Whats up Big..
Here's my 2 cents.. Do you have any dumbbells at all or other free weights? Or is it simply just a chinup/pullup bar and then your two hands for pushups? I'll go off of just the equipment you mentioned. To build some size, try doing a 2 sec. count going down on push ups and then a 3 sec. coming back up. same with the pullups, try to focus on the negative. Negative's will make you grow tremendously, but a negative workout should only really be done 1 to 2's a week when training those muscle groups, b/c it's such an
intense workout. Also, rest for about 60-90 seconds in between sets. You can also limit it to 30, just to change things up, but keep the intensity the same.
Hope this helps!