Blake

Yaw wrote it so it must be true, is that what you're saying? I happen to disagree and think quite highly of inductive discharge ignitions, provided the coils have adequate time to rise (only a problem at high RPM). OEMs continue to favor them, even through the crisis of stricter and stricter emissions laws. Misfire is hell on emissions, wouldn't you agree?

EDIT: BTW, how many sparks is the MSD giving you at, say, 3,000 RPM?

Jeff20B

iTrader: (13)

According to some guy (sorry, I can't remember who), the cut-off point of the MSD's multiple sparks to one short duration spark, on a 4 cylinder or 2 rotor, is either 3k or 6k. Then again, who knows since MSD leaves this kind of info out of their instruction booklet.

Hey, Paul Yaw also says that at 6k, the engine could miss 10 times in a row and you wouldn't even notice it. Or maybe it was 6 times in a row at 10k? Maybe I should go see if I can find that old info on Paul's new web pages to refresh my memory? Nah, I feel he steered me wrong with all his MSD on two coils stuff, so I think I'll pass. He installed it on his REPU! How could I resist?

To set the record straight, I'm not a fan of MSD, and haven't been since some time in '01 when I made the switch back to stock ignitors. I only decided to pick the MSD up off the shelf, dust it off, and bench test it with a 2nd gen leading coil recently in hopes that maybe I could actually use it on a rotary again and not suffer the consequences. The results were favorable. I might throw it back in my test vehicle (REPU), only this time with the FC coil, but it'll have to be after the rebuild's had a chance to break in for a while.

purple82

Actually, it's the second law of thermodynamics that makes it true, Yaw is just reporting it.

That's cool if you favor inductive ignition, everyone's gotta pick a favorite right? But as you note, there are principles that favor capacitive discharge at higher speeds.

My point is that you'll always be better off with a higher energy spark. There are differences in the air/fuel mixture from cycle to cycle and locally within a charge, your best chances of lighting it every time is to send as much energy as possible across the gap.

Blake

The second law of thermodynamics is that the air/fuel mixture in a rotary engine varies cycle to cycle and that a higher energy spark is required for more consistent ignition? Wow, my memory is really terrible! I thought it had to do with entropy. My bad.

Anyway, you (and Mr. Yaw) seem to be claiming that misfires will happen frequently with a stock inductive ignition and I dispute that assertion. You also seem to be saying that ever higher energy spark discharges are desirable. I'm saying, once you reach the threshold of consistent ignition, that's all you ever need. I am also saying the stock system reaches that threshold in almost every situation on the street with a well-tuned car. I never doubted that there are variations in the air/fuel mixture across the spark plug gap; I am only doubting that it is of any consequence with the capabilities of the stock inductive ignition system.

Anyway, I'm hitting the road for a few days, so talk among yourselves....

purple82

Entropy => disorder => non-homogeniality

DriveFast7

iTrader: (1)

How come my REPU and 1st gen made more power, started easier, and has better gas mileage when I switched to MSD 6AL direct fire wasted spark?

Jeff20B

iTrader: (13)

lol, exactly. Of course my REPU had more power when I switched from MSD and two coils to DLIDFIS, but that's beyond the scope of this post.

I'd like to some day recreate that experiment now that I have a 2nd gen leading coil to play with. Maybe I could compare stock through the cap to MSD through the cap, MSD direct fire on two coils, MSD in an FC coil, DLIDFIS and 2GCDFIS. The mounting holes for the MSD are still on the inner fender well.

Today seems like a good day to start cleaning parts for the rebuild...

purple82

Jeff, Didn't you say that the MSD setup actually showed a power increase on the dyno? Even over the DILDFIS?

I switched from running my MSD on 2 blaster 2s to the twin post GM style coil over the weekend. Comparing the two, it does seem to have better throttle response now. Power's really hard to tell.

DriveFast7

iTrader: (1)

Real Dyno'd numbers would add validity to speculation.

Jeff20B

iTrader: (13)

If I did say that, it was way back in '01 and I could have been mistaken (that old DLIDFIS write up is grossly in need of updating). We need some real dyno numbers and driveability feedback. Whatever the total power is with which ever ignition system you decide to use, I'd think driveability is more important than peak power. Even Paul Yaw thinks so (in regard to the Nikki mods he used to do, which translates over to the subject of ignition as well).

DriveFast7

iTrader: (1)

Wider and higher PowerBand is more important than peak horsepower. Both of which are measured on the dyno.

