CDI to MSD...? Opinions?

[levdeb]

So, I actually have TWO sets of original working CDI Bosch boxes. Waynes "101" book says to go to MSD. Would it be a benefit to me to sell these two boxes and get an MSD setup, or wait till something dies??

Or, if I do sell them both, would it be possible to sell these to get a complete MSD system?

Love your thoughts on this.

Thanks!

[JK-81SC]

I would hold on to one of the Bosch CDI units. Put it in your trunk as a back up in case the MSD dies. I had a Pertronix unit that starting failing and almost left me stranded. I installed an MSD and it's been working great so far. More than great so far, I really like the way the engine runs with the MSD. The car starts way easier, and seems to rev much more easily. I have read that the MSD units can be hit or miss in their reliability, depending on how well they are installed in your car. So if the MSD unit dies, be prepared to do a roadside install of the Bosch CDI. This seems to be a very emotional topic, so there will probably be some very strong opinions on this topic.

[ischmitz]

I don't think this topic is too emotional. You haven't followed discussions about chipping a car with some of the former board members.....

Seriously, the Bosch CDI units work fine for the task at hand and given their average age have shown an awesome reliability track record. Still, as they age some do fail. The good news is that they can be repaired. That is not true for some aftermarket units. Remember that even a 935 uses the very same principle of Bosch CDI ignition down to the same capacitor and switch. So it can't be too bad.

Aftermarket solutions (Permatune, MSD) were introduced with various marketing statements. They have been pitched as performance upgrades due to "hotter spark", "multi-spark" etc. I find these hard to believe and measurements haven't really substantiated these claims. If you have plug fouling issues you might as well address the root cause rather than using a multi-spark to mask and band-aid the problem.

On the flip-side reliability was less than stellar for some of the aftermarket units and many failed fairly early in their service life. MSD requires splicing into the factory harness and then there is the tachometer compatibility to watch out for.

With the MSD you do get the variable rev limiter that some find a nice feature. Many hot-rodders use MSD.

That being said I still don't see why one would rip into the stock harness to install an aftermarket ignition system if the stock Bosch system works fine. IMHO the benefits do not justify this. In the past when the Bosch unit failed and the only option was a 2600$ Bosch replacement it was a different story.

Ingo

[al lkosmal]

I have had an MSD-6A installed for several years now. Has worked very well. My Bosch also worked very well.....my blue Permatune worked very well....my Electromotive crankfire worked very well......what I'm trying to say is I didn't see a real change in performance between any of these ignitions. My preference from a bang for the buck standpoint is the MSD. For one, it's new and affordable, relatively straightforward install and has been bulletproof. Also, they can be found everywhere.

regards,

al

[Eagledriver]

Your current set-up is fine. I doubt you would notice a difference with a MSD. You also have a spare box to use if the first one ever fails.

-Andy

[Brando]

Instead of the MSD brand Multi-Spark Discharge system I would highly recommend a Mallory Hyfire 6A, 6AL if you don't have built-in rev-limiting. Mallory uses an all-digital processing system as opposed to the "MSD" system that's analog. I've seen much better reliability from the Mallory box, IMHO.

Just remember to upgrade to a better coil!

As to the stock/aftermarked msd argument... People always say "Well if it's so much better why didn't it come stock?" Very simple answer: Expense. A CDI ignition "works fine", where as the MSD system "costs more".

Also improvements you'll see with a msd system: Cleaner lower-end emissions (for smog testing reasons), slight increase of sub-3000rpm torque, some claim to feel a smoother transition from 2k-4k rpms, smoother idle. You can also get away with running a little richer in the lower RPMs, that's another benefit of msd systems.

But that's all icing on the cake. The best advantage imho is that you're putting newer and better technology in-place. Until you get to single coils on each hole.

