Type II Ignition Swap Question

[38turbo]

Quote:
Originally Posted by TurboBob
at lower rpm it will not help, as the coil charges up to the limit imposed by the ignition module.

I need to look back at my notes, but the coil on my car charges in about 3 ms if I remember correctly.

There is a minimum off time which I don't remember, but its probably .5ms or so.

So we start losing spark energy when the coil doesn't have enough time to charge.

the coils charge and fire 3x in one revolution.

6000 RPM is 10ms for one revolution.

if the time between coil cycles is .5ms, then 3 + .5 + 3 + .5 + 3 + .5 is the total time required to fully charge the coils.

thats 11.5ms, which is 5217 RPM. Above that (based on my theoretical numbers and fading memory) we lose spark energy.

With higher applied voltage, the coils will charge faster, extending our range.


Note also, when they get hot, coils charge more slowly.



Bob

Bob

I understand the dwell time for saturation of the coils is gonna be less as higher rpms.

But one would think that it you use 14 volts at the primary VS 11 volts the more voltage will make a difference all the way up.


As we noted last night The output voltage was always 2 volts less than the input voltage.

so if the input voltage is say 12 volts that means the coils are seeing 10 volts. then there is the current limiting issues. but i can't see how the current limiters are being a issue if the max output voltage on the limiter is not met.


I also understand that as the coils heat-up the resistance goes up.


BTW i love a good tech discussion!

didn't RJC start addressing this already with there mega coil pack design getting rid of the waste spark by using 6 coil packs instead of 3 your gaining 50% charge time unless im not understanding somthing right

 

[TurboBob]

Alright, so let's say all the Type II coils and ignition modules are total garbage and GM went backwards in designing these and producing them.

What makes the stock style coil pack and modules so good?

I'm not saying one is better than the other. I don't think we know enough yet.

There is considerable feedback from people that the Type-II has issues at high power and/or high RPM. And we are starting to see possible reasons.

There are also stories about peoples cars running much better after switching, but no details about the condition of their old parts.

Bob

 

[TurboBob]

didn't RJC start addressing this already with there mega coil pack design getting rid of the waste spark by using 6 coil packs instead of 3 your gaining 50% charge time unless im not understanding somthing right

I don't know what they were doing with their stuff. But the dwell time is set by the ECM.

I remain unconvinced that wastespark is a problem.

B

 

[SloGN]

at lower rpm it will not help, as the coil charges up to the limit imposed by the ignition module.

I need to look back at my notes, but the coil on my car charges in about 3 ms if I remember correctly.

There is a minimum off time which I don't remember, but its probably .5ms or so.

So we start losing spark energy when the coil doesn't have enough time to charge.

the coils charge and fire 3x in one revolution.

6000 RPM is 10ms for one revolution.

if the time between coil cycles is .5ms, then 3 + .5 + 3 + .5 + 3 + .5 is the total time required to fully charge the coils.

thats 11.5ms, which is 5217 RPM. Above that (based on my theoretical numbers and fading memory) we lose spark energy.

With higher applied voltage, the coils will charge faster, extending our range.


Note also, when they get hot, coils charge more slowly.



Bob

k

 

[38turbo]

I don't know what they were doing with their stuff. But the dwell time is set by the ECM.

I remain unconvinced that wastespark is a problem.

B

im by all means no expert but, in a waste spark system when a cylinder on the compression stroke fires its companion cylinder on the exhaust stroke fires at the same time through the same coil. so the cylinder on the exhaust stroke takes very little energy from the coil to fire leaving the companion cylinder the majority of voltage to fire its plug which is under compression.... so as rpm increases and things are happening much faster isnt the cylinder on the exhaust stroke going to start stealing more of the available energy from the coil leaving less for the cylinder on compression.... or is it such a minute amount that it wouldnt affect anything.....(and no matter how minute it is the higher the rpm the more its going to affect the cyl on compression) i love my caspers coil tester but i've always felt because of the waste spark whatever i saw happening during a test was much worse when the coil/module was actually driving the 2 plugs....

is the single magnavox coil wired the same internally as 3 seperate coil packs are on the type 2???

 

[Nick Micale]

nick-------i might be interested in those coils since i do not have any MSD's to test---------i want to be able to totally quantify this-------if they don't work i want to know the reason why-------usually when we know the why clearly enough we can come up with a fix...............RC

I will send them tomorrow.

 

[scot w.]

Subscribed for this one!

 

[dentmasters01]

.....popcorn bucket....

 

[esinger]

the coils charge and fire 3x in one revolution.

6000 RPM is 10ms for one revolution.

if the time between coil cycles is .5ms, then 3 + .5 + 3 + .5 + 3 + .5 is the total time required to fully charge the coils.

thats 11.5ms, which is 5217 RPM. Above that (based on my theoretical numbers and fading memory) we lose spark energy.

Bob,

I believe your coil time off is longer if I understand this right. One coil fires once per revolution. So the time off for a single coil would be the revolution time minus the coil charge and firing time.

Correct??

Eric

 

[RmvBfrFlght]

Bob,

I believe your coil time off is longer if I understand this right. One coil fires once per revolution. So the time off for a single coil would be the revolution time minus the coil charge and firing time.

Correct??

Eric

The actual off time is higher, but only because there are three coils. So in this sense you are correct.

The difference is that when the ECM code calculates the dwell, it also ensures that there is a minimum firing time of 600 usec (Bob was close at the 500 usec from memory).

To the ECM the Buick ignition module is along the lines of a distributor. There is no individual control over each coil. So the ECM can't overlap the charging of the coils. And the ECM is always taking into account the required 600 usec minimum firing time.


