Ignition Coil advice...

[Kaleid]

I've done a ton of searching around on this site as well as Pelican in search of the final word on ignition coils (original black OE coil, current Bosch silver replacement), but it seems that there is no "right" answer on a replacement coil...or is there? New to the game, so any thoughts on this topic are appreciated...Assuming a Bosch CD unit, what's the safest bet when looking for a new coil? Didn't realize these were so hard to get- It seems you can't find them anywhere...

Thanks,
MT

[Steve@Rennsport]

MT:

If your car has the OEM Bosch CD ignition, you need to get the Bosch black coil made for this application.

Some people use the old Bosch blue coil (and others) but the turns ratio is wrong and the car will not run as well as it should. Further, the impedance match is wrong and makes the Bosch CD ignition draw more current than it should.

[jhora]

MT...

Here is a picture of the "coils" left to right....left.. original black Bosch from 1969 911E with the Bosch CD unit coil PN 0.221.121.001, center one..silver new Bosch PN 0.221.121.001, right one...Bosch "Blue" PN 0.221.119.027

I agree with Steve that many Porsche owners have used the wrong coils with mixed results. Regular coils will work with the Bosch CD unit but many of the ignition problems seen are probably related to this miss match and are most likely the cause of many CD box failures. Permatune also requires a special "coil" with their replacement CD box.

The correct one is the PN 0.221.121.001. The new one I have is not painted black and has the natural silver finish. It is made by Bosch in Brazil. I think Bosch has a new numbering system and it may show up as PN 00025.

As noted in the picture the origianl black and new silver ones are shorter in size than the Bosch "Blue" and other black Bosch coils. Get the correct PN one and don't just go by the size. There are some short coils that are used on early aircooled VWs but they are not correct either.

John

[Steve@Rennsport]

MT:

John offered some great information & advice,..

I would only add that the Bosch silver (Brazilian) coils are a real POS and there have been an abnormal number of failures with this part.

Welcome to "Globalization" where making the cheapest possible product is now King.

My best advice would be to try to source a good used one from a Porsche salvage operation. These might be in short supply as people begin to figure this out.

[Richardnew]

is the Bosch 00025 coil still a POS? Any other recommendations?

Richard Newton

[304065]

The best bet is still a used Black coil that meets specifications.

[BURN-BROS]

IIRC, the MSD Blaster 2 hi vibration coil will also work on Bosch CDI.

[304065]

Aaron, guys report using the HVB II, it specs as follows:

Primary resistance .7 ohms
Secondary resistance 4.5K ohms
Inductance 8mH
Turns ratio 100:1

Compare that to my measured specs for the factory CDI coil 0 221 121 001, primary res 0.2 ohms, inductance 1.8mH.

The MSD coil has too much inductance if you ask me, although you are correct that people report that it works OK. No dyno information, however.

[BURN-BROS]

What's the alternative? The Brazilian coils can be bad right out of the box.

I have heard of no failures using the MSD coil with the original CD. However if someone has I would hope they chime in...would love to know.

[69Sman]

The best bet is still a used Black coil that meets specifications.

+1 ten times over