[T77911S]

no performance gain on a stock motor. a lot of good advice, price, reliability, using one bosch as a spare. not to say the multi spark could help at idle, but i could not tell.

the bad thing about the bosch is that they are old, the capacitor is the main failure, they go bad. the good, they can be repaired. just like in guitar amps, as they age they need to be replaced.
i like my MSD, i carry a spare CD and coil, but you can always buy an MSD at your local hot rod shop.

[JK-81SC]

One more thing to clarify with my choice. My car didn't have a Bosch CDI in it when I bought the car. I looked for a used Bosch in the classifieds when I needed something to get my car running reliably. I couldn't find an affordable one, so I was forced to go with the MSD. No regrets so far, since it runs great.

I think Wayne offered the MSD as an affortable alternative, since the Bosch units are insanely expensive new. I would hold on to both of the Bosch units. If you are handy with a soldering iron, change out the parts that are known to go bad over time. Then you'll be good to go for another 20 years.

[RoninLB]

Bosch is great for a good running stock engine with factory spark plug gaps.

Forget about MSD unless you need it due to engine mods or your car is beat with bad valves and rings. If you have an old clunker on its last legs and smokes like hell the MSD will help keeping it running, as per my experience.

[scarceller]

I'd stick to the stock CDI as it works just fine for stock setup. If you had very high cylinder pressures like in a turbo then you would benefit from more spark gap (Wider Gap). In my opinion you could better spend your money else where.

[avendlerdp]

I gained a real and measurable improvement at low rpm using an MSD on my 1970 T with Webers. Fuel injected cars gain less from the conversion. Carbs tend deliver a slightly inconsistent mixture at low RPM and having a bigger spark helps.

[levdeb]

Thanks guys! So I guess I will get it all running and tuned, and if it "needs" more, then I will go MSD. Appreciate it!

[fred cook]

Actually, if you have a Porsche that used a 6 pin CDI box then you don't need to "cut into" anything. When I installed an MSD 6A in my 1980 SC (the Bosch unit had failed), I used crimp on male terminals and simply plugged the MSD into the stock plug on the cars' wiring harness. That way, if I or a future owner decides to go back to "stock", it will be a very easy and painless process.

As to the functionality of the MSD, I also believe that the MSD makes for easier cranking and a smoother idle. And, my car at least pulls very strong right up to 7,000 rpm where the rev limiter cuts in.

So, what we have here is 1) easy to install, 2) works well and 3) cost much less than even a rebuilt Bosch CDI. I have had the 6A unit in my car for 6-7 years and it has worked perfectly during that time. Sounds like a winner to me.

[T77911S]

Originally Posted by RoninLB

Bosch is great for a good running stock engine with factory spark plug gaps.

Forget about MSD unless you need it due to engine mods or your car is beat with bad valves and rings. If you have an old clunker on its last legs and smokes like hell the MSD will help keeping it running, as per my experience.

sounds like you are saying the MSD is better?
if an MSD will help keep an old tired engine running, that means it will be fine in a fresh engine so why forget about it? after all, it is a cheaper replacement and readily available at your local shops.

[RoninLB]

Originally Posted by T77911S

sounds like you are saying the MSD is better?

I don't want to push that argument.

Many MSD wiring installs suck. Many don't realize how hot they get and install them under the engine comp elect panel cover, some repair shops will shy away from diagnosing until any possible MSD issue is removed, and if the car is to be sold a prospective buyer may be spooked.

btw... MSDs work great in small ocean racers with built engines. If it can be pounded like a sledge hammer all day and keep a twin carbed big block running clean it's good enough for me. Marine MSDs are blue.

[T77911S]

no argument, everyone has their own opinion.
just messin with ya

i have always like your install, very nice.

[911st]

The stock ignition is a very good system.

Where the MSD might show improvement would be on a CIS turbo with varying AFRs and very low compression where is can be difficult to fire or maybe on single plug MFI car that has less than ideal AFR's early in the rpm range.

Again, the stock system is said to be among the best made.

Not an expert on this, just what I believe.