturation of the coil. As 3ms @ 6500 is the whole time between each spark and 2ms are at least needed for saturating the coil.

So with 12.5 volts at the Coil ....
Original BOSCH IDI Coil comes with 0.7 ohms and 3.6 mH and with 2ms dwell --> this results in 5.77ampere and 60 mj at the spark
MSD 8222 Comes with 0.7 ohms but with 8.0 mH and with 2ms dwell --> this results in 2.87 a and only 33 mj at the spark

So it depends on how or even if the DME varies the time of dwell. And even if it would seem like it works without problems, it "could" result in a non optimal ignition of the mixture. As IIRC at least 40 to 60 mj are needed to fully ignite the mixture in an optimal way. And here also the compression ratio counts (i.E. up to 10.3:1 with an Euro 3.2 engine and 231hp).
---> BUT if 33 mj are enough (I guess not), then ... trust on luck and even less amperes/heat are needed to be handled by the DME.
See also discussion here:
https://forums.pelicanparts.com/porsche-911-technical-forum/1151696-ignition-question-71t-s.html
And here:
https://nineelevenheaven.wordpress.com/the-ignition-of-the-911-3-0-and-3-2/

1. Yes, the DME ECM used for the 911 3.2 varies the coil dwell time.

2. The 8222 coil and the OEM 911 3.2 coils are basically identical. The website referenced below has had Bosch coil parameters included for over 25 yrs,
and referenced before here on this forum.

Check here for coil parameters under Typical Ignition Coil Values https://www.systemsc.com/diagnostic.htm

Therefore, the spark parameters should be identical when using the 8222 vs the OEM Bosch coil!

[john walker's workshop]

Good to know, thanks all.

[AndrewCologne]

@ Dave
On that website I see "MSD Blaster (8222) - R(primary) = 1.1 ohms, L(primary) = 4.2 mH"
But on several sites which offer the MSD 8222 other values are mentioned. One btw. is Summit Racing:
https://www.summitracing.com/parts/msd-8222
R = 0,7 Ohms and L = 8 mH.
And even if the DME varies the coil dwell time, at 6.500 only approx. 2 ms are available for coil saturation, and if these values of the MSD 822 are the real ones then the maths and comparison above do make sense and proof that at 6.500 RpM with 2ms dwell time the result is 33 mJ.

So the question is regarding that website .... did you measure the diff. values at the MSD 8222 on your own?
Cause if your values above are actually the real ones thenwith 2ms an energy at the spark of 45 mJ occurs which would be enough then.

[mysocal911]

Originally Posted by AndrewCologne

@ Dave
On the page I see " MSD Blaster (8222) - R(primary) = 1.1 ohms, L(primary) = 4.2 mH"
But on several sites which offer the MSD 8222 other values are mentioned. One is Summit Racing
https://www.summitracing.com/parts/msd-8222
R = 0,7 Ohms and L = 8 mH.
And even if the DME varies the coil dwell time, at 6.500 only approx. 2ms are available for coil saturation, and cause of this my maths and comparison above do makes sense that at 2ms the result is 33 mJ.

So .... Did you measured diff. values at the MSD 8222?
Cause if your values above are actually the real ones thenwith 2ms an energy at the spark of 45 mJ occurs which would be enough then.

Their email address is; https://www.systemsc.com/
You can always order a 8222 and measure it yourself.