Dizzy Vs. DIS v.What's your thoughts?

[Guest]

Time for an indepth technical discussion comparing the use of a Dizzy (Distributer) and the use of DIS (Distributerless Ignition System).

Now, for myself I'm looking at this from an all out performance standpoint, this will be for the Franken60 (3.2L Turbo hybrid) or the FrankenBeast (The next build that I am collecting parts for).

Now my understanding of the DIS system that is used on teh GM 660 is mostly for emmisions, mainly due to the wastespark system that is used.
My understanding also is that waste spark will actually slow the exhaust gases when it fires, which is not something that is desirable with a turbocharged engine, high rate of flow + lots of heat = quickly spooling turbo.
Another benefit of DIS is the dwell and charge times can be LONG, so the spark can be very strong, and last for a long duration of crank degrees.

Benefits for Dizzy, would be no wastespark, which if the theory is correct, then the exhaust gasses would not be slowed any, upon exit from the cylinder, cheaper aftermarket ignition systems, I.E 6AL/6BTM/Digital6, one coil, so cheaper there too.
Drawbacks include custom intake manifold (GenIII heads), which is going to happen anyway, in my quest for mo' powa, so the manifold isn't THAT much of a concern, shorter dwell time, though there can be things dne to change that, and less coil charge time, which may or may not be a factor.

The other thing I have noticed is that most of the faster turbo cars are running a dizzy, some have even been converted from DIS, such as a few late model F-bodies, so there has to be some ultimate reason for that.

What are your thoughts?

[bszopi]

RE: Dizzy Vs. DIS v.What

Not exactly my thoughts...

http://www.needboost.com/forum/forum_posts.asp?TID=11&PN=1

http://www.findarticles.com/p/articles/mi_m3306/is_2_115/ai_n13479007

http://www.webcon.co.uk/alpha/alpha_ignition.htm

[Guest]

RE: Dizzy Vs. DIS v.What

Cool, thanks for the links, but not really what I was after, especially that 3rd site.

Great descriptions of how each system works, but I didn't see how easch has an effect on the combustion process, or more specifically what happens to the exhaust gasses, comparitive between each system.

The first one related it to turbocharging, and yes I do agree the DIS does have some real specific advantages, like the charge time and dwell, also less connections that need to be bridged, which I forgot to mention in my first post.

But what I'd really like to know is why a lot of these turbo cars, the fast ones are distributer based, when we are told DIS is so much better?

Even look at GM, the Ecotec race Cav, uses a Distributer for distributing the spark, there has to be something to that.

Anyone know how to take our DIS system and make it fire 6 coils in succesion? basically a coil on plug set-up.

[RednBlack]

How about a Magneto? Just a thought...

[geoffinbc]

Well I have not looked at the race Cavalier yet. But I can tell you why we run a distributor on our funny car.

We run a 44A magneto ignition and we are not alowd to run a computer. So right there DIS is out of the question. I would asume the race Cavalier is this way too. But like I said I have never seen it.

DIS affecting exhaust flow sounds a little bogus to me. Having a spark go off in what is suposed to be inert gasses (if all the fuel gets burned) would do nothing.

DIS has more power stock than my cow killer ignition coil does. Plus the whole system has more efficency so its even better in that respect too.

Since the task of a custom intake is a daunting one I would stick with the DIS and its benefits over a dizzy.

[sharkey]

hey betterthanyou, who's funny car do you work on???

i cant help you with the flow theorys or anything, but i like the distributor simply for the quick and easy timing changes at the track. the cheaper ignition upgrades are a bonus as well.

[geoffinbc]

I just started with the Big Eagle Hydrovac funny car. My uncle has been on the team for a bit. They are from Alberta

If Roadway towing team buys the Top Fueler they are looking at I will be working with them next season.

The TF Dragster is 75000 UDS with no wing. A wing is 20,000 itself. Thats no ricer wing baby.

[StudlyCamaro]

just a side note, you can disable the waste spark ignition with an MSD DIS4. i know when i had mine turned off it seemed like the car was revving much faster ... i dont have any numbers, just that i noticed the tach was moving quicker than it had before i turned the waste spark switch off

[bszopi]

Yeah, the third one I should have mentioned was just something I found interesting... 3D ignition only mapping standalones. Of course, now that I think about it, our stock computers may utilize 3d ignition mapping. Oh well...

[evilmiata]

just a side note, you can disable the waste spark ignition with an MSD DIS4. i know when i had mine turned off it seemed like the car was revving much faster ... i dont have any numbers, just that i noticed the tach was moving quicker than it had before i turned the waste spark switch off

How do you do that? The coil packs only have 2 inputs, so it will fire both posts at the same time, every time.

[geoffinbc]

Yea with the coil pack you have no choice. It is going to fire 2 cylinders regardless.

[Guest]

just a side note, you can disable the waste spark ignition with an MSD DIS4. i know when i had mine turned off it seemed like the car was revving much faster ... i dont have any numbers, just that i noticed the tach was moving quicker than it had before i turned the waste spark switch off

How do you do that? The coil packs only have 2 inputs, so it will fire both posts at the same time, every time.

Exactly what I was gong to say, i knw for a fact (Since I work with many MSD products) that the DIS 4 can NOT diasble the wastespark, that setting is for setting up the DIS, to know that the ignition it is running is a wastespark system.

The task of building a custom intake does not bother me, I will be doing this either way, with or without DIS, since I don't see the factory 3400 intake supporting 600 to 800 HP (My ultimate goal is over 700HP).

The Race Cav most certainly has an ECM, it runs EFI. I'll see if I can find some pics.

So far, I have heard of one account, though I'm still trying to verify it, that a Dutweiler turbo 3.8, picked up 100HP on the dyno, by switching to a dizzy, I'm also trying to find out the rest of the set-up.

I can see how a spark would effect the exhaust gasses, look at the effect a spark has on the surrounding air, it charges it, and makes the molecules accelerate, either away or towards the spark, depending on the natural charge. Also if it didn't do anything to the "inert exhaust gasses", why does it help with emmisions?

So anyone know a way to run coil on plug? (Fires each cylinder once like a Dizzy would.)

[SappySE107]

It helps emissions because it will partially burn whatever is left in the exhaust gases (guess, though makes sense). When it fires both plugs, one is getting most of the juice. The DIS coils should be putting out a lot more energy to the cylinder that needs it vs the distributor and single coil setup though. I wonder if the people that run the distributor and pick up power are just using different timing as well. I haven't read those links...no real time as im on a schedule today:P

Coil on plug would be the way to go but that isn't the option. Does remind me of the carb/dizzy DOHC setup I saw on ebay a long time ago and laughed at though. I mean, to me a distributor is to DIS as a carb is to FI.

[EspanolaGuitarista]

DIS....

may not work at well. A distributor with a hall-affect switch would be just as accurate. With a computer it can be advanced and retarded just like a DIS.

[geoffinbc]

If your engine has a cam and crank sensor then you can run Coil on Plug ignition. You would need a stand alone to support it though.