spark ignition dwell time

[slimtastic]

hey i was wondering on the bs3 plug and play application, whats the largest ammout of ignition dwell time (in milliseconds) that can be safetly run on a stock ignition module and coil pack? is it even possible to adjust dwell time if the stock ignition module is used?

im having hard breakup issues over 12 lbs of boost and before i start pointing fingers at the coil pack and box, id like to make sure my dwell settings are correct....

 

[S2V6RACER]

The dwell tables are for the LS1, or Mod motor COP firmware.

 

[slimtastic]

yea i know. and the limit that i read on ls1 coils is 6.0 milliseconds of dwell. can the buick coil packs be ran for longer dwell time without destroying them

 

[John at J&S]

The Buick coil pack ignition has internal current limiting. Increasing the dwell beyond a certain point only heats the ignition transistors and the coils.

Duttweiler gave me one to play with several years ago, to see if I could soup it up. I was able to unpot it and reverse engineer it.

I added the wires so I could test it without the Weatherpack connector.

 

[TurboBob]

yea i know. and the limit that i read on ls1 coils is 6.0 milliseconds of dwell. can the buick coil packs be ran for longer dwell time without destroying them

6 ms is plenty if I remember correctly.


But.

at 5000 RPM you have 12ms to fire the coil 3 times. which gives you a max of 4ms, if you had no "off time".

I would think that the BS3 will handle this for you, and force your dwell to shorten as you climb in RPM, perhaps you can see it on a datalog.

what is your dwell set to at the moment? if you hold the boost down, does the breakup happen at a higher RPM?

Bob

 

[neo240sx]

Buick dwell time

I'm having the same issue. I'm running a buick coil pack (the 6 in 1) and it seems to break up a 4800 to 5200 rpms under boost. The tuning program I'm using lets me adjust dwell time and says that at that point with the old coils its set at 4.94 ms. At this point i should take it to 6ms???

 

[TurboTR]

With the stock ignition you have to realize the physical dwell limits imposed with climbing rpm and adjust the plug gaps down to compensate for weaker spark there. Think I used to run like .025 or .028 with 30 psi. But would also shift by about 6500 too. It worked, but the plugs needed to be kept fresh; otherwise it would begin to pop.

There was also a breakup issue when people would convert over to a type 2 coil setup. Think John could expound more, but suspect that problem might be solvable with a proper "hot wire" kit. Not sure if it addresses what appeared to be the root cause or no for the type 2 conversion.

At a minimum I'd check John's page and see what's offered to help the stock ignition work as well as it can for high performance.

I'd run the hot wire kit to it, and the volt booster setup he offers as well. Should work pretty well then, IME.

Edit- I mean John above, but also long time turbo Buick person John Spina: http://www.casperselectronics.com/store2/

TurboTR

 

[TurboBob]

I'm having the same issue. I'm running a buick coil pack (the 6 in 1) and it seems to break up a 4800 to 5200 rpms under boost. The tuning program I'm using lets me adjust dwell time and says that at that point with the old coils its set at 4.94 ms. At this point i should take it to 6ms???

what ECU?

B

 

[neo240sx]

This is in a nissan that I put a 2001 skyline motor in. I changed the ignition setup because the stock coils were bad. I got this coil out of a park ave at the junk yard. Under boost (10lbs) the spark gets blown out at around 5K. I want to switch to a ACDelco or stock GN coil pack. Which ever makes the most spark. I've found theres a discrepancy between the two. What are your thoughs on this?
I think as I turn the boost up its only gonna get worse. I know you GN guys push more boost than almost everybody else so I figured this was a step in the right direction.

 

[turbobuick]

This is in a nissan that I put a 2001 skyline motor in. I changed the ignition setup because the stock coils were bad. I got this coil out of a park ave at the junk yard. Under boost (10lbs) the spark gets blown out at around 5K. I want to switch to a ACDelco or stock GN coil pack. Which ever makes the most spark. I've found theres a discrepancy between the two. What are your thoughs on this?
I think as I turn the boost up its only gonna get worse. I know you GN guys push more boost than almost everybody else so I figured this was a step in the right direction.

Megasquirt? You are adapting a GM DIS system to a Nissan that ran something else or are you trying to run the Nissan system with the GM coil pack? What ignition module are you using? What crank and cam sensors?

 

[neo240sx]

I'm using a nissan J30 igniter. The ecu I'm using is a nistune daughterboard. The crank and cam sensor is all in one. I think its a optical sensor. I have full control of dwell time and duty though.

 

[turbobuick]

I'm using a nissan J30 igniter. The ecu I'm using is a nistune daughterboard. The crank and cam sensor is all in one. I think its a optical sensor. I have full control of dwell time and duty though.

