What is the larges engine I can put behind my 915 trans axle?
 

I am new to porsches and I would like to know what is the largest engine I can put in my 1972 targa. Currently a 911 T 2.4l without modifying anything.
Thank you.

Your '72 915 is a poor candidate for a larger engine than a mild 3.0 litre.

A late, '77-on 915 can handle (if properly modified) up to a 3.8.

or does he want to just Chev it?

My 74' 7:31 915 is still doing fine (>25k miles and counting with a modified 3.6, spririted driving, 150k miles total). I believe an eary 915 with proper modifications (reinforced side cover, one-piece bearing retainer) is as good as the later aluminum 915.

and if you plan to track it then you need cooling.

Ingo