2.7 Cylinders

[NYSCAR]

Are the 74+ 2.7 cylinders the same as RS 2.7 cylinders? (i.e. could I use 74+ cylinders to build my 2.4S into a high compression 2.7RS spec engine?).

Thanks,

Brad

[911pcars]

74+ 2.7 pistons/cylinders are typically for CIS fuel injection. The piston domes are shaped for this fuel system (low emissions), pistons are not forged and cylinders are Alusil, not Nikasil (better). The CIS system is also intolerant of more radical cams for increased power. For your objectives, a set of 2.7 RS pistons/cylinders in either 8:1 or 9.5:1 configuration or aftermarket pistons (e.g. JE) in Nikasil (RS type) cylinders. This also means a change in induction systems. Weber carbs, S-spec MFI or modern EFI. You can also skip all the above and opt for a later, larger displacement engine as well. Many on this board have done this.

The archives are full of info on this subject.

Sherwood Lee
http://members.rennlist.org/911pcars

[NYSCAR]

Thanks Sherwood. I'm thinking about the 2.7 Nikasil with custom JE pistons, but I'd also like to be able to return the engine to original 2.4S specs in the future since it is a numbers matching S. Are there any significant modifications involved with fitting 2.7 cylinders to a 2.4S engine that aren't reversible (i.e. any block modifications, etc)? I woudln't want to permenantly 'butcher' a good shape 911S for a bit more power

Thanks,

Brad

[911pcars]

If you want to keep this factory original, you can't do much. To mate 2.7 cylinders, you have to bore out the spigots in the crankcase and a few other mods. There's more info outlined in B. Anderson's Perf. Handbook - must reading.

Sherwood

[Scott Clarke]

Find yourself a 7R 2.7 case. They are a dime a dozen. I got one for $300 that was in reasonable shape. Save that S case! It will add to the value of your car.
-Scott

[Bobboloo]

Ditto Scotts advice. Preferably a 74' 7R case that hasn't lived with thermal reactors baking it.