If you are not using the GM ign module then it is just a coil and function is pretty much dependent on the # primary and secondary windings. It is not like the LS based coils. It is typically used in a wastespark setup in the GM DIS system and will fire each coil once every 360*. As far as dwell time you need as much dwell as possible to fully saturate the coil. I would think 5ms is plenty but really have no idea but I am sure it can easily be tested. As Bob pointed out as rpm goes up you will have less dwell time less saturation and less coil output especially with an inductive ign setup. I would take a look at your ignition strategy and find out how often you are firing the coil, once every 120*, 360* or 720* which will tell you how much dwell time you have for the rpm you want to run. You also need to find out if you have a CDI or inductive ignition setup.

 

[neo240sx]

Yeah I'm not using the gm ignition module. It is the wasted spark setup like you mentioned. As far a I can tell the coil fires twice a cycle. once on compression and once on exhaust being the coils are linked to opposite cylinders. The spark just seems to be not that strong. I was thinking there was a better coil pack set that I could order.
The one I have is off a park ave 3800. I has a made in mexico sticker on it and aluminum posts.
It works well up to about 5000 rpm under boost then it breaks up. Off boost I can free rev to 7500 and its fine.

 

[John at J&S]

Have you tried a Boost-A-Spark? It steps up the coil supply voltage to 20v.

 

[neo240sx]

It looks like that system is around $240 shipped. If I can find out which GN coils work the best I could get that set for $100 and probably be done with it. But I need the part number. I think the one I got is a maganvox but I'm not sure. I got a 10 gauge wire feeding it so I know its not a problem with the power supply

 

[neo240sx]

With the stock ignition you have to realize the physical dwell limits imposed with climbing rpm and adjust the plug gaps down to compensate for weaker spark there. Think I used to run like .025 or .028 with 30 psi. But would also shift by about 6500 too. It worked, but the plugs needed to be kept fresh; otherwise it would begin to pop.

There was also a breakup issue when people would convert over to a type 2 coil setup. Think John could expound more, but suspect that problem might be solvable with a proper "hot wire" kit. Not sure if it addresses what appeared to be the root cause or no for the type 2 conversion.

At a minimum I'd check John's page and see what's offered to help the stock ignition work as well as it can for high performance.

I'd run the hot wire kit to it, and the volt booster setup he offers as well. Should work pretty well then, IME.

Edit- I mean John above, but also long time turbo Buick person John Spina: CRE Loaded 6 - CEI - Casper's Electronics, Inc.

TurboTR

I'll buy this coil set if you guys think it will fix the problem????
CEI - Casper's Electronics, Inc.

 

[TurboTR]

Well the problem is, with a single EST line to command the dwell and firing events, you don't just have less time for dwell as rpm climbs, you actually wind up with insufficient time to dwell. Whether you have command of the dwell or not, there is just not enough time available to dwell 3 coils adequately (v6 case) at high rpm with an inductive ignition, commanding them with a single EST line. By 6000 rpm you already have less than 3 ms to dwell each coil with the classic FAST (there is a dead band enforced between firing events).

The solution for that is to move to a CD ignition, like an MSD. They have ~ no dwell requirement basically. Or just live with the limitations and do the best you can with it (as I did, and many others). Backing down the gap is one of the biggest helps there.

The 3800 setup you refer to is the type 2 we referred to below. When GN's tried to convert to that setup (as type 1 packs were dying off), many had spark related popping problems. Do you see the spark get weaker as you move towards the outermost coil?

That said, I once sent a classic box to FAST for some work on it (in a turbo Nissan 240 app with optical distributor) and when it came back it was no longer dwelling adequately and the spark was very weak. The scheme had been changed, unknowingly. I have a scope though and could see that the EST was no longer commanding dwell as it should.

TurboTR

 

[neo240sx]

I already have a pretty small gap (.025) I really dont wanna back it down any further. I can't even get it up to 6k rpms under light boost. I might just ditch this setup and try ls2 coils or something. It seems waisted spark setups are just less powerful as far as I can tell.

 

[TurboBob]

do you have a link to a wiring diagram that is representative of your setup?

You are driving just the coil pack from your ignitor ?

Do you know for a fact that it is producing the dwell time you are specifying?

You are specifying a dwell time, but most ECU's reduce the dwell time so that the coil charging never overlaps. If the time between the coil cycles is too long, then your dwell will over-shorten. You said you can program the dwell and dutycycle. What is the "Dutycycle" set to?

The Buick coil pack is plenty powerful for what you are doing. Wastespark itself gets a bad rap, but it works very well when set up correctly.

Bob

 

[TurboBob]

The Buick coil is fully charged in about 4ms. The stock ignition module limits the current, so overdwelling doesn't kill the coil. This setting is about 7 amps.

Bob