Other GM DIS systems are more sophisticated then the Buick DIS. Our system is dumb as a rock. There isn't even limp mode self advance built in. The other DIS systems actually control their own dwell. On a cycle to cycle basis they measure the coil current and adjust the dwell accordingly. The also have built in advance when in limp mode.

The ECM still goes through the dwell calculation, but the DIS only uses the falling edge of the EST signal for when to fire the coil.

RemoveBeforeFlight

 

[RmvBfrFlght]

the output does increase with increasing voltage up to a point-------drive voltage to the coils was always about 2 volts less than the input voltage to the ign module---------but the two limiting factors seem to be the voltage drop across the transistors internal to the ign module and what appears to be a ballast resistor probably in series with the emitter-------its just another clear case of "higher voltage results in improved performance"-------a case that speaks strongly to the use of a voltage booster.............

The resistor in series with the emitter would be for the current sense. To be used with the current limiting of the module. They may also be using bipolar darlington transistors. They typically have a 1.4 volt drop from collector to emitter.

This is where MOSFETs shine.

drive voltage to the coils was always about 2 volts less then the input voltage to the module.

I think that the voltage to the coils is direct from the +12 volt input to the module. Or, is the 2 volts less at the coil minus? If it is at the coil + that shows a lot of drop in the module connections and wiring.

The required time to charge the coil has more to do with it's inductance. Place a current probe on the +12 volt coil feed. With that you can watch the coil charging along with when the module goes into current limit.

By using different voltage input levels you can also see the effect on the charge time. I most definitely agree with you on higher voltages. It does make a difference in coil charge time.

A CDI is a prime example of this. Discharging a capacitor into the coil at 400 volts causes nearly instant saturation and subsequent firing of the coil.

The current limiting is to prevent over heating the coils. Once a coil saturates (which you never want to do), the current is only limited by the resistance of the coil.

RemoveBeforeFlight

 

[87GN_70GS]

Last night Richard Clark, Pat (SloGN) and I started testing the original coilpacks and modules versus the Type II coils and module.

There's a lot more testing that'll have to be done, but in our short session the Type II was showing superior performance versus the original stock coil and module.

Pat also has MSD coils, so we'll more than likely be testing them as well.

We plan on posting the data to back up our claims once the testing has been completed.

Did you test the GM methanol coil?

 

[87GN_70GS]

Were you able to measure primary inductance (L, in mH)?

With that number for each, you will be able to compare primary energy stored for each box:

W = 1/2 L i^2 (Joules)

Note that primary current (i) will be a function of rpm. At low rpm, it will be limited by the current limiter (they do this to cut down on heat buildup). At high rpm, i will be limited by the time to charge the coil:

i = imax [1 - e^(-R/L t)]
imax = V/Rpri

 

[LOT]

curious also

Did you test the GM methanol coil?

GM part # 1106008--wonder if they are still available? I had 2 sets (6) 2 of the 6 have gone bad. Wonder if that is the down side to them?

 

[87GN_70GS]

GM part # 1106008--wonder if they are still available? I had 2 sets (6) 2 of the 6 have gone bad. Wonder if that is the down side to them?

Delco D546
Standard Motor DR47
Airtex/Wells 5C1077
Duralast C1316
KEM Parts 343Q
Original Engine Management 50047
Borg BWD E219
Master Pro 2-50047
NAPA Echlin IC406

rockauto has some

 

[Turbo6Smackdown]

WOW. I love to hear (or watch) technical experts talk, compare, therorize, and hypothisize. Very interesting. I hope you guys find out what you need to find out.

 

[turbo nasty]

Schools in Session...Subscribed

 

[A2000RICH]

Were you able to measure primary inductance (L, in mH)?

With that number for each, you will be able to compare primary energy stored for each box:

W = 1/2 L i^2 (Joules)

Note that primary current (i) will be a function of rpm. At low rpm, it will be limited by the current limiter (they do this to cut down on heat buildup). At high rpm, i will be limited by the time to charge the coil:

i = imax [1 - e^(-R/L t)]
imax = V/Rpri

type II coils primary inductance measures 3.1MH with a Q of 9.5------type I measures 3.8MH with a Q of 7.86

certainly with all factors being equal (again not likely) the coil with the lowest inductance should be able to work at higher speeds----------as far as issues dealing with coil saturation a realistic judgement cannot be made as to the real effect unless a hysteresis curve of the core is known-----and considering that these coils have many sources and countries of origin it is not likely that they are at all similar-------the bulk of current limiting in the module appears to be a single resistor that is in series with the ground connection common for all three coils-------in my measurement the scope was floating so the voltage reading was correct across the coils and actual location of the drop was not relevant -------i am not convinced that the coils cannot be driven harder but i am going to set up a variable voltage constant current driver to determine this-----my guess is that the limiting is to protect the module as much as the coil?? -------as far as higher voltages allowing for faster charge times that is obviously true since RC and RL time constants are independant of voltage-------i never took the time to analyze this critter before but its certainly a different animal--------current paths are certainly not anything like the kettering or CD systems that are so common

 

[TurboBob]

its not that different than a kettering idea.

I think just measuring the primary current risetime with it running will give us a good idea of the effects of the applied voltage.

I agree with you, but to go further I think the current limit protects everything (connector pins, module, transistors, coils, etc) All these components needed to survive the validation cycles over temperature, altitude, etc.

Bob

 

[TurboBuRick]

Very interesting read.

Thinking out loud,

If coils perform better with more time between ignition, wouldn't eliminating waste spark double the coils charge time?