Aftermarket inginition on 81 911SC

Has any one had any experience with any aftermarket ignition on a mostly stock 911? My 81 911SC is daily driven and I am considering the Jacobs or the MSD systems. The car will eventually have headers and a early muffler. I've done the MSD on water-cooled VW's and Alfa Romeo's with great success but am unsure of how well the work on the 911s'.

It seems to me that the hotter spark might give a teeny bit better mileage and smoother running. I saw better overall drive-ability on the other cars as well.

Any advice is always greatly appreciated.

Thanks,

Dave
1981 911SC

I was interested in the Jacobs ignition upgrade myself. However, everyone says the OEM is the best. This seems hard to believe, just look how far the newer Porsche engines, transmissions, computers etc have come I would think I new factory ignition, or a newer aftermarket ignition would be a good improvement. I would like to know if it would be worth the $200 - $800 for the ignition upgrade.

To me this seems like a lot of money for minor improvements. It goes back to why spend $1500 (exhaust) for 10 more horses? This seems silly.

Well.. Have FUN!
Nick

I installed an MSD on my 87 about 3 months ago. It was easy to install and I have had good success. It makes the car start easier, idle better, and eliminated the slight flat spots around 3-4500 rpms. I think that it helped top end as well and seems to pull strong from 4000 now rather than 4500. BE CAREFUL THOUGH. in the Haynes manual is says that some of the earlier 911's (pre-dme) already had captive discharge ignitions from the factory. If this is the case with yours, you cannot use either system. (maybe that is why people are recommending staying w/ stock?).
My neighbor also put it on his 88 rx-7 and has seen excellent results.

Like SplitFire anecdotal claims, I am highly skeptical of any significant gains by changing the ignition unit from the factory BOSCH CDI unit, which was essentially the same from 1969 through 1983, first with the point-triggered model through '77, then breakerless, '78-'83. If your car is a daily driver, get a Permatune replacement for your BOSCH unit, and you will have a spare working unit! Not that you will ever need it, my OEM BOSCH unit has never failed, but paranoia about a dead CD unit from horror stories of friends with FORD products in the 80s inspired me to get a PERMATUNE unit, and it worked fine, no perceptible difference, it went back in the box as a spare!

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Warren Hall
1973 911S Targa

I completely agree with Warren, the Bosch CDI stock system is quite powerful. I would not touch the stock ignition system on an SC. There's just no reason to do so.

Brian