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Well, Salvage, as DJ is a true guru with no time, or maybe desire, to cash in on his talents, why don't you become his manufacturing arm? :)

You have the talent and the experience, and such things have a market waiting.

When Zap gets his Neon and I get a WRX, we will definitely need one!

Two customers already! :)

I am sure you recall the pics he posted long ago showing some of the data he captured. You may also recall the data that Tom Chou took showing that even the most minor detonation slowed the acceleration of the crankshaft. His point, of course, that detonation of any magnitude hurt performance and it was NOT all right to run with a couple of degrees of retard resulting from detonation.

So, I see two big benefits. One is in longevity of the drivetrain, and the other is in enhanced peformance.

Forget that german/french you learned! :D The entire world awaits you.
 

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Discussion Starter #22
Only one cylinder can be knocking at a given instant. The unit knows that the cylinder that is knocking is the one that just fired, and that it won't fire again for two more revolutions.

Waste spark systems are no different. Say the 1-4 coil has just fired, and cylinder 1 is on the compression stroke. The unit doesn't know which cylinder is knocking, but it had to be the one that was on the firing stroke. The detector knows that it won't be on its compression stroke for two more revolutions.

****

I did a search on "detonation" and one thread had this link:

http://www.autospeed.com/cms/article.html?&A=0348&P=1

The story briefly mentions a test of one of our units, saying it didn't work that well.

I'm speculating here, but I think what they were experiencing was "pre-ignition".
car was running high boost and advanced timing - enough to make it detonate when the non-intercooled air hit the combustion chambers.
By definition, pre-ignition happens before the spark event. Spark retard will not stop pre-ignition.

Our system listens only for detonation, which occurs around TDC.
 

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It seems to be a fuzzy subject between the various writers.

Here is a Link from John's site http://www.streetrodstuff.com/Articles/September_2000/Engine_Basics_I.php

and another from elsewhere http://www.zhome.com/ZCMnL/PICS/detonation/detonation.html

Note the second one seems to tend to combine the two as different forms of abnormal combustion with similar effects.

Does the abnormal combustion created by preignition have a different frequency spectrum from that caused by detonation near tdc? I am wondering why any form of abnormal combustion cannot be captured and treated? Is it because detonation at tdc is related to timing while the other is caused by a hot spot such as a plug electrode or carbon deposit? I guess that is the answer? The former can be treated with reduced timing while the second occurs no matter what?

Another question...if you were to monitor the normal plug firing voltage which must be somehow related to the "resistance or cylinder pressure", could you build a profile and kill that cylinder for a revolution if a sudden upward deviation from the profile is noted? Maybe that is a fantasy based upon something other than reality. :)
 

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I only know Goobers circuit which obviously is his. :)

Didn't mean to imply how JohnP's device works but since he is explaining it a bit, it sounds cool.

Goobers is more of a high tech. scanmaster for detection/diagnostic purposes. :)

I don't have any time either but a super module would probably sell better than a power plate. :cool:

Assuming it worked well however... powersix headbang
 

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I meant with DJ's blessing. :)

If it sold for $60 bucks, I bet it would! :D

John's setup is very interesting. Makes me wonder how many times our sensor is triggered by an event that cannot be handled with timing. I would not think it was that common, but, I am not sure.
 

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JohnP:
Only one cylinder can be knocking at a given instant. The unit knows that the cylinder that is knocking is the one that just fired, and that it won't fire again for two more revolutions.

Waste spark systems are no different. Say the 1-4 coil has just fired, and cylinder 1 is on the compression stroke. The unit doesn't know which cylinder is knocking, but it had to be the one that was on the firing stroke. The detector knows that it won't be on its compression stroke for two more revolutions.
<snip>
Our system listens only for detonation, which occurs around TDC.
Gotcha. And that was an err on my part mixing up pre-IGN and detonation.

Steve, I have a funny feeling that if we are suffering from pre-IGN it is going to require some parts swapping, a cleaning agent, or a polish of the combustion chamber (a must for me if/when I get ported heads).

Thanks, JohnP. :)
 

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JohnP:
The module is an inductive discharge ignition, with coil current limited to about seven amps.Here's an inside look at the coil pack ignition module, and the schematic:
Digging this topic out again: :) John, I have a few questions about the RCA chip that does (I assume) the dwell setting and spark sorting for output to the coil packs. Do you have any tech data on that chip? Specifically, I'm wondering if it would upset by delaying the EST trigger input to allow varying timing between individual ignition pulses. I assume it does some sort of latching count after initial sync to sort the spark for the correct coil pack... :confused:

If it's not obvious from my question, I am wondering what it'd take to use the stock module/coil pack with an oddfire application.
 

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Discussion Starter #28
Kendall:

The RCA chip is a mystery. Note that they are using an op amp oscillator for a clock.

Our first approach to control timing was to use a one channel retard unit to delay the EST signal. This would work fine, when our system was set to "Retard All" mode.

In "Retard Separate" mode, delaying the firing point on one cylinder cuts into the dwell time on the next one.

The bottom line was that we had to limit knock retard to 10° in individual cylinder retard mode, especially above 4000 RPM.

Our 2-3-4 channel DIS system does not have this problem. In fact, when our unit retards, it increases the dwell by the retard amount.

I can't see the GN module working in an odd fire application, but I could be wrong. I think they fire 90°-150°-90°-150°, etc.

I would think that the RCA software is expecting trigger pulses to arrive every 120°.

I built an odd fire generator for a DeLorean application. Maybe I'll fire it up and see what the GN module does with the signal.

If I get to it, I'll take some scope photos.
 

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John,
John great job cutting through all that goop and showing us whats under there.

