930 3.0 and 3.3 heads

[hannu_911]

All 930 3.0 turbos heads are based on 930.104.341.2R casts on Y-alloy. Ports are I-32 E-36.

All 930 3.3 turbos heads are based on 930.104.341.3R casts on RR350-alloy. Ports are I-32 E-34.

Right? Maybe not.

Some background info first.
My 1978 930 3.3 turbo 930.62 (Japan) left factory November 1977 with thermal reactors, exhaust gas recirculation and air injection.
Thermal reactors and silencer have different part numbers to those on US models.
Both thermal reactors and end silencer have protection covers on them to prevent grass fire. There was also a temperature sensor on exhaust to lit a light in dash when it got too hot.
Ignition distributor 0 237 301 006 PGFUD6(L) is specific to Japan versions 930.62,65
WUR is 0 438 140 112 on 930.62 engine (also used on 930.66)
All thermal reactor 930 turbos have special AAR to adjust higher RPMs when engine cold to help thermal reactors function better/earlier.
930 606 102 02 in 930.62
930 606 102 03 all other thermal reactor turbos 930.61,63,64,65
930 606 102 00 non-thermal reactor turbos 930.60,66,68 M30.69 M64.50

Heads in my 930.62 engine have 930.104.341.2R, 7-77 and Y cast on them.
Ports were 32mm intake and 34mm exhaust. After porting I-38 and E-36.

How can that be?
Option 1: Very early 930 3.3 turbo heads were actually manufactured from the very same cast as the heads for all 930 3.0 turbos.
This could be because they decided only late 1977 that they need RR350-alloy. Or because of something else.

Option 2: Only 930.62 continued using the Y-alloy heads for some reason.

Option 3: some other reason.

The earliest 930.104.341.3R RR350-alloy heads that I have seen on pictures were cast January 1978.

Do you have early 3.3 liter engine that you have could check which alloy the heads were made of? You can see it under the engine if you look closely. Here is a picture from my engine on a bench.


Or if you have pictures available from you rebuild that could show which version your engine has.


There are a lot of good discussions on to be found on RR350-alloy like the following.
RR350
My quess is that Porsche changed to RR350-alloy because of the worries that they might have had on long term reliability on thermal reactor cars. Keeping in mind that they continues using Y-alloy heads on their 934 and 935 engines. They could have used 930.104.341.3R casts from standard 3.3 turbos but for some reason they decided to cast additional 930.104.341.2R at least as late as 1980.

[Ollies930]

FWIW,
my US '78 930 had heads cast in '77, but were RR350s. I do not remember the exact date, but from memory the dates were not all the same (77, but different months). The serial number on my car is sub 200, if that helps.

[hannu_911]

Originally Posted by Ollies930

FWIW,
my US '78 930 had heads cast in '77, but were RR350s. I do not remember the exact date, but from memory the dates were not all the same (77, but different months). The serial number on my car is sub 200, if that helps.

Thanks!
I know that US car number 131 was build December 1977 (currently on BAT), so yours could be early 1978 depending on the exact number.
https://bringatrailer.com/listing/1978-porsche-930-turbo-46/

Unfortunately the pictures on this 131 car are not clear enough that I could see if it has Y or RR350 heads.