DriveFast7

iTrader: (1)

silly double post

Hyper4mance2k

iTrader: (40)

Blake, I made 140 wheel hp aprox170-80hp. 135 stock is flywheel, about 105whp. And if i recall correctly pineapple's 186 was flywheel hp. I wonder what they'd get to the wheels prolly about 140-50. About what I'm putting out. And pineapple has been building rotarys for years! I started this whole thing 4 years ago and I had a year in the Army, negating one year. lol

Hyper4mance2k

iTrader: (40)

oh also I contacted MSD and they said the multipule sparks stop at 4k RPM. then the spark energy in used in one continus spark insead of smaller multipule sparks. Also I dynoed at 140 whp without the dis coil. since the last dyno nothing has changed except that. Springs and shocks too, but I don't think those would effect power to the ground. If i get another engine rebuilt I'll dyno the one currently in the car again. (don't want to risk blowing it up it is the daily driver) and she burns a little oil now

Jeff20B

iTrader: (13)

I just ran some bench test comparisons of dwell, current usage, and good old eyes and ears to observe the sparks from J-109s and diamond coils to 2nd gen stuff. The 2nd gen leading ignitor can provide a much more powerful spark well after the J-109's peak at around 3-4k RPM.

J-109 and Diamond coil peak dwell duty cycle was 65.5% at 3100 RPM and draws 2.38 amps (it's a little closer to 4k on an actual engine, according to some tests I ran on my DLIDFIS powered REPU today). These numbers go down as RPMs go higher or lower from this point (tested from 500RPM to 9k). This is with semi-conservative settings tweaked specifically for the J-109 and Diamond coils (higher performance is possible, but then the broad RPM range is reduced and/or the ignitors/coils overheat).

The 2nd gen stuff draws about 5-6 amps peak and around 2-3 amps in the normal RPM range. The dwell duty cycle % is consistantly higher all throught the RPM range, which results in a more powerful spark. I was quite impressed by the very nice sparks at 9k RPM at a 50% duty cycle. Much better than a J-109 with the same (conservative) settings.

Oh also, I first tested with a totally stock leading coil assembly and compared results with the J-109. Then I electrically disconnected the leading coil from its ignitor and hooked up a 2nd gen trailing coil in its place. The result was even more powerful sparks on a single plug since nothing is shared. If I can scrounge up enough 2nd gen ignitors and trailing coils, I'd like to some day replace all the J-109s and diamond coils on my 20B.

I'd venture a guess that this setup I just tested, consisting of a 2nd gen leading coil assembly and ignitor, triggered by my MegaSquirt, can offer a better quality spark than an MSD. That is to say, a spark that is better suited to the rotary's unique (long) combustion chamber.

Actually, the more I think about it, the dwell settings I used were specifically for the J-109. It was an attempt to mimic the stock output when a J-109 is connected to a dizzy (the curves turned out to be surprisingly similar). I'm sure the settings are way off for a 2nd gen ignitor, which was designed to be triggered from a 5V square wave rather than a 0-100V variable reluctance sensor. The 2nd gen ignitor also got a little warm in a short time where the J-109 would stay cool for several minutes. Oh well. It was still really great to see such freakishly powerful sparks.

purple82

I'd be suprised if the energy draw on this tested setup is higher than the MSD judging by the obvious increased load on the electrical system when the MSD is wired up.

Jeff20B

iTrader: (13)

Way off as in way too high, causing the 2nd gen coil and ignitor to get warm quickly. The settings would need to be toned down in order to use the 2nd gen stuff and have it live.

prefix

Oh man am I glad I started this thread so no one could answer my questions, like can I run an MSD with the stock NGK wires; but who cares about that when they can just bicker with each other about if MSD is good or not.

Hyper4mance2k

iTrader: (40)

your question was answered on page one cry baby. Maybe you should read the thread and leard something. Basicly this yes you can run the msd throught the cap only on the leading side with stock plug wires, but it will eat caps and rotors and not offer nearly any bennifit over stock. Your real increase would be to buy the $30 dis coil and run MSD-DIS DF.

Hyper4mance2k

iTrader: (40)

... and jeff howcome you never test the MSD? If you need I'll swing buy one day and you could run your tests on my car.

prefix

Why don't you go back and look at the posts on page 1 and then tell me that someone answered my question about the wires. Yes my question about running it through the cap was answered but not my other one, about the wires. So sorry I have inconvenienced everyone in the middle of their big MSD vs DLIDFIS battle which is in like it's 5000000000000000 round.

Hyper4mance2k

iTrader: (40)

okay the wires will work as long as you pack the boots with dieletric grease. cause they will most likely leak spary. One guy even said his magnacore wires leaked spark until he packed them with grease. If your running low on cash I recomend NGK stock wires and grease.

prefix

K, got it all wired up. The car actually idles now.

