engine and drivetrain Ballast resistor, blue coil, black coil: questions, questions

[RAS-2002]

I've searched and re-searched, and I confess: I am now suffering from information overload.

 

As if this subject hasn't been flogged enough!

 

My current set-up: 1972 2002 (non-tii) with Ireland Engineering's 2002tii electronic distributor, Bosch blue coil, and stock ballast resistor.

 

I've now learned that the Bosch blue coil has an internal resistor which negates the need for the separate ballast resistor.

 

Since its installation 2 years ago, I've been running the above setup with the ballast resistor connected.

Which, from what I have read, this is incorrect. The ballast should not be used with the blue coil, as you risk burning out the elec ignition unit.  I guess I should consider myself lucky that I haven't fried anything yet. But I've seen other FAQers post that they've run this same set-up with no problems, and other who have fried their igniters... luck of the draw?

 

So, here's the question I haven't seen asked or answered:

If I keep my current set-up with the blue coil, do I just disconnect one (or both) ballast connections, and just put tape over them, or do I disconnect both wires and use a jumper between them? (see attached pics)

 

From the info I've gathered, using blue coil with the ballast will result in higher ohms, which translates into a lower spark output (and might even fry the unit).

Question 2: Will I notice any increase in performance by using the blue coil and taking the ballast out of the circuit?

 

Note: I still have the old black coil, (and the car ran fine with it).  If I re-install it, it will require the ballast resistor.

Question 3: other than it being newer, is there any advantage of using the blue coil over my old black coil?

 

Thanks,

-Bob (and hot damn!, it feels good to be driving it again!)

 

Weather-permitting, I'll be at the Bear Mountain (NY) car show on Wednesday night.

[Stevenc22]

1) By removing the ballast resistor you will increase the spark energy to the spark plugs theoretically making the car run better.

 

2) Your thinking about the ballast resistor burning out the ignitor is backwards. People who need a ballast resistor but don't run one might burn out the ignitor, not the other way around(having a ballast resistor and not needing one)

 

3) You will need to put a jumper wire between the 2 connections of the ballast resistor. If you disconnect the wires from the ballast resistor and do not connect them with a jumper wire the car wont start.

PS - Are you sure your current coil is a blue coil? Measure the resistance across the coil + and - and confirm it is about 3 ohms.

[jmiller]

^ +1.    That does not look like the Bosch blue coil.  

[RAS-2002]

Thanks for the responses. I just measured it: a little under 3 ohms. It says Bosch "made in Brazil" on it. It's actually an aluminum can with a blue paper label on it... close-up picture attached.

So, what do you think: "yay" or "nay" on using the ballast with it?

Thanks,

-Bob

[RAS-2002]

The Bosch part# on it is: 0 221 119 027

-Bob

[Stevenc22]

2.8-3.0 ohms is a bosch blue so remove the ballast resistor.

[RAS-2002]

Hi Steve,

Thanks; I'll remove the ballast.

 

Much obliged,

-Bob

[PaulTWinterton]

FWIW, I have a blue-colored coil that is actually a black (tii) coil in disguise.  Per Blunt.

[RAS-2002]

Okay, it looks like I'm all set; I removed the ballast resistor from the circuit, installed a jumper to connect the two leads.

I also found a loose wire on the coil; crimped it; that seems to have smoothed it out; runs nice.

Thanks again!

 

FAQ rocks! You're all the best!

 

-Bob

[Roland]

Conventional wisdom says that all so-called blue coils contain internal resistance, negating the need for any external ballast resistors.  I would caution that conventional wisdom is not always correct and that not all blue coils are the same even though they can look the same mounted in your engine bay.

 

Zenon's write up will tell you that Bosch coils originally came in three colors, Black, blue and red. http://www.bmw2002faq.com/_/technical-articles/electrical-and-ignition/ignition-coil-myths-busted-r52 They were actually painted those colors rather than merely adorned with a colored sticker.  Back when coils were actually colored, Bosch made a substantial number of coils for 6 volt systems (mostly for VW ).  While coils were predominantly black  -  some were blue.  Bosch, of course, produced blue 12v coils too.  I have reason to believe there were some 6v and 12v blue coils  made without any internal resistor - that, in turn, required an external ballast resistor.  (I remember wasting an afternoon going through parts books to determine exactly what kind of blue coil was on a dune buggy that ran dual bosch blue coils with external ballasts.)  My point is that unless you check the part numbers usually imprinted on the coil bottom or obtain a coil with accompanying packaging/documentation, it is unlikely, but not impossible for it to be different than the so-called over the counter blue coil.  (I'm pretty sure this topic was discussed before, see e.g., http://www.bmw2002faq.com/topic/75974-boschs-bleu-blue-coil-marketing/ ; see also http://www.ratwell.com/technical/BlueCoil.html#summary)

