2.7L to 2.8 with Carbs
 

If you take a stock 2.7 and want to increase performance, it seems the going suggestion is 92mm P&C, with 964 Cam, Carbs and backdated exhaust. If you go to the 92mm P&C, you have to machine the heads, right? I think that is what I am understanding from Bruce Anderson's book.

To do the headwork, what is an estimated cost?

Why would you use 964 cams? early S or Solex would be the way
The cylinders are slip in, what would you do with the heads, they should bolt right up, youre only opening 2.7 cyl 1mm of the wall.

Bruce
Bruce

old style vs new style
 

Depends on what kind of pistons you get for the 2.8. Old 'honest to goodness' 2.8 pistons had crowns for the larger volume unobtainium 2.8RSR heads. So with 2.7 heads they have lots of compression and will touch at the edges. A chamfer on the heads is required. More modern versions exist that have 'correct' crowns for the 2.7 heads.

Bruce's book talks about needing to widen the heads to 36mm from 32. I am not sure if that is for all set ups with bigger cylinders or specific to a certain setup. I was wondering if you increase the cylinder size, do you also increase the head size to be compatible.

Tadd, thanks. I think they clears up what Bruce was saying in his book. I was thinking of having my 2.7 cylinders bored to 2.8 so I assume the clearance would stay the same and I could use the existing heads without machine work on them (other than clean up and valve job).

bored 2.7 cylinders
 

Do you have the CE ring grove? The cylinder gets mighty thin at 92mm and is prone to breaking off at the whiff of detonation. Mahle deleted the grove on there 92s.

Not easy to rebore Porsche cylinders and still have a Nikasil wear layer remain intact. Your choices are to purchase larger cylinders with a new Nikasil coating (so-called "Nickies") or purchase the requisite Mahle 92mm cylinders. However I think Mahle only provides these as a set with pistons.

Thus, an aftermarket piston (JE or other) along with larger cylinders begins the process.

Sherwood

Ln
 

I'm pretty sure that Charles (LN Engineering) can strip, bore, then recoat.

Hes going to strip and replate/hone as set of 92s for me, so tossing in a bore should be pie... but talk to the man first.

t