3.8l GM coils on z900 with dyna s?

Anyone know if I could use 3.8l chevy car coils with a dyna s if I wired in resistors to total 3.0 ohms? And how about the output comparison with dyna coils?

nads.com wrote:

Anyone know if I could use 3.8l chevy car coils with a dyna s if I wired in resistors to total 3.0 ohms? And how about the output comparison with dyna coils?

They will probably work, but you have to put a 2.5 ohm resistor in line with each coil. Since the resistor will need to dissipate about 45 watts, you should get 100 watt resistors. They will get hot.
Edit: wattage

Just to make sure we are on the same page, are we talking about these coils (in the photo)?



If so, it's a shame to run them on the Dyna S since you will be burning away 100 watts in the resistors. They need about 5 to 6 amps to get a good spark. They measured about a nominal 0.5 ohms, but may be closer to 0.4 ohms depending on the manufacturer. They only need about 1 msec to charge to 5 amps, and the Dyna S will give them about 50 msec at idle and 6 msec at 10,000 RPM. That's a lot of time to sit burning away amps. If the coils can handle it (they probably can since they are huge, but they will be hot), they should work.

loudhvx wrote:

nads.com wrote:

Anyone know if I could use 3.8l chevy car coils with a dyna s if I wired in resistors to total 3.0 ohms? And how about the output comparison with dyna coils?

They will probably work, but you have to put a 2.5 ohm resistor in line with each coil. Since the resistor will need to dissipate about 10 watts, you should get 25 or 50 watt resistors. They will get hot.

Just to make sure we are on the same page, are we talking about these coils (in the photo)?

If so, it's a shame to run them on the Dyna S since you will be burning away 20 watts in the resistors. They need about 5 to 6 amps to get a good spark. They measured about a nominal 0.5 ohms, but may be closer to 0.4 ohms depending on the manufacturer. They only need about 1 msec to charge to 5 amps, and the Dyna S will give them about 50 msec at idle and 6 msec at 10,000 RPM. That's a lot of time to sit burning away amps. If the coils can handle it (they probably can since they are huge, but they will be hot), they should work.

Yes that's the coil but mine is a couple years older and is one piece with all three coils in one pack. They measure .8ohms. I just want to start the bike with them is all and thank you so much for the reply. I was hoping you would reply and the extra info is always welcome. That stuff RULES!

If you are talking, Just firing the bike up and running it for a minute or two you can skip the resistors. But just for a minute or two. For that short time you will have a real killer spark. Might be as much as 90KV.

I hate to disagree with Otakar, but I would not skip the resistors with a 0.8 ohm coil. The Dyna wants the current to be less than 5 amps, but at .8 ohms, you will be around 15 to 18 amps. That's way out of any safety margin. I wouldn't recommend firing that up for even one crank revolution.

Also, those coils are to be used with a current limiting ignitor. The Dyna does no current limiting that I know of, (so the resistors are needed to do the current-limiting). The coils probably are designed for the 5 to 8 amp range, but once again, you'll be near 18 amps. You might have a melted plastic blob under the tank.

