Andy,

Actually,...Permatunes were OEM on many '75-'77 911's as Bosch boxes were in short supply. :) :) :)

Porsche used them interchangeably during that time.

Wow, I did not know that. Thanks for the info, we will add it to the site!

Ignition
 

Perhaps getting back to the question. There seems to be a large canyon between comments about the reliability of current Permatune units in comparison to MSD. Also as important what about measurable performance differences?

Sorry, Grandmaster Snow, that we derailed you.

How about you crank up the old search engine and do a little work yourself.

I'm out.

Also, folks are certainly most welcome for the appreciation you have shown for their time.

Ignitio
 

Bob, Sorry to see that you are leaving. Your comments have been greatly appreciated. As always its a pleasure to have Steve from Rennsport give his time to comment on many subjects for Pelican questions. As is having Lonnie from Permatune help with proper installation of his products. Having read many Permatune and MSD comments in the forums, there has been problems with both products. Permatune Legacy products appear to be where the bad press has come from. Both companies appear to do a very good warranty program. How are Legacy Permatunes identified?

Silver case.

Mine has 932019 and 911SC on the the base mounting flange.

All is good re above. I'm simply a jerk sometimes. Apologies.

Best to get confirmation on this but pretty sure this is the box.

http://forums.pelicanparts.com/uploa...1375038745.jpg

"I'm simply a jerk sometimes"
Ain't we all Bob, nice to see someone back up and say howdy. More of that on sites would be a good thing.
Well said snow96.

Bob, Thanks for the pic and info. Hoping Permatune can give some input, so as to clarify how to identify the problem units.

Here is some good info from their website. It relates to the SC.

Not sure what year your car is.

Perma Tune Technical Support for Porsche 911 SC

Looks like Permatune has laid out some very sound information that can be applied to all ignition system applications.

Im not that familiar with these boxes, but in 1992 I had the opportunity to test a Blue Box and draw the circuit, which I posted above.

I don't know the failure modes but it couldn't hurt to add an MOV voltage suppressor on the 12v input.

The one I use is the V24ZA50P. They look like a ceramic capacitor, 20mm in diameter. Mouser has them for about a dollar in single quantities:
http://www.mouser.com/ProductDetail/Littelfuse/V24ZA50P/?qs=i82%252bPC3tdLNfsjOWYPYmmA==

In 1990 I had a couple pre-production units die from voltage transients. The spike went right through the five volt regulator and into the micro-processor. I added the MOV and have never lost another processor.

Years later I was visiting Blower Drive Service and Craig opened one of the MEFI-1 engine management units manufactured by Delphi. It had the same MOV on the back of the board.

JohnP

I've for the little blue box in my '76 3.0 carrera. I think it's original but not sure.

I was set on getting a MSD street fire but after reading so e threads I think a modern Permatune may be the way to go.
Can't say that I've had much trouble from the Permatune.

Willcall, you can check if it is original by looking to see if it has a Porsche part number on the silver label. Also, underneath the box where there is a yellow/white mounting pad there is a date code stamped.

A blue Permatune was originally fitted for my '76 built in June 1976, with the Permatune stamped May 1976.

MOV's can be very helpful....I used to have one on the AC plug of my dryer (140V) to stop the pulses from upsetting my TV upstairs when the dryer (gas...with a high voltage ignitor) was running.
You can get MOVs in many voltage ratings.
I can think of many places where ignition spikes would be eliminated in a car to protect electronic equipment.
Bob

MSD Power Draw
 

I think the instructions that came with the MSD6A that I put in my SC said that the power draw would be approximately 1 amp per 1000 rpms.

.7 amps per 1k rpm. on the MSD 6 series.

The multiple sparks are an advantage, but above 3000 rpm you get a single HOT spark that is a big advantage. Other boxes run out of juice at higher rpms. The fact that the MSD box continues to draw more amps as the rpms go up is actually a good thing.

Thanks for the info.
My '76 was delivered in November '76. May have been pretty close to each other on the assembly line.
Here is a pic of the unit. Couldn't see much other than its all in German.http://forums.pelicanparts.com/uploa...1385351029.jpg