 

As far as what coil you should use, the blue is probably the winner when it comes to underhood aesthetics, although red and yellow are close seconds.  When it comes to performance (that you are unlikely to notice unless you drive competitively), you would be better off with black or red, in no particular order.  Zenon's write up provides several reasons why, including:

 

On all North American '02s (at least from '72-on), BMW fitted the "heavy duty" ignition system that was apparently an option for carby '02s in other markets and standard on tiis and turbo. According to the factory specs and part numbers, the tii and carby external-resistor coils are the exact same part.

 

The marketing for the Bosch blue coil has not been particularly well articulated.  It has often been described as "high performance" and "super."  This brings to mind certain non-alkaline 9volt batteries that are labeled "Super Heavy Duty."  Are the latter any better than the usually-more-expensive alkaline 9volt batteries?  Are the more expensive platinum tipped Bosch plugs better than the standard copper core plugs?  Marketing suggests they are but Toby may have a different opinion.

 

I don't think there is anything wrong with using the blue coil but, aside from availablity, vanity and cost, it is no better than a functioning black coil and probably slightly inferior to the black coil.  Again, this thread is worth re-reading. http://www.bmw2002faq.com/topic/75974-boschs-bleu-blue-coil-marketing/

 

Finally, something else to consider is that the blue coil was apparently an upgrade for some, but not all, ignition systems.  The specs do not favor it being an upgrade for the '02 ignition system - unless the stock coil were dead or dying.  One Saab site offers a pretty straight forward illustration:

 

 

The OEM coil has a 100:1 ratio of primary to secondary voltage.  The application of 12 volts on the primary will produce (a maximum) of 12,000 volts on the secondary.  I say maximum because there is a cycle time or rise time of the coil.   If the coil is asked to "fire" before fully "charged" then something less than the maximum voltage will be delivered.

The classic approach to fixing this problem is with a high performance or "sport" coil.  Such coils are available from Bosch, Lucas, MSD, Mallory, and a raft of others.  The Bosch coils are of greatest interest because of their vintage heritage and close kinship to the stock coil.

The Bosch Blue coil is rated at 18KV or a ratio of 150:1  It will deliver a  maximum voltage of 18,000 when fully cycled up. This is advantageous at low RPM where a higher electrical potential is needed to jump the spark gap in a dense cylinder mixture.  At high RPM, even when not fully charged, it delivers a stronger spark than the OEM coil.

For even greater punch, Bosch makes a Red coil.  It is rated at 25KV and has a ratio of  200:1.  Its attributes are pretty much the same as the Blue coil only more so.  Lucas also makes a high performance coil which is gold in color.   I believe it offers 200:1 windings.

The most powerful aftermarket coils offer secondary voltage as high as 55,000 volts.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

    or    

 

 

 

 

 

 

   0r           "Super"

 

 

 

Edited June 4, 2015 by Roland

[RAS-2002]

Hi Roland,

Great write-up!  One more question: are all the different hi-output coils you pictured (with the proper ballast resistors, if needed) compatible with electronic ignitions?

For example, I have Ireland Engineering's 2002tii electronic dizzy, Bosch blue coil, resister removed (and it's running great!). No changes planned, just askin'...

Thanks,

-Bob

[Stevenc22]

^ properly resisted yes

[RAS-2002]

One last thing (my apologies, and I promise this is the last you'll hear from me on this over-flogged subject)...

 

In summary, if I'm correct, (and thanks to everyone for the info, especially the posts by Stevenc22 and Roland), it appears that there is no real performance advantage of using one of the three Bosch coils over the other (if the correct ballast resistor is used, when required). 

 

I searched but couldn't find any actual performance data comparing these three Bosch coils:

- OEM black coil (ballast resistor required)

- blue coil (ballast resistor not required)

- red Super coil (ballast resistor required)

 

Over and out.

Thanks to all,

-Bob

['76mintgrün'02]

I never get tired of discussing the ignition system...  

 

I thought this was an interesting bit of information:

 

But I have a chart for you. The chart compares the black (E), the blue (K), and the red (KW)

Bosch

coil and shows how fast a modern transistor driven coil loads. 

Photo courtesy of unknown.

Photo courtesy of unknown.

Photo courtesy of unknown.

Photo courtesy of unknown.