HOLY! What an excursion! I think both u guys are right. And I'm glad you are because I would have fried that dyna. Pretty scary all the way. When you smell those resistors heating up it's automatically assumed to be the dyna! I got 2 packages of 2 1ohm resistors in each package and wired 2 in series to hook up the coils input line. They tested at 2.1ohms. With the coils in the circuit total resistance was 2.9. Safe! Yeah right! Only for a while then helter skelter took place. They were rated at 20watts each by the way. The problem was, they fired the test plug a few times then all the sudden the plug would seem not to fire. After ensuring a good ground and testing many times over and over it seemed that the spark would just not happen more than a few times after powering the system,(by the booster charger). It soon became apparent that this was time related and it also seemed as if the spark may have lost intensity as well. For a while it seemed that if I waited a second before alighning the contacts it would spark, but it soon would do nothing. SO. I burned out the dyna. NO. It would work after a moment or so but would soon not spark. I was pretty nervous throughout the whole process, hence the memory of smoking my points and wiring with the same coils. Though I figured it would happen at the time I didn't care. Hey it's a memory! Now were talkin 120bucks and world class stupidity> what an honor. All right all right I'll get to the point. When hot the resistors varied values related to temp. They increased to an array of different resistance values like 60hms (for one alone) where as the other would be dead shorted. There was no limit to what they became when heated. It only took 30sec to 1.5min to start whackin. Dyna never got hot (course), coils never got hot. What puzzles me but I'm guessing is normal is the test light never did "go out" like the instructos said. It just got brighter and dimmer in and out of the field. I basically hooked up the coils to the booster pos. and the ground clamp when onto the engine. Resistors were inline between the pos. clamp and coils. I could hear the dyna buzz as soon as I turned on the charger so I reversed polarity at the coils and got nothing. Radio snack only had 20watters and from there it was way too high impedence so I went for what was available. Man those suckers got hot and quick. Good news is I got the timing nailed down and some practice wiring along some damn good wheelies on the bicycle on the way to the mall. Bottom line: I sank for lack of ballast! OH. Got the exhaust hooked up too. So I'm ready, just need some guidance for round two. Poor dyna's probally rolled off the bike and is hiding in the farthest corner of the garage with eyes big as saucers! Should I turn up the wattage or just turn myself in to the authorities now before I get in too deep? How could I explain to the cops I was playing Loudx??

Yeah, the resistors probably went belly up under the heat. If you are going to use 1 ohm, 20watt resistors, you will need 8 of them (don't use the ones you already have, get new ones) wired like this:



This will reduce the current below the maximum the Dyna can handle, but you don't need to run it at maximum to get spark. The coils will likely have no problem creating spark with 3 amps.

The other option is to get really big wattage, 2.5 ohm resistors, but you'll have to special order them through MCM (mcminone.com? I think) or Newark, maybe Fry's if you're lucky.

Also, you are using a booster to run this? There still needs to be a battery in the bike to smooth out the pulses from the booster or it can fry the Dyna or regulator. Also make sure you are not getting more than 14v average on the battery, with the booster or you could fry the regulator.

Ok in reviewing this posting I can't for the life of me come up with a good reason to do this versus spending the $120 for say a Dyna coils or something that was designed for the KZ...

With that said, have to ask....
Why in KZ gods name why? :blink:

I can see for experimentations, seeing if it could just be done, boredom whatever but for actually running your KZ, I just don't get it... What's the benfit... For what you're going to pay in good high wattage resistors, then figure a proper heat sink for them, throw in all the possible FUBAR's that can occur....

Maybe I'm just not understanding... So be it...

OMR

OMR - I'm thinking about installing a KZ Dyna-S ingition and coils on my wife's Buick Regal 3.8 litre V-6. Will I run into any problems with this setup? :evil:

hahahahahahaha... Ed, I like the way you think... :whistle:

Lot of things in life not figured out. Send me a check for coils and that'll be one less thing to figure. Time's better spent tuning 600.00 carbs before a header pipe gets looking like a Coral Snake. I spent 4 bucks and started my bike. And I made ya look. Opinions are like resistors, they heat up and burn out in a matter of seconds. I got it to work. It sounded pretty good considering I used 4 very fouled plugs. I used the same resistors but the way I wired it wasn't anything like the diagram posted. I soldered two resistors together and soldered the other two together. Then soldered the two pairs together paralell. I twisted the two coil positives together and soldered to the one end of the resistor setup. The other end of the resistors went to the booster charger. Now I had twice the surface area for heat dissapation since I now have two pairs in paralell. Consistant spark and not near the heat to alter the values. At first I thought I'd have twice the resistance but It actually dropped. Maybe because they were FRIED. Once again, I didn't care. The pulses from the charger seemed to help scavenging at high rpms.:woohoo: Only regret is it wasn't as smooth as would of liked but those plugs were the blackest most fouled plugs on the planet. I think they belonged to Old Man Rock before he spent 4,000 dollars on all the latest go fast goodies. All in all I have only half an ignition and and it's working already! That's batting 1000 in my book. Wait. I don't have a book. Used that to wipe up the gas leak.:ohmy:

Have you checked your float level lately?