Aftermarket ignition systems/disty opinions

[87turbot-type]

Well I have done a bit of reading on this but not alot, to be honest it doesn't really seem like it is needed for these cars not trying to go lower than 10 flat. Figured I would make a post on some ideas vs what some people have run to get everyones opinions on setups.

1st off
Distributor - Don't really see the reason for this. Seems most stage cars run disty's with high power. Couldn't really find the reason for this and I would think this would be a backwords kind of thinking. We switched to waste spark to increase dwell time to fully saturate the coil before firing. More dwell more consistant spark at higher rpm. I know norbs a member (local to me) has been working on running a stock computer and using a hall effect sensor in the disty to work as his cam sensor for position. (Import style) Most disty setups seem to run fast xfi or some sort of stand alone to achive this. (easier) If someone would like to chime in on the reasoning for going to these extra steps to make something more primitive. Only thing I can think off is to eliminate the crappy module we have stock.

2nd
Aftermarket Boxes/coils
I tried searching for msd and couldn't get much to show up (word being too short) This dis boxes come to mind of what would work on these cars. So has anyone used one with good sucsses? Any issues with module problems after wiring in the box and what coils were used?

I'm just trying to get ideas for later on down the road of fun things to play with and try out on my car. In this case I am thinking that less maybe more and sticking with what it came with maybe the best thing but getting everyones opinons on this topic is also a good way to learn.

I thought I had heard at one point that fullthrottle was working on setting up a coil on plug setup similar to an ls1 engine setup and would think this would be the best possible setup for our cars.

 

[DailyDrifter]

If you could adapt the COP to individually pull timing out of a specific cylinder that would be the ultimate system to go with if you can use it to its full potential. A dizzy I would imagine, would be the most reliable out of all the systems, 1 coil, a cap, and a rotor, IMO easier to diag a problem. Waste spark, what can I say, between coils and modules it becomes a crap shoot. FWIW I would rather have a COP for efficency, with a newer style ecu that can pick up on misfires based off of Spark voltage.

 

[RmvBfrFlght]

My understanding of the GN coil pack system is that the ECM still controls the dwell. So there isn't any more or less versus a distributor.

My guess to why folks run a distributor is that they can also run a CDI box. With a good CDI box dwell is no longer a concern. Note that there is a dwell of sorts in a CDI, it is the time it takes to recharge the internal capacitor.

As the RPM increases there is less time for this. So eventually the spark starts to drop off.

RemoveBeforeFlight

 

[steve hughes]

Two steps work much better with a distributor setup. As far as i'm concerned that's the only reason to go to one. I switched out the stock dis to the distributor at the track one night to see if there was a difference in performance. It ran 9.40 with either one . No difference. I'm running an Accel DFI with an MSD 6 box on a TSM car.

 

[Alky V6]

Besides spark energy, spark event accuracy should also be an important consideration.

Spark energy. Nothing beats a powerful inductive spark.

The finer the teeth of the pickup wheel, the finer the dwell control and spark event accuracy.

I know this has probably been discussed before, but why is a distributor necessary to get good 2 step control? What other systems are being compared to come up with this conclusion?

 

[87turbot-type]

My understanding of the GN coil pack system is that the ECM still controls the dwell. So there isn't any more or less versus a distributor.

The ECU may control the dwell but with a distributor you have only a single coil, so dwell time would be considerably less than stock with 3 waste spark coils.

I am not sure either why the two step works better with the disty but I would assume it would have something to do with the waste spark. I belive a two step would work just as well on a coil on plug setup.

Good info guys keep it up.

 

[RmvBfrFlght]

The ECU may control the dwell but with a distributor you have only a single coil, so dwell time would be considerably less than stock with 3 waste spark coils.
...

This is not true. The ECM will raise the EST line to start dwell. At the time the plug needs to fire the ECM will pull the EST line low. That tells the coil pack module or the distributor to fire the coil (spark plug(s)).

Look at it this way, the EST line to the coil pack ignition module is required to signal when the dwell starts, and then when the coil fires. This is 3 times per engine revolution.

And is true whether there is a distributor or a coil pack. No difference in dwell.

Recall that there is only one EST signal. Which operates for the firing of each spark plug.

RemoveBeforeFlight

 

[87turbot-type]

That doesn't really make any sense? I would agree that the est line would be used to collapse the primary circuit to induce the seconday circuit. However the job of the module and ECM would be to control the dwell as needed to completely saturate the primary circuit. There would be no need for a est line to do this.

Just my thoughts

 

[RmvBfrFlght]

In some GM DIS systems the module controls the dwell. This is such as the LT5, the 4-cylinder stuff and the 60* V6 engines. It is a 'closed loop' dwell system where the module measures the time that the coil(s) is in saturation and adjusts the dwell accordingly.

However, the Buick 3.0l, 3300, and 3.8l engines use an ignition module that the dwell is under ECM control. When the EST line goes high the module will start to charge (dwell) the proper coil. When the EST line falls the module fires that coil.

This is one reason that the GN DIS system is referred to as the C3I system. The computer controls the coil dwell and firing point.


On the 2-stage with the DIS system, it may not be usable as the ignition module may get out of sequence. This is just conjecture on my part. I don't know if the crank signal or the EST line is intercepted by the 2-stage unit. Or which signal advances the coil sequence.