But I would like to suggest building something for the Buick folks.It would be a ignition amplifier box, using the voltage boosting capabilty as you mentioned, along with a rev limiter and a 2 step.
I other words something that works similar to a MSD DIS 4 (HO) without the problems and reliabilty problems associated with it. If you do a search you will find many unhappy customers with the MSD who are in a constant battle fighting false rev limits, no start conditions and just overall unacceptable service from these things. Unfortunately we are still forced to rebuy and replace because of the need for a basic 2 step or secondary rev limiter.

Something to think about. wink

<small>[ July 21, 2003, 05:50 PM: Message edited by: Louie L ]</small>
 

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I am glad when I see that I am not the only one that has had MSD problems. When they work, they work well, but I have found, they don't work long.

They always cover their warranty, tho.
 

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Louie L:
John,
John great job cutting through all that goop and showing us whats under there.

But I would like to suggest building something for the Buick folks.It would be a ignition amplifier box, using the voltage boosting capabilty as you mentioned, along with a rev limiter and a 2 step.
I other words something that works similar to a MSD DIS 4 (HO) without the problems and reliabilty problems associated with it. If you do a search you will find many unhappy customers with the MSD who are in a constant battle fighting false rev limits, no start conditions and just overall unacceptable service from these things. Unfortunately we are still forced to rebuy and replace because of the need for a basic 2 step or secondary rev limiter.

Something to think about. wink
Great idea!A replacement module box that can do an MSD style spark and retard.
:)
 

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Discussion Starter #32
I did a search on "rev limit", and saw threads stating that the stock module has gotten people into the 7's, at 7500 RPM. Several posters have questioned the need or value of the DIS4.

The alternative to a new design (which may not sell) is to modify what already exists.

Photo of circuit card here:
http://www.jandssafeguard.com/images/4ChProto.jpg

You will see that there isn't a lot of room left for rev limit knobs.

Fixed rev limits, anyone? 3000 RPM and 6000 RPM?

If you could have only one adjustable limit, and one fixed, which one is more important to be adjustable? Staging or top end?

Two of the mode select switches are normally used to set the number of cylinders. Instead, they could be programmed to select from one of four rev limits.

The "Aux" input pin would be used to enable the lower limit.
 

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Can the existing module be modified to emit an MSD style spark reliably?
It would be nice for us guys who want to run big injectors on the street and pass emissions.
As to the guys running sevens,I think they're running 16 volt charging systems.

<small>[ July 22, 2003, 12:46 PM: Message edited by: The Radius Kid ]</small>
 

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Discussion Starter #35
Short answer, no, the unit cannot make MSD style sparks.

Long answer:

CDI systems use a transformer in a DC-DC converter circuit, to convert 12v to 450v, and store the energy in a high voltage capacitor. The DC-DC converter can recharge the storage capacitor in a millisecond or less.

At idle, an MSD makes a series of sparks, spaced about a millisecond apart, lasting for 20° of rotation. Above 3000 RPM, on an eight cylinder engine, there is only enough time for one spark.

The Ford DIS is an inductive sytem, which they double spark below 1500 RPM.

By the way, I saw a reference to "two parallel lengths of 0.75 ohm resistor wire" feeding the coil packs. At seven amps of coil current, this cuts the coil voltage by over 2.6 volts, which could rob you of spark energy at high RPM. Anyone try running full 12v to the coils?
 

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JohnP:
At idle, an MSD makes a series of sparks, spaced about a millisecond apart, lasting for 20° of rotation. Above 3000 RPM, on an eight cylinder engine, there is only enough time for one spark.

The Ford DIS is an inductive sytem, which they double spark below 1500 RPM.
Isn't this where a "Boost-A-Spark" system/piggy back compliments these needs? Regardless of the fact that the factory parts are good past any point we'll take it.
 

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JohnP:
By the way, I saw a reference to "two parallel lengths of 0.75 ohm resistor wire" feeding the coil packs. At seven amps of coil current, this cuts the coil voltage by over 2.6 volts, which could rob you of spark energy at high RPM. Anyone try running full 12v to the coils?
I believe this may apply to some of the earlier cars but not the later IC cars. Not in the diagrams and I have not seen any sign of them.
 

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Steve Wood:
JohnP:
By the way, I saw a reference to "two parallel lengths of 0.75 ohm resistor wire" feeding the coil packs. At seven amps of coil current, this cuts the coil voltage by over 2.6 volts, which could rob you of spark energy at high RPM. Anyone try running full 12v to the coils?
I believe this may apply to some of the earlier cars but not the later IC cars. Not in the diagrams and I have not seen any sign of them.
Yeah,we got into this on the "other" board.
John Spina corrected the misinformation[as posted at GNTTYPE.ORG].
It seems the resistor wire is only there for the earlier hotair cars[84-85].
It was used to prevent coil saturation.
 

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Discussion Starter #39
Did a search at gnttype, but couldn't find the reference to the explanation by JSpina.

If the early modules needed a ballast resistor, that implies that they did not use active coil current limiting.

If that is the case, the hot tip might be to run the old modules, and feed them with full 12v. Don't go overboard, though, or you can damage the power transistors.

With a scope, it's easy to tell if the module uses active current limiting.

During dwell, the coil negative is pulled to ground, through the ignition transistor (electronic points).

If present, the current limiter will kick in just before the spark event, and you will see the voltage on the coil negative rise a few volts. as the current limiter, in effect, turns the transistor into a ballast resistor.
 

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Discussion Starter #40
How does the factory rev limiter work? Is it a fuel cut, or does it cut the spark?

Does anyone retard the timing at the line, to build boost?
 
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