Duty cycles, or dwell angles aren't what you should be looking at, unless you include an exact RPM for each setting. Looking at duty cycle or dwell angle is an "old school" way of looking at dwell, when it wasn't fully computer controlled.

Now that it is computer controlled, you need to pay attention to the dwell time. This time should be consistent. Which will mean as your RPMs climb, your dwell duty cycle will climb as well(same dwell time, less total time = higher duty cycle). If you have a steady dwell duty cycle, you either have too little dwell at high RPM, or too much at low RPM. Too much at low RPM can cause the power transistors to overheat, killing the ignitor(DSM) or coil(Evo).

You could definitely map dwell time so that it decreases when not needed. If you were going to do that, I would make it so that the dwell mirrors the torque curve of the engine. Most dwell at peak torque, decreasing outside of that range.


Experimentation to find out what will work is a very good idea, and your results are showing that there are gains to be had. But I'd highly suggest doing your calcs based on "dwell time" instead of duty cycle, just because that is what matters to the system, from an electrical standpoint.

For the people suggesting the Evo coils are better than the DSM combo, they aren't. Get them both mapped properly, and you will see the DSM is still slightly stronger. Not a lot, but a little. I don't know that it's worth the $ and time to do the swap though.

The real issue with both setups, is that no one has really mapped the dwell time out to be optimal. The factory ECUs even allow dwell time to drop at higher RPM, which hurts the overall output of the stock ignition.

 

Again thanks bradrs for the suggestions. I am indeed trying to map things to a point that I don't see dwell charge time fall off. But with your explanation of following the torque curve probably being more important I see where the two Max Dwell settings could have very similar results.

 

Do you have a scope or other way of actually looking at the coil signals? Matching the torque curve would be nice, but just getting a flat dwell time across all RPM, and dialed in to produce constant current regardless of battery voltage should make a big difference.

It sounds like the results you guys are having are already pretty good results, doing that extra dialing in might not get that much more.

 

I might be able to get access to a SUN machine that will allow me to measure but I will have to find out.

Right now I am dwelling less until around my RPM target for full boost then trying to hold a constant dwell time from there forward and I am pretty close but still need to do some testing to dial in. Things really do seem to be much better but I agree there might still be some improvements to be had.

 

I think every paragraph has aleast one false statement in it.

In your first statement about don't look at duty cycle but dwell time? We are only talking about duty cycle is so that we do not over run the coils and burn them up that is roughly 60%.

The second paragraph, yes we are running a set time across the board, that is the 110 in my case.

The third false statement is almost the same as the first. we are using dwell time to calculate but we are speaking of duty cycle, the same dwell time at lower rpms have a different duty cycle, then the same dwell time at higher rpms.

I don't a single person has ever said that the evo coils are better then the older DSM coils.

And your last false statement. What do you mean no one has mapped the proper dwell time? The proper dwell time would be the maximum time possble at a given rpm without over running the coils and burning them up.

 

On that note i have rasised my minimum dwell up to .25 and raised the dwell vs rpm at lower rpms. I replaced my old crap plugs with some new bpr8es gapped at .024". Wow, the car idles like a dream and even my vac is stronger.

 

I have no idea what your hostility is about.

I'll address the easiest statement though

From earlier in this very thread:

I'd explain the rest of the statements as well, but I don't feel like an argument today.

 

I think some of this may but just misunderstanding, this is bound to happen with threads and a testing process. Its not that big of deal, people can keep testing and posting results. We are all way better off than we were in the past and I think we can all agree to that.

I could go back and re-test the DSM coil but my test is just pushing the coil to its limits of spark. I was at those limits which was another reason I decided to come back and revisit this issue but others may be able to get it work better with more testing. This was just my 02 but I am only one person and am by no means an expert, just always trying to learn something new.

 

How the system runs on the car is the final thing that matters. So finding improvements as it runs on the car is a big deal, and the fact that you guys are finding it is great.

I was just pointing out a few other things to look at. I usually would start off testing ignition systems for their electrical characteristics with the car not running.

You can tell a lot about it by the charging current and voltage at a few key places. The DSM ignitor had issues with current limiting, and you could easily have turned up the dwell on it to get it to start limiting, getting hot, and then losing some of its performance.

These things aren't as easy to diagnose when you are just looking at spark power. But with a scope and a few probes, you could easily tell if there is something else causing the problems. Turning down the dwell time could allow you to extend it out to a higher RPM, and possibly get more peformance. It all depends on what you were running it at.

The dwell settings you are picking for the evo might not be a bad starting point if you were to go back to the DSM coils, the charging characteristics of the 2 coils are not that far off.

 

I am not trying be hostle, but you are coming from left field and basically telling us what we have been testing and calcutlating is the wrong way to go about it.

We are proving that the new settings work there have been 3 cars now making over 500whp without a miss on the stock coils and ign that is almost unheard of with the AEM EMS. One of those cars just made 6xxwhp.

 

I cant wait to try these new settings on my evo8......waiting to install the new turbo & then i'll give them a try.

will be done on 91 oct.....I had to reduce my plug gap down to 0.19" on ngk br9eix's to eliminate misfire @ ~7k.

 

Another great candidate for testing! I don't think you will be disappointed.

 

Hi, GTVEVO
please, check your pm. Thanks

 

Reply sent.

 

would this cause a rod bearing to spin? i mean if one of the cylinders is maybe set up different from the rest? just seeing if this has anything to do with timing or just spark to the coil???