2.0S engine options

[powderfinger911]

Hello All

Im new to the forum and have a matching numbers 911 with a 1969 2.0E engine which has been modified to S spec in the past (Heads, Cams, MFI, Crank, Intakes etc etc). Its a low miles engine which is very freshly rebuilt, even so I would like to get more power out of it which essentially means more displacement. Is this reasonably possible without discarding most (or all) of what I currently have? I have read a lot about 2.5/2.6 short stroke engines but they all seem to be built using 2.2/2.4 engines as starting points. Is it possible to build one with 2.0S heads using custom pistons e.g. JE and still get decent compression?

Im not in a position to simply put my engine on a shelf and buy another one, ($$$) and Im loathe to sell the matching numbers (1R) block I have. The only other option I have is to sell the entire S spec setup, heads, crank, MFI pump etc and build an entirely new engine which is a lot of money and effort considering most of what I have is brand new. Im hoping I can maybe just go to 90mm pistons and have the space cam changed and see a big improvement this way, maybe with a change in cams too if necessary. What do we think?

Along the same vein. Is building a 2.5/2.6 on a 1R block doable? I know it is far from the best choice of casing. What mods to the casing should be performed if doing this? (i wouldnt be tracking the car and reving at >7k for long periods, just spirited road driving). I know my casing has had updates including squirters and intermediate shaft bearing and hydraulic tensioners etc but im unsure of what else it may have had done regards integrity (doweling etc). This will check for these checked upon disassembly regardless of what direction I take.

[Mixed76]

Cost to buy a larger displacement running engine is not so different from cost to rebuild what you have, a lot less trouble, and it preserves the value of your current setup.

Another option is to sell what you have and buy what you want, much lower transaction cost. Hot rods are cheaper than numbers matching cars.

Assuming that what you have is running correctly and delivering the power it should- maybe something to confirm.

You could also look at reducing weight instead of adding power.

[mepstein]

Buy a 2.7-3.0 hot rod engine and put yours on the shelf. Less downtime and you will have two engines for close to what it will cost to hot rod yours.

[targa72e]

You are limited on the engine you have without starting over as almost any upgrade requires machine work so complete rebuild. That said the early aluminum cases are a good starting pint but need lots of machine work. Couple reasons below
2.0 Heads not best and require machine work for larger P&C
Larger P&C generally require piston squirters requires case split to install.
90mm Cylinders (for 2.5 short stroke) requires case to be machined for larger cylinders and squirters for sure.
largest displacement with 86mm cylincers that do not require case machining and using 66mm crank is 2.3
All of the above will require changes to the MFI system $$$
Selling the numbers matching engine for 69E to fund build will lower value of car significantly.
If you are going to build on your early case might as well go 2.8 or 2.9 as cost is about the same as smaller displacement.

As others have said buying a later (preferably 2.4 or larger) is the better place to start. Still will be expensive.

john

[stownsen914]

It is possible to install larger pistons and cylinders on your engine. You may be able to go up to 86mm or so without boring the case. The heads will be a limitation. 2.0L heads are sub-optimal for larger displacement engines. One option would be to put your 2.0L heads on the shelf and source some S spec 2.2-2.4 heads to go with larger P&Cs.

Sounds like you have the squirters already installed, which is good.

[911pcars]

My first engine transplant was a 2 liter S engine that had 90mm RS P/C, thus ~2.5 liters. Luckily, the previous owner had performed the requisite crankcase machining (e.g. spigot boring, etc.) via Ray Litz of Competition Engineering fame. I swapped out the 2 liter crank and rods for a 2.4 liter crank and rods, thus, 2.7 liters.

The valves in later 911 heads are just 1mm larger than the '69 S valves (45mm In./39mm Ex.). The heads were ported and milled as well to exceed the later spec factory heads.

E cams and Webers and it was fine until I sold it 15 years later.



However, at this time, I agree with those who recommend installing a later engine and to keep the original on the shelf. The car will be more valuable to the next owner who will most likely keep the engine on his shelf unless it ends up as a static piece of automotive history. :-(

Sherwood