Good idea or bad idea....MSD unit for 67S?

[Sacto S]

Opinions and experiences welcome!

[ThomasWilkinson]

Hello,

Saw your post and decided to contribute.

I had an MSD on a mildly modified 914 2.0 with a Crane breakerless module.
Car ran fantastic after the change. Started up on the first try in temperatures ranging from 30-100F. Never had any problems in several years of daily use.

2 years ago my modified 914-6 engine had just completed several power runs on the engine dynomometer using the stock OE Bosch CD and coil.
I was asked if I wanted to try a MSD unit to see if it offered any improvements. Lost ~5-6bhp. A second MSD unit was connected, same result.
The Bosch CD was reconnected and the 5-6bhp came back.
Both the shop owner and dyno. operator were surprised, but commented "the numbers don't lie." Needless to say I am currently running the OE Bosch unit.
I am willing to accept that the MSD may simply have been a poor match for my particular motor as it was set up. The same unit might work great on other configurations.
Just thought I'd toss that in.

Tom Wilkinson
R Gruppe #130
1970 914-6 2.5LS
1973 911 2.7RS spec. motor (really)

[HarryD]

Tom,

Interesting results. Not quite what is claimed by MSD. Think I'll keep my Permatune (aka Bosch 3 pin CDI Clone)....

[ThomasWilkinson]

Harry,

A few more comments.
I believe (and the tech. experts here can confirm or expand) that the real gains with the MSD are in the lower rpm range. It's very possible that with a MSD my Weber 2.5 motor may start easier from cold and run smoother in the lower rpm ranges. At top rpms (where the power loss occurred) any gain from the multiple spark feature is not as apparent due to the very short time allowed between cycles. It might be a great install for regular use and again might help some motors from idle to redline. I just couldn't justify the cost or change after witnessing the dyno results on my admitedly unique motor.

Tom Wilkinson
R Gruppe#130

[Sacto S]

Improved low end, but as the cycle shortens, the system cuts out.

Thanks for the input!

[ThomasWilkinson]

You are most welcome.
The MSD results I enjoyed on the first car were great starting and good smooth operation on a much lower rpm motor.
Maybe the 7300rpm six was not as good a candidate for their technology.
Could also be that those German guys really knew what they were doing way back then...

Tom Wilkinson
R Gruppe #130

[911pcars]

Multiple spark only occurs up to 3000 rpm. Thereafter, it's a single spark/cycle just like the Bosch.

Interesting dyno results, but I have no idea why that occurred.

Sherwood

[ThomasWilkinson]

Sherwood,


I did not know at what point the multiple spark feature was shut off or if it simply "merged" to the degree of become a single spark due to high rpm.
Good to know.

I can tell you the shop owner and dyno. guy both chuckled too.
They looked at me and said "I can't explain that, but the numbers don't lie."
I was actually happy to save the money. If the MSD resulted in a gain I'd have probably bought one.

Tom Wilkinson
R Gruppe #130

[Justin]

I am also considering the MSD unit, so this info makes me hesitate. In the "101 projects for your Porsche" book (I think thats the name), it claims that early model 911s should receive a 10HP boost from the change over.

[911pcars]

Tom,
I wonder if the 5 HP difference is due to a normal error range from run to run?

Wanna try again? :-)

I'm skeptical. If they had an ignition scope attached, they might have seen a voltage drop off that could have revealed a defective ignition box. What was the disposition of the coil? Same Bosch or compatible MSD? Same Crane breakerless setup?

Sherwood