Not surprisingly, it's basically a matter of film choice/speed and development, plus negative size vs. print size.(posted 8922 days ago)If Kodak still makes it, Recording Film - with a standard speed of 1000, this was the 1950s version of TMax P3200 - is famous for producing big "pointallistic" grain (especially when pushed a stop or two). Failing that, you're stuck with 400-speed old-tech films like Tri-X and HP5. (There's no point in using the newer TMax or Delta films - they're totally engineered for fine grain!) The trick with getting mega-grain with these films is, once again, exposure speed and development.
Tri-X or HP5 shot at 1600 and (over)developed in straight D-76 (or ID- 11) for TWICE the standard time will give you some grain. You can also go further and up the speed and development even more - go ahead and experiment. Another thing to try is harsher-working developers: old sheet-film developers like Kodak DK-50 yield pretty grain results with smaller-format films; print developers like Dektol should also produce mega-grain. (I have no clue what kind of developing times to use for prints developers with film, though - maybe somebody else can help with this.)
Also, agitate the heck out of your film during development. While the new-tech films flourish with even constant (machine-style) agitation, the older films will definitely show more pronounced grain. Agitate violently and as much as you can stand to - that should promote some grain.
Another approach is to blow up your negative more. Try shooting with a subminiature camera like a Minox, or an Olympus Pen half-frame 35mm - or just simulate it by using only a fraction of the full frame. A quarter of a 35mm frame is roughly equivalent to a Minox negative, and this will yield grainy 8x10s even with a fine-grain film: with something like pushed Tri-X, you'll get grain like cannonballs!
And while you're busy breaking the rules, try for partial or full reticulation by using radically different solution temperatures: a 20- degree hotter water rinse between the developer and fixer, a much colder fixer, a final wash in hot water, etc. While full reticulation isn't grain, per se, it can still create an interesting image full of jagged transitions.
Basically, have some fun breaking the rules and experimenting!