930 questions

[Gunter]

What to look for in maintenance/history for a mid-eighties turbo with 100k miles?
Is MSD ignition a common upgrade? Did 930s have issues with valve guide wear?
Clutch issues?
Why do some have a 4-speed transm. and others have a 5-speed? What is preferrable?
Without CAT, what header/muffler combination is recommended? I would like SSI's with some kind of sport muffler dual in/dual out.
Possible?

[kenikh]

The older 930s had 4 speeds due to the fact that the 5 speed trannies of the day not being able to contain the higher HP of the turbo. I believe the advent of the G50 tranny cured this and gave turbo owners a 5 speed. I think I am missing something related to the Euro cars, but I'll leave the rest to the experts.

[930addict]

I can only speek to the 4 spd vs 5 spd transmission issue.

The 4 spd transmission is commonly refered to as the 930 transmission. This tranny was used in all 930's between '86 and '88. This is a heavy duty transmission that uses a lot of the same components as the porsche race cars (except the gearing). The 5 spd tranny is also a very good transmission that is more refined as far as how the shift feels. It's also a very strong transmission. As to which one is better - that's a personal preference. You can do a search a read the discussion on this. I have and like the 4 spd because I'm not changing gears in traffic all the time. It's kind of like having an automatic. However, the 4 spd is a real dog off the line so it's no fun if you're hitting a lot of stop lights. Also, it does not keep the car on boost as well as a 5 spd. But there are things you can do to mitigate this. The 5 spd does a better job at keeping the car on boost, but you're shifting gears more frequently. The 5 spds are more preferable to most, but I still like my 4 spd and did not think the premium you pay for a 5 spd was worth it. To each his own.

I haven't heard of any valve guide wear issues on a 930. I think the best thing to do is buy Adersons porsche performance handbook as it goes into details of all the changes and troublespots for the different year Porsche 911's and Turbos. It's a great read and very informative.

[beepbeep]

4-speed 930 tranny was used from 1975 to 1988. It's gearing was esentially the same troughout the years but early variants (75' to 77') had shorter clutch-housing and is often called "short transmission". Later version (78' - 88') had rubber-damped clutch and longer clutch housing.

Only 930 that had 5-speed transmission was 1989 model.

[David]

I would think the MSD would work great on a 930 but I haven't done it.

Turbo's do eat clutches faster than a non-turbo but you sure enjoy them while they last.

Valve guide wear depends on how the car was driven.

Look at GHL, Fabspeed, or B&B exhausts.

The 5 speed is prefered but you pay a premium for the '89 model that came stock with it.

[930addict]

BeepBeep you are correct the 930 was used between 1975 and 1988.

[magic930]

The MSD works very well on the 930, I used to have one on mine. The Multiple Sparks help produce better combustion below 3000 rpm. Above 3000rpm it has no effect.

Valve guide wear is more common on the turbos because they produce a lot of heat under boost conditions. But as 125shifter says it depends on how it has been driven.