from 2,7 to 3,0 litre possible?

[otto in norway]

Is it possible to replace the original P/C on a 2,7 case with P/C from a 3 liter case?

If not, -why...?

(I'm selling my old P/C's and got a question I've never thought of checking)
Thanks!


Figured out this by comparing my 3,0's measurements with a 2,7's. Mine are larger in diameter on the outside (~102mm), and the cylinder bolts are further apart (~85mm c-c).

[Grady Clay]

No. The cylinder head stud spacing is different between 2.7 and earlier (80 mm spacing) and the 3.0 & 3.2 (83 mm spacing). Each case, cylinder and head has to be compatible. Even if you could get the cylinder to fit the stud spacing, there isn’t enough crankcase metal to support the change from 97 mm cylinder spigots to the 3.0’s 103 mm cylinder spigots.

There are larger bore P&C sets for the 2.7. Most are relatively unavailable or are VERY expensive. There was a Mahle Nikasil set for SCCA racing that was 90 + 1 mm = 91 mm (2747 cc). These were 10.5:1 compression ratio racing pistons.

There were 10.3:1 CR, 92 mm racing P&Cs standard for the 2.8 RSR (2808 cc).

I think Andial still has 93 mm Mahle Nikasil racing P&C sets (2869 cc). Again about 10.3:1 compression ratio. Pricy.


Probably your best option is the 90 mm, 8.5:1 CR Mahle Nikasil sets for the Carrera RS 2.7 (2687 cc as yours). Available aftermarket for ‘reasonable’ cost. With a VERY careful build, you can bring these up to about 9.0:1 CR. These will fit the early 911S cams.

Best,
Grady

[T77911S]

i think JE sells the 2.8 P/C for the 2.7

[Bill Verburg]

Actually Andial used to have 2 different kits to do the 2.7 to 3.0 conversion
AND 104 192 00 Nikasil Mahle, 9.5cr, CIS also need x24 longer dilivar studs(AND 101 170 00) and mahine work to the case and heads

AND 103 929 95 Nikasil Mahle, 9.8cr, domed w/ valve clearance pockets for S cams, only for MFI/Carb you can also use this w/ 2.4 for a 2.8

[otto in norway]

Thanks, that's what i thought...

[Grady Clay]

Bill,

Were any of those sets 95 mm? My recolection is that 93 mm were the largest bore ever for the early case.


I hear that the JE pistons seem to have relatively short life. I understand they work Ok in racing situations (replaced anually or so). It is necessary to carefully fit the piston to the cylinder (or vice versa) in order to get an acceptable piston-to-cylinder clearance. The big issue is the difference in expantion rates between available cylinders and JE pistons.

Aside from performance, the durability of the Mahle Nickasil cylinders and the matching forged pistons is increadable. There are many sets still in service after 30+ years of use and abuse.

Otto, I'll stick with the 90 mm RS P&Cs for your 2.7.
If you want a 3.0 or larger, start with a 3.0 or 3.2 engine.

Best,
Grady

[Bill Verburg]

Originally Posted by Grady Clay

Bill,

Were any of those sets 95 mm? My recolection is that 93 mm were the largest bore ever for the early case.


.........
Best,
Grady

Yes, 95mm, 85.6mm cyl. height, 22mm wrist pin

[TRE Cup]

and no longer available

[kenikh]

You can get up to 2.9L on a 80mm stud case with Nickies and JEs. Not that I would do it - those are some thiiiin cylinder skirts.

Originally Posted by Grady Clay

The big issue is the difference in expantion rates between available cylinders and JE pistons.

Best,
Grady

FWIW, JEs do indeed have a short life in the wrong cylinder (Biral/Mahle Nikasil). Nickies solve this by matching the cylinder material to the JE pistons - same coefficient of thermal expansion. Stories of 100K mile JE/Nickie motors are the norm.

Apparently there are some newer JEs available in different alloys to match other cylinders now, too.