911T Engine to S specs?

[blackbird225]

What would it take to get the same performance numbers of an 1970 S in a 1970 T? Is it just MFI or a host of tweaks? I know that this has probably been tossed around before, but I thought I might dig it out again.
TIA,
michael

[Peterfrans]

A S has compared to a T the following differences:
forged pistons, giving higher compression, biral barrels
nitrated conrods
higher lift, more duration camshaft.
Heads with bigger ports and valves
a counterweighted crankshaft which copes better with high rpm's (at which the S has its max power)

You would at least need pistons, cams, and heads if you would stick with carbs. A MFI setup would offer another 10hp in the same setup.

In all no simple tweaks. If you are considering to go this way you could also opt for a short stroke 2.5

[exc911ence]

How about the T and the E spec engines. Would this be a simpler upgrade?

[Randy Webb]

Worse than that -- the T's crank is not counterwt'd so it may not last of reel well at high revs. PAG used a base T engine for some races but I dunno how often they had to rebuild it.

Unless you find a new crank and a lot of other items, you should think about swapping in a whole new engine. What's your goal? A built 2.7L is a great project and can be very fast. My '73 T had a stock 2.7L when I bought it, and I am putting in a hotrodded 3.2. The sky is the limit -- or at least a hotrod 3.8 is the limit. That will be enough to kill the unwary in short order.

Take a look at BA's book and also the "best engines" chart in Wayne's book.

[silverc4s]

I think there are a few racers on this board the use or have used the non-counterweighted crank with good results...don't just throw it in the trash.

[Peterfrans]

The crank is strong enough, the problem is a non counterweighted crank puts more stress on the main bearings. Apparantly Porsche decided that this was permissable for the lower reving T but not for the E and S. For the 2.4 all cranks are counterweighted.
Racers like this crank as it is lighter, and therefore revs easier (just like a lightened flywheel), the higher wear on the bearings is not such an issue in these applications as these engines are probably opened more often.