Some ignition modules check that the EST is active for each crank signal activity. And if they don't match up clamp the EST line and revert to bypass mode. That too may be an issue. Again, I am not positive that the GN DIS system does this check.

It would be best tested on the bench before trying it in a car.

Note that the ECM would detect the clamped EST. And then set code 42 and open the bypass.

RemoveBeforeFlight

 

[norbs]

I am working on the distributor on the stock ecm, but I have been so busy that i havent had time. I may have time this weekend to continue progress. The cam sensor is mounted in the cap and its just a matter of getting the dist back in the car and rewiring it all. I had to pull the distributor out because i was getting cam sync errors on my gen 7 with 2 different dfi boxes and two different distributors with no solution. Tech support is zero from DFI (they wont return calls).

But anyway the reason to go to a distributor is, it lowers the egt's since it elminates the wastespark. The waste spark skews the wide band readings under high boost/ airflow I don;t know the specifics why but this is what i have heard.

 

[Alky V6]

Steve Hughes. Did you notice any difference in how the o2 read when you switched to the distributor at the track?

 

[steve hughes]

Don the only difference i saw was at idle. I could lean the car out more with the distributor. I noticed no difference in egts with the distributor. The two step will work with the stock system just not very well. The module loses #1 if your on the 2 step more than a split second. With a distributor it works great. I didn't have to change the VE table at all between the 2.

 

[norbs]

Interesting results Steve, I guess the rumours that i heard about the waste spark are just not that accurate in the real world. I do know that wastespark can;t be used in a hydrogen engine since it causes pre-ignition.

 

[87turbot-type]

Very good write up removebeforflight. Kind of silly of the engineeres!

Steve I remeber reading that you had no changes on your car before, it's almost amazing that at those times you can make such a big change and not effect your et's.

So it almost seems that unless you are attempting to use the two step option it doesn't seem worth while to use the disty option.

After seeing the videos of Jim L's buick go high 8's and seeing the pictures of that car with the stock coils I can't see a reason to change my setup. However I will also mount my coils on the heater box delete pannel as he did, looks much cleaner.

Norbs just wondering why did you choose the GEN 7 over the XFI. Seems like most buick owners that run stand alones are using fast with some luck. Hope to see your car out either way soon. Alot of time and hard work has been put into that beast.

 

[steve hughes]

I see no reason to go to expense and hastle of going with a distributor unless your useing a 2 step.
I've been running a Gen 7 DFI for a few years and have had very good luck with it. I also had good luck with a batch fire gen 6 long before the gen 7 or the XFI came out.
Norbs i'm not trying to start anything here but i don't understand your comment about waste spark causeing pre ignition. And not being able to use hydrogen on a waste spark engine. If it causes preignition how can stock block TSM cars run 9.30's more than one pass?

 

[norbs]

The pre-ignition is only for hydrogen engines, they can ignite at a/f ratios of 180:1, but we don;t use hydrogen so not to worry about it.


I bought the gen 7 since it had a lot of nice features, but it does not have all the comforts of a stock ecu for the street. I could go into detail on this but i will be off topic. I"ll do a write up on my webspace if your interested.

 

[Alky V6]

The pre-ignition is only for hydrogen engines, they can ignite at a/f ratios of 180:1, but we don;t use hydrogen so not to worry about it.


I bought the gen 7 since it had a lot of nice features, but it does not have all the comforts of a stock ecu for the street. I could go into detail on this but i will be off topic. I"ll do a write up on my webspace if your interested.

A wastespark ignition of hydrogen on the exhaust stroke is assuming batch injection, or more appropriately with hydrogen, a continual feed, and not sequential injection. Injecting batch style with hydrogen would not be proper at all, no matter what the ignition style. You could get around the wastespark ignition of the hydrogen with a properly executed sequential injection of the hydrogen and special cam timing. Regardless, the technology to burn hydrogen in our cars is beyond the vast majority of us.

No matter, hydrogen has a high tendency to cause intake backfires, even when properly introduced into the engine.

 

[SS/GN]

More input

I do not understand the dist thing either,it is kinda like going back to the ice age.I am only just staring to play with these cars and my experience is minimal.The system RJC has looks interesting,however still not 4 sale.I think he is tired of people copying his stuff and re-selling it.Is the RJC system better than stock?I see many low 9 sec cars with stock ignition and chips seems to be working,however new ideas are always interesting:biggrin:

 

[87turbot-type]

Kevin I remeber seeing this but forgot about it.

Here is how it reads from the RJC site

RJC-MEGA-COILPACK;
Eliminating the waste spark on the turbo regal is worth some serious HP. In our tests we picked up 4 mph in the 1/4 and 40 HP on the dyno. In the past the only way to achieve this was to go with a distributor. This required eliminating the A/C not to mention going back 30 years in technology. RJC has devised a way to eliminate the stock waste spark with dual stock coil packs. It is a simple installation with no wires to cut. it simply plugs in. We are currently running these through the testing phase. As soon as they are ready they will be released, These are on hold until further notice, but we are still working to make these available.

This is something I would really be interested in trying. I have seen one other car with msd coils in the stock location does any one know if there is a coil that is a direct replacement for one buick coil. Would probably be pretty costly as well but the 6 coils setup would look nice.

 

[SS/GN]

Costs vs gain

I remember reading that the biggest exp is you need 2 msd boxes with RJC set up.Do the math that is real expensive for 40 hp.