best compression ratio for a 2.2T ?

[stuntman mike]

Hello everyone,
this is my first post on this forum, so let me first briefly introduce myself: My name is Oliver, I live in France and I usually drive around in old diesel Land Rovers, but about a year ago we have bought our first Porsche, a 1988 3.2, which is an amazing car, gives us tons of pleasure driving it. It had been modified to a 964-look, and I have put it back to original, did a thorough servicing, rebuilt the alternator, adjusted the suspension back to factory spec (it had been lowered a lot). Simple stuff, but this allowed me to get a general peek at the car and a basic understanding of the philosophy behind it. After that "cleaning up" job, I was a bit frustrated because it's just way too reliable, and I want to do more on it.

I'm not used to this (cars where nothing needs to be fixed all the time) anymore, as I have built most of my cars myself and I keep on modifying them all the time. It just kind of doesn't feel right to turn the key and drive away.

So, earlier this year, we have bought a project. It's a 1970 2.2T Targa which is a complete wreck. Everything needs to be rebuilt from scratch: the body, the engine and transmission, the interior, everything. Exactly what I was looking for
I'm starting with the engine, as it was filled with water (the car stood oustide without an air filter on the carbs) and it was more than urgent to open it in order to save whatever could be saved. Plus it's the area where all the really expensive components are, so I want to get rid of those surprises first.
We are getting closer to my question now
Apparently the engine had been rebuilt in the recent years, but not too well. So there's not a lot of wear, but lots of parts need to be renewed anyways. So even without the water issue, an egine rebuilt had to be done.
The main problem I have right now is the decision I have to make regarding pistons.
The cylinders have a little corrosion and therefore need to be rebored. The best option I have over here for oversize pistons are Woessner pistons. The thing is, that it makes no difference in price if I buy 2.2T, 2.2E or 2.2S pistons. Apparently they would all fit exactly the same, giving only a different compression ratio.
Now we are really getting to my question, won't keep you much longer
I have read the performance handbook and of course Wayne's book (about 25 times !!), but i still can't figure out what would happen if I was to install 2.2E or 2.2S pistons in my engine, without changing anything else (keeping the 2.2T crankshaft and camshafts, and the Weber IDTP carbs).
I would have thought this could give me more torque in the lower revs and a better fuel economy, but I really don't know anyone who has spent years messing around with these engines and who could tell me "I've already tried this , its good because blablabla or its a really crap idea because blablabla...".
If it was on a 2CV, I'd just go ahead, do it and see what happens, but here the amount of work and the amount of money involved are just too much to just "play".
So, if anyone has done this or something similar, I'd be very interested to hear their story, so I can decide what's going to be my option ... the car would be used for touring, mostly mountain roads.
Thanks you in advance!

Oliver

[Flieger]

With your cam, the dynamic compression ratio may be too high if you go with S pistons. These may cause detonation. Twin plug may help that. E would likely be a nice medium.

[larrym]

it depends a LOT on what fuel you intend to run in it

you want a daily driver

- if you want to be running on cheapest gas, stick with the T specs

you want street "grunt" - you will probably find it cheaper overall to just go buy a used 2.4 or 2.7 engine that was running when removed and do a top-overhaul on it instead

[Henry Schmidt]

We recently built a 2.2 T (for a 914/6) using a 2.4 crank, stock 2.2T pistons & cams then ported the heads to 36mm. The change in crank added about .6 point to the compression ratio, well within the confines of street gas perimeters.
The engine produced 177 peak hp @ 6400. The T cams guaranteed the engine made great low end power.

[piggdekk]

Henry,
may I ask you what did You do to the carbs to run 36mm heads?
I guess you must be running at least a 32 ventury or more.
many thanks
luca