[TitaniumTT]

Originally Posted by Force13b

You can you LSX coils for a PFC but you're only going to get about 1/2 of the power out of them. The stock FD ignitor uses a falling edge signal from the ECU to trigger the coils, just like the signal that the LS coil needs. But because the PFC only drives the stock coils at 2.5 or so MS, you couldn't get anywhere near the full capability of the LS coils which can be driven at 5 MS. There's nowhere in the PowerFC to alter the charge time either...so you're stuck with low output.



Brian i just ordered a set of MSD Blaster coils 8245 they are just like the ls truck coils but more power.

Huh, I didn't know that about the PFC - lame. However, that's sorta the problem that I'm having with the LS1 coils that I have. The problem with the rotary is the incredibly short charge time that's allowed between spark events. I sat down with my engineering buddy/MoTeC guru and we came up with a dwell table that allows basically the most charge time, and it's not all that suitable for the LS1 coils. Becuase of the rev's the charge time is dropped to (I THINK) 3-4ms in the high load/high RPM sites. Again, NOT getting full charge time. We just had a chat and he rec'd some coils out of an LS7 (I've got the Delco number written down) that can fire happily ALLLLLLLLL day long @ 2ms charge and produce the same mJ and up to 20% more than the LS1 coil @ 5ms. And they bolt in..... sorta.

So my plan is to hit the dyno again in April, Dave and I will tune the car with the new injectors, new coils. Then swap coils and make another pull. Same dwell table, same conditions and see if there is a drop in power from the LS7 to the LS1 coils.

Then I'll swap in the LS1 specific table dwell table and make another run. Side by side comparisions and we'll know for sure if the LS1 coil is suitable or not when given the full charge time allowed by the rotaries "timing."

Again, this is on the MoTeC with retarded amounts of adjustability so I'll be able to get the most out of the coils.....(I can even bump the dwell time when the boost comes on although right now it's just basic rpm vs dwell) just for fun if we remember though, we'll do a pull with the LS1 coils @ 2.5ms and the LS7 coils @ 2.5 ms (if they don't auto-discharge at that length) and see where we land. Ahhhhh, the beauty of dyno's..... I need to make a list.

End result will be dyno proven power gains from coil to coil at full allowed charge time and whether or not the LS1 coil is really suitable for a rotary. I tend to think, based on what Dave and I found on the Dyno, that the spark is a little weak, as you're pointing out Tyler, becusae we can only dwell the eff'er for 3-4 ms.

Tyler, just as an aside, when I first started this pj, I was warned AGAINST those coils by my MoTeC guru. He had a few engines pop on the engine dyno becusae of them. Now they may have changed some, and I know a few guys use them, but I would think twice about them. I would go with something else. I'm curious what the difference in mJ output to charge time is with those vs a stocker Denso D5whatever the LS1 is. Do you know? Are those the auto Multiple Spark they toyed around with years ago?