TurboTommy

Hmmm,
so what are we looking at if I went this route; DME running a bit hotter? I guess, if I understand correctly, high current is running through there constantly; no matter how hard or slow you drive the car, unlike the injector drivers which get a break when you're demanding less power from the engine. I wonder if the ignition transistors/drivers can be easily replaced?

I wonder why Porsche used this OEM coil; it's practically overkill in the low mid-RPMs and yet falls off quickly in the high power regions. Maybe they meant for the long duration spark (achievable from the high peak coil energy) to help with crispness in the otherwise sluggish part of the powerband. Also, maybe at high RPM, spark duration doesn't do much if the spark lasts 20 degrees of crankshaft rotation and the piston is almost already at TDC!
Just stupid thoughts.

Rogue_Ant

The current is only going through the coil & driver when the DME is charging the coil... So it isn't constant (which is why it is hard to measure). Yes, without adjusting dwell, the Blaster coil will pull a little bit more current, thus adding heat to the driver. But, it is definitely do'able, as many have run this coil for years without issue.

Porsche used this coil, probably for a few reasons. First, and maybe most important, it was available at the time. It is sufficient for a stock engine (even if not ideal). Additionally, for the time, the system is pretty impressive: automatic current limiting, adjustable dwell based on both voltage and RPM, no dedicated pickup/reluctor. Compare it to a GM HEI system to get a better reference point of the time.

TurboTommy

Yes, that's right, the current is not actually constant.
I just meant there's no difference on the work load of the DME ignition components whether you're going for 30 minute country drive or if you're doing a half hour stint on the track. Is this correct?

Rogue_Ant

Not correct.
Lets say, the dwell is 3mS. During a normal drive, lets say at 3000RPM, then there is 20mS per revolution. Two ignition events per revolution, means two charges of 3mS each. So the coil & driver will be conducting for ~6mS out of 20mS, or working at a duty-cycle of 30% if you will.
At the track, you will be much higher RPM, lets say 6000RPM, which gives 10mS per revolution. And again with the same dwell time, that means the coil is now conducting for 6mS out of 10mS, or 60% duty-cycle.

The higher RPM is harder on the driver, because it has less time off between ignition events.

TurboTommy

Ah yes; that's right

Thom

Ok, thanks.

For what it's worth here is a word of caution from the Link/Vi-PEC help file :

During the short cranking period it is unlikely that excessive dwell will generate enough heat to cause any problems. Although, most igniters have current limiting to prevent coil damage if excessive dwell is used, care should be taken as some do not. There are also a few igniters (such as those found on the GM/Holden LS1) that will generate spark too early if excessive dwell is used. These igniters will fire the coil if the dwell time exceeds a built in maximum. In these cases, using too much dwell can cause serious engine damage.

Rogue_Ant

Good to see that they agree with my findings - and that they are trying to alert their customers to a potential issue with using the LS coils.

I think we've covered enough about the LS-coils.

eman930

I just purchased a MSD blaster 2 coil, For now it will do, I don't have a M-tune yet so it's the best I am do for my setup.. With the blaster 2 can we run slightly larger gaps or should we stay stock?

Rogue_Ant

With inductive ignition a large gap is not as important (compared to a CDI type system).
So, I would run a typical stock gap. The benefit is that the coil will have more energy, and therefore sustain the spark longer.

Spastik monkey

So with the MAF tune setup, I can adjust dwell?

Rogue_Ant

The DME Tuner gives you access to the coil-dwell data.

I can also setup the chip/software beforehand if I know what coil you are using.

snb13

Josh, how's my NA-Tune coming? Looking forward to getting it and my HVC-II in and running.

Voith

Did you test this coil? I wonder how this one performs..

IGN-1A Race Coil



http://www.diyautotune.com/catalog/i...oil-p-394.html

azmi951

I have traced a no start issue to the ignition transistor in my DME. I have been running a blaster 2 for over 100k miles and this is my second DME to pop in the 10 years I have had my car. So it is anecdotal but it seems to me that the blaster 2 is harder on the ignition transistor than the stock coil to the point of premature failure.

My setup is all Vitesse with a stock ignition system excluding the coil. I think I will look into a wasted spark setup.

URG8RB8

I certainly don't have enough time on the system to make a valid conclusion, but so far I have no issues running the MSD HVCII on the modified M-tune DME. People should note this is NOT to be installed without having a slight hardware mod to the DME by Josh and installing the proper Dwell time map.
You should ask Tom about the wasted spark, before making the switch.