84_Carrera

This may be a silly question, but has anyone done an MSD ignition box upgrade / does anyone know if this would benefit the 3.2L?

I ask, because it occurred to me that if the twin-plug setup is beneficial for added power, wouldn't a multi-spark igntion also be a bonus?

It's probably one of those right-in-front-of-your-nose / RTFM questions, but I didn't see anything in the 911 sections for N/A 911's. Thanks.

HY M8NC

I just removed the MSD 6A and coil from a race car we built-we ended up doing the Electromotive Twin Plug ignition on the car. If you decide to go this route-I'll give you this one cheap.

I'll let the 911 experts answer your question as far as performance improvements-I think they are better for the old CIS cars, but I'm testing the limits of my memory (and knowledge) there.

84_Carrera

Ben, I suspected the CIS cars would benefit more than the Motronic ones. We have a similar "discussion" in the SHO community, since we use a higher-end (for the day) distributorless ignition system. Some people swear by them, some swear at them.

Are you talking about the TEC-3 system? If so, let me know how you like it, I debated using one on my supercharged SHO track car last year.

Thanks!

Lorenfb

"I ask, because it occurred to me that if the twin-plug setup is beneficial for added power, wouldn't a multi-spark igntion also be a bonus?"

The MSD type systems have NO technical merit. It's basically a marketing gimmick
to differentiate the product from other capacitive discharge ignition systems.
The real benefit comes from a twin plug system as Porsche and others have used.
By the time the next MSD spark comes, the fuel charge has been fully ignited.

Bottomline: If the MSD system had any real merit, Porsche and others would buy/use
the technology in a nanosecond. It's a very simple design to implement and would not
add much overall cost to an ignition system. Therefore, its non-OEM use is further
indicative of ZERO merit.

Steve Weiner-Rennsport Systems

Fred:

MSD's are fine ignitions and are best suited for cars with imperfect fuel/air mixtures such as carbureted and MFI-equipped ones.

A stock Motronic engine does not gain anything with an MSD as long as the A/F ratio is within spec; the ECU does a fine job here.

Twin-ignition is required for compression ratios at or above 9.7:1 and one uses a Motronic splitter box, 2 stock coils, and a 3.6 distributor to do this. Custom software is also required due to the necessary changes in the ignition advance maps.

84_Carrera

Thanks guys, much appreciated on all the info.

Given the A/F below, would further custom tweaking (read: new chip) to lean it out a smudge above 4500rpms do much for this engine, or is it preferred to be more rich on the 911's?

Steve Weiner-Rennsport Systems

Fred:

You can do a LOT better in the chip department than Weltmeister.

That A/F is too rich from 4800 to 5700, but that not the whole story as these tests are all done at WOT.

A better chip will provide much improved results and whats most important; drivability.

Chris M.

So based on this would you NOT recommend an MSD ignition unit for an 82 Euro SC?

Steve Weiner-Rennsport Systems

The benefits of the MSD would be very modest on your SC unless you opened the plug gaps to .040.

I like the performance and drivability of MSD on carbureted and MFI'ed cars since they operate with less-than-perfect AFR's.

That said, if your Bosch CD ever fails, I would consider installing an MSD as a more viable replacement.

Chris M.

I'm not looking for any kind of performance gain (in fact I'm hoping the MSD is legal for stock class racing) but as I'm troubleshooting a starting issue (along with a bouncing tach) it looks like my Bosch unit may on the outs. The MSD seems like a good replacement and is certainly cheaper than a rebuilt Bosch. First step is to install a friend's healthy Bosch and see if it works in my car.
What's your take on the MSD vs. stock coil while using the MSD box?

Steve Weiner-Rennsport Systems

You can use the stock coil, but I prefer the High-Vibration MSD ones. Simply remove the gross MSD sticker and it looks OEM.

Chris M.

Also, will I need a tach adapter?

theiceman

hey .. who ya callin old ?

r911

an '82 should not need a tach adapter

the msd can be altered to look silvery if you don't like the orangey red color

OTOH, the Bosch just plugs right in...

BTW - twin plugs ignite a much larger flame front - on a 911 the plug is way off to the side of the combustion chamber (unlike a modern water cooled 4 valve design with the plug dead center) - that's the adv. of twin plugging and one adv. of water cooling