OK, so, I'm considering updating my ignition along with the motors. I have done a little research on the DUI and other board members seem to like it. How about an opinon between MSD and DUI? The DUI looks more simple as there is only one piece instead of 3 with the MSD.

What would you do? Who has used both and which did they like better or dislike less?

Mongo

Sorry, no experience with DUI, Many MSD failures. I only use Crane HI-6 now as do many ex MSD users, never had a problem with one, timing ramps and rev limits built right in.

I have never had either one. I just use the stock TBolt. If I ever do upgrade I will go with the DUI. For one thing, it is a great price. I also like the simplicity of the HEI style. And, Dennis Moore likes them, too.

The DUI is an induction style ignition system that has a long spark duration in the 3,500 to 5,500 rpm range (that a marine engine operates in). A CD ignition is weak at this rpm. The only advantage to a CD ignition is that the spark doesn't begin to fall off at 5,500. For engines operating at high rpm the CD ignition will not cause as much of a power loss from a weak ignition as the induction style will.

With all of the high tech electronics available for modern automotive engines you would think that at least one automobile manufacturer would install a multiple spark CD ignition on a new car but they all still use induction style ignitions.

Distributorless induction style ignition systems with a coil per cylinder are the best ignition systems available and are what the automotive industry is using on all of the new cars and trucks.

Sincerely
Dennis Moore

Thanks Dennis!

From what it seems, the DUI is the way to go. So far, I haven't heard a bad thing about the DUI but it seems there can be problems with the MSD. I'll have a look at the Crane system too for comparison. Any comment on the Crane vs DUI?

Mongo

IMHO , most aftermarket ignitions will not help any on a good running and set up engine under 5500 rpm like Dennis said, little or no hp gain at top end. The capacitive discharge system like msd and crane do multiple fires at idle and up to about 2000rpm which can help with starting, idling, fouling and other low rpm problems with exotic cams or poorly setup carbs or programmed ecu's. Cant hardly beat a Thundebolt 4 if properly maintained. The MSD distributors have been a corrosion problem and when the box goes haywire it sometimes increases the timing causing the engine to detonate and boom. I liked the build in rev limiter of the Crane and it saved me an engine when my drive exploded at WOT. Aside from that, a spark is a spark is a spark, the right fuel air mixture ignited at the right time is the best you can do. Just my 2 cents.

imongo, are blowers in your future? If so, go with the Cranes. You can adjust the advance curve, and they hook up to your tbolt distributors.

I had numerous problems with my Merc ignition and replaced all of it with a DUI. Less wires, adjustable curve, all my ignition related problems went away. I tried a Crane and it would barely run with the Thunderbolt. I talked to Crane and they admitted that it was not designed for that application - that was several years ago and my guess is they've revise, upgraded, etc., so this is certainly not meant to slam them. My Hi-6 is still sitting on the shelf gathering dust though.

Cig, no, blowers are not in the future. I think the new motors will take me where I want to go.

Thanks for the words, John. I like the idea of an all in one system!

Mongo