Blake

Okay, I'm back in town....

I don't really have anything new to add at this point, but I wanted to clarify some stuff people are apparently misunderstanding about my point. Mainly, this is in response to DriveFast7's question about why he picked up power by switching to an MSD.

I never said the stock components never misfire -- we're talking about 20+ year old components that probably were never replaced or maintained -- nor that there are circumstances that the stock system can't handle (e.g. mis-tuning). If you find an improvement from "upgrading" the ignition, you are not comparring new-to-new but new-to-used (100,000+ miles, typically). That being said, the OEM stuff is very robust (something I cannot say about MSD boxes! -- mine failed after one week and I've seen many similar failures) and degredation of performance may be attributed to something as simple as corrosion on the electrical contacts or an iffy ground. Simply disconnecting and cleaning the contacts may have positive results. Also, if you are running a highly modified fuel system, I doubt your tuning is as precise as the factory. Most people tune way too rich, just to be on the safe side (nothing wrong with that), but that makes the mixture harder to light, so you may, indeed, need a "hotter" spark to get consistent ignition. But my point remains:

The ignition is nothing more or less than the means to initiate combustion. It can't make the AF mixture burn faster or hotter or whatever. The power potential is entirely the result of the chemical energy of the fuel and air mixture and your ability to light it at the correct time (timing is *everything*). Once you have reliable ignition, that is ALL YOU EVER NEED. A "hotter" spark will not result in even a fractional HP in any RPM range whatsoever unless you were experiencing misfire for whatever reason (poor components or unfavorable mixture). In my experience, a well-maintained stock system is very, very reliable and consistent, even in highly modified environments (in my case, a peripheral port 13B). Others may have different experiences and I won't deny it if you claim that you picked up HP...I'm just saying you were probably either asking the stock system to handle a hard to light mixture or the components were sub-standard due to age and use. Something was wrong and you worked around it by "upgrading". Also, most people don't upgrade only one component at a time, so how do you know the change was the result of the high-dollar item? Did you change the plugs, wires, cap, rotor, coils or any other component? Even just disconnecting and reconnecting the power and ground wires can scrape away a little corrosion that affected performance. All I'm saying is that few people test scientifically, using apples-to-apples/back-to-back comparrisons with no emotional baggage (butt dynos always tend to reflect an improvement proportional to the dollars invested!). And, even then, there are other possibilities that explain differences.

My other point, which I don't think I clearly stated, is that the investment in igntion upgrades hardly provides the same kind of retun that other upgrades do. I, personally, bought a used Racing Beat downpipe and presilencer for my 89 GTUs for $99 and picked up no less than 23 rwhp. The MSD I bought netted exactly zero HP. My custom cold air intake I spent a lot of time and $$$ creating resulted in 1 rwhp...on only one of four runs. Trust me, I've wasted a lot of money myself learning the hard lessons. Now, I don't worry about 1-2 hp gains; my sights are no less than 10-15 hp and the ignition is not remotely part of my plans.

Just my $0.02. Don't confuse my attempts at sharing my experience with any sort of Jihad against experimenting and learning from your own mistakes. I like that Jeff20B is trying new (to him) things. I especially appreciate that his efforts are low-cost, as opposed to those advocating MSDs and such.

DriveFast7

iTrader: (1)

Hi Blake, I agree that stock ignition is reliable, but when i switched to MSD direct fire I eliminated 1 ignitor and spark for leading no longer had to jump from rotor to cap. Besides that it's all MSD. I doubt my ignitor was bad, it behaved like any other ignitor I've ever used. Nothing else was changed; same plugs, wires and Blaster2 coils. I don't think anything was wrong with my ignition; it was just upgraded then gave a better spark.

There is such a thing as weak spark. My cars, rotary and otherwise have always run better when battery has been on the charger overnight. Only logical idea is stronger spark from more voltage.

Don't get me wrong, I've had probs with MSD and have replaced two. They do not like to be hooked up when battery is on a charger!!!!! Says so in owners manual.

As for ROI, exhaust system is a great bang for the buck. But from my experience MSD Direct Fire wasted spark does give better gas mileage. ^ 1 or 2 mpg common. Adds up all year long.

Plus MSD 6AL has a rev limiter which is one of the main reasons I purchased it. I do auto-x my REPU and NEEDED a rev limiter for saftey and peace of mind. We've all read here of peoples over-revving their motor and with MSD 6AL I don't have to worry about that anymore.

No prob with other people doing other things. Jeff20b has uncovered some good things. We're all here to share, pick and choose what we want to do within our budget. To each their own and different strokes for different folks