i have a 6A and a 6AL. i have two cars, the "fun" SA and the daily driver GSL. im debating either throwing both on the SA or one on each. i want to use the 6AL without the rev limiter. i already have a 2nd gen coil on the GSL and if i run the MSD ill run it through that coil. ill also be running it through a 2nd gen coil on the SA. i have MSD blaster coils for the trailing.

i just dont know if itll be more beneficial to run 2 boxes on the SA or one on each. for the GSL i just hope to maybe gain a little better "umph" and maybe better economy.

so, who has ran both on the same set up? how did one compare to two? thanks.

 

6a has no rev limiter, the AL does. If you use one, it will be on either leading or trailing, so it is best to do both on one than just on L or T, cause you will only limit the plugs you put them on.

 

No point in boosting up the trailing ignition,it wont be worth much and it wont be direct fire since you need 2 seperate ignitors to direct-fire both trailing plugs.Routing hot,multiple sparks through the cap,non-direct-fire style,just burns up the cap contacts.

Direct fire MSD on the leading system,using FC or aftermarket coils, is a great upgrade for any 1st gen.
It eliminates the crappy stock ignitors,bypasses the distributor cap,wasted sparks both chambers like the stock 2nd gens and with the capacitive MSD youll have hot,multiple sparks from the leading plugs,which do most of the work.

Id do both cars and dont worry much about the trailing.Youll engines will thank you,especially at idle.

 

id do a box on each firing a 2nd gen coil. Easy to do and you will LOVE it. I have a 6AL on mine like that but don't have the limiter chip in it.

 

anybody on the gas milage question if using 1 or 2 boxes?

 

Probably won't see much, but the car just runs better!

 

thanks. i guess ill use one on each. now ive got to find some damn room in the GSL for it. the SA is easy, ill relocate the battery, but the GSL is anther story. i thought about using the MSD direct fire two prong coils, but ive got two 2nd gen coils and ones already hooked up, so why waste money?

theres someone who will have experience with both going to be posting in here in a few days

 

I put my box on the passenger side radiator side paneling where the overflow is and relocated the overflow. My car is with trochoid right now, but you might be able to talk him into snapping a few photos of it.

 

on teh GSL i have a resovoir mounted there for premix for the OMP. ill get creative

 

You can't do two.

You can do one for the Leading since you can fire the leading in a "wasted spark" setup, but if you wanted to do trailing, you'd need one *per rotor*.

So that would be three boxes to do leading and trailing.

Since the trailing are only for emissions control really, there's no point. There may be a grand total of 1-2 hp lost by completely disconnecting your trailing ignition compared to stock or MSD. Definitely not worth it. Run one.

Jon

 

My personal experience with an MSD unit in my REPU was that it wasn't necessary. The cost, the space required to fit the big red box, the cumbersome harnesses (if you don't want to cut anything, which I didn't), and finally, the performance.

I test ran it in my truck for a month or so back in '01 right after trying two coils is series hooked to one ignitor. It was an improvement but then when I removed it and reinstalled two ignitors, in what we know as DLIDFIS, it (my truck), showed even more improvement. It was mainly in the idle and decel (zero backfires and smoother running), but also in acceleration. Maybe the difference in timing compensation has something to do with it.

I later learned that my exhaust system was built improperly and the engine had some missing chrome. When I swapped the truck engine into my MG Midget rotary project, with DLIDFIS of course, it really woke up and the power took you by surprise. Same engine - different car and better exhaust system (actually a little small at 1 7/8 OD, blaiming the PO, but I'm upping it to 2" thickwall RB pipe soon hehe).

I don't mean to steer the topic away from the MSD, and the thread starter is obviously genuinely interested, but I'd just like to state for the record that I see no reason to use an MSD on an NA daily driver because it's simply not needed. Heck it's not even needed on a supercharged application like my friend's orange '81, which has run for years like that.

However on a race car where it might foul at low RPM, or in a highly boosted application, or even running exotic fuels, sure an MSD would be a godsend, but I just don't see a practical reason to use one on the majority of 1st gens you read about in this subforum. I just don't. Then to hear (read) talk of wanting to use one on trailing or cough two! cough cough. Ahem.

