Going one step further

[g-force]

Hi everybody,

I am new to this Porsche forum.
Originally from germany I live now with my family on the east coast.

I worked on classic Porsche's since I am 16 and have rebuilt a few boxer engines.

But now I wanna go one step further after building a type 4 engine up, and build one or two 911 engines up.
So now I have a lot and even more questions about 911 engine details,
but lets start with some more basic stuff:

- are any cylinders sizes interchangeable on all cases?
or do only certain cylinders work, like 2.2 and 2.4 cylinders on the according case and 2.7 and 2.8 cylinders on a different case type?

- are 1974 2.7 targa cases magnesium or "just" aluminum?

- are 1973 and 1974 2.7, 2.8 and 3.0 RS and RSR cases magnesium?

- what changes are necessary for twin plugs? Are the "normal" heads altered for it, or do I need to find special heads, if where? what else is necessary except the distributor or course?

- do 2.7 and 2.8 cylinders have different bore? Or are the 2.8 deep strokers?
- what other changes are necessary for a change from 2.7 to 2.8?

- I know that this questions is to general but what cam works with what displacement and what carbs?

Thank you all for helping!

CG

[Steve@Rennsport]

Originally Posted by g-force

lets start with some more basic stuff:

- are any cylinders sizes interchangeable on all cases?
or do only certain cylinders work, like 2.2 and 2.4 cylinders on the according case and 2.7 and 2.8 cylinders on a different case type?

- are 1974 2.7 targa cases magnesium or "just" aluminum?

- are 1973 and 1974 2.7, 2.8 and 3.0 RS and RSR cases magnesium?

- what changes are necessary for twin plugs? Are the "normal" heads altered for it, or do I need to find special heads, if where? what else is necessary except the distributor or course?

- do 2.7 and 2.8 cylinders have different bore? Or are the 2.8 deep strokers?
- what other changes are necessary for a change from 2.7 to 2.8?

- I know that this questions is to general but what cam works with what displacement and what carbs?

Thank you all for helping!

CG

Hi,

The very first thing I'd strongly recommend is buying some books to get you up to speed on 911's. You should have both of Wayne's books, along with Bruce Anderson's 911 Performance Handbook in your library as all of these are indispensable for what you are proposing to do.

To your questions:

911 engines vary in head stud spacing so all cylinders are not interchangeable.

Late 2.0 and 2.2 through 2.7 engine cases are all magnesium; there are several versions.

2.8 RSR cases were magnesium, but 3.0 RS & RSR ones are all aluminum.

2.7 cylinders use a 90mm bore; 2.8 RSR ones are 92mm. 92mm ones fit a 2.7 case without machining. One can also build a short stroke 2.8 using the rare 3.0 Turbo case with the early 66mm crankshaft, but this is NOT cheap to do.

There are LOTS of different cam profiles and one would consult an experienced engine builder to provide the guidance to make the right choice for your application.

Read all those books I suggested and absorb all the info written there. This will provide the data which will answer your questions in detail.