The lower the the resistance of the coil the faster the coil loads up to a definite voltage line - important at high engine speed.

The limit for the breaker points is the 5A line. For this reason the red E-coil needs a fat 1.8 Ohm resistor in series connection. The resistor may be shortened by a relays while starting.

If you want more amps you must use electronic components. Modern Guzzi coils - e.g. Jackal - have less than 1.0 Ohm resistance in the primary circuit.

 

 

Taken from this :  http://www.thisoldtractor.com/moto_guzzi_loopframe_coil_information.html

[percy]

I never get tired of discussing the ignition system...

 

I thought this was an interesting bit of information:

 

 

But I have a chart for you. The chart compares the black (E), the blue (K), and the red (KW) Bosch coil and shows how fast a modern transistor driven coil loads. 

 

Taken from this :  http://www.thisoldtractor.com/moto_guzzi_loopframe_coil_information.html

 

 

With respect, the Moto Guzzi chart is incomplete for purposes of this thread and, as you point out, the black coil charted is of the lowly "e"-variety rather than the KW, found on most '02s..  As has been mentioned in earlier posts, the color of a Bosch coil does not necessarily indicate saturation times and energy output.

 

The Saab quote mentioned earlier in this thread suggests the black coil for an OEM Saab is an "E" type with fewer windings and lesser maximum output voltage than other available black, blue and red coils.  Hence, the advice to move toward blue or red.       Zenon's article substantiates that information with a list of two differently rated Bosch black coils  -  along with blue and red.    Here is an excerpt from the Z article clearly differentiating type "E" black coils from type "KW" black coils.     Returning to the Moto Guzzi article, the black coils that author used were apparently VW coils and as you note, his chart reflects that the black coil is an "E-Spule" with 14kv output.  The MG chart never mentions or considers the Black "KW" type. 

 

 

 

 

from the archives Bosch lists four types of coils for induction type ignition systems

• Type E(Black)6V-12V systems for 4 cylinder engines. No resistor needed. Output 13.5 KV. This was the type commonly found on small 4 cylinder engines i.e. Volkswagen, etc.

• Type K(Blue)6V-12V systems for up to 6 cylinder engines. No resistor needed. Output 17.5KV. This was the type commonly found on 6 cyl VW and as a performance upgrade for 6V systems and lower power 12V systems. Should never be used on BMWs.

• Type KW(Black) 12V-24V systems for up to 6 cylinder engines. Output 22.5KV. For 12V operation use ballast resistor 0.6-1.0 ohms, for 24V operation use ballast resistor 4.5 ohms. This is the coil that came standard on all [North American] BMW engines. As you can see going to a Blue coil would be a significant step backwards.

• Type KW(Red) 12V systems for up to 8 cylinder engines. Output 26.5KV. Use with 1.4-1.8 ohm ballast resistor. If the ballast resistor is omitted, the points will burn up very quickly. If a transistor trigger is used, then a ballast resistor is not required.                       http://www.bmw2002faq.com/_/technical-articles/electrical-and-ignition/ignition-coil-myths-busted-r52

 

 

Read the Z excerpt carefully and one should notice some interesting editorializing regarding the Type K(Blue) coil:  "Should never be used on BMWs" (emphasis added)      I do not share the same opinion, since I think in all but competitive situations, most would never notice the difference between coils - except for the color.          Also, because of so much unexplained confusion concerning impedance and the need for ballast resistors - maybe blue is the easiest to plug and play.       BUT, if I use non-stock super-wide spark plug gaps, lean mixtures and push the engine hard at high revs, the better choice would seem to be "KW"black, red, yellow or chrome before blue.  Again, special attention should be paid to using a "KW" black coil.       Occasionally, overkill is a good idea.

 

As comprehensive as the Z article seems to be, it omits discussion of several exceptions to the above rules, including the fact that there were 6v and 12v "blue" coils and a few blue coils that require an external ballast resistor.  Nor does the article account for the fact that BMW used different part numbers for various 12 volt KW "black" coils.  E.g., realoem lists the OEM coil in an E9 CSL as BMW part no. 12138730002.  Yet, a lighter-in-weight KW "black" coil is listed for the tii 12131359637.  (Yes they have both been superseded.)  The Z chart also states that the KW "red" coil does not require the use of a resistor if a transistor trigger is required.   Yet the narrative is silent respecting the similar KW black coil.  (I could be wrong, but some cd ignition instructions may not be so emphatic about deleting the ballast on all "high performance" coils.)

 

 

Did someone mention "KW" ?   Color optional?

Edited June 10, 2015 by percy