Guys, I'm SELLING my MSD. I can't, in good conscience, recommend something that I wouldn't use myself. You can get the same performance with a couple of cheap $17 GM HEI ignitor clones from an auto parts store and one more stock coil. There's no need for multiple sparks, at least I've never needed any to keep my engines running smoothly. There's no need for a rev limiter, unless you're a... anyway. There's no need to spend so much to get so little when the alternative works this well. At least it has worked well for me. Your mileage may vary.

 

However, to date, we continue to hear about wasted spark BUT no actual proof (dyno sheet) to back it up.

 

I don't really care to be honest. All I know it it improved the way MY engines run over the stock FB through-the-cap original configuration. That was good enough for me back in the day.

These days, I don't really care. I know it doesn't hurt performance, at least.

 

Jeff, was your MSD firing a stock coil? Have you tried the 2GCDFIS? If so, how does it compare to DLIDFIS setup?

 

i wont say youre wrong, but i bought this complete set up off of a guy that was running both his leading and trailing off these same two MSD boxes. he even gave me directions on how to wire them up and everything

 

It was firing two stock coils. The exhaust had a big leak allowing for some rightous backfires. On FB cap stock style ignition, it would backfire all the time. On dual coils with single ignitor, it would have less backfires and a smoother idle, but less power up high. On the MSD it had almost no backfires but more power up high. On DLIDFIS it had no backfires! I took it to mean all the left over fuel was finally getting burned. The power up high was the same as the MSD. I saw no need to keep using the red box.

I haven't tried 2GCDFIS on a running engine yet. Maybe on the 4 rotor, with two of 'em phased 90° apart or something.

 

I've got a Crane-Cams HI-6 unit running two MSD Blaster 2 coils for the Leads. I like the hi-6 as its got a decent adjustible rev limit on it. There was a significant difference over stock, and a little bit more over the FC ign setup.

 

You can run the entire ignition system(leading&trailing) off 2 MSD boxes,they are basically just replacing the stock ignitors,of which there are two.
The leading system can have both plugs fired at the same time,using one MSD to fire #1 and #2 leading plugs as one.This will actually turn the leading plugs into trailing plugs in a way,since the second firing will be as the trailing edge of the rotor chamber passes by.You can fire 2 coils with the MSD box because it has the power to juice up two coils,whereas the stock ignitors cannot handle the load.

But, the trailing system must retain its passage through the distributor cap,so the sparks are sent to the correct chamber,one at a time.You cant wire up 2 coils to one box and fire both plugs simultaneously like with the leading because the rotor/port timing isnt correct so far back in the cycle.By running one MSD box on the trailing(replacing the stock ignitor and using one coil),youll still get the hot,capacitive/multiple sparks of the MSD,but it will accelerate the wear of the cap/rotor contacts,and youll be boosting a system that has almost no effect on engine performance anyways.

 

Out of curiousity, how does MSD verses, DLFISL, compare to using just a stock 2nd gen ignition. I'll be running the second gen ignition through the Megaquirt, those together are also probably cheaper than 2 MSD boxes. Megaquirt is 250$ for the latest edition can be bought for cheaper to older models and stuff. Just curious and might be another option thats capable of doing a little more than just ignition.

 

1. You can run 1 MSD box to run both leading and trailing. You have to use the "white" wire and jump it from one igniter to another.

2. Run 3 boxes. 2 for both leading coils and 1 for trailing. Except the trailing stays in the distributor.

 

DLIDFIS vs 2GCDFIS ?
with or without transistor trick
anybody?
vs msd

 

^ the transitor trick isnt even an option. i dont thik the new model willbe completed and the old ones just eat up ignitors. no offense to the designer, its just a problem that cant seem to be beat. i know of one member who has used it without frying an ignitor, but thats only one.

i think using the one MSD box for thr trailing through the dizzy is a waste. i think ive decide to use one of each car for the leading.