2.0 Engine rebuild options

[zmayne]

I have a question about engine options for my 2.0 69 911. I would like to rebuild it into something larger (2.2, 2.4, etc.) but have no idea where to start. I would like to do as much of the work myself. What can you do with the 2.0? And what parts are needed? What power gains can I expect from the various displacements? Any help would be greatly appreciated.
Zach

[ttweed]

Start with Wayne Dempsey's book "How to Rebuild & Modify Porsche 911 engines", and Bruce Anderson's "Porsche 911 Performance Handbook". Everything you want to know is there.

TT

[Scott Clarke]

Zach-
Tom's advice is right on the money, but I can give you a bit of a preview of your options.

You can make it a 2.2 by simply using 2.2 (84mm) pistons and cylinders. This requires no case modifications, so it is your easiest option. You could build a 2.4 by finding a 70.4mm stroke crank and rods (a dime a dozen), along with 84mm pistons and cylinders. Those are the easier options. The going gets rough from here on out. Any further displacment increase will require case modifications to accommodate even larger pistons and cylinders. The spigots that accept the cylinders would need to be machined to accept 90mm or 92mm cylinders. This would result in a maximum of 2.8 liters 92 x 70.4). It is also possible to use the larger cylinders with your 2.0 crank to create a 2.5 or 2.6 short-stroke motor.

You didn't state what kind of 2.0 you have. Its specification would play a major role in determining cost effective options.

You may find that starting with a core motor of larger displacement is a way to go. In my case, I decided to turn my 2.2E motor into a short-stroke 2.5E. This was a decision based on the need for new pistons, and the fact that my crank and rods were in great shape. I am using a 2.7 case that is stronger than the 2.2 case and does not require machining for the larger cylinders. I didn't predict that I would choose this path. It worked out that way as the project progressed.

So, do some homework and keep an open mind!
Good luck,
-Scott

[zmayne]

Thanks guys, the waters not quite so murky now . I'll post pix as it progresses. I'd like to join R Gruppe when its done, but since I live so far away from CA I'd miss most events!

[zmayne]

Scott,
I forgot to ask how you like the 2.5. What crannk and pistons result in this displacment? About how much power does it have? I'd like to get at least a reliable 190hp, if thats possible.
Thanks!
Zach

[Scott Clarke]

Zach-
I'm afraid it's still a work in progress. The stroke is 66mm (same as a 2.0), while bore is 90mm. I'm using E cams and 32mm ports. I think this should produce 175hp using MFI. For 190hp, you would need S cams and S ports. With a short stroke, high compression 2.5 this would result in about 200hp (again assuming MFI, 10hp less with carbs).